University of Wollongong
Research Online
University of Wollongong Thesis Collection
University of Wollongong Thesis Collections
1992
Soil stabilisation using some pozzolanic industrial
and agricultural products
Chassan Chmeisse
University of Wollongong
Recommended Citation
Chmeisse, Chassan, Soil stabilisation using some pozzolanic industrial and agricultural products, Doctor of Philosophy thesis,
Department of Civil and Mining Engineering, University of Wollongong, 1992. http://ro.uow.edu.au/theses/1268
Research Online is the open access institutional repository for the
University of Wollongong. For further information contact Manager
Repository Services: morgan@uow.edu.au.
SOIL STABILISATION USING SOME
POZZOLANIC INDUSTRIAL AND
AGRICULTURAL BY PRODUCT
A thesis submitted in fulfilment of the
requirements for the award of the degree of
Doctor of Philosophy
from
THE
UNIVERSITY
OF
WOLLONGONG
by
CHASSAN CHMEISSE,
B.E.(Civil), M.Eng.Sc
DEPARTMENT OF CIVIL AND
MINING ENGINEERING
January 1992
DECLARATION
This is to certify that the work presented in this
thesis was carried out by the author in the Department
of Civil and Mining Engineering, The University of
Wollongong and has not been submitted for a degree to
any other University or such Institution.
Ghassan Chmeisse
ACKNOWLEDGEMENT
The Author wishes
to express
his gratitude
to his
Supervisors, Associate Professors, R.N. Chowdhury and
D.G. Montgomery from the Department of Civil and Mining
Engineering, University of Wollongong, NSW, for their
guidance, encouragement and support throughout this
research and to all others who helped in the
preparation of this Thesis.
He also wishes to thank his Parents, Wife and children
for their support, patience and understanding during
the years of study.
i
CONTENTS:
Page
Abstract: xi
List of Notations: xiv
List of Figures: xv
List of Tables: xx
List of Appendicies: xxvii
Chapter I
-
Introduction, Aims and Scope
1.1 Basic concepts of Soil Stabilisation 1
1.2 Historical Background 2
1.3 Soil Stabilisation in Australia 5
1.4 Applications of Soil Stabilisation 6
1.5 Types of Soil Stabilisation 7
1.6 Pozzolans 9
1.7 Mechanism of Pozzolanic Activity 9
1.8 Types of Pozzolans and Pozzolanic by-products 10
1.9 Products Investigated as Stabilising Agents 12
during research work reported in this Thesis Rice Husk Ash and Granulated Blast Furnace
Slag
1.10 Aims and Scope of this Thesis 13
ii
Page
Chapter II
-
Review Of Relevant Previous Work
Concerning Rice Husk Ash and
Granulated Blast Furnace Slag
2.1 Rice Husk - Description and Production 17
2.2 Disposal of Rice Husks 17
2.3 Properties of Rice Husk Ash 18
2.4 Engineering Applications of Rice Husk Ash 19
2.5 Applications of Rice Husk Ash to Soil 20
Stabilisation
2.5.1 Rice Husk Ash : Soil Stabilisation 20
2.5.2 Lime - Rice Husk Ash : Soil 21
Stabilisation
2.5.3 Cement - Lime-Rice Husk Ash : Soil 22
Stabilisation
2.6 Scope for further research 23
2.7 Blast Furnace Slag - Description and 25
Production
2.8 Types of Blast Furnace Slag 27
2.8.1 Air Cooled Slag 27
2.8.2 Foamed Expanded Slag 27
2.8.3 Granulated Blast Furnace Slag 28
2.9 Properties and Engineering Applications of 28
Granulated Blast Furnace Slag (GBFS)
2.9.1 Use of Granulated Blast Furnace Slag 29
in the manufacture of cement
2.9.2 Use of Granulated Blast Furnace Slag 30
in road construction
2.9.2a Use of Granulated Blast Furnace 30
Slag in road works Overseas
2.9.2b Use of Granulated Blast Furnace 33
Slag in road works in Australia
2.10 Scope for further research 35
iii
Page
Chapter III
3.1
-
Experimental Techniques and Methodology
Scope of chapter
38
3.2 Existing tests used in soil stabilisation 38
3.3 The validity of existing tests 39
3.4 Tests used in this investigation 40
3.4.1 Grading and compaction tests 41
3.4.2 Plasticity and volume changes 42
3.4.3 Compressive strength - Unconfined 44
compressive strength (UCS) and
undrained triaxial strength (UTS)
3.4.4 California Bearing Ratio test (CBR test) 45
3.4.5 Repeated dynamic load test 47
3.4.5a General 47
3.4.5b The loading system 48
3.4.5c Measurement of the permanent 49
deformation
3.4.6 Powder X-ray diffraction 50
3.4.7 Scanning Electron Microscopy 51
Chapter IV
4.1
-
Experimental Investigation using
Rice Husk Ash
Scope of chapter
4.2 Objectives of investigation 62
4.3 Materials used 63
4.3.1 Rice Husk Ash 63
4.3.2 Cement 64
4.3.3 Lime 64
4.3.4 Soils 64
62
iv
Page
4.4 Testing regime 65
4.5 Initial tests - optimum ratios of lime to 66
RHA and Cement to RHA
4.5.1 Preparation, curing and testing of 67
specimens
4.6 Treatment of soils with various additives 68
4.7 Testing of stabilised soils 68
4.7.1 Compaction characteristics 68
4.7.2 Unconfined compressive strength 69
4.7.3 Linear Shrinkage 69
4.7.4 Atterberg limits 70
4.7.5 Effect of delay in compaction on the 71
strength of stabilised soils
4.7.6 Effect of various additives on the 72
shear strength parameters of soils
4.7.7 Effect of various additives on the CBR 74
value of soils
4.7.8 Repeated dynamic load test 75
4.7.9 Scanning Electron Microscopy 78
4.7.10 Powder X-ray Diffraction Analysis 79
Chapter V
-
Discussion and Analysis of Results
concerning Rice Husk Ash
5.1 RHA as a single additive 137
5.1.1 Effect of RHA additive on compaction 137
characteristics of soils
5.1.2 Effect of RHA additive on the strength 139
properties of soils
5.1.2a Effect on UCS 139
5.1.2b Effect on CBR 140
V
Page
5.1.3 Effect of RHA on the Atterberg limits 140
and linear shrinkage of soils
5.1.4 Effect of RHA on the behaviour of soils 142
under the action of repeated dynamic load
Lime-RHA additives 143
5.2.1 Effect of lime-RHA additives on 143
compaction characteristics of soils
5.2.2 Effect of lime-RHA additives on the 144
strength properties of soils
5.2.2a Effect on UCS 144
5.2.2b Effect on CBR 146
5.2.3 Effect of delay in compaction on the 147
strength of lime-RHA treated soils
5.2.4 Effect of lime-RHA additives on the 148
shear strength parameters of soils
5.2.5 Discussion of the results of the XRD 150
analysis of lime-RHA stabilised soils
5.2.6 Discussion of the results of the SEM 152
examination of lime-RHA stabilised
soils
5.2.7 Effect of lime-RHA additives on the 153
Atterberg limits and linear shrinkage
of soils
5.2.8 Implications of lime savings 155
5.2.9 Effect of lime-RHA additives on the 156
behaviour of soils under the action of
repeated dynamic load
Cement-RHA additives 159
5.3.1 Effect of various cement-RHA additives 159
on compaction characteristics of soils
5.3.2 Effect of cement-RHA additives on the 161
strength properties of soils
5.3.2a Effect on UCS 161
5.3.2b Effect on CBR 163
vi
Page
5.3.3
Effect of delay in compaction on the 163
strength of cement-RHA treated soils
5.3.4
Effect of cement-RHA additives on the 164
shear strength parameters of soils
5.3.5
Effect of cement-RHA additives on the 166
Atterberg limits and linear shrinkage
of soils
Implications of cement saving 167
5.3.6
5.3.7
Chapter VT
-
Effect of cement - RHA additives on the 169
behaviour of soils under the action of
repeated dynamic load
Experimental Investigations using
Granulated Blast Furnace Slag (GBFS)
6.1 Scope of chapter 179
6.2 Objectives of research 179
6.3 Materials 180
6.3.1 Blast furnace slag (GBFS) 180
6.3.2 Cement 181
6.3.3 Lime 181
6.3.4 Soils 181
6.4 Testing regime 181
6.5 Optimum ratios of lime or cement to GBFS 183
6.6 Treatment of soils with various additives 184
6.7 Testing of stabilised soils 184
6.7.1 Compaction characteristics 184
6.7.2 Unconfined compressive strength 185
6.7.3 Linear shrinkage 185
6.7.4 Atterberg limits 186
vii
6.7.5
Effect of delay in compaction on the
strength of stabilised soils
6.7.6 Effect of various additives on the 187
shear strength parameters of soils
6.7.7 Effect of various additives on the CBR 189
value of soils
6.7.8 Repeated dynamic load test 190
6.7.9 Scanning Electron Microscopy 191
6.7.10 Powder X-ray Diffraction Analysis 192
Chapter VTI
-
Discussion and Analysis of Results
concerning GBFS
7.1 GBFS as a single additive to soils 239
7.1.1 Effect of GBFS additive on compaction 239
characteristics of soils
7.1.2 Effect of GBFS additive on the strength 240
properties of soils
7.1.2a Effect on UCS 240
7.1.2b Effect on CBR 241
7.1.3 Effect of GBFS additive on the Atterberg 241
limits and linear shrinkage of soils
7.1.4 Effect of GBFS additive on the behaviour 243
of soils under the action of repeated
dynamic load
7.2 Lime-GBFS additives 244
7.2.1 Effect of lime-GBFS additives on 244
compaction characteristics of soils
7.2.2 Effect of lime-GBFS additives on the 246
strength properties of soils
7.2.2a Effect on UCS 246
7.2.2b Effect on CBR 248
viii
Page
7.2.3 Effect of delay in compaction on the 249
strength of lime-GBFS treated soils
7.2.4 Effect of lime-GBFS additives on the 250
shear strength parameters of soils
7.2.5 Discussion of the results of the XRD 251
analysis of lime-GBFS stabilised
soils
7.2.6 Discussion of the results of the SEM 252
examination of lime-GBFS stabilised
soils
7.2.7 Effect of lime-GBFS additives on the 253
Atterberg limits and linear shrinkage
of soils
7.2.8 Implications of lime savings 255
7.2.9 Effect of lime-GBFS additive on the 256
behaviour of soils under the action of
repeated dynamic load
7.3 Cement-GBFS Additives 259
7.3.1 Effect of various cement-GBFS additives 259
on compaction characteristics
7.3.2 Effect of cement-GBFS additives on the 260
strength properties of soils
7.3.2a Effect on UCS 260
7.3.2b Effect on CBR 262
7.3.3 Effect of delay in compaction on the 263
strength of cement-GBFS treated soils
7.3.4 Effect of cement-GBFS additives on the 264
shear strength parameters of soils
7.3.5 Effect of cement-GBFS additives on the 265
Atterberg limits and linear shrinkage of
soils
7.3.6 Implications of cement saving 266
7.3.7 Effect of cement-GBFS additives on the 268
behaviour of soils under the action of
repeated dynamic load
ix
Page
Chapter VIII -
8.1
Discussion of Economic Feasibility of
the applications of RHA and GBFS to
soil stabilisation
Introduction
278
8.2 Availability of RHA 279
8.3 Economic feasibility of RHA as a single 281
additive to soils
8.4 Economic feasibility of lime-RHA additives 281
to soils
8.5 Economic feasibility of cement-RHA additives 282
to soils
Summary
283
8.
.6
.7
8.
Availability
of GBFS 283
8.
.8
Economic
feasibility of GBFS as a single 284
additives to soils
8.
.9
Economic
feasibility of lime-GBFS additives 286
to soils
8.
,10
Economic
feasibility of cement-GBFS 287
additives to soils
Chapter IX
-
Recommended Design Procedure
9.1 Introduction 289
9.2 Mix design procedures of lime-RHA soil 290
stabilisation
9.3 Mix design procedures of lime-GBFS, 293
cement-GBFS and cement-RHA soil
stabilisation
Chapter X
References
-
Conclusions, Recommendations and
Suggestions for Future Work
310
X
Appendices
Appendix A - Methods of operation of the
fatigue control panel used in
the repeated dynamic load test
Appendix B - Equivalent specific gravity and
calculated porosity of various
mixes
xi
ABSTRACT
Rice husk ash (RHA) and granulated blast furnace slag (GBFS
have been investigated as pozzolanic materials for soil
stabilisation. They contain siliceous and aluminous
materials, and react with lime or cement, having the
economic potential to replace some of the lime or cement
presently used as an additive in the stabilisation of soil.
Four (4) types of soils were treated with varying quantitie
of lime, cement, rice husk ash, granulated blast furnace
slag, combinations of rice husk ash with lime or cement and
combinations of granulated blast furnace slag with lime or
cement under laboratory conditions.
To determine the effectiveness of RHA and GBFS as
stabilisers, general geotechnical soil properties, including
unconfined compressive strength, undrained shear strength,
CBR, plasticity index and linear shrinkage, were measured.
X-ray diffraction analysis, scanning electron microscopy an
a repeated dynamic load test were also carried out in this
investigation.
It is revealed that rice husk ash alone is not suitable for
modifying soil properties, however, beneficial results are
obtained when it is used in combinations with lime or
cement. It is shown that lime-rice husk ash and cement
xii
rice-husk ash additives increase the unconfined compressive
strength, the CBR and the undrained shear strength of soils.
They also improve the behaviour of soils under the action of
repeated dynamic loads and improve the workability and
volume stability of soils.
It is revealed that granulated blast furnace slag alone is
suitable for modifying the volume stability of heavy clays
and the workability of gravel-sand soils. It increases the
unconfined compressive strength and the CBR of soils and
improves their behaviour under the action of repeated
dynamic loads.
The effects of lime-granulated blast furnace slag and
cement-granulated blast furnace slag additives on soils are
shown to be similar to those of lime-rice husk ash and
cement-rice husk ash additives.
The effectiveness of rice husk ash and granulated blast
furnace slag can be expressed in terms of ratios of rice
husk ash and granulated blast furnace slag required to lime
or cement saved. Information relevant to these ratios and
the current and projected future availability of granulated
blast furnace slag and rice husk ash in Australia is
presented.
xiii
A suggested mix design procedures for lime-rice husk ash,
cement-rice husk ash, lime-granulated blast furnace slag and
cement-granulated blast furnace slag soil stabilisation is
also presented.
xiv
LIST OF NOTATIONS
c
Cohesion
Cc
Compression index
CBR
California bearing ratio
e
Voids ratio
GBFS
Granulated blast furnace slag
IP
Plasticity index
L.L
Liquid limit
L.S
Linear shrinkage
MDD
Maximum dry density
OMC
Optimum moisture content
P.L
Plastic limit
RHA
Rice husk ash
SEM
Scanning Electron Microscopy
UCS
Unconfined compressive strength
UTS
Unconsolidated triaxial shear strength
Wt
Weight
XRD
X-ray Diffraction
0
Angle of internal friction
CV
Effective vertical stress
<r n
Effective normal stress on the plane
of failure
T
Shear stress
XV
LIST OF FIGURES
Figures
Description
3.1 Repeated dynamic load test - View of 56
test structure and pavement
3.2 Repeated dynamic load test - Principle 57
of longitudinal movement due to
rotation
3.3 Repeated dynamic load test - Initial 58
setup arrangement
3.4 Repeated dynamic load test - The 59
fatigue control panel during operation
3.5 Diagram showing grid of locations at 60
which deflection measurements were
taken in relation to the wheel and the
pavement boundaries
3.6 Repeated dynamic load test 61
- Illustrations of deflection beam
in use
4,1 UCS of lime-RHA pastes 113
4.2 UCS of cement-RHA pastes 114
4.3 UCS of lime, RHA and lime-RHA 115
stabilised soils
4.4 UCS of cement, RHA and cement-RHA 116
stabilised soils
4.5 Linear shrinkage of lime, RHA and 117
lime-RHA stabilised soils
4.6 Linear shrinkage of cement, RHA and 118
cement-RHA stabilised soils
4.7 Plasticity index of lime, RHA and 119
lime-RHA stabilised soils
4.8 Plasticity index of cement, RHA of 120
cement-RHA stabilised soils
Page
xv i
Figures
Description
4.9 Effect of delay in compaction on the 121
UCS of cement and cement-RHA
stabilised Soil A
4.10 Effect of delay in compaction on the 122
UCS of lime and lime-RHA stabilised
Soil A
4.11 CBR of cement, cement-RHA, lime, 123
lime-RHA and RHA stabilised Soil A
4.12 Effect of lime, cement, RHA and 124
lime-RHA additives on the CBR of
Soil B
4.13 Effect of lime, lime-RHA and RHA 125
additives on the CBR of Soil C
4.14 Permanent deformation of the 126
untreated pavement at row H
(row of max deformation) of the
grid after various number of load
cycles
4.15 Permanent deformation of the 2% 126
lime stabilised pavement at row H
(row of max deformation) of the
grid after various number of load
cycles
4.16 Permanent deformation of the 3% 1:1 126
lime-RHA stabilised pavement at row H
(row of max deformation) of the grid
after various number of load cycles
4.17 Permanent deformation of the 1.5% 127
cement stabilised pavement at row H
(row of max deformation) of the grid
after various number of load cycles
4.18 Permanent deformation of the 3% 1:1 127
cement-RHA stabilised pavement at
row G (row of max deformation) of the
grid after various number of load
cycles
4.19 Permanent deformation of the 8% RHA 127
stabilised pavement at row G
(row of max deformation) of the grid
after various number of load cycles
Page
xvii
Figures
Description
Page
4.20 Repeated dynamic load test - Removal 128
of trolley from beneath materials
containment bin
4.21 Scanning electron micrograph of the 129
fracture surface of the untreated
Soil A
4.22 Scanning electron micrograph of the 130
fracture surface of the untreated
Soil C
4.23 Scanning electron micrograph of the 131
fracture surface of Soil A stabilised
with 8% content of 1:1 lime-RHA
additive after 7 days accelerated
curing
4.24 Scanning electron micrograph of the 132
fracture surface of Soil C stabilised
with 8% content of 1:1 lime-RHA
additive after 7 days accelerated
curing
4.25 X-ray diffraction pattern of 133
untreated Soil A
4.26 X-ray diffraction pattern of 134
untreated Soil C
4.27 X-ray diffraction pattern of Soil A 135
stabilised with 8% content of 1:1
lime-RHA additive after 7 days
accelerated curing
4.28 X-ray diffraction pattern of Soil C 136
stabilised with 8% content of 1:1
lime-RHA additive after 7 days
accelerated curing
6.1 UCS of lime-GBFS specimens 221
6.2 UCS of cement-GBFS specimens 222
6.3 UCS of lime, GBFS and lime-GBFS 223
stabilised soils
6.4 UCS of cement, GBFS and cement-GBFS 224
stabilised soils
6.5
Linear shrinkage of lime, GBFS and
lime-GBFS stabilised soils
225
xviii
Figures
Description
6.6 Linear shrinkage of cement, GBFS and 226
cement-GBFS stabilised soils
6.7 Plasticity index of lime, GBFS and 227
lime-GBFS stabilised soils
6.8 Plasticity index of cement, GBFS and 228
cement-GBFS stabilised soils
6.9 Effect of delay in compaction of the 229
UCS of cement and cement-GBFS
stabilised Soil A
6.10 Effect of delay in compaction on the 230
UCS of lime and lime-GBFS stabilised
Soil C
6.11 Effect of lime, cement, GBFS, 231
lime-GBFS and cement-GBFS additives
on the CBR of Soil A
6.12 Effect of lime, cement, GBFS, 232
lime-GBFS and cement-GBFS additives
on the CBR of Soil B
6.13 Effect of lime, cement, GBFS, 233
lime-GBFS and cement-GBFS additives
on the CBR of Soil C
6.14 Permanent deformation of the 8% GBFS 234
stabilised pavement at row H (row of
max deformation) on the grid after
various number of load cycles
6.15 Permanent deformation of the 3% 1:1 234
lime-GBFS stabilised pavement at row H
(row of max deformation) on the grid
after various number of load cycles
6.16 Permanent deformation of the 3% 1:1 234
cement-GBFS stabilised pavement at
row H (row of max deformation) on the
grid after various number of load
cycles
6.17 Scanning electron micrograph of the 235
fracture surface of Soil A stabilised
with 8% content of 1:1 lime-GBFS
additive after 7 days accelerated
curing
Page
xix
Figures
Description
6.18 Scanning electron micrograph of the 236
fracture surface of Soil C stabilised
with 8% content of 1:1 lime-GBFS
additive after 7 days accelerated
curing
6.19 X-ray diffraction pattern of Soil A 237
stabilised with 8% content of 1:1
lime-GBFS additive after 7 days
accelerated curing
6.20 X-ray diffraction pattern of Soil C 238
stabilised with 8% content of 1:1
lime-GBFS additive after 7 days
accelerated curing
9.1 Determination of the composition of the 294
preferred mix in a lime-RHA soil
stabilisation
Page
XX
LIST OF TABLES
Table
Description
2.1 Typical oxide composition of blast 37
furnace slag compared to Portland
cement, after Spence and Cook (2)
3.1 Tests used for evaluating stabilised 53
soils, after Shackel (44)
3.2 Suggested utilities for various 54
simulation tests, after Shackel (44)
3.3 Laboratory tests used in this study 55
4.1 Properties of soils used 81
4.2a Compaction characteristics of lime, 82
RHA and lime-RHA stabilised Soil A
4.2b Compaction characteristics of lime, 83
RHA and lime-RHA stabilised Soil B
4.2c Compaction characteristics of lime, 84
RHA and lime-RHA stabilised Soil C
4.3a Compaction characteristics of cement, 85
RHA and cement-RHA stabilised Soil A
4.3b Compaction characteristics of cement, 86
RHA and cement-RHA stabilised Soil B
4.3c Compaction characteristics of cement, 87
RHA and cement-RHA stabilised Soil C
4.4a UCS of lime, RHA and lime-RHA 88
stabilised Soil A
4.4b UCS of lime, RHA and lime-RHA 89
stabilised Soil B
4.4c UCS of lime, RHA and lime-RHA 90
stabilised Soil C
4.5a UCS of cement, RHA and cement-RHA 91
stabilised Soil A
Page
xxi
Table
Description
4.5b UCS of cement, RHA and cement-RHA 92
stabilised Soil B
4.5c UCS of cement, RHA and cement-RHA 93
stabilised Soil C
4.6a Effect of lime, RHA and lime-RHA 94
additives on the Atterberg limits
and linear shrinkage of Soil A
4.6b Effect of lime, RHA and lime-RHA 95
additives on the Atterberg limits
and linear shrinkage of Soil B
4.6c Effect of lime, RHA and lime-RHA 96
additives on the Atterberg limits
and linear shrinkage of Soil C
4.7a Effect of cement, RHA and cement-RHA 97
additives on the Atterberg limits and
linear shrinkage of Soil A
4.7b Effect of cement, RHA and cement-RHA 98
additives on the Atterberg limits and
linear shrinkage of Soil B
4.7c Effect of cement, RHA and cement-RHA 99
additives on the Atterberg limits and
linear shrinkage of Soil C
4.8 Effect of delay in compaction on the 100
UCS of lime and lime-RHA stabilised
Soil C
4.9 Effect of delay in compaction on the 101
UCS of cement and cement-RHA stabilised
Soil A
4.10 Effect of lime and lime-RHA additives 102
on the shear strength parameters of
Soil C
4.11 Effect of cement and cement-RHA 103
additives on the shear strength
parameters of Soil B
4.12 Effect of various additives and curing 104
time the CBR of stabilised Soil A
4.13 Effect of various additives and curing 105
time the CBR of stabilised Soil B
Page
xxii
Table
Description
4.14 Effect of various additives and curing 106
time the CBR of stabilised Soil C
4.15 Permanent deformations of untreated 107
pavement
4.16 Permanent deformations of 2% lime 108
treated pavement
4.17 Permanent deformations of 3% 1:1 109
lime:RHA treated pavement
4.18 Permanent deformations of 1.5% cement 110
treated pavement
4.19 Permanent deformations of 3% 1:1 111
cement:RHA treated pavement
4.20 Permanent deformations of 8% RHA 112
treated pavement
5.1 Effect of RHA additive on the grading 172
of soils
5.2a Deflection per load as number of load 173
applications increases at point eH of
3% 1:1 lime-RHA treated pavement
5.2b Deflection per load as number of load 173
applications increases at point eH of
2% lime treated pavement
5.2c Deflection per load as number of load 174
applications increases at point eH of
untreated pavement
5.2d Deflection per load as number of load 174
applications increases at point eH on
the grid of 8% RHA treated pavement
5.3 Ratio of RHA required to lime saved or 175
identical economic cost ratio of lime
to RHA
5.4 Ratios of strength at 7 days to strength 176
at 90 days of soils treated with 8%
content of various additives
5.5 Ratios of strength at 28 days to strength 176
at 90 days of soils treated with 8%
content of various additives
Page
xxiii
Table
Description
5.6 Ratios of RHA required to cement saved 177
or identical economic cost ratios of
cement to RHA
5.7a Deflection per load as number of load 178
applications increases at point eH on
the grid of untreated pavement
5.7b Deflection per load as number of load 178
applications increases at point eH on
the grid of 1.5% cement treated pavement
5.7c Deflection per load as number of load 178
applications increases at point dG on
the grid of the 3% content of 1:1
cement-RHA treated pavement
6.1a Compaction characteristics of lime, 193
GBFS and lime-GBFS stabilised Soil A
6.1b Compaction characteristics of lime, 194
GBFS and lime-GBFS stabilised Soil B
6.1c Compaction characteristics of lime, 195
GBFS and lime-GBFS stabilised Soil C
6.2a Compaction characteristics of cement, 196
GBFS and cement-GBFS stabilised Soil A
6.2b Compaction characteristics of cement, 197
GBFS and cement-GBFS stabilised Soil B
6.2c Compaction characteristics of cement, 198
GBFS and cement-GBFS stabilised Soil C
6.3a UCS of lime, GBFS and lime-GBFS 199
stabilised Soil A
6.3b UCS of lime, GBFS and lime-GBFS 200
stabilised Soil B
6.3c UCS of lime, GBFS and lime-GBFS 201
stabilised Soil C
6.4a UCS of cement, GBFS and cement-GBFS 202
stabilised Soil A
6.4b UCS of cement, GBFS and cement-GBFS 203
stabilised Soil B
Page
xx iv
Table
Description
6.4c UCS of cement, GBFS and cement-GBFS 204
stabilised Soil C
6.5a Effect of lime, GBFS and lime-GBFS 205
additives on the Atterberg limits and
linear shrinkage of Soil A
6.5b Effect of lime, GBFS and lime-GBFS 206
additives on the Atterberg limits and
linear shrinkage of Soil B
6.5c Effect of lime, GBFS and lime-GBFS 207
additives on the Atterberg limits and
linear shrinkage of Soil C
6.6a Effect of cement, GBFS and cement-GBFS 208
additives on the Atterberg limits and
linear shrinkage Soil A
6.6b Effect of cement, GBFS and cement-GBFS 209
additives on the Atterberg limits and
linear shrinkage Soil B
6.6c Effect of cement, GBFS and cement-GBFS 210
additives on the Atterberg limits and
linear shrinkage Soil C
6.7 Effect of delay in compaction on the 211
UCS of cement and cement-GBFS
stabilised Soil A
6.8 Effect of delay in compaction on the 212
UCS of lime and lime-GBFS stabilised
Soil C
6.9a Effect of lime and lime-GBFS additives 213
on the shear strength parameters of
Soil B
6.9b Effect of lime and lime-GBFS additives 213
on the shear strength parameters of
Soil C
6.10 Effect of cement and cement-GBFS 214
additives on the shear strength
parameters of Soil B
6.11 Effect of various additives and curing 215
time on the CBR of stabilised Soil A
Page
XXV
Table
6.12
Description
Effect of various additives and curing
time on the CBR of stabilised Soil B
6.13 Effect of various additives and curing 217
time on the CBR of stabilised Soil C
6.14
Permanent deformations of 3% content of
1:1 cement:GBFS treated pavement
6.15 Permanent deformations of 3% content of 219
1:1 lime:GBFS treated pavement
6.16 Permanent deformations of 8% GBFS 220
treated pavement
7.1 Effect of GBFS additive on the grading 271
of Soils A,B and C
7.2 Deflection per load as number of load 272
increases at point of maximum deflection
on the grid (ie, point eH) of the 8%
GBFS treated pavement
7.3 Ratio of GBFS required to lime saved or 27 3
identical economic cost ratio of lime to
GBFS
7.4a Deflection per load as number of load 274
applications increases at point eH on
3% 1:1 lime-GBFS treated pavement
7.4b Deflection per load as number of load 274
applications increases at point eH on
2% lime treated pavement
7.4c Deflection per load as number of load 274
applications increases at point eH on
untreated pavement
7.5 Ratio of UCS at 28 days to UCS at 90 275
days for soils treated with 8% content
of cement and cement-GBFS additives
7.6 Ratio of GBFS required to cement saved 276
or identical economic cost ratio of
cement to GBFS
7.7a Deflection per load as number of load 277
applications increases at point eH on
the grid of the untreated pavement
218
xxv i
Table
7.7b
Description
Deflection per load as number of load
applications increases at point eH on
the grid of the 1.5% cement treated
pavement
7.7c Deflection per load as number of load 277
applications increases at point dH on
the grid of the 3% 1:1 cement-GBFS
treated pavements
277
xxvii
LIST OF APPENDICES
Appendix
Description
Methods of operation of the
fatigue control panel used in
the repeated dynamic load test
B
Equivalent specific gravity and
calculated porosity of various
mixes
1
Chapter I
INTRODUCTION. AIMS AND SCOPE
1.1 Basic Concepts of Soil Stabilisation
Soils are formed by the decomposition of rocks and through
the subsequent removal, transportation and weathering of the
products of decomposition.
The concept of soil may also
include the accumulations of inorganic sediments, organic
peats, plant roots and various wastes and rubbles of an
industrial society.
defined
as
rocks" (1).
in
ordinary
"any
The soil in the general context can be
loose
surface
material
overlying
solid
It is usually the surface which is dealt with
construction
activities
for
buildings
and
transport systems.
It is understandable that soil, which is one of the most
ancient construction materials, is still among the most
widely used materials because of its low cost of winning,
wide spread availability and easy workability.
Besides its use in dams and roads construction, soil has
been used for building in a great variety of ways.
In
different traditions, it is used for walling, flooring and
roofing and in some instances, for all three (2).
2
Many soils, in their untreated state, lack strength and/or
dimensional stability which render them unsuitable, wholly
or partially, to the requirements of construction.
The
Engineer
the
then
will
have
the
choice
of
"accepting
limitations imposed by the insitu soil properties, replacing
the available soil by another one which complies with the
specified requirements or improving the properties of the
existing soil by stabilisation so as to fulfil the design
criteria" (3).
1.2 Historical Background
In the area of building practice, soil stabilisation has a
history which reaches at least 5000 years into the past (4).
Compacted
masses
of
clay
and
lime
were
used
construction of the pyramids of Shensi in Mexico.
in
the
Ancient
buildings in India and China, in which lime-clay mixture
were used, are still standing (5). Even in ages and places
where engineering skill has been minimal, soil stabilisation
has often been used:
for example, in the lime stabilised
floors of Saxon England, or the straw and blood stabilised
mud houses of West Africa (4).
In pre Roman times, there were many trafficable roads
throughout much
of
England
(The
Pilgrim's
Way), Europe
(Denmark to Tuscany) and Asia (Afghanistan to Egypt, China
3
to Persia)
(6).
Periodically, however these roads were
transformed into masses of mud by rains, whereas in dry
seasons the carts created clouds of dust.
It is obvious for these reasons that the history of
stabilised roads began (7). Despite significant work by the
ancient Egyptians, Persians and Greeks, the Romans were the
great road builders of the ancient world. They built
80,000km of excellent roads with a base of heavy, hand
fitted stones. Above this was a course of smaller stones,
topped by a layer of broken tiles, brick or chalk, held
together with pozzolan mortar.
For many hundreds of years after the fall of the Roman
Empire in the fifth century, few new roads were built in
Europe and few Roman roads were regularly maintained.
The wheeled vehicle began to gain popularity again in the
seventeenth century and subsequently craftsmen developed the
stagecoach.
While these vehicles created some demand for better roads,
it was the Industrial Revolution, with its great need for
trade and transportation, which gave encouragement to the
development and improvement of the transport system in the
western world. John Loudon Macadam (1756 - 1836) developed
the thick, one size stone pavement, made up of 25mm broken
4
stones.
In Europe the Macadam roads received no competition
for almost a whole century.
The first highways of the
United States, too, were constructed using Macadam methods
(7).
The roads thus constructed did not meet the requirements of
the continuously
were
ruined
increasing and accelerating
faster
than
they
could
be
traffic and
repaired.
New
economic methods had to be developed, therefore, to enable
construction of durable roads.
In
the field of urban roads
and highways, this development has led to the introduction
of concrete and block paving, and in the case of secondary
roads, to the regular use of stabilised soil.
The first experiments in the USA were conducted with sandclay mixtures in 1906 (7). The favourable results motivated
subsequent construction projects using various mixtures.
Cement, bitumen and certain chemicals were employed for soil
stabilisation
purposes
and
a
number
of
different
stabilisation techniques were established.
In Europe, it was not until the 1930's, when the vast
increase in the motor vehicle traffic had begun and soil
mechanics approaches entered the field of road construction,
that the idea of stabilisation was accepted (7). During the
second world war 1939 - 1945, more than 140 military air
fields
are
known
to
have
been
constructed
with
cement
5
stabilised bases by the Germans and their allies, in places
as far north as Finland and as far south as Sicily, in
addition to an unknown number in Russia (26). After the war
many European countries continued soil stabilisation for
secondary road construction and as highway base courses.
1.3 Soil Stabilisation in Australia
In Australia, it was not until the 1940's that the idea of
stabilisation was accepted. This acceptance has grown
dramatically since then. A survey conducted by Ingles (8)
has shown that 56.5 million square yards (47.2 million
square metres) of pavement were stabilised in Australia
between 1963 and 1968.
The Cruickshank Survey (9) into the use of stabilisation by
local governments and road authorities has revealed that:-
a) The area of stabilised pavement constructed by 12 of
the 14 Main Roads Department districts covering
Queensland, between 1970 and 1975, was about two
million square metres.
b) Fifty percent of local government authorities in NSW
and Victoria had constructed four million square metres
during the same period.
6
The use of stabilisation is still increasing in Australia.
It is carried out virtually in every road construction,
rehabilitation and heavy patching maintenance throughout the
countryside areas.
The Author has had extensive experience of soil
stabilisation (more than 90,000 square metres of pavement)
while working with the Roads and Traffic Authority at Glen
Innes Works Office in NSW between 1986 - 1989 and has known
of tens of thousands of square metres of pavement stabilised
by South Grafton, Tenterfield, Moree and Armidale Works
Offices during the same period.
Ingles (8) has predicted that, in the next one hundred
years, there will be a rapidly improving technology for
stabilisation techniques, a marked increase in applied
research for stabilisation and an increased usage of soil
stabilisation in a wider range of applications.
1.4 Applications of Soil Stabilisation
Soil stabilisation is the treatment of soil in order to
rectify its deficiencies in engineering properties and
especially as a road construction material. Among the
important aims of soil stabilisation are the following:-
7
Increase in strength and stiffness of soils
Increase in durability
Enhancement of workability
Reduction of compressibility
Reduction of permeability
Reduction of volume instability
Control of dust and protection from erosion
1.5 Types of Soil Stabilisation
Soil stabilisation is often classified into two main types,
namely "shallow stabilisation" and "deep stabilisation"
(10).
The best known techniques of deep stabilisation are:preloading, surcharging, freezing, prewetting, grouting,
thermal treatment (heating), dynamic consolidation, vibro
compaction, blasting and the use of fabrics and meshes.
In conventional shallow soil stabilisation several methods
have been used, such as granular or mechanical soil
stabilisation, compaction and additive-use soil
stabilisation. Regarding the additives, the materials used
may be divided into a relatively few types, being, bitumen,
Portland cement, lime, lime-pozzolan, chlorides of salts and
chemical materials. In this classification, chemical
8
materials are not considered
to involve cement and lime
although these are chemically effective agents.
Methods using additives form the basis for soil
stabilisation.
proportion,
Cruickshank
by
type
of
(9)
has
stabilisation,
shown
for
that
the
the
work
undertaken by the local governments in Victoria and NSW
between 1970 and 1975 were:-
Mechanical stabilisation 34.75%
Lime stabilisation
38.00%
Cement stabilisation
22.00%
Bitumen stabilisation
3.75%
Other
1.50%
The survey has also shown that cement stabilisation
accounted for 45% of the total stabilisation conducted by
the Main Roads Department in Queensland between 1970 and
1975.
As the general knowledge on the conventional additive-use
method is common to soil engineers, attention is given in
this thesis to the practicality of utilizing pozzolanic byproducts in soil stabilisation because a large number of
these materials have not been used in practice although they
may
have
a
stabilisation.
significant
role
in
the
future
of
soil
The Author wishes to discuss the properties
9
of some of these materials and their potential contribution
to the soil stabilisation.
1.6 Pozzolans
Lea (11) has defined pozzolans as "materials which, though
not cementitous in themselves, contain constituents which
will
combine
with
lime
at
ordinary
temperature
in the
presence of water to form insoluble compounds possessing
cementitous properties".
1.7 Mechanism of Pozzolanic Activity
Suwanvitaya (27) stated that in 1980 Takemoto and Uchikawa
have
proposed
the
following
mechanism
for
the
paste
hydration of a lime-pozzolan reaction.
When mixed with water and lime the SiOH^- group on the
surface of the pozzolan dissociates to SiOH 4- and H + leaving
the grain negatively charged.
This
is followed by the
dissolution of alkalis leaving Si and Al~ rich layer which
dissolves and combines with Ca 2 + .
The reaction products
form a layer around the pozzolan grain.
Further dissolution
and reaction is achieved by breaks in the layer due to
osmotic
pressure
developed
from
the
difference
of
concentration of ions such as alkalis and SiO 4- and AlO 2between the outside and inside of the layer.
10
The concentration of Ca 2 + which enables Ca-Al hydrate to
precipitate is higher than that of CSH.
The precipitation
of Ca-Al hydrate therefore occurs at locations apart from
the grain.
1.8 Types of Pozzolans and Pozzolanic By-Products
Traditionally pozzolans have been divided into two groups,
natural and artificial.
In Europe the natural materials
which have been most exploited are the Italian pozzolans and
the German trass (2) whereas inorganic volcanic ash soils
are often utilised in Japan for soil-cement and soil-lime
stabilisation (12).
Pozzolanic by-products or artificially burnt inorganic
materials obtained as industrial or agricultural by-products
are similar to such volcanic soils from the view point of
good
cementation
products
are
construction,
with
hydrative
increasingly
hence
additives.
playing
minimising
the
a
Those
part
problem
in
of
byroad
resource
depletion, environmental degradation and energy consumption.
Of the artificial pozzolans probably fly ash, which is the
residue from the combustion of pulverised coal in power
stations, is the most commonly used globally.
In 1976 it
was estimated that some 30,000,000 tonnes were used annually
and that the annual increase was about 10% (2).
11
With the discovery by Havelin and Khan (13) that lime and
fly ash impart particular properties to fine aggregates and
soils, attention was drawn to the use of fly ash in soil
stabilisation.
Much valuable work has since been carried out in this field
by Minnick and Miller (14) and Davidson and his associates
(15) at the engineering experimental station of Iowa State
College.
In
Great
Britain
the
Central
Electricity
Generating Board was active in the field of possible uses
for fly ash (16).
In Australia valuable work was done by
Davidson and Mulling (5), Croft (18), Herzoc and Brock (19)
and others.
This research has led to the utilisation of fly
ash in soil stabilisation in USA and Europe.
In Australia
the use of this new technique was further encouraged by the
Department of Main Roads, NSW, issue of Circular M&R 115
(20).
The bottom ash, which is a residue collected from the bottom
of the furnace, is generally not as reactive as the fly ash
(2).
However, reports from USA (21) have shown that bottom
ash has been used, either singly, in combination with fly
ash, or with
other materials, in a variety
of
highway
applications in West Virginia and the surrounding states.
Apart from fly ash and bottom ash, there are a number of
other industrial wastes which have pozzolanic properties.
Mehta (22), (23) discussed them in detail.
They include
12
blast furnace slag which is more reactive with cement than
with lime
(2) and the kiln dust, collected during the
manufacture of cement.
This material contains large amounts
of alkalies and free lime.
Dave (24) has reported that in
India, cinder obtained from railway locomotives and certain
thermal power stations has pozzolanic activity but generally
less than that of fly ash.
Shale, clay and bauxitic soil
can be converted into pozzolans by heat treatment.
(25) has shown that bauxitic waste
Hammond
is also suitable as
pozzolan after calcination and up to 40% of Portland cement
can be replaced with little effect on the characteristics of
cement.
Many plant ashes have a high silica content which, by
suitable treatment, can be made to be pozzolanic.
In recent
years, attention has been drawn to the uses of rice husk ash
as a pozzolan although other agricultural residues such as
bagasse, bamboo leaves and some timber species are also of
interest.
1.9 Products Investigated as Stabilising Agents during
Research Work Reported in this Thesis - Rice Husk
Ash and Granulated Blast Furnace Slag
It is understandable that a fundamental investigation in
which all the pozzolans mentioned above
could be assessed
as soil stabilisers, is beyond the reach of this research.
13
However, the
emphasis
in this
thesis
has been
directed
towards two of these materials, rice husk ash and granulated
blast furnace slag because:-
i) There is an increasing need for research to find
solutions for the disposal problem of the
accumulating surplus of these by-products
worldwide.
ii) Employing the pozzolanic properties of these
wastes in soil stabilisation may reduce the cost
of roadmaking and help minimise the problem of
resource depletion and fuel consumption.
iii) The state of knowledge concerning this employment
has not been sufficient to permit an effective
application of these materials to soil
stabilisation.
1.10 Aims and Scope of this Thesis
The main aims of the work reported in this thesis are as
follows:-
a) To investigate the pozzolanic reactivity of rice husk
ash and granulated blast furnace slag, produced in NSW,
with lime and cement.
14
b)
To study the influence of rice husk ash and granulated
blast
furnace
slag
as
lone
additives
on
various
properties of a range of soils.
c) To examine the effects of lime-rice husk ash, cementrice husk ash, lime-granulated blast furnace slag and
cement-granulated blast furnace slag combined additives
on the properties of soils.
d) To discuss the economical feasibility of the use of
rice husk ash and granulated blast furnace slag in soil
stabilisation.
e) To develop a mix design procedure for soil
stabilisation with rice husk ash and granulated blast
furnace slag additives.
The two stabilising agents, rice husk ash and granulated
blast furnace slag are discussed in Chapter 2 with emphasis
on their production, characteristics and applications.
this
chapter
the
existing
knowledge
and
practice
In
are
reviewed and attention is given to the application of these
materials to soil stabilisation, some gaps in this knowledge
are
highlighted
and
areas
investigations are identified.
which
require
further
15
The experimental investigation reported in this thesis, has
been based on the conventional laboratory tests currently
used in the design of stabilised soil mixes.
Chapter 3 summarises the tests used, discusses their
suitability and gives a brief note on supplementary tests
conducted in this research, particularly those relevant to
the prediction of the in-service behaviour of stabilised
pavements.
Chapter 4 is devoted to providing details of the
experimental
investigation
carried
out
to
evaluate
the
pozzolanic reaction of RHA with lime and cement and to study
the influence of RHA
mixes with lime and cement on the
geotechnical properties and behaviour of soils.
used, tests
conducted
and results
Materials
are all presented
in
detail in this chapter whereas analysis and discussion of
these results are given in Chapter 5.
Details of the work carried out to determine the pozzolanic
reactivity of GBFS with lime and cement and to examine the
effect of GBFS various mixes with lime and cement on the
properties and behaviour of soils are given in Chapter 6.
Details of materials, soils and tests used are all presented
in this chapter together with the results derived.
Analysis
and discussion of these results are reported in Chapter 7.
16
The economic feasibility of the application of RHA and GBFS
to soil stabilisation is discussed in Chapter 8 whereas
Chapter 9 contains a recommended design procedure for the
lime-RHA, cement-RHA, lime-GBFS and cement-GBFS soil mixes.
General conclusions and recommendations are reported in
Chapter 10.
17
Chapter II
REVIEW OF RELEVANT PREVIOUS WORK CONCERNING RICE HUSK
ASH AND GRANULATED BLAST FURNACE SLAG
2.1 Rice Husk - Description and Production
A constituent of the crop popularly known as paddy, rice
husks are the harsh woody outer covering of the rice grain,
consisting of two interlocking halves.
The husk content of paddy varies, depending on the
differences in season, temperature, geographic location and
cultivation practices. Most variations however, are
confined to a narrow range, (variation of 4-5%) and a husk
content of 20% of dried paddy is generally expected.
With the world's annual production of rice at about 400
million tonnes (17), the husk produced each year amounts to
approximately 80 million tonnes on the basis of these 1983
figures.
2.2 Disposal of Rice Husks
Due to seasonal variability, high transport cost, bulkiness,
high abrasiveness, slow biodegradation and poor nutritive
value, only a small percentage of the husks can be disposed
18
of in certain low value applications, such as animal feed,
fertilizer and fuel.
The remainder serves no useful purpose
and simply poses disposal problems.
The simple disposal
methods used are openfield burning and combustion in an
incinerator with a defined controlled temperature.
2.3 Properties of Rice Husk Ash
Incineration of rice husks produces ash with properties
which
vary
considerably
incineration.
dependent
on
the
manner
of
The parameters affecting these properties are
temperature, the time of incineration and the environment in
which the burning takes place.
The weight percentage of
ash, for example, can vary from about
17% for complete
combustion to approximately 35% for cases where only the
volatiles are driven off the raw husk and the full content
of carbon is retained.
Rapid burning at low temperature
produces
ash
carbon
burning
at
with
high
high
temperature
content, while
results
in
prolonged
predominantly
crystalline silica in the ash.
Rice husk ash (RHA) has generally been accepted as being
pozzolanic.
is based
materials.
Its use as a component in cementitous materials
on
its
reaction
with
lime
to
form
cementing
The lime may be present as a primary constituent
of the mix or as a result of the hydration of Portland
cement.
The
development
of
mechanical
strength
is
19
influenced by the nature of silica, the carbon content and
the fineness of the ash.
2.4 Engineering Applications of Rice Husk Ash
Hough and Bar (28) reported the use of rice husk ash (RHA)
in the manufacture of building blocks as early as 1923.
A
large house had been constructed from these blocks and was
reported to be in excellent condition thirty years later.
They also reported a study on concrete using rice husk and
RHA with cement and concluded that although the mixture of
the three components gave a better insulator than normal
concrete, the low strength made it unsuitable for structural
use.
A potential application of the ash which has received
increasing interest in recent years has been in the cement
industry.
Mehta and Pitt
(23) described
a furnace for
producing a predominantly amorphous silica ash.
The concept
was adopted in a pilot plant near Sacramento, California and
a 7.5 tonne/hour plant began operation.
Data on the ash
produced indicated that cement containing the ash was highly
resistant to dilute organic
extremely
useful
in
Increasing attention
the
and mineral acids making it
food
and
chemical
has since been directed
based cements, particularly in South East Asia.
industries.
toward
RHA
At least
20
three workshops have been organised since 1979, resulting in
the adaptation of the Indian standard
(50) for masonary
cement based on RHA.
2.5 Applications of Rice Husk Ash to Soil
Stabilisation
2.5.1 Rice Husk Ash : Soil Stabilisation
The use of rice husk ash as a single additive for the
purpose
of
soil
stabilisation
has
received
attention in the relevant literature.
very
little
However, Rahman (29)
has made an attempt in this direction to find the effects of
rice
husk
ash
on
various
geotechnical
properties
of
lateritic A-7-6 group soil obtained from the University of
Ife Campus, Ile-Ife, Nigeria.
The researcher concluded that
well burnt rice husk ash has appreciable effects on the
geotechnical properties of the lateritic soil tested and
that "the liquid limit and plastic limit increase with the
increase
of
decreases.
in
ash
rice
ash
but,
the
plasticity
index
The maximum dry density decreases with increase
content,
increases.
husk
while
the
The unconfined
optimum
compressive
increases with increase in ash content.
moisture
content
strength and CBR
The undrained shear
strength parameters, cohesion as well as angle of internal
friction, also increase with increase in ash content".
such work has been conducted or reported in Australia.
No
21
2.5.2
Lime-Rice Husk Ash : Soil Stabilisation
Lazaro and Moh (30) probably were the first who tried to
stabilise deltaic black clay soil by a mixture of lime and
rice husk ash.
Subrahmanyam et al (31) followed the steps of Lazaro and Moh
and conducted their experimental programme in the Department
of Civil Engineering, University of Malaya, Kuala Lumpur to
study the effect of
lime-rice husk ash mixtures on the
properties of an inorganic black clay soil taken from an
open pit near a house construction site at Klangtown.
They concluded that:-
i) Rice husk ash in combination with lime can be used
for the stabilisation of clays.
ii) The plasticity index of clay is significantly
reduced by the addition of lime and RHA admixture.
iii) The maximum dry density is decreased and the
optimum moisture content
is increased when the
clay is treated with the admixture of lime and
RHA.
22
iv)
The unconfined compressive strength of the clay is
increased when the clay is treated with admixture
of lime and RHA. The unconfined compressive
strength is maximum when the quantity of admixture
added to the soil is 10% of the total weight.
v) As the curing time is increased, the strength of
the treated clay is increased.
No such study has been conducted or reported in Australia.
2.5.3 Cement-Lime-Rice Husk Ash : Soil Stabilisation
Raj an et al (32) in the Karnataka Engineering Research
Station, Krishnarajasagara, India have studied the effect of
cement-lime-RHA admixtures on the consolidation and strength
properties of black cotton soil of Yelandur in Mysore
district, India. The study considered the undrained
triaxial shear strength and the compression index Cc (the
usual method of presenting compressibility data is to plot
the void ratio, e, against the log of the vertical effective
stress, v""V. Compression index is the slope of
compressibility curves which plot as straight lines on the
e-log v"V presentation where Cc=e0-e log ZTTp)
and has
revealed that:-
i) In the soaked condition, the soil stabilised with
RHA will have little strength.
23
ii)
Rice husk ash, to a certain extent, contributes to
the
development
of
strength
when
used
as
an
additive in conjunction with lime and cement which
indicates that RHA may be acting in a pozzolanic
role for the improvement of strength behaviour of
black cotton soil.
iii) In the presence of lime, rice husk ash
considerably decreases the compression index.
iv) For a given percentage the compression index value
decreases
as
the
quantity
of
lime
in
each
proportion increases.
v) The compression index values of lime-rice husk ash
stabilised
soil
closely
follow
that
of
lime
stabilised soil.
No such study has been conducted or reported in Australia.
2.6 Scope for further research
It can be easily seen that there are still certain gaps in
the fundamental understanding of the applicability of RHA to
soil stabilisation.
The following are identified:-
a) The results of Rajan et al (32) concerning the effect
of RHA as a lone additive on the properties of soils
24
are not consistent with those results of
Rahman (29).
Further studies, therefore, are required
to clarify
this ambiguity.
b) Rajan et al (32) have studied the influence of cementlime-RHA additives on the properties of clay.
However,
cement-RHA additives have not been contemplated and it
is not known whether RHA in combination with cement
alone can be used for the stabilisation of soils.
c) Lazaro and Moh (30), Subrahmanyam et al (31) and Raj an
et al (32) have examined the effect of lime-RHA and
cement-lime-RHA
Although
the
properties
on
the
effect
of
non
of
properties
these
cohesive
soils
of
clays
additives
may
be
only.
on
of
the
more
importance, this application has not been attempted.
The effect of these additives on the properties of
organic clays has also not been tested.
d) The effect of lime-RHA additives on some properties of
soils relevant to roads and road performance are still
to be defined.
parameters,
Such properties are the shear strength
the
California
Bearing
Ratio
(CBR),
shrinkage, swelling and in-service behaviour.
e) The proportions of lime to RHA in the lime-RHA and
cement-lime-RHA
additives
tested
literature were all arbitrary.
in
the
surveyed
No comprehensive study
25
was made to find the optimum proportions to be used.
Design procedures need to be developed to specify both
proportions and best application rates for these
additives to soils.
f) The resultant properties due to the use of lime-RHA and
cement-lime-RHA additives have not been compared with
those that may result from adding lime or cement to the
same soils. The economical feasibility of using RHA
singly or in combination with lime or cement to
stabilise soils is still to be determined.
A major aim of one part of this research work is to bridge
some of these gaps in the knowledge of the use of rice husk
ash in soil stabilisation.
2.7 Blast Furnace Slag - Description and Production
Blast furnace slag consists essentially of silicates and
alumino-silicates of lime and of other bases produced
simultaneously with iron in a blast furnace. An iron blast
furnace is a facility for converting iron ore into iron, to
the stage called 'pig iron'. The blast furnace derives its
name from the fact that the air to support combustion must
be forced into it under pressure because of the resistance
offered by the column of raw materials to the passage of the
combustion gases.
26
Iron ore is a mixture of oxides of iron, silica and alumina
and the chemical reactions within the blast furnace reduce
the iron oxides to iron; the silica and alumina compounds
combine with the calcium of the fluxing stone (limestone and
dolomite) to form the slag.
The chemical reactions occur at temperatures between 1300
and 1600°C produced by the burning of coke which is fed into
the furnace along with the ore, limestone and dolomite.
When preheated air is blown into the furnace the oxygen
combines with the carbon of the coke to produce heat and
carbon monoxide.
The iron ore is reduced to iron, mainly
through the reaction of the carbon monoxide with the iron
oxide to yield carbon dioxide and metallic iron.
The fluxing stone is calcined by the heat and dissociates
into calcium and magnesium oxides and carbon dioxide.
These
oxides of calcium and magnesium combine with the silica and
alumina of the iron ore to form slag.
Thus, compounds of
lime-silica-alumina and magnesia are formed which collect in
molten strata at temperatures between 1300 and 1600°C and
which form a liquid layer that floats on top of the liquid
iron.
The liquid iron is tapped and run along freshly made
sand channels either to the casting bed or, in the case of
the most modern fully integrated works, into large torpedo
cars for conveyance direct to the steel conversion works.
27
The slag is usually run into ladles having a capacity of
between five and twenty tonnes or more for conveyance to the
cooling pit. In some cases it is allowed to solidify in the
ladle.
2.8 Types of Blast Furnace Slag
2.8.1 Air Cooled Slag
When slag is allow to solidify either in the ladle or the
pit, it develops a crystalline structure similar to that of
a natural igneous rock. Crystals range from microscopic
sizes to as large as three metres. This slag is used as
road stone, concrete aggregate, filter media in sewage
purification plants and as a railway ballast.
2.8.2 Foamed or Expanded Slag
If water is introduced under controlled conditions into the
molten slag as it is tipped into a special pit or container,
the sudden generation of the occluded gases and steam
produces an expanded product. This is a strong lightweight
aggregate suitable for making lightweight concrete, either
as building blocks or as insitu structural element for
buildings, roof screed and for the decks of bridges.
28
2.8.3
Granulated Blast Furnace Slag
When the molten slag is cooled rapidly by means of high
pressure
waterjets
and
excess
of
water
is
maintained,
crystals do not have time to form and it solidifies as a
glassy type material.
This material is known as granulated
slag because it takes the form of small granules.
2.9 Properties and Engineering Applications of
Granulated Blast Furnace Slag (GBFS)
The essential components of granulated blast furnace slag
are the same oxides produced in the manufacture of Portland
cement but as can be seen from Table 2.1, they are present
in different proportions.
Granulated blast furnace slag has marked hydraulic-setting
properties
when
ground
to
a
powder
and
mixed
with
an
alkaline activating agent such as lime, portland cement or
gypsum.
Besides its use as sand, in the manufacture of concrete and
certain types of glass, granulated blast furnace slag has
been used
in two other
applications
concerned with
the
manufacture of cement and the construction and strengthening
for roads.
29
2.9.1
Use
Of
Granulated
Blast
Furnace
Slag
In
The
Manufacture Of Cement
It has been said that the year 1862 marked the industrial
start to the production of well integrated mixture of slag
cement and clinker when Hangen in Germany confirmed what
Vicat foresaw of the hydraulic properties of slag (33).
Since then Germany, France, USA, Japan, South Africa and
many other countries have used slag in cement manufacture.
Although granulated slag itself can be used as raw material
in the production of cement (34), it is more common for the
slag
to
be
utilisating
slag.
cement
with
other
raw
materials
thereby
the hydraulic-setting properties of granulated
Three
produced.
cement
blended
types of blended
slag cements have been
The first is low heat portland blast furnace
which
is
clinker
manufactured
with
the
by
intergrinding
granulated
slag.
portland
Various
specifications permit the cement to contain as much as 80%
granulated slag.
The second, super sulphated cement, is
made from granulated blast furnace slag activated by calcium
sulphate (anhydrite).
It is commonly made by intergrinding
a mixture of 80 to 85% granulated slag, 10 to 15% anhydrite
and about 5% of portland cement or lime.
slag cement, lime-slag cement
about 30 to 40% hydrated
slag.
The third type of
is manufactured
by mixing
lime with 60 to 70% of granulated
30
2.9.2
Use
Of
Granulated
Blast
Furnace
Slag
In Road
Construction
2.9.2a Use Of Granulated Blast Furnace Slag In Roadworks
Overseas
France was the first country to utilise granulated slag in
The Ponts et Chaussees Departement took
road construction.
a special interest in this field and carried out research
and development in three of its laboratories, situated at
Autum
in
Burgundy,
Versailles.
Vitri-le-Francois
near
Nancy
and
The soil stabilisation group at the Laboratoire
Central in Paris undertook the more fundamental aspects of
research
and
laboratories.
work
of
co-ordinated
work
of
the
other
This interest had arisen from the pioneer
Monsieur
Department, who
the
Prandi,
showed
formerly
that a
an
engineer
slow setting
of
the
concrete is
produced when 15 to 25% of granulated slag is mixed with a
coarse aggregate such as limestone, or crushed air-cooled
slag (35). The setting properties of this mix have made it
possible to manufacture slabs giving a compressive strength
of 50MPa (33).
The development of this technique led the
French roadmakers into further research to try to master
this hardening effect with addition of lime while at the
time
improving
the
(gravel-sand mix).
size
distribution
of
"sable-grave"
31
The outcome of this research has permitted the adoption of
the "grave laitier" (gravel-slag) or "sable laitier" (sandslag) which became commercially available in 1960.
Similarly, in Rhodesia (now Zimbabwe) tests were carried out
on various gravels, plastic quartz and granitic sand using
10 and 20% of ground and unground GBFS (41).
One percent
lime was added in all samples to act as a catalyst.
Results
have shown that:-
a) In all cases there was an increase in compressive
strength.
b) Ground GBFS is a better material than unground GBFS
even when as little as 10% is used.
In Great Britain GBFS is not produced in sufficient
quantities to cater for a substantial use of this kind of
stabilisation
(34).
Any relevant research therefore, is
unlikely to be found.
In Japan little research concerning the application of steel
slag to concrete aggregate and soil stabilisation has been
established
(36, 37).
With an eye to the
hydraulicity
stimulating effects of steel slag, Haga and his associates
conducted various experiments in co-operation with Hirohata
32
slab processing Co Ltd, on a mixture of crushed steel slag
and GBFS, called SBS and used as fills on poor road beds and
soft clay subgrades.
This study (38) revealed the technical
feasibility of SBS as a shielding bed fill.
(Fill usually
required
entering
to
prevent
poor
road
beds
from
the
subgrade and to provide a working platform for plant and
equipment).
Although an efficient proposition regarding a useful
application
of
GBFS
to
soil
stabilisation
in
Japan
is
unlikely to be found (39) Hasaba and his associates (40)
used
X-ray
diffraction
analysis
and
scanning
electron
microscopy to examine the reaction products and strength
characteristics of lime-gypsum-GBFS stabilised soil.
Their
observations indicate that:-
a) The high compressive strength was mainly attributed to
the formation of ettringite (3CaO-AL203-3CaS04-31H20).
b) The reaction between lime and clay minerals is
restricted with high gypsum content.
c) A "reticulated network" type C-S-H gel and plate shaped
calcium aluminate hydrate co-exist with needle
like
ettringite crystals in the stabilised soil containing
high granulated slag content.
33
2.9.2b
Use of Granulated Blast Furnace Slag in Roadworks
in Australia
In Australia, slag has been used in pavements since the late
sixties
(53) in areas from Wollongong to Newcastle.
In
recent years, with changes in the iron making process, the
chemical composition of GBFS has altered and the crushing
strength has dropped (42). Under these conditions there was
concern that the slag could break down under traffic leading
to
rutting
conditions
and/or
were
significant
implications.
surfacing
needed
to
environmental,
To
generate
loss.
resolve
Realistic
testing
the
doubt
industrial
and
political
short
term the
data
in the
which
had
Department of Main Roads, NSW, in co-operation with the
Australian Road Research Board, arranged for an Accelerated
Loading Facility (ALF) testing at the Prospect test site, 30
kilometres west of Sydney and approximately one kilometre
west of the start of the Western Freeway (F4).
Five base materials consisting of a control of basalt
crushed rock and four other materials consisting either of
slag or slag mixtures were used in the trials.
Over two
million load cycles were applied to 18 test sections before
the trials were concluded on 23 May 1988.
of these trials were:-
The main findings
34
a)
Unbound crushed slag had equivalent performance to high
quality crushed rock as a road base under heavy traffic
conditions.
b) The performance of crushed rock, stabilised with 20%
GBFS and 1% lime exceeded the design expectations.
These findings have resulted in the use of crushed slag
stabilised with cement-flyash additive as a base course at
Port Kembla Access Road and Appin Road in the Wollongong
regional area.
Crushed slag was also used as base course at several
locations on the F3 Freeway, the Pacific Highway (SH10) and
Lake Macquarie district in the Newcastle regional area.
Laboratory tests are currently being undertaken in the Roads
and Traffic Authority Divisional Office at Wollongong to
examine the performance of crushed rocks stabilised with 20%
GBFS and 1% lime.
A base course constituted of crushed
rocks stabilised with 20% GBFS and 1% lime was also used in
the trial section at Tomago on the Pacific Highway near
Hexham in the Newcastle regional area in September 1989.
However,
the
pavement
developed
some
shrinkage
approximately six months after construction.
cracks
This raised
the concern that some measures should be taken to waterproof
or slow the propagation of these cracks.
35
Although France has used GBFS to stabilise crushed rocks for
almost 30 years the transverse cracking as a result of
shrinkage of the hydraulic GBFS treated materials has not
been successfully controlled there to date (43). A range of
techniques have been used to waterproof these cracks or to
slow down their propagation.
These include the placement of
200mm of bituminous mix over the stabilised layers.
techniques
include
interlayers
or
a
bitumen
25mm
impregnated
thick
surfacing
of
Other
geotextile
gap
graded
aggregate bound with polymer modified bitumen.
2.10 Scope for Further Research
The application of GBFS to soil stabilisation in France and
almost
the
entire
relevant
research
in
Australia
and
overseas has been restricted to the addition of 15-25% of
GBFS with 1% lime to selectively graded crushed rocks or
slags.
In
this
context
GBFS
is
mainly
acting
as
a
mechanical stabiliser with relatively little emphasis given
to its hydraulic cementing effect.
In contrast an important
aim of the research reported here was to try and extend the
use
of
GBFS
to
the
stabilisation
sand-silt soils and clays.
of
natural
gravels,
A totally different approach was
planned, namely the use of lime-GBFS and cement-GBFS in
different proportions and at low additive rate of not more
than eight percent of the total dry weight of treated soils
36
to avoid the occurrence of shrinkage cracking in pavements
with high percentages of GBFS.
The possible partial replacement of lime or cement with GBFS
and
the
lime-GBFS
economical
and
feasibility
cement-GBFS
examined in this Thesis.
for
of
soil
the
application
stabilisation
of
are
37
Table 2.1
OXIDE
Typical oxide composition of blast furnace
slag compared to Portland cement, after Spence
and Cook (2)
BLAST FURNACE SLAG
PORTLAND CEMENT
CaO
35
63
Si02
35
22
A1 2 0 3
15
6
Fe 2 0 3
1.5
2.5
8
2.5
Na20
1.5
<1.0
K20
1.5
<1.0
so 3
<1.0
2.0
MgO
38
Chapter III
EXPERIMENTAL TECHNIQUES AND METHODOLOGY
3.1 Scope of Chapter
This chapter is concerned with a broad examination of the
research
programme
and
other
an
tests
evaluation
which
were
of
used
the
various
laboratory
and
during
the
research.
It contains a summary of all the conventional
laboratory tests used in this investigation together with a
brief note on
other unconventional tests used.
3.2 Existing Tests Used in Soil Stabilisation
A summary of the most common tests used, in Australia and
overseas, for soil stabilisation is given in Table 3.1.
This table shows that the physical, chemical and engineering
tests vary in number and type between different methods of
stabilisation.
The widest range of tests comprise those
associated with bituminous stabilisation whereas only few
tests are specified for evaluating stabilisation by lime or
chemical additives.
The assessment made by Shackel (44) of the functions
fulfilled by each of the tests is included in Table 3.1.
It
may be seen that the majority of tests serve either in the
39
selection of a soil for stabilisation or in the design of
the stabilised mix while few provide any indication of the
likely in-service performance of stabilised material.
3.3 The Validity of Existing Tests
Tests used to evaluate the suitability of soils for
stabilisation are generally based on physical or chemical
attributes
and
have
been
shown,
by
experience,
to
be
satisfactory (44). By comparison, tests used in the design
of stabilised mix are less satisfactory
for providing a
reliable indication of pavement performance in relation to
mix design.
The majority of engineering tests shown in
Table 3.1 are based
measurement
of
solely on
static
some direct
strength.
or
Moreover,
indirect
even
such
physical criteria as those based on grading are established
to promote maximum strength.
However, strength improvement is not the only reason for
soil stabilisation and attention should be paid to whether
the treated soil is adequate in playing its role in the
field
application.
established
that
In
this
simulation
regard,
tests
Shackel
are
(45) has
capable
of
contributing towards the evaluation of service performance
and the design of stabilised mixes.
simulation testing
Shackel (46).
The various methods of
have been described
and evaluated by
Table 3.2 shows the suggested utilities for
40
each type of simulation test and for the major categories of
stabilisation as presented by Shackel (44). These utilities
were intended to reflect the amount and usefulness of the
engineering information which the tests yield and do not
take into account either the cost or complexity of each
technique.
3.4 Tests Used in this Investigation
Lime-pozzolan and cement-pozzolan stabilised materials have
many of the behavioural characteristics of lime and cement
stabilised materials.
It is not uncommon therefore, that methods used for the
evaluation of lime-pozzolan and cement-pozzolan products are
similar to those required for cement and lime stabilisation
(47).
Therefore, in the present investigation, all of the
tests associated with lime and cement stabilisation, listed
in Table 3.1, were used.
These tests are those concerned
with grading, compaction, liquid limit, plasticity index,
compressive strength and CBR.
However, additional tests
such as linear shrinkage, scanning electron microscopy and
X-ray diffraction analysis were carried out to determine
more comprehensively the physical and chemical attributes of
the components of the stabilised products.
In addition, a repeated dynamic load test, being the best
41
suggested
technique
behaviour
of
the
(refer
Table
stabilised
3.2)
materials
to
under
traffic, was also used in this research work.
performed in the laboratory.
evaluate
the
simulated
This was also
Most of the laboratory tests
used in this study were carried out in accordance with test
methods specified by the Department of Main Roads, NSW.
(Subsequently, Roads and Traffic Authority, NSW) (56).
The titles of the methods used are listed in Table 3.3.
Brief comments on these tests, together with brief notes on
other tests used, are provided in the following subsections.
3.4.1 Grading and Compaction Tests
Grading and compaction tests are still some of the most
valuable guides to the engineering behaviour of soils in the
context of road engineering.
Ingles and Noble (1975) have
shown that, for base course materials, these tests have high
utility ( utility refers to the combined precision, cost
benefit and predictive values of tests).
Coarse particle and fine particle size distributions were
determined, in this study, in accordance with test methods
T106 and T107 (56), respectively, whereas test method T110
(56) (ie., Standard Compaction Test) was used to determine
the OMC (optimum moisture content) and the maximum density
to which various mixes can be compacted at this moisture
content.
42
Although these tests form a part of the procedures of other
tests
used,
they were
performed
primarily
to
determine
whether or not there was an increase in density upon the
addition of various additives to the soil.
Improvement of
grading and/or compaction of soil to higher density results
in reduction in settlement, reduction in permeability and an
increase in shear strength.
3.4.2 Plasticity and Volume Changes
Plasticity refers to the ability of a material to deform
without cracking or crumbling and then to maintain that
deformed shape after the deforming force has been released.
This non-reversible, or plastic, deformation is probably the
sum of a large number of small slippages at grain-to-grain
contact
points
and
minute
throughout the soil mass.
local
structure
collapses
Frequently, deformation occurs in
soil masses without any application or removal of external
loads.
This may be the result of what is known as swell or
shrinkage by the action of moisture change within the soil
mass.
Plastic deformation and volume change can become large and
are important factors in highway and foundation engineering
work.
In most highway engineering applications, soils with
high plasticity and volume change are avoided as far as
possible.
Where their use cannot be avoided, stabilisation
43
measures
often
are
taken
to
improve
soil
properties
(reduction of volume change and deformation).
tests are
available
to help
Laboratory
identify and determine the
volume change and plasticity of soils.
These tests do not give a precise measurement of a definite
soil property, but are merely arbitrary tests relying on a
strictly standardised
procedure
for their wide
application and reproducibility.
It
field of
was in this general
context that it was decided to use Atterberg limits and
Linear Shrinkage tests as quick, convenient and standard
methods, familiar
differences
to all engineers, for determining the
in magnitude
and
nature
of
the
effects
of
various additives on soils.
Plasticity is assessed by the plasticity index which is the
numerical difference between the liquid limit and plastic
limit of a soil.
Liquid limit can be defined as the water content
corresponding to a shear strength of about 2.5 KPa (10).
Liquid
limit
is
determined
by
test
method
T108
(56).
Plastic limit is the lower boundary of the range of water
contents within which soil exhibits plastic behaviour.
is determined by test method T109 (56).
This
44
Linear shrinkage is a valuable test due to the lack of other
good
tests
for
the
determination
of
volume
It is expressed as the decrease in
stability of soils.
length relative to the initial length when a sample is oven
dried from the liquid limit.
This is determined by test
method T113 (56).
3.4.3 Compressive Strength - Unconfined Compressive
Strength
(UCS) and
Undrained
Triaxial
Strength
(UTS)
The effect of the various additives on the strength of
stabilised soil has little direct application to pavement
design.
Compressive
strength
test
has
been
used
to
determine the relative response of materials to cement and
lime stabilisation (47) and to give an overall picture of
the quality
of
stabilised
materials.
It
is
generally
assumed that the higher the compressive strength the better
the quality
of
stabilised
mixes
(48).
However, it is
interesting to note that the Department of Transportation ,
California USA, has recently reached the conclusion that:
"unconfined compressive strength
is more appropriate
for
evaluating the effects of adding lime to soils than is the
result which derives from CBR and the so called "R-Value"
test" (49).
45
In this study the unconfined compressive strength tests were
performed
in
determine
the
accordance
effect
with
of
test
adding
method
various
T116
(56) to
additives,
of
different proportions and at various rates of application,
to
different
soils.
Moreover,
the
undrained
triaxial
compression test was also carried out on selected stabilised
mixes to determine whether or not the increase in UCS of the
stabilised mixes was influenced by an increase in cohesion,
angle of internal friction or both.
out in accordance with Australian
This test was carried
Standards
test method
AS1289.F4.1.
3.4.4 California Bearing Ratio Test (CBR Test)
The CBR test is a penetration test which gives a measure of
the load spreading ability of the pavement.
This is only
justified in the case of flexible pavements and modified
pavements (5) but not in the case of bound materials (47).
There are no established criteria for demarcation between
"modified" and "bound" although an arbitrary limit of 0.8MPa
UCS
after
seven
days
moist
curing
(modified < 0.8MPa, bound > 0.8MPa).
has
been
suggested
However, there are
limitations to the use of CBR tests in modified materials.
Some studies suggest that it is applicable within the range
of UCS between 0.5MPa and 1.5MPa, depending on the nature of
46
the physical properties of the soil,the chemical
reaction
with the stabiliser and on curing and preparation techniques
(49).
Elsewhere, it was established that it is the most
suitable method to use where the stabilised strength is less
than three times that of the unstabilised soil (47). Larger
strength
increases
cementation
of
will
usually
particles,
modified behaviour.
result
negating
the
extensive
assumption
of
This large increase in strength may
lead to large increase in measured CBR.
1.76MPa would
from
give CBR
values
For example, UCS of
ranging
from
100 to
600
depending upon soil type (3). As the original CBR procedure
related all materials to a satisfactory, well graded, noncohesive crushed rock which was given the ratio 100, the
significance of any value in excess of this is in question.
For these reasons the application of the CBR test in this
study was limited to some selected mixes.
Its main role was
to determine the general trend of the effect of various
additives on the CBR
property
of
soils
and
to
confirm
results derived from the UCS test.
The procedures specified in test method T117 (56) were
adhered
to
with
instead
of
the
the
exception
standard
mould,
of
to
extraction for the purpose of curing.
using
a
split-mould,
facilitate
specimen
47
3.4.5
Repeated Dynamic Load Test
3.4.5a General
The procedure for such a test was developed some years
previously to utilise testing equipment already commissioned
at the University of Wollongong for testing pavements.
The
test structure is illustrated in Figure 3.1.
Due to the dimensions and restrictions of the test structure
the pavement section for testing was determined as 2. Om
square in area and 0.8m in depth.
The pavement was loaded in the central portion by the 1000mm
diameter pneumatic
tyred wheel.
Some longitudinal travel
of the loading was obtained by allowing the pavement to
oscillate up and down at one end of the pavement and having
the other end on a rotating support.
The principle of the
operation is shown in Figure 3.2.
Springs of sufficient stiffness at one end and a rotating
joint at the other end were placed to allow the movement
illustrated in Figure 3.2.
The bin which enclosed the pavement structure was set up
outside the testing frame area to facilitate filling with
the pavement materials.
A trolley was then used to move the
48
bin into the testing frame after the pavement structure had
been compacted.
The trolley and initial arrangements are
illustrated in Figure 3.3.
3.4.5b The Loading System
Loads are applied by a pneumatic tyred wheel, 1000mm in
diameter and 200mm in width, with an inflation pressure of
0.7 MPa (approximately lOOpsi) .
The maximum load which can
be applied by means of a double acting servo controlled
hydraulic jack is 100KN.
The jack, which is connected to
the tyre, is controlled by a fatigue control panel, some 20
metres away.
Figure 3.4 shows the fatigue control panel in
some detail.
The fatigue control panel has a display meter for indication
of loads and displacement.
The meter may be used for the
indication of mean, upper or lower peak load and deflection
values.
The panel has controls for selecting and applying
static or dynamic loads or deflections to the pavement and
an oscillator provides dynamic loads, with sine, triangular
or square wave cyclic wave forms and ramp functions.
counter records the number of completed cycles.
A
Appendix A
contains a list of the panel controls and the method used in
operating the panel for the test.
49
3.4.5c
Measurement of the Permanent Deformation
A "deflection beam" was built to measure the permanent
deformation of points in a grid which covered the loaded
section of the pavement.
The beam was made of an aluminium
channel section to which seven dial gauges were attached.
The dial gauges had a 20mm travel and were graduated to
0.01mm.
The reference points at which deflections were
measured
are
illustrated
in Figure
3.5.
The
grid was
located with reference to the wheel so that the centreline
of
the
wheel
(longitudinally)
and
the
wheel
axle
(transversely) coincided with the centrelines of the grid.
The spacing between grid lines was chosen to be 150mm.
Each
grid line was labelled by either an upper or lower case
letter
depending
on whether
the
longitudinal or transerve direction.
grid could be referenced.
grid
line was
in
the
Hence any point in the
For example, the centre point of
the grid, directly below the wheel, was designated as point
Gd.
The use of the deflection beam is illustrated in Figure
3.6.
Deflection readings were taken for the whole grid, following
the application of a certain number of loads, by positioning
the beam on the marked points on the two bin walls.
50
3.4.6
Powder X-Ray Diffraction
Powder X-ray diffraction is a method widely used in the
analysis of solid solution, crystallinity and, particularly,
with small angle scattering, the size and, to some extent,
the shape of small particles.
The diffraction technique in
this study was used to identify the hydration products of
lime-RHA and lime-GBFS stabilised materials.
Theory of X-Ray Diffraction
When a beam of monochromatic X-rays is directed onto a
crystalline surface, diffraction occurs, the diffracted beam
being built up of rays scattered by the atoms in the crystal
lying in its path.
The reinforcement of scattered rays
occurs when Bragg's law is satisfied.
n X = 2d sin 6
where
X =
d
=
wave length of the X-ray
crystal spacing characteristic of each
mineral component
0
=
angle of incidence of the X-ray
n
=
integral number
By using X-rays of known wave length, and measuring the set
of 6 which produced diffracted beams, d spacings of the
51
various planes in a crystal can be calculated.
In the
powder diffraction method, the sample is reduced to a very
fine powder and placed in the beam of X-rays.
Each particle
is therefore a crystal oriented randomly with respect to the
beam.
However, some particles must be oriented so that a
particular set of lattice planes makes the correct Bragg
angle for the beam diffraction.
The presence of a large
number of particles having all possible orientations ensures
that the diffracted beams represent every set of lattice
planes in the crystal.
The diffracted beams are detected
and their intensities and associated angles determined and
recorded by a movable counter.
The d spacings and their associated intensities form the
pattern
which
is
characteristic
of
the
substance.
Identification of a particular substance is made with the
aid of standard tables of crystal reflections and their
intensities.
3.4.7 Scanning Electron Microscopy
The SEM in this study was used to investigate the morphology
of the reaction products of the lime-RHA and lime-GBFS soil
stabilisation.
The basic operation of the microscope comprises the
following.
Electrons
emitted
from
the
filament
are
52
accelerated down the electron optical column.
The electron
beam is focused by three magnetic lenses onto the specimen
surface as a fine probe.
The probe is directed by scan
coils to scan the specimen surface in the form of square
rasters.
The cathode ray tube screen is simultaneously
scanned in synchronisation with that of the probe.
Its
brightness is modulated by secondary electrons leaving the
specimen which are collected and amplified.
There is thus a
point-to-point correspondence between the CRT screen and the
rasters on the specimen.
progressively formed.
The image of the specimen is thus
The three magnetic lenses mentioned
are not image forming lenses as in optical microscopes.
They act as condenser lenses for the probe incident on the
specimen surface.
The magnification of the image is a
function of geometrical effect, ie., the ratio of the size
of the scanned raster on the CRT screen to that on the
specimen.
The range of magnification that can be achieved is from
about 20 times to 10,000 times.
The brightness of the image
is a function of the intensity of electron emission from the
irradiated
surface
characteristics
of
while
the
the
sample
contrast
depends
surface, eg.,
on
the
topographic
features, back scatter coefficient, composition and crystal
orientation.
Thus high points on the sample surface would
appear bright and low points dark.
On smooth surfaces other
characteristics determine the contrast.
53
Tests used for evaluating stabilised soils,
after Shackel (44).
Plasticity index
X
X
X
X
O
Grading
X X
Compaction
X
X
X
X
X
0
X
X X
0
Sulphate content
X
0
Organic matter
X
O
X
X
O
Swell
X
o
Water absorption
X
0
X
Permeability
^
X
X
Compressive strength
Hveem stability
Hveem cohesion
Hubbard-Field stability
Triaxial tests
Freeze-thaw or wet or dry
X
0
0
0
X
0
x
X X X X
X
X
X
X
x
x
x
o
o
o
o
o
o
o
= Test commonly used
= Function fulfilled by test
X
X X
|
X
Florida bearing
Cone penetration
O
X
Seepage intensity
CBR
0
0
pH
Linear shrinkage
Performance
0
Silicification
X
Resin Stabilisation
X
Thermal Stabilisation
X
Bitumen Stabilisation
X
Lime Stabilisation
Liquid limit
TEST
Cement Stabilisation
Selection of Material
Test
Function
Chloride Stabilisation
Mechanical Stabilisation
Stabilisation
Technique
Mix Design
Table 3.1
[
54
Table 3.2
Suggested utilities for various simulation
tests, after Shackel (44).
i
Soil-Cement
Soil-Bitumen
Repeated compression
C
B
A
C
B
B
B
B
Repeated tension
D
B
B
D
D
B
B
D
Repeated flexure
D
B
B
D
D
B
B
D
Repeated plate load
D
C
C
C
B
B
B
B
Rolling load or test track
D
C
C
C
A
A
A
A
B
C
D
useful
useful
useful
little
Soil-Lime
Soil-Cement
TEST
Soil-Bitumen
Mechanical Stabilisation
Mechanical Stabilisation
Mix Design
as primary test
as secondary test
supplement to conventional tests
or no useful application
Soil-Lime
Performance
Evaluation
A
55
c
id
1
5 2 2
•H
««««««««
QQQ QQQQQQQQ
4-1
•H
co
•H V
H u
id id
1-1 "0
4->
m
3
c
id
4J
< to
I
W
0)
9
r> t-
to C
r» ro>
<n
rt H
P
•n
*H •A
•H
•W n
0 &;
CD 8
M
M
Q 0
•*
r»
1-1 1-1 Ol
0) 0J <H
A ja
0 O >i
•P +J <-t
3
oo o
O s
*"3
o
CO
•a*
r> r- 00
(T>
r» r- rH
a\
as
rH i-H
«*
U
rCO
CT*
H
P- ro
CO
00
0\
rH
>i
Ol
fl)CT>00 Vl H
rH 01 0) i2 t-i cr> id fl)
u u
A A g
0) O 0 0)
o
c 4O-> -P0 <D
3
h) o o Q
ri 3 J
5-1 O
.H >i ja .P
r>
ro
>
rH
>i
3 id 0) o
*3 S fa O
>1
•p
•H
SH
0
-P
3
<:
o
•H
. -a
-^
to idc
M
0)
to
c
>i 0
-rl
4-i
id
4J
g
•
«—1.
c 5;
0) -H
•r| X )
id CO Cl)
r-{ ^- IQ
.*
en to
c rH
•A
u
w
4-> 0
to
•H
cd
i
<u
-u £4->
SH Q)
g 4->
^-* co
O
4-1
T3
(D
» •r|
c
CO
i-H
0) •H
U
4J
w
4J
I
0
•p
•P
•p
id
to
M
0
g
c
id
73
id 4J 4-> id
SH
•W 4-1
g 10 CO 0
id ~ >H
TJ r-{
id ft >1 <rl
•P 0
0
u -a •H
•-1 fl)
CO N
g
id g
id
u
-o
ai
U 4J
1H •H TJ
-H
•rl
0) 01
rH rH 0) TJ
N
a A
CO
+J
id •
ft CO
S rH
O id
O -rl
id >1
•rl 4-> id id
(0 to TJ CO
(fl
0)
•
X
ai
T)
C 1
O
•H
•P c
O
3 -H
XI -P
•W 3
H JQ
•-H
•P
O
•H
to ai
to CO
0) CO
id C Oi
MH c
tH <u rH
0) id
O
4-1 •O ,*
O 0)
0 O •rl
1
rH
4J •rl
c
•rl
4J O
c
c
e >i-r<
!H 1H
0 •rl
0 U -H c
0 •r|
•H
e
id -u •H
rH •o si
••H
4J 4-1 Ol 1H 4J rH
to
id <d
i
d
U g
n>
1-1 1H 0) Qi 4-1 •a •H
id id CO
•rl 4J
SH 0) id 3 CO
id c 0 O1 id
SH 1H O -H ai •-H rA
04
U fa •a (J Ol
ft
0)
a
a>
a.
c
3
g
il
id
•rl
Q)
X c
Id -rl
X
rH
73
0)
•o
0)
co
TJ
c
4->
CO
Tl
0)
id
-a
MH
id
4-1 4-1
3
0 C O
0) .C
s:
g 4->
4-1 •H •rl
•
Ol
u
u) 3 0I)
_ c d
1
73 0) ft C SH
O SH CO 0 3
•rl to
J3
J3 4J
4J
4J (0 4-4 CO CO
a
i
0
o> g 0) C0O) 0SH)
ci •
a
> -C
ft
SH CO 73 •rl 4-> u
ft
4J e U CO cn g SH
CO 0) id in c 0 0)
g Tl 0) 0) 0 4i-d1
0) •rl c SH SH
id ft 4-1 H
>
•rl u
0) 4J g CO id s
to ft CO O
fl)
(0 to *~. 0 0) X SH
0)
> id 0
!H Tl 4-1 MH •rl •rl ft
OI 01 C 0 to U
Tl fl) CO 4J 4-4
g
0 •-t 4-1
0
c SH0)
0 3
0
c •H
o 4J
O 0
ft 0)
Tl g 0 4J g
rl c
0) 0)
id O •c
fl)
SH 0)
0
i
d s
•c
rl
rl
SH •c
u fl)
MH 4H 3 s 1 73
SH
O 4-1 u
C 3
c
0
to 0) H 3 CO
id
0 (X •r| 4-> •rl
CQ O 0) O B fl)
Dc u s Q CO •rl e
r-<
c
0
•H
•
u
4->
id
•
-—. 0) C
Q)
Cn
s
•p
4-1
id
•H
•rl
•-H
id
C
id
4-1
id
3
O
g
0)
•r|
id
0
«
fl)
•P
CO
id
c
o
c
3
o
2
CO
73
id
0
«
c
•rl
id
X
>w
0
4J
C
0)
g
•p
V4
id
ft
0)
Q
S
•
a
H
•8
En
X)
in in vo r^
o o o o
H
H
rH rH
H M H H
fa
ooionior^Ofli
O O H H H r K S O )
iHrHrHrHrHrHrHCN
H H U H h f H H H
CO
fl!
Q
56
ELEVATION
PLAN
FIG.3.1 - Repeated dynamic load test - View of test
structure and pavement
57
WHEEL
BIN
FIXED
X* RELATIVE
MOVEMENT OF BIN TO
WHEEL
FIG.3.2 - Repeated dynamic load test - Principle of
longitudinal movement due to rotation
53
N
TEST •
FRAME
f
WHEEL
STOCKPILE OF
MATERIALS
• -w •
J^.-
— J — REMOVABLE
BEAM
BIN PUSHED IN
TROLLEY
SPRINGS "
L_S TONNE'SKATE' U OFF)
ELEVATION
FIG.3.3 - Repeated dynamic load test - Initial setup
arrangement
59
FIG.3.4 - Repeated dynamic load test - The fatigue
control panel during operation
60
FIG.3.5 - DIAGRAM SHOWING GRID OF LOCATIONS AT WHICH
DEFLECTION MEASUREMENTS WERE TAKEN IN RELATION
TO THE WHEEL AND THE PAVEMENT BOUNDARIES
TRANSVERSE DIRECTION
o
o
o
H
S
o
o
E
En
U
W
F
G
H
Q
XT
AXLE
H
<:
M
Q
I
EH
h
H
o
o
r-
O
o
rH
rH
f g
W
w
IS
BOUNDARY OF PAVEMENT
h
550
900mm
550
NOTES:
1. Dimensions of pavement
2. Scale is 1:20
2000 x 2000mm
61
FIG.3.6 - Repeated dynamic load test - Illustration of
deflection beam in use
62
Chapter IV
EXPERIMENTAL INVESTIGATION USING RICE HUSK ASH
4.1 Scope of Chapter
This chapter is concerned with the experimental
investigation used to determine the behaviour of rice husk
ash in relation to its use in soil stabilisation.
It sets
the objectives of this part of the investigation, describes
the materials used and details the programme and procedures
for testing.
The results of all the various tests used are
presented.
4.2 Objectives of Investigation
The main aims of the investigation reported in this chapter
are as follows:
a) To study the influence of rice husk ash as a single
additive on various properties of a range of soils.
b) To examine the effects of lime-rice husk ash and
cement-rice husk ash additives on the properties of
soils.
63
4.3
Materials Used
4.3.1
Rice Husk Ash
The rice husk ash used was a light-weight, fine black ash
produced in Griffith, NSW, and brought in 200 litre drums to
the Department of Civil and Mining Engineering, University
of Wollongong.
The specific gravity of the sample was 1.79 and the grading
was:
% passing 2.36mm
100
% passing 425 pirn
60
% passing 75 pm
17
% passing 13.5 /jm
12.5
The chemical analysis of the sample was:
Si02
58.2%
A1203
0.10%
Fe203
1.09%
CaO
0.37%
MgO
0.21%
Na20
0.21%
K20
1.37%
Loss on ignition
34.2%
64
4.3.2
Cement
'Kandos' commercial grade, ordinary portland cement was
used, conforming to Australian standards (AS1315) as given
below:
Loss on ignition Max 3.1%
Insoluble residue
Max 2.1%
Sulphuric anhydride (SO3)
Max 3.1%
Magnesia
Max 4.2%
Time for initial set
•£ 1 hour
Time for final set
$> 12 hours
4.3.3 Lime
'Blue Circle' commercial grade, hydrated lime was used,
conforming to Australian standards (AS1672) as given below:
Ca(OH)2 > 70%
MgO
< 4.5%
C02
< 5%
Particles Fineness, passing 250/jm
<$ 98%
4.3.4 Soils
Four soils were selected to be stablised and tested in this
investigation.
65
Soil A was a crushed rock conglomerate from a deposit known
as Yeoman's Pit in the Shire of Guyra, NSW.
Soil B was taken from a sandy silt pit at Stone Henge in the
Shire of Severn, NSW.
Soil C was an organic clay taken from a construction site in
the town of Glen Innes, NSW.
were taken in
Samples of these three soils
plastic bags and kept in the laboratory of
the Divisional Office of Road and Traffic Authority at Glen
Innes to be used as and when required.
Soil D was a marginal roadbase material consisting of
igneous dolerite crushed rock.
This material was quarried
at Prospect in the western suburbs of Sydney, NSW.
cubic metres
of
this
material
was
obtained
from
Four
local
suppliers by the Department of Civil and Mining Engineering,
University of Wollongong and used in the repeated dynamic
load tests.
The properties of the four soils (A,B,C and D) are shown in
Table 4.1.
4.4 Testing Regime
RHA varies according to the environment in which the
combustion of the rice husks takes place.
The variations
66
are reflected in the chemical composition of the RHA with
particular
emphasis
on carbon
content.
The
pozzolanic
reaction between lime, either added directly or from the
hydration reaction of cement and RHA is governed largely by
the carbon content of the ash.
It was considered that
initial testing be carried out to determine RHA reactivity
and the optimum ratio of lime or cement to RHA.
The second step in the programme was then to treat the three
soils A, B and C with lime-RHA and cement-RHA additives at
their optimum and practical ratios.
Soils A, B and C were
also teated with cement, lime and RHA single additives.
The treated soils were then subjected to the various
laboratory tests described in Chapter 3.
The final stage in the programme was to treat soil D with
various additives in the light of best results, derived from
the second step in the programme and subject this treated
soil
to
the
repeated
dynamic
load
test
described
in
Chapter 3.
4.5 Initial tests - optimum ratios of lime to RHA and
cement to RHA
The use of an unconfined compressive strength test on
lime-RHA and cement-RHA paste specimens was selected as a
suitable indicator of the RHA reactivity.
67
4.5.1
Preparation, curing and testing of specimens
Dry mixtures of lime-RHA and cement-RHA were prepared, mixed
and proportioned by weight.
The ratio of lime to RHA and
cement to RHA was in the range of 1:1 to 1:10.
of
compacted
specimens
were
then
prepared
Two series
at
optimum
moisture content using standard Proctor equipment.
All specimens were wrapped in paper, aluminium foil and
contained
in plastic
bags
at
constant
(22°C) during the curing periods.
room
temperature
At the conclusion of the
various curing periods (28 days and 90 days) the specimens
were air dried for approximately 30 minutes and subjected to
the unconfined compressive strength test.
The results of the UCS tests on the lime-RHA paste specimens
are presented in Figure 4.1, whereas those of cement-RHA
paste specimens are presented in Figure 4.2.
The results presented in Figure 4.1 for both curing periods
(28 days and 90 days) indicate that the optimum ratio of
lime to RHA is the ratio 1:2.
Figure 4.2 shows that there is no optimum ratio of cement to
RHA.
This is indicative that the strength of cement-RHA
pastes is dominated by the hydration reactions of cement
rather than by the pozzolanic reaction between the released
lime and the RHA.
68
4.6
Treatment of soils with various additives
Various additives, namely RHA, lime, lime-RHA, cement,
cement-RHA, were used individually to stabilise the soils
(A,B & C).
The various quantities of additives were 2%, 4%,
6% and 8% of the total weight of the dry soil and additive.
The ratio of lime to RHA for each quantity of additive was
varied as 1:1, 1:2, 1:3 and 1:4.
Although the ratio 1:2 was
found to be the optimum ratio of lime to RHA (section 4.5),
the values 1:1, 1:3 and 1:4 were considered to be within the
practical range.
The initial testing indicated that no optimum ratio of
cement to RHA occurs (section 4.5).
In the test series the
values 1:1, 1:2, 1:3 and 1:4 were considered to be within
the practical range and were used for comparison.
4.7 Testing of stabilised soils
4.7.1 Compaction characteristics
The optimum moisture contents (OMC) and the maximum dry
densities (MDD) of soils stabilised with various additives
and various quantities
(section 4.6) were determined by
carrying out the standard compaction test T110 (56).
test results are presented in Tables 4.2 and 4.3.
The
69
4.7.2
Unconfined compressive strength
Three series of specimens of soils stabilised with the
various additives and various quantities were prepared and
compacted to their maximum dry densities at their OMC using
the standard compaction test equipment.
All specimens were
wrapped in paper, aluminium foil and contained in plastic
bags at constant room temperature (22°C) during the curing
periods.
At the conclusion of the various curing periods (7 days, 28
days, 90 days) the specimens were air dried for 30 minutes
and then subjected to unconfined compression.
are shown in Tables 4.4 and 4.5.
The results
The 90 days test results
for the treated soil A, B and C are also shown in Figures
4.3 and 4.4.
4.7.3 Linear shrinkage
The linear shrinkage of all mixes was determined using
materials
collected
from unconfined
compressive
strength
crushed specimens which had been previously cured for 7 and
28 days.
The materials were ground using a porcelain mortar
and rubber pestle to produce samples passing a 2.36mm sieve.
The prepared samples were air dried and sufficient water was
then added to the samples to bring them to a consistancy
70
similar
to
the
liquid
limit.
Shrinkage
samples
were
prepared using linear shrinkage moulds of 250mm length.
After air drying and subsequent oven drying, values of
linear shrinkage were determined.
The results are presented
in Tables 4.6 and 4.7, results of the 28 days curing period
are shown in Figures 4.5 and 4.6.
4.7.4 Atterberg limits
Plastic limit, liquid limit and plasticity index of all
mixes
were
determined
using
materials
collected
from
unconfined compressive strength crushed specimens which had
been previously cured for 7 and 28 days.
of
each
specimen
were
collected
and
Individual pieces
ground
to
powder
fraction using a porcelain mortar and rubber pestle.
All
prepared fractions were then air dried and subjected to
testing.
The Atterberg limits of the various treatments after the
curing periods of 7 days and 28 days are given in Tables 4.6
and 4.7.
The results of the plasticity index of the 28 days
curing period also are given in Figures 4.7 and 4.8.
71
4.7.5
Effect of delay in compaction on the strength of
stabilised soils.
It was decided that limited testing of some of the soil
mixes would be sufficient for determining the general trend
of the effect of delay in compaction on the strength of the
stabilised soils. Samples of dry soil A were mixed with
cement and cement-RHA additives.
The ratio of cement to RHA
was varied as 1:1 and 1:4, whereas the quantity of additives
used in each case was 8% of the total dry weight of the
treated soil.
Samples of dry soil C also were mixed with lime and lime-RHA
additives.
The ratio of lime to RHA was varied as 1:1 and
1:3, whereas the quantity of additives used in each case was
8% of the total dry weight of the treated soil.
Water was added and every mix was put in a covered metal
container
periods.
and
maintained
at
its
OMC
during
the
delay
At the conclusion of the various delay periods (2
hours, 4 hours, 6 hours and 24 hours) the various mixtures
were immediately compacted using the standard compaction
test equipment.
The compacted specimens were then wrapped in paper,
aluminium foil and contained in plastic bags at constant
72
room temperature (22°C) for 90 days.
the 90 days curing period the
unconfined compression.
At the conclusion of
specimens were subjected to
The strength of these specimens is
given in Tables 4.8 and 4.9.
The losses in strength due to
delays in compaction, expressed as percentage of strength of
undelayed compaction specimens, also are given in Tables 4.8
and 4.9 and shown in Figures 4.9 and 4.10.
4.7.6 Effect of various additives on the shear strength
parameters of soils
As discussed in section 3.4.3, the undrained triaxial
compression test was carried out on selected
stabilised
mixes to determine whether or not the increase in UCS of
stabilised mixes was influenced by an increase in cohesion,
angle of internal friction or both.
Samples of dry soil B were mixed with cement and cement-RHA
additives.
1:4.
The ratio of cement to RHA was varied as 1:2 and
The quantities of additives in each case were 4% and
8% of total dry weight of the treated soil.
Samples of dry soil C also were mixed with lime and lime-RHA
additives.
1:3.
The ratio of lime to RHA was varied as 1:1 and
The quantities in each case were 4% and 8% of the
total dry weight of the treated soil.
73
Water was added and every mix was compacted at its OMC using
standard compaction test equipment.
A thin walled steel
pipe was driven into the compacted mixes to collect two
cylindrical specimens, 50mm in diameter, from each compacted
mix.
The specimens were extruded from the pipe by pushing
them with a manual jack extruder.
The specimens were then
trimmed to size (50mm dia x 100mm) by cutting with a sharp
edge spatula.
All prepared specimens were wrapped in paper, aluminium foil
and put in pastic bags at constant room temperature (22°C)
during the curing periods. At the conclusion of the various
curing periods (7 and 28 days) the specimens were subjected
to the unconsolidated, undrained test in accordance with
Australian Standards test method AS1289.F4.1.
Data obtained from the tests were used to plot a Mohr's
stress
circle
using
the
cell
pressure
cr3 and
the
corresponding major principal stress a\ at specimen failure.
By plotting two Mohr's circles using test data based on
different initial cell pressure a3 for each test and on two
identical specimens of every mix, an approximate tangent to
the circles was established.
The slope of this tangent was
taken as angle of internal friction 0, of the mix, and the
intercept of the tangent on the Y axis was taken as the
cohesion C in Coulomb's equation ( T = C + crn tan 0) .
The
values of 0 and C for the various mixes are given in Tables
4.10 and 4.11.
74
4.7.7
Effect of various additives on the CBR value of
soils
As discussed in section 3.4.4, there are limitations to the
use of CBR tests in the context of stabilised materials.
However, application of the CBR test in this study was
limited to some selected mixes.
determine
the
general
trend
Its main role was to
of
additives on the CBR property
the
of
effect
soils
of
various
and to confirm
results derived from the UCS test.
Dry samples of soil A, B and C were mixed with RHA, lime-RHA
and cement-RHA additives.
cement
to
RHA was
The ratio of lime to RHA and
varied
as
1:1,
1:2
and
1:3.
The
quantities of additives in each case were 4% and 8% of the
total dry weight of treated soil.
Cement and lime, at the
rates of 2% and 4% of total dry weight of treated soil, also
were used for comparison.
Water was added and all mixes were compacted at their OMC in
accordance with the standard procedures of the CBR test with
the
exception
of
using
a
special
split
CBR
mould
to
facilitate specimen extraction for the purpose of curing.
The split mould was opened and the specimens were taken out,
wrapped in paper, aluminium foil and put in plastic bags at
constant room temperature (22°C) during the curing periods.
75
At the conclusion of the various curing periods (28 days and
90 days) the specimens were put again in the split mould,
the surcharge weights were added and the specimens were
subjected to the standard piston penetration at a uniform
rate of 1.27mm per minute.
The CBR values of the various mixes for the various curing
times are presented in Tables 4.12 to 4.14, and the results
of the 90 days curing period are shown in Figures 4.11 to
4.13.
4.7.8 Repeated dynamic load test
This test was conducted on six pavements. Soil D stabilised
with various
additives
formed
the
base
course
of
five
pavements, whereas the untreated soil D formed the control
base course of the sixth pavement.
The various additives
used to stabilise soil D were cement, lime, RHA, cement-RHA
and lime-RHA mixtures.
The ratio of cement to RHA and lime
to RHA used was 1:1, whereas the quantity of additives used
was 1.5%, 2%, 8%, 3% and 3% respectively and expressed as
percentage of the total dry weight of the treated soil.
The sub-base of all of the six pavements consisted of beach
sand from the Illawarra region.
of sand was as follows:
Particle size distribution
76
% passing 1.18mm sieve
100
% passing 600 ym sieve
90
% passing 425 pm. sieve
74
% passing 300 pm sieve
49
% passing 150 pm sieve
5
% passing 75 pm sieve
0
The sand sub-base was placed, by shovel, in the bin in its
natural state (moisture content 3%) in six, approximately
100mm thick layers and compacted.
plate compactor
was
used
to
A walk-behind vibratory
compact
the
layers.
The
compaction was carried out until the layer showed no further
movement under the compacting equipment.
The top of the
surface was then levelled and screeded with an appropriate
implement.
A protective section of stiff rubber conveyor
belting (900mm x 600mm x 20mm thick) was put in the centre
of the sub-base surface.
This material was selected because
it is compressible, elastic and maintains its properties in
all tests. Thus the results from the tests can be related
to the various stabilised pavement bases.
The various stabilised base materials were mixed and
prepared at their OMCs and then placed, by shovel, in two
layers of 100mm thickness.
carried
out
compactor.
by
using
Compaction of the two layers was
a
walk-behind
vibratory
plate
77
Once the material containment bin had been filled and the
pavement constructed, the next step was to assemble and
connect all the components to allow the test to proceed.
Prior to the bin being pushed into place under the wheel,
the springs were tied to the bin (see Figure 3.3). With the
aid of a block and tackle and some manpower the bin was
rolled into position by means of the 'skate' trolley.
The
trolley was then removed by raising the bin clear of the
trolley.
This was done as follows:
Two hydraulic hand operated jacks were placed at position A
and B beneath channels supporting the bin (see Figure 4.20).
They were then jacked up simultaneously causing the eastern
side of the bin to rise and to rotate about axis E of the
trolley.
Continued lifting of the bin resulted in the semi-
circular bearer of the hinge joint (line C-D) resting on the
test frame.
Further raising caused rotation about line C-D.
The raising continued until the tolley was completely free
and could be removed.
The pressure on the jacks was then
released slowly allowing the springs on the eastern side to
be positioned over the bearing plates on the testing frame.
Once the springs were located, the jacks were completely
released.
After the pavement had been constructed and the test rig
assembled, zero readings were taken at the grid points at
78
which the deflections were to be measured.
The pavement was
covered by a damp cloth and cured for 7 days. At the
conclusion of the curing period the pavement was subjected
to 50,000 42kN load applications during which deflection
readings were taken at intervals.
The basic criteria for the evaluation of the stabilised road
bases was the relationship between the load and deformation.
In total, 840 readings were taken of the deflections of
various pavements at various intervals during the tests and
at various positions on the pavements. The results of the
deflections are given in a tabular form in Tables 4.15 to
4.20. Figures 4.14. to 4.19 show the deflections of
pavements after the various intervals at the cross sections
of the maximum deflections.
4.7.9 Scanning Electron Microscopy
It was decided that limited testing of some of the soil
mixes would be sufficient for determining the morphology of
the RHA pozzolanic reaction products in soil stabilisation.
Samples of untreated Soil A, untreated Soil C, lime-RHA
treated Soil A and lime-RHA treated Soil C were compacted at
their OMC using the standard compaction test equipment. The
ratio of lime to RHA was 1:1 and the quantity of lime-RHA
additive was 8% of the total dry weight of the treated soil.
79
Each sample of the treated soils was then wrapped in wet
newspaper, sealed with aluminium foil, put in an oven bag
and stored for 7 days in an oven at a maintained temperature
of 65°c.
At the conclusion of this accelerated curing, all
samples were fractured and small specimens of the fractured
materials were taken for testing.
The specimens were of the
order 8-12mm maximum dimensions and had a length to width
ratio in the general range of 1:1 to 2:1.
The thickness was
in the range 4-6mm.
All specimens were oven dried at 110°c for 24 hours and then
glued
to
aluminium
stubs
with
organic
adhesive.
The
specimens were coated with a thin layer of gold alloy to
provide an electrically conducting surface.
The surface
from the gold layer to the stub was also painted with silver
to ensure a good electrical contact with the stub.
All specimens were then examined in a Hitachi S450 Scanning
Electron Microscope and micrographs were obtained.
These
micrographs are shown in Figures 4.21 to 4.24.
4.7.10 Powder X-ray Diffraction Analysis.
X-ray diffraction patterns were determined for all soil
mixes used in the preceding scanning electron microscopy
examination.
80
Samples
of
the
fractured
material
of
the
treated
and
untreated Soils A and C were pulverised with a mortar and
pestle to produce a powdered material suitable for placing
in aluminium mounts ready for powder X-ray diffractometry
(Cukoc Source).
Figures
4.25
to
4.28
show
the
X-ray
diffraction patterns determined for the untreated Soil A,
untreated Soil C, lime-RHA treated
treated Soil C.
Soil A
and
lime-RHA
81
Table 4.1 Properties of Soils
Properties
Soil A
Soil B Soil C
Soil D
1. Grading % passing
19mm
9 .5mm
4.75mm
2.36mm
425pm
75pm
13.5pm
100
73
36
22
15
8
4
100
100
100
85
43
24
17
100
100
100
100
85
71
53
100
88
69
43
16
4
2. Atterberg limits
L.L
P.L
P.I
33
24
9
32
24
8
100
45
55
22
16
6
3. Volume stability
Linear shrinkage %
3.5
2.75
17
-
4. Compaction
characteristics
OMC %
Max dry density g/cm3
13
1.83
15
1.82
22
1.32
9.00
2.01
5. Unconfined compressive
strength (MPa)
.33
.26
.21
-
6. Unified soil
classification
GMu
SMu
OH
GW
Gravel/sand
Sand
Organic
Well graded
silt mix
silt mix
clay
gravel/sand
7. Description
mix
8. Colour
White
Reddish
Black
brown
9. Specific gravity
2.93
2.86
2.83
Blue
82
T A B L E 4.2a
ADDITIVE
Compaction characteristics of lime, R H A and Lime-RHA
stabilised soil A
OMC
(%)
(%)
MDD
gnn/cm3
LIME
LIME:RHA
0%
2%
4%
6%
8%
1:1
13.00
14.50
16.00
16.50
17.00
1.83
1.82
1.77
1.74
1.73
0%
2%
4%
6%
8%
13.00
15.00
16.00
16.50
17.00
1.83
1.82
1.77
1.74
1.73
LIME:RHA
1:2
13.00
15.00
16.00
16.50
17.00
1.83
1.82
1.76
1.73
1.73
LIME.RHA
0%
2%
4%
6%
8%
1:3
13.00
15.00
16.00
16.50
17.50
1.83
1.81
1.76
1.73
1.72
LIME:RHA
0%
2%
4%
6%
8%
1:4
0%
2%
4%
6%
8%
13.00
15.00
16.00
17.00
18.50
1.83
1.81
1.75
1.72
1.69
0%
2%
4%
6%
8%
13.00
15.00
16.50
17.50
18.50
1.83
1.79
1.74
1.70
1.66
RHA
83
T A B L E 4.2b
ADDITIVE
Compaction characteristics of lime, R H A and lime-RHA
stabilised soil B
(%)
OMC
(%)
MDD
gm/cm 3
LIME
LIME:RHA
0%
2%
4%
6%
8%
1:1
15.00
16.00
16.50
17.00
18.00
1.82
1.81
1.78
1.75
1.73
0%
2%
4%
6%
8%
15.00
16.00
16.00
17.00
18.50
1.82
1.80
1.77
1.73
1.70
LIME:RHA
1:2
15.00
16.00
16.00
17.00
19.00
1.82
1.79
1.76
1.72
1.66
LIME:RHA
0%
2%
4%
6%
8%
1:3
15.00
16.50
16.50
17.50
19.00
1.82
1.78
1.76
1.70
1.66
LIME:RHA
0%
2%
4%
6%
8%
1:4
0%
2%
4%
6%
8%
15.00
16.50
16.50
18.00
19.00
1.82
1.78
1.76
1.70
1.65
0%
2%
4%
6%
8%
15.00
16.00
16.00
17.00
19.00
1.82
1.78
1.76
1.70
1.65
RHA
84
Compaction characteristics of lime, R H A and lime-RHA
stabilised soil C
T A B L E 4.2c
ADDITIVE
(%)
OMC
(%)
MDD
gm/cm3
LIME
22.00
23.00
24.00
24.50
25.00
1.32
1.32
1.31
1.30
1.29
22.00
23.00
24.00
25.00
26.00
1.32
1.30
1.26
1.24
1.21
22.00
23.00
24.50
26.00
26.50
1.32
1.29
1.27
1.23
1.23
0%
2%
4%
6%
8%
22.00
24.00
25.00
26.00
27.00
1.32
1.26
1.25
1.23
1.22
0%
2%
4%
6%
8%
22.00
24.00
25.00
26.00
26.00
1.32
1.28
1.24
1.22
1.21
0%
2%
4%
6%
8%
LIME:RHA
1:1
0%
2%
4%
6%
8%
LIME:RHA
1:2
0%
2%
4%
6%
8%
LIME:RHA
1:3
RHA
85
T A B L E 4.3a
ADDITIVE
Compaction characteristics of cement, R H A and cementR H A stabilised soil A
OMC
(%)
(%)
MDD
gin/cm3
CEMENT
0%
2%
4%
6%
8%
CEMENT:RHA 1:2
13.00
14.00
14.50
15.50
16.50
1.83
1.85
1.85
1.85
1.85
0%
2%
4%
6%
8%
13.00
14.00
14.50
15.50
16.50
1.83
1.83
1.81
1.75
1.76
0%
2%
4%
6%
8%
CEMENT:RHA 1:4
13.00
14.00
14.50
16.00
17.00
1.83
1.83
1.80
1.78
1.73
0%
2%
4%
6%
8%
13.00
14.50
15.00
16.00
17.50
1.83
1.81
1.78
1.76
1.72
0%
2%
4%
6%
8%
13.00
15.00
16.50
17.50
18.50
1.83
1.79
1.74
1.70
1.66
CEMENT:RHA 1:3
RHA
86
T A B L E 4.3b
ADDITIVE
Compaction characteristics of cement, R H A and cementR H A stabilised soil B
OMC
(%)
(%)
MDD
gm/cm3
CEMENT
0%
2%
4%
6%
8%
CEMENT:RHA 1:2
15.00
15.50
16.50
17.00
17.50
1.82
1.82
1.84
1.84
1.84
0%
2%
4%
6%
8%
15.00
16.00
17.00
17.50
18.00
1.82
1.82
1.78
1.73
1.70
0%
2%
4%
6%
8%
CEMENT:RHA 1:4
15.00
16.00
17.00
17.50
18.50
1.82
1.82
1.78
1.72
1.68
0%
2%
4%
6%
8%
15.00
16.00
17.00
17.50
18.50
1.82
1.82
1.76
1.71
1.67
0%
2%
4%
6%
8%
15.00
16.00
16.00
17.00
19.00
1.82
1.78
1.76
1.70
1.65
CEMENT:RHA 1:3
RHA
87
T A B L E 4.3c
ADDITIVE
Compaction characteristics of cement, R H A and cementR H A stabilised soil C.
OMC
(%)
(%)
MDD
gm/cm 3
CEMENT
0%
2%
4%
6%
8%
CEMENT:RHA 1:1
22.00
23.00
24.50
25.00
26.00
1.32
1.34
1.35
1.39
1.40
22.00
24.00
25.00
26.00
27.00
1.32
1.32
1.30
1.28
1.26
22.00
24.00
25.00
26.00
27.00
1.32
1.31
1.29
1.26
1.25
0%
2%
4%
6%
8%
22.00
24.00
25.00
26.00
27.00
1.32
1.30
1.28
1.26
1.24
0%
2%
4%
6%
8%
22.00
24.00
25.00
26.00
26.00
1.32
1.28
1.24
1.22
1.21
0%
2%
4%
6%
8%
CEMENT:RHA 1:2
0%
2%
4%
6%
8%
CEMENT:RHA 1:3
RHA
88
TABLE 4.4a
ADDITIVE
U C S (MPa) of lime, R H A and lime-RHA stabilised soil A
(%)
7
C U R I N G (DAYS)
90
28
LIME
0%
2%
4%
6%
8%
LIME:RHA 1:1
0.33
0.43
0.46
0.43
0.41
0.33
0.55
0.76
0.73
0.70
0.33
0.69
1.00
0.95
0.90
0%
2%
4%
6%
8%
0.33
0.36
0.63
0.61
0.58
0.33
0.50
0.68
0.73
0.71
0.33
0.55
0.92
1.00
0.97
0.33
0.36
0.60
0.58
0.55
0.33
0.45
0.68
0.70
0.68
0.33
0.58
0.85
0.92
0.89
0.33
0.35
0.64
0.58
0.52
0.33
0.45
0.68
0.70
0.65
0.33
0.50
0.75
0.82
0.81
0%
2%
4%
6%
8%
0.33
0.34
0.46
0.44
0.44
0.33
0.45
0.50
0.48
0.46
0.33
0.50
0.66
0.67
0.65
0%
2%
4%
6%
8%
0.33
0.33
0.34
0.34
0.34
0.33
0.34
0.34
0.34
0.34
0.33
0.34
0.34
0.34
0.34
LIME:RHA 1:2
0%
2%
4%
6%
8%
LIME:RHA 1:3
0%
2%
4%
6%
8%
LIME: R H A 1:4
RHA
89
TABLE 4.4b
ADDITIVE
U C S (MPa) of lime, RHA and lime-RHA stabilised soil B
(%)
7
C U R I N G (DAYS)
90
28
LIME
0%
2%
4%
6%
8%
LIME:RHA 1:1
0.26
0.32
0.34
0.28
0.27
0.26
0.40
0.42
0.38
0.36
0.26
0.50
0.57
0.50
0.45
0%
2%
4%
6%
8%
0.26
0.30
0.40
0.34
0.34
0.26
0.38
0.46
0.41
0.38
0.26
0.45
0.54
0.53
0.48
0.26
0.27
0.36
0.33
0.32
0.26
0.31
0.43
0.39
0.36
0.26
0.41
0.52
0.52
0.45
0%
2%
4%
6%
8%
LIME:RHA 1:4
0.26
0.26
0.28
0.28
0.27
0.26
0.30
0.32
0.32
0.30
0.26
0.40
0.45
0.46
0.38
0%
2%
4%
6%
8%
0.26
0.26
0.26
0.26
0.26
0.26
0.31
0.32
0.32
0.29
0.26
0.36
0.42
0.43
0.35
0%
2%
4%
6%
8%
0.26
0.24
0.24
0.24
0.25
0.26
0.24
0.24
0.24
0.25
0.26
0.24
0.24
0.24
0.25
LIME:RHA 1:2
0%
2%
4%
6%
8%
LIME:RHA 1:3
RHA
90
TABLE 4.4c
ADDITIVE
U C S (MPa) of lime, RHA and lime-RHA stabilised soil C
(%)
7
C U R I N G (DAYS)
90
28
LIME
0%
2%
4%
6%
8%
0.21
0.25
0.34
0.43
0.41
0.21
0.30
0.41
0.51
0.50
0.21
0.33
0.44
0.56
0.55
0%
2%
4%
6%
8%
0.21
0.24
0.26
0.34
0.34
0.21
0.27
0.34
0.41
0.39
0.21
0.31
0.37
0.45
0.44
0.21
0.23
0.25
0.29
0.33
0.21
0.25
0.30
0.34
0.37
0.21
0.27
0.32
0.39
0.41
0%
2%
4%
6%
8%
0.21
0.24
0.24
0.26
0.29
0.21
0.24
0.26
0.30
0.32
0.21
0.25
0.29
0.33
0.35
0%
2%
4%
6%
8%
0.21
0.21
0.22
0.23
0.23
0.21
0.21
0.22
0.23
0.23
0.21
0.21
0.22
0.23
0.23
LIME: R H A 1:1
LIME:RHA 1:2
0%
2%
4%
6%
8%
LIME:RHA 1:3
RHA
91
TABLE 4.5a
ADDITIVE
U C S (MPa) of cement, RHA and cement-RHA stabilised
soil A
(%)
7
CURING (DAYS)
90
28
CEMENT
0%
2%
4%
6%
8%
0.33
1.26
1.75
2.45
3.00
0.33
1.95
2.70
3.50
4.30
0.33
2.00
3.15
4.00
4.60
0.33
0.68
1.00
1.40
1.75
0.33
0.98
1.65
2.10
2.30
0.33
1.35
2.27
2.53
3.10
0.33
0.62
0.90
1.25
1.50
0.33
0.80
1.25
1.68
2.00
0.33
1.08
1.70
2.30
2.70
0%
2%
4%
6%
8%
0.33
0.52
0.70
0.57
1.00
0.33
0.55
0.85
1.10
1.40
0.33
0.70
1.10
1.42
1.80
0%
2%
4%
6%
8%
0.33
0.33
0.34
0.34
0.34
0.33
0.34
0.34
0.34
0.34
0.33
0.34
0.34
0.34
0.34
CEMENT:RHA 1:2
0%
2%
4%
6%
8%
CEMENT:RHA 1:3
0%
2%
4%
6%
8%
CEMENT:RHA 1:4
RHA
92
TABLE 4.5b
ADDITIVE
U C S (MPa) of cement, R H A and cement-RHA stabilised
soil B
(%)
7
C U R I N G (DAYS)
90
28
CEMENT
0%
2%
4%
6%
8%
CEMENT:RHA 1:2
0.26
0.43
0.62
0.90
1.40
0.26
0.67
1.02
1.50
2.30
0.26
0.74
1.15
1.70
2.57
0.26
0.28
0.35
0.48
0.55
0.26
0.42
0.60
0.77
0.90
0.26
0.57
0.83
1.05
1.25
0.26
0.28
0.32
0.45
0.48
0.26
0.37
0.51
0.69
0.82
0.26
0.55
0.75
1.00
1.18
0%
2%
4%
6%
8%
0.26
0.26
0.31
0.42
0.45
0.26
0.32
0.42
0.50
0.61
0.26
0.40
0.52
0.62
0.77
0%
2%
4%
6%
8%
0.26
0.24
0.24
0.24
0.24
0.26
0.24
0.24
0.24
0.24
0.26
0.24
0.24
0.24
0.25
0%
2%
4%
6%
8%
CEMENT:RHA 1:3
0%
2%
4%
6%
8%
CEMENT:RHA 1:4
RHA
93
TABLE 4.5c
ADDITIVE
U C S (MPa) of cement, RHA and cement-RHA stabilised
soil C
(%)
7
C U R I N G (DAYS)
90
28
CEMENT
0%
2%
4%
6%
8%
CEMENT:RHA 1:1
0.21
0.25
0.32
0.42
0.48
0.21
0.32
0.41
0.52
0.60
0.21
0.35
0.46
0.58
0.70
0.21
0.23
0.25
0.30
0.39
0.21
0.26
0.29
0.35
0.41
0.21
0.28
0.37
0.43
0.48
0.21
0.22
0.24
0.30
0.32
0.21
0.25
0.26
0.32
0.37
0.21
0.27
0.32
0.37
0.41
0%
2%
4%
6%
8%
0.21
0.21
0.23
0.28
0.26
0.21
0.23
0.26
0.30
0.32
0.21
0.26
0.30
0.34
0.37
0%
2%
4%
6%
8%
0.21
0.21
0.22
0.23
0.23
0.21
0.21
0.22
0.23
0.24
0.21
0.21
0.22
0.23
0.24
0%
2%
4%
6%
8%
CEMENT:RHA 1:2
0%
2%
4%
6%
8%
CEMENT:RHA 1:3
RHA
94
u
JS
o m o m tn
o o o m o
o o o o m
u
in r« in CN CN
co rH o o o
m in in r- m
ro CN rH o o
m in in o r-
a ^
o o o o o
o o o o o
OS
en m «-H o
rH
z
M
PO CN rH rH O
o m in m in
O o o o m
in r- r- CN r- in o m m r("0 rH rH rH O
ro ro CN rn o
o o o o o
o o in o o
O O O O O
O O O O O
o o o o o
o o in o o
O O O O O
O O O O O
OS VO •<»• CN rH
CM t~- VO rH ro
at oo vo in ^*
otcsMsm
o o o
o o o
o o o o o
o o o o o
o o o o o
o o o o o
o o o o o
o o o o o
•"** co O EU EU
«* CN OS VO
O O O O O
O O O O O
** ai m oo CN
CN CN ro co **
o o o o o
o o o o o
o o o o o
o
o in in m o
m CN r» CM o
ro ro CN CN CN
o o o o o
o o in in in
as as t-» vo m
Doe
1
00
CN
•dP
O
1" r-l CO VO 00
o o o o o
o o o o o
*oeoHin
CN ro ro ^* m
CN ro ro ^* ^*
CN ro ro ^* ^*
o o o o o
o o o o o
O O O O O
CO 00 r—1 00 cr>
O O O O O
o o in o o
noocoH
ro ro .* **< «*
ro ro ^t* ^* m
ro ro TI" in in
ro ro ^* ^* ^*
o o o in in
m in m CN CN
ro i-H o o o
o o o o in
in o o o t^
o in m o in
m CN CN o r~
o in m o o
ro ro CN H
o o o o o
o o o o o
0>«>(*100
o o o
o o o
PH
o o o o o
o o o o o
•dp
^* r~ rH m o
CN CN ro ro TJ<
ro r*- ro ^ p**
ro ro ^* ^* ^*
o o in in in
ro vo oo rn m
ro ro ro ^* ^*
in CN CN in o
o in in in o
in CN r» r- o
o in in in o
in CN I^ CN o
ro ro CN >-i O
rO ro CN rH rH
ro ro CN rH rH
ro ro CN CN CN
o o o o o
o o o o o
o o o o o
o o o o o
o o o o o
o o o o o
o o o o o
o o o o o
as oo vo •* ro
cn cn i^ in ^*
as as co r» m
O O O O O
as os oo t- in
o o in in in
cn as r> vo m
o o o o o
o o o o o
<t O P * * 00
o o o o o
o o o o o
o o o o o
o o o o o
O O O O O
o o o o o
o o o o o
o o o o o
CN ro ro TJ* •*»•
*d« as t-» ro rCN CN ro ^< **<
"S* Ol VO Ol CN
CN CN ro ro **•
•5»< VO CN C- rH
CN CN ro ro ^
<* r » H i n o
CN CN ro ro rf
ro 00 •* O
I-I
o o m o o
mco^iooi
u
Xi
M
DAYS CURING
P.L
OK
HP
CM ro ro Z
Z
o
r~
o o o o o
o o o o o
o o o o o
o o o o o
o o o o o
o o o o o
o o o o o
o o o o o
o o o o o
O O O O O
fHOOO**
ro ro ro ^* ^*
ro CO ro 00 rH
ro ro i* Tf m
ro CO **< CO iH
ro oo *s< vo rro ro ^* ^* ^*
ro in o •>* vo
ro ro .3* ^* ^
ro VO CO rH m
ro ro ro ^* ^*
dp dP dP dP dp
O CM **• IO 03
dP dP dP dP dP
O CN ^< VO 00
dp dP dP dP dp
dP dP dP dp dP
O CN ^J" VO 00
dP dP dP dP dP
O CN T*< VO 00
dP dP dP dP dP
O CN T»- vo 00
CN
ro
o o o o o
•dP
dP
••
rH
W
63
>
H
M
Q
Q
<
•a
m rn -a- ^r in
••
H
H
•1
iH
rH
rH
..
H
X
o o in in m
H
hi
a
••
a
X
H
3
••
w
X
H
i
95
u
A
cn
•dP
m in m o in
r> CN r~ in CN
M O O M t l
tn in in o o
r~ t~ CN o in
in m o in in
t— r- in CN r»
m o in o o
r^OMfiin
in o m o o
r- in CN o o
CN <H O O
CN rH rH O
O
CN rH rH rH O
CN rH rH rH O
CN CN rH rH rH
CN CN CN CN CN
O
m o o m
o
u
CURING
UNIT
rH
s
CO
CN
•dP
PH
rH
•dP
rH
o o o o o
o o tn o in
O O O O O
O O O O O
o o in o m
o in m in o
O O O O O
O O O O O
o o o o o
o o o o o
o o o o o
o o o o o
00 rO rH rH
00 "tf CN CN rH
00 ^* CO CN CN
oo m
oo vo in "tf ^«
oo r- vo in T»*
o o o o o
o o o o in
o o o o o
o o in o in
o o o o o
o o o o o
O O O O O
o o o o o
o o o o o
o o o o o
o o o o o
o o o o o
.* rn ro m co
CN ro ro ro co
Ttf Ol <-i "tf vo
CN CN ro CO CO
^fOlH^VO
CN CN CO CO CO
"tf oo o
CN CN CO CO CO
CN CN CN
o o o o o
o o in o o
o o o o o
o o o o o
o o o o o
o in tn in o
o o o o o
o o o o o
o o o o o
o o o o o
CN «* "*• VO OS
CO CO CO CO CO
CN CO Tl" VO 00
CN CO rH VO CO
ro «* in r»
CM "tf VO Ol CN
co co ro ro ro
CN co ri" in co
co ro ro co ro
CN
co co co ro ro
CO CO CO CO CO
co ro co co ^*
m in in o in
r^ CN r~ in CN
CN rH o o o
m m o o
in in o o
o
in o o o o
r- o o in o
in o tn o o
r» o r» in tn
in o in o o
M f l N O O
CN rH rH rH O
CN rH rH rH
O
CN CN CN rH rH
CN CN rH rH rH
CN CN CN CN CN
o o o o o
o o o o o
O O O O O
O O O O O
o o o o o
o o o o o
O O O O O
o o o o o
O O O O O
O O O O O
o o o o o
o o o o o
oo in CO CN CN
oo "tf •<*• r o C N
CO Tf Ttf CO CO
co v o in «tf T**
co r» in re «tf
oo r~ vo "tf "tf
o o o o o
o o o o o
o o o o o
o o o o o
o o o o o
o o o o o
o o o o o
o o o o o
o o o o o
o o o o o
o o o o o
o o o o o
"tf C- <-t -tf vo
CN CN CO CO CO
T* as
CN CN
CN CN
•>* as o ro m
ro ro co
"tf VO 00 rH CO
CN CN CN CO C0
CN CN CN CO CO
CN
o o o o o
o o o o o
O O O O O
O O O O O
o o o o o
o o o o o
o o o o o
o o o o o
o o o o o
o o o o o
o o o o o
o o o o o
CN CN ^" VO 00
CM CO •# VO 00
co ro ro ro co
CM ro TT VO CD
CO ro co co co
CN CN ro in rro co co co co
CN rH CN "tf VO
co ro ro ro ro
co co co co ro
CN Ttf VO 00 rH
CO CO CO CO ^*
dP dp dP dp <#>
O CN T*1 VO CO
dP dP dP dP dP
O CN "tf VO CO
dP dP dP dP dP
dP dp dP dP dP
O CN "tf VO CO
dP dP dP dP dP
© CN "tf VO 00
dP dP dP dP dP
O CN "tf V© 00
>-H
CN
ro
"tf
•a
•a
O
<-i c o co
CN
in
ro ro
"** r~ o "tf co
CN CN ro ro ro
o o o o o
o o o o o
rl
A
W
•dP
M
o
r- t-» in o in
hH
EH
DAYS CURING
P.L
M
OJZ
MP
o ro vo
ro ro ro
<tf "tf r- o cs
tf r-- o Ti" rCN co ro ro
r~
•dP
M
dP
O N
"9* VOCO
rH
i-H
W
Ed
>
•a
H
••
EH
H
Q
Q
<
H
M
H
rH
H
H
H
PS
96
rl
A
•dP
O O
O O
o o o o o
O O O O O
o o m o o
M n n o o i
O O O O O
o o in o o
r^ in CN H o
rH rH CO
rH rH rH rH
rH rH rH rH rH
o o o o o
o o o o o
O O O O O
O O O O O
ino^or-
o o o o o
o o o o o
r- C N
u
rH
• "tf "*
o o o o o
o in in o o
O
O
O
O
O
o in o in in
r- co ro CN o
r- vo in ro CN
rH rH t-l f-i rH H H H H r t
O
z
M
EH
PS
H
PrQHZD
U
O O O O O
o o o o o
iniftfflcio
tn >tf ro C N H
m TJ< r-CT>co
m "tf CO CN CN
m Tt> ro ro CN
o o o o o
o o o o o
o o o o o
o o o o o
o o o o o
o o o o o
O O O O O
o o o o o
in r~ co cn Tj«
^* ^" "tf rH in
in r- oo as os
m vo r- co C M
tf* tf* tf* tf* tf
in o P» o «tf
in ro rH rH
O O O O O
o o o o o
tn as
rn as tn
mtf1tf"co ro
w
tH
cl
oo
CN
•dP
PH
m vo vo p- r-
o o o o o
o o o o o
in r» os o o
"tf "tf TT "tf tf
tf-tf-Tr in in
O
O O O O O
• o o o o
© . . . .
o
o o o o o
•o o o o
o • • • •
o vo CN as m
" " " " "
rH
•dP
rH
o
© o © © ©
•o o o o
o • • • •
o
o o o o o
•o o o o
© . . . .
<-H r~ vo in
O O CN OS VO
rH Ol 00 VO VO
O O "tf f» CN
rn as co r - 1 ~
o o o o m
© © © © r~
rxNosm"*
o o o o o
o o m o o
M O H O m
o o o o o
o o o in in
o o o o o
o in in o o
o o o in m
o in o r- p-
r- in co < H
r^ m
rH rH rH rH
rH rH rH rH rH
ro C N < H
rH rH rH rH rH
p~ vo in co C N
rH rH
O O O O O
O O O O O
o o o o o
o o o o o
O O O O O
O O O O O
O O O O O
o o m o o
O O O O O
O O O O O
in o oo o> in
tn ro rH
m ro "tf rH P»
in «tf ro C N "H
m T»* ai rn m
m "* co ro CN
in in oo C N rin «tf co ro C N
in oi co oi m
mtf*tf"ro ro
o o o o o
o o o o o
o o o o o
o o o o o
O O O O O
o o o o o
o o o o o
o o o o o
O O O O O
o o o o o
in r» oo as as
m vo vo r- co
** ** 'tf *tf "tf
m vo vo r- r»
•tf tf" tf" tf* tf*
"tftf""tf in in
o
o o o o o
• o o o o
o • • • •
o o in OD ro
o
o o o o o
• o in o o
© • • • •
o
o o o o o
• o o o o
©
. . . .
o
r» in as in
m
o
o o o o o
•o o o o
o
. . . .
O H ^ O l *
H0103r»t>
rH OS OS CO CO
r(
.C
•dP
J
EH
HH
HOZ
P
u
z
H
PS
p
Ur3
•dP
03 PH
W M B O N
•tftf<"tf m
m
tf "tf "tf Tl" "tf
o
o o o o o
•o o o o
o
. . . .
O M o m r "
rH r- vo m m
o
o o o o o
•o o o o
dP dP dP dP dP
O CN "tf VO CO
o
rH rH rH rH rH
inr-»oo
p»
rH
•dP
J
dP
*—.
r*>
.
.
.
.
O O CN o VO
rH os oo r- vo
as oo r» f>
Hmcoi^r-
o vo CN as in
I-H os as co co
dP dP dP dP dP
© CNtf*VO CO
dP dP dP dP dP
O CN "tf VO 00
dP dP dP dP dP
O CN "tf VO CO
dP dP dP dP dP
O CN "tf VO CO
rH
H
O H ^ S l f
CN
ro
H
•«
H
•a
rH
SSPS
gjOS
2j
B
H
X
••
03
>
H
EH
H
Q
Q
<
H
X
H
rH
••
H
X
H
J
aa
a
H
*A
o•Sa
H
j
SSPS
o o o in o
in o m CN o
ro rH o o o
o in o in m
in r^ o p» r~
o in o in o
m CN in CN o
o o © in o
o in in in o
in CN P~ CM o
CO rH rH O
CO CN rH rH rH
CO CN CN rH rH
ro ro CN CN CN
o o o o o
o o o o o
O O O O O
o o o o o
o o o o o
o o o o o
© © o o o
© o in in in
as oo p~ vo m
o o m in in
OS vo in "tf m
O O O O O
os co r» vo m
o o o o o
o o o o o
o o o o o
o o o o o
© © © © ©
o o © in in
o o o o o
o o o o o
tf* CO 00 CO OO
CN ro rotf*tf<
tf* o in os tf*tf* as in o <H tf* P» rH m o
CN CN rotf*tf* CN CN ro ro tf"
CM ro co co «tf
o o o o o
o o o o o
O O O O O
o o o o o
o o o o o
o o o o o
ro oo p* co as
ro rotf*tf*tf"
ro os ro p* r-i
ro rotf*tf"in
co co CN in os
ro co CN r» P»
ro rotf<"tf tf* CO CO ^"tf"tf*
CO CO COtf"tf*
o o in © m
o m o m m
in in r» in CN
in r» o r» P»
o in o in o
in CN in CN o
o in m in o
m CN t~ CN o
f) H O O
CO rH rH ©
CO CN rH rH rH
© m in in ©
in r» P» r- in
PO CN rH rH rH
as in rA o
O
o o o
o o o
•tf ro vo Z
CM ro tf*
Z
O
<
OS VO CN O
ch vo vo m TI<
as oo oo p* P*
os as oo p~ P *
o> as r- vo in
o o o o
o o o ©
• • • •
o o o o o
o o o o o
o o o o o
o o o o o
ooooo
ooooo
o © o o o
o o o o o
PH tf* ro P~ CN p>
tf* © in oo z CN ro rotf""tf
CN rotf*tf"
"tf O tf* O CN
CN ro rotf"tf"
tf* astf*o
o
CN CN rotf*tf*
"*P-rlinO
CN CN ro ro tf*
o o o o o
o o o o o
o o o o o
o o o o o
o o o o o
o o o o o
o o o o o
o o o o o
o o o o o
o © in in m
ro vo p- co os
ro rotf*tf<tf*
ro os ro P** r^i
co co tf* tf* m
ro 00 CN P- OS
co co
ro rotf*tf*"tf
CO CO "tf "tf "tf
CO VO CO rH m
CO CO CO "tf tf*
dP dp dp dp dP
O CN "tf VO 00
0%
2%
4%
6%
8%
0%
2%
4%
6%
8%
0%
2%
4%
6%
8%
CO ro CN CN CN
o o o o o
H
Z
w
u
O
O O O O O
CEMENT:RHA 1:4
H
Q
Q
o © in in in
ro vo oo H m
O O O O O
O O O O O
CEMENT:RHA 1:3
EH
o o o o o
ooooo
ooooo
03
H
o
o o o o o
o o in o o
o © o o o
© o o o ©
dP
W
>
O
CEMENT:RHA 1:2
L.L
%
7 DAYS CURING
P.L
Ip
% UNIT
Lr.Shr
%
L.L
%
P.L
28 DAYS CURING
Ip
Lr.Shr
% UNIT
%
97
CM
r~ r~
O O O O O
o © in in in
dP dP dP dP dP
O CNtf*VO 00
98
01
r|
is
03
•dP
in in in in o
i~ r~ CN CN ©
in © © in in
r» m © r» r-
in in in o in
P» P» CN © P»
u
CN o o o
CN H H ©
CN H H H
o
©
O
in © in o in
r» o r- in CN
CN CN H rH rH
m © in © ©
M f l N O O
CN CN CN CN CN
u
u
z
IS
o o o o o
o o o o o
o © © o o
o o o o o
O O O O O
O O O O O
o o o o o
o o o o o
O O O O O
© © © © ©
00 CO CN rH ©
COtf"ro CN
H
co in "tf ro C N
co vo mtf*tf*
co r» vo m tf*
o © © o
o © © o
. . . . tXi
tf" H CO VO Z
CN CO CO CO
o o o o o
© © o © o
o o o o o
© © o © ©
o o o o o
o o o o o
o o o o o
o o o o o
<tf oi C N vo ro
CN CN ro ro ro
tf< r- o in co
CN CN ro ro ro
tf" 00 Ol O rH
CN CN CN CO CO
"tf P^ O tf" 00
CN CN co ro ro
O O O O O
© o © © o
© © © © ©
o o o o o
© © O O O
O O O O O
o o o o o
o o o o o
o o o © ©
o o o o o
CN "tf in P» o
CN ro m oo oi
ro ro ro ro co
CN CN "tf ro o
ro ro ro ro TJ*
CNtf*•**tf*m
ro co co co co
CNtf*VO Ol CN
CO CO CO CO tf*
m o o o o
p» o m in o
m o o in o
r» m m CM o
in o m in o
r- o r» P> o
in m o in o
in o in © o
M f l N O O
CN H © © ©
CN H
CN CN H H rH
EH
H
© © © o ©
o o o o o
o o o o o
o o o o o
oz
co mtf*CN o
co in «a< co
o o o o o
o o o o o
H EH
PS H
03
POZ
UMp
V
e
is
to
JJ
©
CN
•H
•dP
CU
U
JS
W
CV
•p
JJ
<
•dP
rH
JJ
ro ro ro ro tf*
c
0
05
0)
rl
•fl
03
•dP
.5
M
M
JJ
•H
h N O M f l
CN CN CN «H H
CN CN CN CN CN
o o o o o
O O O O O
O O O O O
© © © ©
© © © ©
ro mtf*tf*CN
ro vo in co CN
CO P- VOtf"tf*
o o o o o
o o o o o
o o o o o
o o o o o
O O O O O
O O O O O
O O O O O
•tf r** a\ ro co
tf* p> H m oo
CN CN CN CO CO
CN CM CO CO ro
««* p» oi ro p»
CN CN CN CO CO
tf* 00 Ol O rH
CN CN CN C0 CO
tf* r» © tf* rCN CN co ro ro
o o o o o
o o o o o
o o o o o
o o o o o
o o o o o
o o o o o
o o o o o
o o o o o
o o o o o
o o o o o
CN CN ro m ve
co ro ro ro ro
CN C N in 00 Ol
CN CN CO p- as
co ro co co co
CNtf*tf"tf*m
ro ro ro co co
CNtf*VO CO rH
ro co co co co
dP dP dP dP dP
O CN "tf VO CO
dP dP dP dP dP
O CNtf"VO CO
dP dP dP dP dP
O CNtf*VO 00
dP dP dP dP dP
O CNtf"VO 00
dP dP dP dP dP
© CN "tf VO CO
CN
CO
H
•fl
H
tf*
••
rH rH rH
IB
I
JJ
C
O O O O O
H
©
©
DAYS CURING
P.L
HP
is
3!
p»
•dP
«w EQ
0
H
4J«H
U 0
ai »}
HH MH
M 0
r•
H
o o o o o
dP
03
U
>
H
H
H
I§
Q
EH
Z
w
X
a
u
•fl
H
z
Ed
u
ro ro co co tf*
•fl
Z
z
w
u
u
,
99
u
A
03
u
u
z
H
EH
H
PS
PQZ
U
HP
o o o o o
© m o in in
rH H
1-H rH r-{ rH rH
O O O O O
O O O O O
o o © in o
o © o ©
P» CN 00 vo vo
r-{ rH
p^ ro H Ol 00
H rH rH
p» in CN i-H Ol
rH rH rH rH
O O O O O
O O O O O
O O O O O
O O O O O
o o o o ©
in o © co oi
o o o m m
o o o o o
o o in ©
in m vo
m CO CN H
m
in CN CN Ol CO
m tf* CO CN CN
intf"tf<o P~
intf<ro ro C M
in oi ro oi in
intf*tf"ro ro
o o o o o
o o o o o
in P- oi © ©
© o o o ©
o o © © in
o o o o o
o o o o o
© © © ©
©
o © in ©
o
m
•dp
M
o o o o o
o o © in in
M f i n n o
© © © in o
© o m r- m
<N
oi
CO CN CM rH
rH rH rH
©
p» vo in ro
CN
© O O O ©
O O O O O
03
<c
Q
00
CN
rH
•dP
CU
tf*tf*tf*m
in vo oo oo ©
m tf*tf*tf*tf*m
o
o o o o o
• o o o ©
o
o o o o o
• o o in ©
in vo co co o
in vo r- oo oo
o o o o o
o o o o o
m P- oi © ©
«tftf*tf"tf*in
„ • * „ „ „
tf*tf*tf*in in
o
o o o o o
• o o o ©
©
o
o o o o o
• o o o ©
o o o o o
• o o o ©
^3
•
•
• •
©
. • • .
© p- oi ro os
rH p» VO VO LO
C5
. . . .
O H "tf O ©
H ro p» p» p»
©
• • • •
© 00 © P~ ro
HOOOP-r-
o o CN co in
© ©
in o
o m o M i i
o o o o o
o m o in ©
P» CO H Ol CO
H rH rH
o o o o o
o m in in ©
p» in ro H H
© © © in in
OITIOM^
P» CN • VO VO
H H O l
© o o o ©
© © in in o
r- m CN H H
rH rH rH rH rH
rH rH rH rH rH
rH rH rH rH rH
© o © © ©
o o o o o
o o o o o
o o o o o
O O O O O
O O O O O
O O O O O
m
o © © in o
o o o o o
in ro CN ro oi
m CO CN H
in P » p» co ©
m CO CN CN CN
in rotf<oi rintf"CO CN CN
in in P~ H oi
intf*ro ro CM
in oi ro oi in
intf"tf"ro ro
PS
p
o o o o o
o o o o o
o o o o o
o o o o o
o o o o o
o © in © in
o o o o o
o o o o o
o o o o o
o o o o o
Or!
•dp
03 CU
in vo oo oi ©
in vo oi o o
tf*tf*tf*in in tf<tf*"tftf*in
in vo r- oo ro
m vo
^•jp •^^ ^3^ ^*r ^"*v
^•j**1 ^LJ*1 *^r ^*HI ^*J^
^<tf*tf*in in
o
o o o o o
• o o o ©
o
o o o o o
• o o o ©
©
© o o o ©
•m o o o
o
o o o o o
o
o o o o o
•o © o o
o co in CN o
o
rlCOP-hh
J•dp
J
rl
J3
03
•dP
U
rH
EH
H
Hoz
P
o in in o
H Ol 00 P» P*
©
. • • .
© vo C N oi in
H Ol Ol CO CO
p- vo in ro
CN
CS
z
H
P-
ro oo
in r» oi ©
o
>H
<<
Q
*>
(J'dP
hH
©
. . . .
O Ol iH ro Ol
H h M O i n
dP dP dP dP dp
O CNtf*VO CO
©
. . . .
r^
. . . .
• © © in ©
rH 00 CO P- P-
© H ttf oi r~
H Ol CO P~ P-
©
. . . .
© vo C N oi in
H Ol Ol CO CO
dP dP dP dP dP
O CNtf*VO CO
dP dP dP dP dP
© CNtf"VO CO
dp dP dP dP dP
© CNtf*VO CO
dP dP dP dP dP
O CN "tf VO CO
H
CN
ro
oi
CN
r~ vo
?—i
^^
dP
a.
aa
H
rH
rH
03
£
*iOS
£K
•a
Cd
>
H
EH
os
EH
EH
Z
••
Z
Cd
X
Cd
U
••
H
pj
Q
§
Cd
Z
Cd
X
Cd
U
U
§
EH
.
.
.
.
• * •
EH
Z
H
X
Cd
u
P
2
100
T A B L E 4.8
Additive %
Effect of delay in compaction on the U C S of lime and
lime-RHA stabilised soil C.
Time elapsed
Since mixing
90 days
U C S (MPa)
loss in
strength
%
8 % LIME
0.00 hours
2.00 hours
4.00 hours
6.00 hours
24.00 hours
0.55
0.52
0.51
0.51
0.48
0.00
5.45
7.27
7.27
12.72
0.00 hours
2.00 hours
4.00 hours
6.00 hours
24.00 hours
0.44
0.42
0.41
0.40
0.39
0.00
4.50
6.80
9.09
12.04
0.00 hours
2.00 hours
4.00 hours
6.00 hours
24.00 hours
0.35
0.33
0.32
0.32
0.30
0.00
5.70
8.57
8.57
14.28
8 % LIME: R H A 1:1
8%LIME:RHA1:3
101
T A B L E 4.9
Effect of delay in compaction on the U C S of cement and
cement-RHA stabilised soil A.
Additive %
Time elapsed
Since mixing
90 days
loss in
U.C.S. (MPa) strength
%
8% CEMENT
0.00 hours
2.00 hours
4.00 hours
6.00 hours
4.60
3.22
2.34
1.47
0.00
30.00
49.00
68.00
0.00
2.00
4.00
6.00
hours
hours
hours
hours
3.10
2.82
2.60
2.44
0.00
9.00
16.00
21.00
0.00
2.00
4.00
6.00
hours
hours
hours
hours
1.80
1.65
1.55
1.51
0.00
8.00
14.00
16.00
8% CEMENT:RHA 1:2
8% CEMENT: RHA 1:4
102
T A B L E 4.10
Effect of lime and lime-RHA additives on the shear
strength parameters of Soil C.
ADDITIVES
7 DAYS CURING
Lime
0%
4%
6%
Lime: RHA
1:1
0%
4%
8%
Lime: RHA
0 (degrees)
C (MPa)
28 D A Y S C U R I N G
0 (degrees) C (MPa)
7.0
30.0
28.0
0.08
0.16
0.23
7.0
35.5
33.0
0.08
0.17
0.22
7.0
20.0
34.5
0.08
0.12
0.15
7.0
21.0
38.0
0.08
0.13
0.17
7.0
13.0
21.0
0.08
0.11
0.11
7.0
15.5
25.0
0.08
0.12
0.14
1:3
0%
4%
8%
103
T A B L E 4.11
Effect of cement and cement-RHA additives on the shear
strength parameters of Soil B.
7 DAYS CURING
ADDITIVES
0 (degrees)
Cement
0%
4%
8%
Cement: RHA
1:2
Cement: RHA
C(MPa)
28 DAYS CURING
0 (degrees) C(MPa)
19.0
36.5
44.0
0.08
0.11
0.16
19.0
40.0
46.0
0.08
0.19
0.29
0%
4%
8%
1:4
19.0
30.0
31.0
0.08
0.12
0.16
19.0
37.0
38.0
0.08
0.20
0.24
0%
4%
8%
19.0
21.5
30.0
0.08
0.09
0.16
19.0
22.0
32.0
0.08
0.15
0.17
104
T A B L E 4.12
Effect of various additives and curing time on the C B R of
stabilised soil A.
CBR
28 Days
90 Days
0%
4%
8%
55
75
72
55
81
76
0%
4%
8%
55
70
75
55
74
80
0%
4%
8%
55
60
65
55
60
68
0%
4%
8%
55
50
45
55
50
45
0%
2%
4%
55
100
120
55
105
116
55
60
102
55
61
112
55
56
100
55
60
110
ADDITIVES (%)
LIME
LIME:RHA1:1
LIME:RHA1:3
RHA
CEMENT
CEMENT:RHA1:2
0%
4%
8%
CEMENT:RHA1:3
0%
4%
8%
105
T A B L E 4.13
Effect of various additives and curing time on the C B R of
stabilised soil B.
CBR
28 Days
90 Days
0%
4%
8%
30
40
37
30
43
41
0%
4%
8%
30
37
39
30
41
42
0%
4%
8%
30
32
35
30
35
37
0%
4%
8%
30
25
25
30
25
24
0%
2%
30
108
30
100
ADDITIVES (%)
LIME
LIME:RHA1:1
LIME:RHA 1:3
RHA
CEMENT
106
T A B L E 4.14
Effect of various additives and curing time on the C B R of
stabilised soil C.
CBR
28 Days
90 Days
0%
4%
8%
19
31
55
19
32
60
0%
4%
8%
19
25
32
19
27
34
0%
4%
8%
19
22
24
19
23
27
0%
4%
8%
19
19
20
19
19
19
0%
4%
8%
19
32
51
19
35
56
ADDITIVES (%)
LIME
LIME:RHA1:1
LIME:RHA1:3
RHA
CEMENT
107
TABLE 4.15
No. of Load
Applications
50
500
5000
50000
50
500
5000
50000
50
500
5000
50000
50
500
5000
50000
50
500
5000
50000
Permanent deformations of untreated pavement (mm)
Row/Column
a
b
c
d
e
f
g
E
1.15
0.96
1.95
-0.11
1.00
4.11
3.00
3.15
0.90
4.00
4.30
5.00
1.15
4.11
4.89
5.42
2.20
4.00
4.95
5.50
1.80
1.95
2.72
3.72
0.25
0.40
0.75
-0.25
F
0.30
0.60
0.80
-0.11
1.80
2.36
3.36
4.56
1.90
3.60
5.00
6.96
2.50
3.60
5.00
6.03
2.50
3.57
4.91
6.50
2.00
3.11
4.02
5.15
-0.04
0.05
0.61
0.86
0.41
0.61
2.30
2.40
2.00
2.50
4.20
5.72
2.85
3.75
5.80
7.88
3.00
4.11
6.74
7.95
3.12
3.95
6.70
8.02
1.60
3.08
4.50
5.34
-0.04
0.25
2.01
2.18
0.05
0.30
0.50
-0.80
2.11
2.33
4.30
6.80
3.00
3.80
5.65
7.90
3.15
4.12
6.90
8.00
3.12
4.25
6.97
8.95
1.51
1.71
2.91
3.80
0.62
0.95
1.01
1.35
0.05
0.80
0.71
-0.50
1.30
1.65
1.85
2.00
1.60
2.00
2.52
2.98
1.00
2.33
4.11
4.98
1.50
1.91
4.30
5.10
1.49
1.63
0.80
0.40
0.41
0.43
0.00
-0.60
G
H
I
108
TABLE 4.16
No. of Load
Applications
50
500
5000
50000
50
500
5000
50000
50
500
5000
50000
50
500
5000
50000
50
500
5000
50000
Permanent deformation of 2 % lime treated pavement (mm)
Row/Column
a
b
E
0.30
0.60
1.30
1.70
F
0.20
0.40
0.95
1.55
d
e
f
g
0.57 1.57
0.75 2.40
1.12 4.25
1.19 4.45
1.70
2.17
2.85
2.90
3.80
4.15
4.58
4.78
1.76
2.20
2.71
2.46
0.50
0.98
1.18
1.01
1.29
1.79
2.17
2.86
3.28
4.44
5.10
5.90
2.39
3.68
3.96
4.41
2.34
3.69
3.52
4.84
1.45
2.29
2.87
3.65
0.40
0.67
0.68
1.68
G
0.95
1.10
1.30
1.43
1.58
1.73
2.56
2.66
4.26
5.01
5.54
6.64
3.12
4.42
4.75
4.69
3.93
4.68
5.32
6.53
1.94
2.55
2.55
3.15
0.47
0.52
0.80
1.49
H
0.20
0.50
0.96
1.33
1.63
2.00
2.40
2.60
4.14
5.03
6.50
7.16
5.50
6.83
5.94
6.83
5.95
6.90
7.12
7.20
2.16
3.48
3.63
3.74
-0.15
0.18
0.10
0.28
I
0.35
0.25
0.25
0.00
0.35
0.30
0.67
0.90
0.58
1.29
1.88
1.85
1.31
3.32
4.15
3.06
2.40
3.35
3.75
4.85
0.45
0.61
1.30
1.48
0.23
0.26
0.30
0.40
c
109
TABLE 4.17
No. of Load
Applications
50
500
5000
50000
50
500
5000
50000
50
500
5000
50000
50
500
5000
50000
50
500
5000
50000
Permanent deformations of 3 % 1:1 lime.RHA treated pavement
(mm)
Row/Column
a
b
c
d
e
f
g
E
0.40
0.50
0.90
1.30
1.36
0.76
1.00
1.15
1.85
2.90
4.30
4.90
1.60
1.97
2.00
2.10
2.00
2.80
3.44
4.00
1.60
1.80
1.90
1.90
0.32
0.79
0.99
0.00
0.30
0.40
0.80
1.00
1.40
1.60
1.80
2.46
2.30
3.30
3.92
4.40
2.20
3.20
3.79
4.40
2.20
3.00
3.70
4.50
1.70
2.08
2.67
3.24
0.50
0.70
1.00
1.15
0.90
1.00
1.31
1.40
1.60
1.80
2.40
2.60
3.95
4.99
5.80
6.00
3.00
4.00
4.40
4.50
3.15
3.75
4.60
5.50
2.10
2.56
2.90
2.95
0.55
0.90
1.11
1.32
0.30
0.70
0.90
1.10
1.50
2.15
2.30
2.40
4.05
4.86
5.60
6.00
4.50
5.16
5.50
6.10
5.85
6.75
6.45
7.00
2.16
3.20
3.42
3.70
0.49
0.60
0.72
0.80
0.30
0.35
0.40
0.20
0.30
0.40
0.60
0.65
1.00
4.00
1.90
2.00
1.30
2.11
2.89
3.00
1.90
2.96
3.48
4.50
0.90
1.25
1.50
1.50
0.30
0.32
0.15
0.22
F
G
H
I
110
TABLE 4.18
No. of Load
Applications
50
500
5000
50000
50
500
5000
50000
50
500
5000
50000
50
500
5000
50000
50
500
5000
50000
Permanent deformations of 1.5% cement treated pavement
(mm)
b
c
d
e
E
-0.71
-1.15
0.12
1.11
-0.36
-1.05
0.28
-1.31
1.50
0.43
1.75
1.63
0.61
1.86
0.28
1.74
1.51
1.34
1.41
2.19
0.19 -1.12
-1.34 0.02
-0.36 0.11
0.97 1.42
F
-1.70
-1.00
0.80
-1.90
-0.79
0.10
0.90
-0.16
-1.65
-0.37
1.87
2.39
3.04
3.40
4.11
4.04
2.43
3.18
3.97
4.13
4.29
2.80
1.77
3.07
1.43
1.84
1.41
1.85
-0.88
-2.15
-1.90
-2.15
-0.49
-0.82
-0.80
-0.65
-0.45
-0.35
1.05
1.25
1.26
1.05
1.34
2.62
1.27
0.35
1.56
2.32
0.91
0.09
0.18
0.90
-0.29
0.90
1.00
0.11
-0.68
-0.14
0.06
-0.91
0.31
0.25
0.02
0.25
1.29
1.79
2.43
2.68
1.56
1.96
1.56
2.00
1.30
2.23
2.53
2.96
-0.33 -0.24
1.22 -0.24
1.22 -0.21
1.52 -0.12
0.02
0.87
0.10
-0.23
0.00
0.35
0.60
-0.73
0.00
0.77
0.64
0.80
0.84
1.58
1.05
1.64
-0.69
2.06
1.47
0.77
1.11
1.55
1.92
1.35
Row/Column a
G
H
I
f
g
-0.29
0.78
-0.69
-0.07
Ill
TABLE 4.19
No. of Load
Applications
50
500
5000
50000
50
500
5000
50000
50
500
5000
50000
50
500
5000
50000
50
500
5000
50000
Permanent deformations of 3 % 1:1 cement.RHA treated
pavement (mm)
Row/Column a
E
F
G
H
I
f
b
c
d
e
0.10
2.20
2.34
1.64
0.33
0.08
0.57
-0.20
0.69
0.19
0.45
-0.13
0.75
1.57
2.43
1.39
0.25
0.80
1.14
1.41
-1.86 1.08
-0.40 0.00
0.37 0.15
-0.44 -0.23
1.44
1.00
0.27
-0.32
1.28
1.45
2.43
2.11
1.65
0.75
1.78
1.76
2.53
1.56
2.57
2.40
2.29
0.01
3.69
4.22
1.60
1.11
2.22
1.55
3.50
2.50
2.33
2.92
0.00
0.04
0.29
1.35
0.82
1.17
1.79
2.90
1.37
1.41
1.88
2.63
2.04
2.55
2.82
2.91
1.61
1.75
1.78
2.41
1.18
1.27
1.15
2.87
0.76
0.81
1.05
2.53
0.00
1.78
2.53
1.90
0.67
1.13
1.46
1.87
0.64
1.14
1.86
2.23
0.05
1.46
1.85
2.01
0.60
1.05
1.77
1.96
0.60
0.53
0.77
1.62
0.00
0.02
0.15
0.30
1.27
0.00
1.28
1.52
0.13
0.62
1.00
1.03
1.05
0.00
1.27
1.30
0.42
0.42
1.53
1.80
2.40
-0.82
-1.22
-0.55
1.18
1.18
0.68
0.94
0.19
-0.42
-0.06
0.47
g
112
TABLE 4.20
No. of Load
Applications
50
500
5000
50000
50
500
5000
50000
50
500
5000
50000
50
500
5000
50000
50
500
5000
50000
Permanent deformations of 8 % R H A treated pavement (mm)
Row/Column a
f
c
d
e
E
1.10
1.20
1.15 3.20
-0.30 3.80
0.10 3.60
1.50
3.50
4.16
4.60
1.80
3.80
4.70
5.10
2.00
3.80
4.80
5.00
1.70
2.10
2.80
3.75
0.41
0.30
0.70
-0.40
F
1.30
1.46
0.44
0.00
1.65
2.23
3.41
4.50
1.92
3.13
4.79
6.00
2.40
3.43
4.89
6.25
2.25
3.75
4.85
6.50
1.95
3.00
4.30
4.75
0.05
0.20
0.55
0.91
1.50
1.75
1.90
2.00
2.00
2.50
4.00
5.80
3.00
3.68
5.50
8.13
3.20
4.00
6.55
8.00
3.36
4.23
6.75
8.16
1.70
3.10
4.20
6.03
0.26
0.41
1.98
2.28
H
1.50
1.60
1.20
1.20
2.20
2.51
4.00
6.30
3.20
3.61
5.91
8.00
3.32
4.00
7.02
8.00
3.40
4.25
7.00
8.20
1.60
2.21
3.00
3.60
0.70
0.95
1.21
1.41
1
0.25
0.30
0.40
0.00
1.60
1.91
2.15
2.70
2.00
2.44
3.06
4.90
2.00
2.50
4.17
5.20
2.40
2.50
4.36
5.30
1.40
1.69
1.90
2.00
0.70
0.99
0.00
-0.40
G
b
g
M.-V
113
CO
LU
CO
Q
O
0)
SI
LU
<
(13
Z
DC
D
O
CO
Li.
$
O
Q
CO
CM
a
CO
o
D
CD
LL
o
z
DC
D
O
\\d
114
CO
CO
<
Q_
<
D
o
O)
<
1
I
CC
LU
2
I
z
rr
I-
O
z
LU
LU
o
i
Q
co
CM
II
ix.
UJ
o
hO
CO
z
o
DC
D
O
D
CM
o
LL
]§
115
O
<
-J
8
O
CO
LU
CO
_J
CQ
Q
LU
CO
_J
m
f
CO
CO
(0
CO
o
o
co
LL
p
«*CO
CO
i
)LL n
D
LU
CO
I
CO
CO
o «
SS
•£
N
<
X
a. i$
j
a
J
tt
g0 l 1
iLL
o
£
V
H
H
Z
3
<
»-
f
r"
•*•
< <
DC
UI
£ £
j -J
\1
O
»
Li!
>
a
<
X
a
H
R
<
IE
UI
£ £
-i
-I
I1
116
o
-J
5
o
CO
CO
Q
LU
CO
-J
CQ
Q
LU
CO
_J
m
co
i£
(V)
TJ-
CO
«t
o
LL
IX.
* o
rv.t»iO"toc^'-o
o o o o o o o
06(f)
CQ
-J
QE<W%
o
ZLU
CO
Q
LU
CO
-J
CQ
CO
JD
0
2 -» LUffi
B
OwE
co<S
•*
TfZQC
LL
117
O
-J
o
CO
Q
LU
o
22
LU
CO
_J
CQ
CQ
o
LO
10
g
LL
LL
£2
CQ
JQ
~ SP
3
CQ CM
z
Q
DC CO
I <
CO X QC
cr
LU
<
CC CL
LU UJ
Q
i
o
z
- J I J CC
IO °0 Q
LL
g
-J
CQ
CO
JQ
IO
O
A
118
«
M
£
•
O
r
: i •fc
a •
\
/
o
j
o
i
7
i
LU
CO
-J
CD
X
tc
o
z
UI
-J
•-
X <
X
U>
O tt.
I
CO
7
<
U.
'• '
o
/
>
\ \
a-
I
*
«V
< <
X
X
a.
e
i- ••
z
z
UI 111
£ £
** H 8 S
Z j I
%
CO
CO
to
o
«2S
/
/
g
-«t
X
•z
1- £
z UIz
£
£
UI 111
o o
UI
LL
CO
w
<s
<
(
if/
i
r
•* IO ffl «"J <N
i
1 \
...i
It)
tO
W W T^
O
<
X
It
h-
o
i i ///
CO
Q
LU
CO
-J
CQ
!i /
l
w
*
•
I
•
z
/
/
3 8
1 1
<
¥W\
l:
LL
a
£
£
z
g
»
rV
o
•
<
X
>
•z
i- H
Z
UI UI
z
3
2
£
UI
o o
O
<
UI
i
«
•
<
I
e
H
V*
52
CQ
_J
O
LU CD 00
CM
CO
O
LU
to
-J
CQ
CO
X)
CO
cc x
cc
XOC
LU
cc z aa.
< LU
L U ^ S=
-JOg
g
LL
y
O
•*
I-
/
o
t
j)
/
/
/
i
<
j
Q
Q
<
1
N
v\
.i
IQ
o
I
•
*
IT
I
t- H
u o
z
/
/
.
1
UI UI
LU
>
_i
•X
^ "»
*a• -a
<
11
l">
*
<
a
iff,
<
X
£ £
?
•Jr
UI
O
7 Z
UI UI
*/
_i h
Z
£
UI
Q
f-
EL*
i
2
111 UI
CO
o
(O
w_
ox
{
5?
wo
CO.'
<
T
£
u.
< <
O «X aX
1- r-
h-CO
Z-J
2 CO
£
IU
O
-J
;>
£
o
z
UI
" CO
7
O
X
£
H
Z
»*•
UI
z
£
UI
111
U
su
1\
y>
119
o
-J
O
o
CO
CO
Q
LU
CQ
CO
o
LU
CO
_J
CQ
I
co
CO
o
K
g
g
LL
LL
liJW
-'coco
LL
>•
CD
-J
Q
O
^ LU oo
Q
D CQ CM
LU
O
CO
o <
z
>-co
Q
g X cc
hLU
cc
CO
CL
<
LUO
<
-J
ZJOL
CL O
*
gx
LL
cc
a
in
co
-j
CQ
I
.Q
g
LL
120
O
o
o
co
a
CO
D
LU
OD
-J
CQ
LU
<£
_J
CD
CO
03
00
i^
g
00
CO
o
g
LL
LL
H CO
z=!
2co
W * en
, LU >:
<§
X
CQ
oo
CM
LU
O
o
zX O
>cc
cc
g z LU
CL
iUi
O
CL W
3
""O z
cc
<
D
X
<
g CC
LL
o
CQ
_J
O
CO
Q
LU
22
CQ
CO
XI
00
g
LL
121
tO
z
LU
5 <
•7
LU
LL
O
-J
o
-o QCO
%co LU Q
HI 3 CO
Q
-J O
LU CQ 0)
LL X
O
*~£ Q
U- Z CO
00O
<
CM
O
I DC
LU h- DC
CD
LL
%
LU
a.LU *= O O O O O O O O O
TCM CO *tf
10 IO N
CO
O DC
1
1
1
•
1
1
1
1
CO
D -1OC0C0 - Z DOCO
#
z*otfQ
'VI
122
o6
LU
co
Q D C O Q
LL. LU
O
o°
UJ O
CO
LU O 9 Q
LL.
LL. Z CO DC
LU
LU O
< CL
X
CEO
i Z
oo
Eo
Ococo
Z
DOCO
^
123
u. >"
Wjj.
Q
_i
2
o
1-
IN
•
<
X
is
z
UI
£
in
<
3
rz
* ui 1
,
<rQ
r CO
LU LU >Z
<
r
«
LJJ -J
OfflO
h^
-3» r"~
u
i-
£ i
Hi
gco
LU X =
ODCg
LL od a.
°<o
DC X Z
OQCCQC
T- «ej \J
xf Zi
2^
"•3
t-
z z
UI
o o
LL
<
DC <
cc
Z CQ Q
LU O)
S5•
UjZO
=ico w
LL UJ Q-
t z
o
h-
O QO CCD
LU
LL << mQ
LL X
CM
LU cc
T—
I O
g LU co
•
LL
o
a:
125
o
<o
wo%
^
Q
-* 0= ~
^o°>
~
LL LU
X
o
Z
I— o
w
o
D
O
DC
LU
CL
CD
tr
LU CO
LL LU
li- >
LU rkm
LLX
cc
126
H
Z
LU
LU
1
z
s
Q
LU
CO
-J
CQ
CO
o o
LU
LU
g s
sis
{t
g
LU
LL
b:
a 8
<
X
<
111
cc
oc
0)
111
V"
LU
2
o o
1(9
a>
h-
s
z
E
I
CO
rx
0
u.
uu
LL
oO
DC
g
zm
g
DC
I
D
T—
LL
DC LU DC
Q cc CO
X LU LU
LL
LU
hLL
O
O
i
LU
rf CO
CO
LU
E
E
z
2
<
h-LL Q
Z o<
LU
DC o O O
LU DC LU
0.X H O
Q
LU
co
Sc O g
I
hZ
LU
DC
LU
>-aJ
o
C
CM
*s
u.
UI
a
'n
127
CO
HI
m
ui
-i
o o
o o
I \
10 n
^z
0)
UI
x 2
o
DC LU
8 8
-•s 55
i
s
a- «
OO DL
£2 LU
co
0 S
H £
LL <
co
CO
il
p u
§ o
o 8
ID
-I
o o
IO
»
IO
I *
CL
UJ CO
LL LU
<
_J
z z
o
Sc g g
DC Q
ft
<
oLU a.-i
ft X
I- °LL
it
oo LL
U J DC
O
X
LL
<
LU
CQ
£o :>
LL
LU
£o
o CO
z
<
£
DC
LU
O
0.
CO D
i
g
cc
UJ DC
LULU
& S:
lO Q
T-- UJ
•3
H
a o
8 8
\ \
s.«8
CQ
5 CO
LL
iu
Sd
o
o
128
©
<¥>
IM
©®
©
•
'
®©
®
PLAN
PA.CXERS
3) JACKS
ELEVATION
FIG.4.20 - Repeated dynamic load test - Removal of
trolley from beneath materials containment bin
129
FIG.4.21 - Scanning electron micrograph of the fracture
surface of the untreated Soil A
130
"Wfei?
X '
-7 V
*?
y
• • . * %
/^*-JfeP '
i*&i*r
A
fir
••K^^^^^^^^MaM^WiaMaW^^HEiSr
[•• ->>*'^^L.'''^S&uiatiK ^-
•w'^'^Wl K i p
H ^ ^ ^ B ( > ^ . ^**^^|3
FIG.4.22 - Scanning electron micrograph of the fracture
surface of the untreated Soil C
131
FIG.4.23 - Scanning electron micrograph of the fracture
surface of Soil A stabilised with 8% content
of 1:1 lime-RHA additive after 7 days
accelerated curing
132
FIG.4.24 - Scanning electron micrograph of the fracture
surface of Soil C stabilised with 8% content
of 1:1 lime-RHA additive after 7 days
accelerated curing
133
5
j-.i
CD
«•«
a-»
.1 i n
rvi
a-tl
ill
Ji
~ji
i
9-11
IS
MS
• ris
-a'SS
9-SS
• a-vs
a-H
j-n
•a-is
• a-«s
o-l»
a-»
Vs —
r *'VT
0-?»
!•»
i I 0i>
---/ L
«•!>
fit
•3^;ui|0T>>J
• m
s-^f
>
-*
— = = ^
«-S
»•«
a-t«
o-rr
a-is
s-of
o-i:
Q-JZ
• o-«
*<??$
o-w
o-sz
a-.z
^on
a
,ui
p>j -..
• i-ol
SI
a-Ll
j-)l
•rsi
051
^.u.jot^
<
-1
•H
0
W
T3
CU
+J
(Q
CU
U
•P
c
3
0
c
u
CU
4J
a
c
o
•H
+J
U
(T3
5-1
VW
4-1
•*H
73
>1
<0
(-1
i
X
o-n
•rn
o JI
a-b
OS
in
CN
o-:
«•?
«s
l-H
134
9»
«-t>
«•«
«•«
0"»1
«-o
O-:J
O-I>
»•«»
, rlS
11S
• «-.s
« • «
OSS
9>S
T
*o*s
«-e
a-a
o-is
OTIS
!•»
9W
I
0-l>
4-1»
fS»
rtt
o-tv
o-tv
u
o
w
9-»v
rK
au
T3
CU
ris
o-st
<H
CU
M
P
9-V£
• o-«
•P
. 9-tt
c
• OMC
4-1
• q-91
0
' Til
eu
• O'R
p
• <ra
P
a
c
0
•H
P
o
(fl
J-l
4-4
4-1
•H
T3
>i
(0
SH
CN
I
X
H
fa
wv'v
135
9'K
0»
'o?5
Q-JJ
^E:.
o-a
o-?>
m?
iw
Vs
o-n
o-»
o-n
«•«>
a-B
-J.:
O-JS
9 a
9-is
a-SJ
•
*
o-K
O-JS
%
a-S
8"S
• a-JS
_./•
• o'£>
• O-lt"
SH
CU CU
CO P
-a
• a-»
•1-S»
•H 4-1
ryr
r-H to
•H
.0 <u
(0 >
P •H
75i"
^J
• a-if
•H
•q«
rfjTJ
•a-tt
• a-tr
•rn
•a-ss
a-rt
4-cc < b
!• a «*. CVj
X)
rH (0
•H
- 0 Li
a-if
(• oaf
y
j-a-sr
**
• a-i:
1
• a-H
- a SI
-o-W
*\
:
Cfl P
• rgv
-«:
r a- 3
?\\~-<°2)1rs~\-*^OO^O
-ru
y>
r
r«
ra-S«
r
^
0 <
T*
W
p-H
4-4 P51
0
cu
•g
rH cn
c
U r4 c
CU •H
P rH SH
P •• 3
(fl rH CJ
ft
4-1 T3
3
0
•H
P
U
0 CU
p
P rfl
C SH
CU CU
«+JH
5-1 c CU
4-1 0 u
4-4 u 0
•H
(0
T3 <#>
!. a-3.
'- a-it
>i
- «•»*,
rd A <d
- J-SI
:. O - M
00 tn
' 0 fl
3
"ay.^V ^
o-n
1o-n
rO'OI
1
rCN
- at
J3
a-t
• a 1
•i i
•
M4J-0
6
H
fa
136
s
cowo
— = A
nw\i <
a-tf
a-SC
a-iC
a-«
• a-SE
r )•«
'• a-JE
?
J*
oo^o
- O'ZE
-a-it
- a-af
- «-w
-a-tz
-a-12
-a-«
- o-sz
- a«
-a-«
z
or$
- o-z:
:
- liZ
-M
-rn
- asi
- a-ii
- O'll
- a-si
- O'W
-'5-cl
C^S
^V-UI
^Ak\*)
L™
* \
- a-II
• ]-fji
/
T3 SH
CU 0)
W P
•H 4-1
H (fl
•H
A CU
(0 >
P -H
k*
cn P
CN
•p
U T3
•o
r-H (0
•H
4H I
0 CU
o 4
3 g
SH •H
CU
•H
p
SH
p
3
(0
O
s
a
4-1 T3
3 O CU
0
P
•H -P (Q
P 3 SH
rj CU 0)
fl+JHrQ
SH 3 <U
4-10 0
4-1 u o
•H
oo ra
>i
>
rd ,3 (fl
H P 73
I -H
oo
CN
X! 15 r>
•3-3
• U
• 3?
IJ.
J-S
H
fa
137
Chapter V
DISCUSSION AND ANALYSIS OF RESULTS
CONCERNING RICE HUSK ASH
5.1 RHA as a single additive
5.1.1 Effect of RHA additive on compaction
characteristics of soils
It has been observed that when RHA was added to the soils A,
B and C the maximum dry densities decrease and the optimum
moisture contents increased (see Tables 4.2a to 4.2c). The
increase in the OMC of all treated soils was related to the
additive quantities. As a general rule, it can be said that
the addition of a quantity of RHA to a soil may lead to an
increase corresponding to about 50%-75% of that quantity, in
the OMC of that soil.
The increase in the OMC was mainly due to the additional
water required for wetting the large surface area of the
fine RHA particles. However, as the RHA is not finer than
soil C it is believed that the increase in the OMC of this
treated soil and other soils could be influenced by the
morphology of the RHA particles' surface and their great
affinity for absorbing water, a characteristic which was
subjectively noticed during the testing programme.
138
The decrease in density of all treated soils was mainly due
to the partial replacement of comparatively heavy soils with
the light weight RHA (specific gravity 1.79). The decrease
in density could also be influenced by the increase in
porosity of all compacted soils due to addition of RHA. The
porosity was calculated in accordance with the following
simple equation:
P = Po(l-E)
where: P is the apparent density of a compacted specimen.
P0 is the equivalent specific gravity of a mix
taking into account the specific gravity of all
constituents.
E is the value of porosity.
Knowing the specific gravity of soils and RHA, it was found
that by adding 8% of RHA to the soils A, B and C, the
corresponding porosities were increased by 10%, 11% and 5%
respectively. The calculations of porosities are shown in
the Appendix B.
The treatment of a soil, therefore, by RHA single additive
increases the OMC of the soil. This can be utilised in
improving the workability of wet soils, particularly if the
139
increase in OMC of the soils due to addition of RHA was more
than that which occurred by adding lime or cement to the
soils (see Tables 4.2 and 4.3).
However, this improvement
in workability could be offset by the increase in porosity
which may affect the strength properties of treated soils.
5.1.2
Effect of RHA additive on the strength properties
of soils
5.1.2a Effect on UCS
It can be observed, as shown in Tables 4.5 and Figure 4.3,
that RHA as a single additive has no positive effect on the
UCS of soils.
This can be explained by:
a) The partial replacement of soils with RHA does not
significantly
change
the
grading
of
the
soils
to
satisfy the requirement of the maximum density curve as
shown in Table 5.1.
b) The minor change in grading was accompanied by an
increase in porosity of the compacted specimens.
c) The RHA used can be chemically termed silica as it
contains 58% silica.
with soil.
Thus it does not chemically react
140
5.1.2b
Effect on CBR
It can be observed from Tables 4.12 and Figure 4.13 that the
CBR values of treated soil A and B decreased with the
increase in the quantity of RHA additive. This could be
attributed to the increase in compressibility caused by the
increase in porosity of these treated soils (see 5.1.1).
A reduction in CBR value was not observed in the case of
treated soil C. This is consistent with the fact that the
increase in porosity in that case was minimal (ie 5%) as
shown in section 5.1.1.
The CBR values of all of the treated soils did not vary with
the variation of curing time. This implies that no
reactions have taken place between RHA and the soil during
the various curing times.
5.1.3 Effect of RHA on the Atterberg limits and linear
shrinkage of soils
Liquid limit and plastic limit of RHA treated soils
increased with the increase in additive quantity, with the
notable exception of high liquid limit soil C, where the
liquid limit decreased with the increase in additive
quantity. In general, the plasticity of all soils is
decreased by the addition of RHA. This is clearly shown by
141
the fact that plasticity index and linear shrinkage of all
RHA treated soils decreased with increasing additive
quantity. These effects are due to the partial replacement
of plastic soil particles with RHA which is an abrasive
non-plastic material.
However, the effects on the plasticity and linear shrinkage
of soils treated with RHA are less than those which occur by
the addition of lime or cement to soils.
For example, the addition of 8% RHA to soils A and B did not
result in comparable linear shrinkage and plasticity index
to that achieved by the addition of 2% lime or 2% cement.
For soil C, which is very suitable for lime treatment, the
addition of 8% RHA resulted in lower values than were
achieved by 1% lime addition. From Figures 4.5 and 4.7, it
can also be deduced that 5 - 6% of RHA is required to
achieve the same results as 1% lime addition. The use of
RHA, to modify the plasticity and linear shrinkage of soils,
therefore is not efficient.
From Table 4.6 it can be observed that liquid limit, plastic
limit, plasticity index and linear shrinkage, after a curing
period of 28 days, are similar to those after a curing
period of 7 days. This implies that no reaction has taken
place between RHA and the soils during this period. This is
consistent with the finding for strength (section 5.1.2).
142
5.1.4
Effect of RHA on the behaviour of soils under the
action of repeated dynamic load
The various measurements of deflections for both pavements
(the untreated soil D and the 8% RHA treated soil D) shown
in Tables 4.15 and 4.20 reveal that:
i) For any point on the grid, where measurements were
taken, the deflection increased with the increase
in number of load applications.
ii) As the number of total load applications to the
pavements increased, the actual deflection per
single load applied decreased, indicating that
pavement stiffness had increased (see Tables 5.2c
and 5.2d).
iii) The maximum values of deflection for the various
number of load cycles occurred close to wheel
contact area and particularly under the wheel
edge.
iv) Deflection profiles for both pavements (Figures
4.14 and 4.19) appear to be similar. The maximum
values of deflection, for both pavements, after
50,000 load cycles were also similar (ie, 8.95mm
for untreated soil and 8.20mm for 8% RHA treated
soil).
143
All of these observations indicate that the behaviour of RHA
treated pavement under the action of repeated loads does not
vary from that of untreated pavement subjected to similar
loading. This implies that RHA does not affect favourably
the stiffness or compressibility of soils and this is
consistent with the finding of strength (section 5.1.2).
5.2 Lime-RHA Additives
5.2.1 Effect of lime-RHA additives on compaction
characteristics of soils
It has been observed that when lime-RHA additives are added
to the soils A, B and C the maximum dry densities decrease
and the optimum moisture contents increase (see Tables 4.2a
to 4.2c). These effects are more pronounced as the quantity
of RHA in the additives is increased.
The increase in OMC is due to the water required for the
hydration of lime as well as to assist flocculation of the
clay clods. Additional water also is required for wetting
the large surface area of the fine RHA particles or is
absorbed by the fine particles of the RHA as described in
section 5.1.1.
The decrease in density of all treated soils is mainly due
to the partial replacement of comparatively heavy soils with
144
the light weight lime-RHA additives
(specific gravity of
lime = 2.35 : specific gravity of RHA = 1.79).
As indicated above, the decrease in density is more
pronounced as the quantity of the lighter constituent (ie
RHA) in the additives is increased.
The decrease in density
could also be influenced by the increase in porosity due to
the addition
of
lime-RHA
additives.
The
porosity
was
calculated by the method described in section 5.1.1 and
calculations are listed in Appendix B.
the
porosities
of
all
compacted,
It can be seen that
treated
soils
were
increased by the increase of the quantity of RHA in the
additives.
The increase in OMC of a soil due to treatment by lime-RHA
additives can be utilised in improving the workability of
wet soils.
Any adverse effect on strength due to increase
in porosity or reduction in density is unlikely to occur due
to the expected
substantial gain in strength of treated
soils because of the cementing action of lime-RHA additives.
5.2.2 Effect of Lime-RHA additives on the strength
properties of soils
5.2.2a Effect on UCS
It can be seen from Table 4.4 that:
145
For a given quantity of additive, as lime in the
additive increases, the strength at all ages, for
all treated soils, increases. The highest
strengths for all treated soils have been achieved
by using 1:1 lime-RHA additive. This is not
consistent with the case for lime-RHA pastes
(section 4.5.3) and implies that lime reacts more
readily with soils than with ash. A sufficient
quantity of lime (ICL or initial consumption of
lime) is required to increase the pH of soils to
about 12.4 at which reaction takes place between
lime and clay minerals and other pozzolans to
produce cementitous hydrated calcium silicate and
aluminate gels (51).
As the curing time increases, strength increases
due to the pozzolanic reaction which takes place
over a long time.
By inspecting the long term strength (ie, the 90
days curing strength) shown in Figure 4.3, it can
be observed that:
For all additives, the strength of treated soil
increases with increasing quantity of additive, up
to a peak value, then decreases with the
continuous increase of the quantity of additive
similar to that in the case of lime stabilisation.
146
iv)
The quantity of additive, at which a peak value of
strength occurs, tends to increase with increasing
amount of RHA in the additive. This conforms to
the previous finding that lime reacts more readily
with soils than with RHA.
v) For all soils tested, the lime-RHA additives were
not able to achieve the highest strength achieved
by lime additive. This is more pronounced in the
case of soil C which, as a heavy clay, is very
suitable to lime stabilisation. This indicates
that lime-RHA additives are more efficient in
modifying the strength of non-cohesive soils than
they are in modifying the strength of cohesive
soils.
It can also be deduced from Figure 4.3 that the UCS of soils
treated with 4% content of 1:1, 1:2 and 1:3 lime-RHA
additives are equal or greater than those of 2%, 1.3% and 1%
lime stabilisation. This indicates that RHA is acting as a
pozzolan and has a role in strength development of lime-RHA
soil stabilisation. The effectiveness of this role will be
examined further in section 5.2.7.
5.2.2b Effect on CBR
It can be seen from Tables 4.12 to 4.14 and Figures 4.11 to
4.13 that:
147
i)
For a given quantity of additive, as lime in the
additive increases, the CBR of all treated soils
increases.
ii) As the curing time increases, the CBR increases.
This is due to the pozzolanic reaction which takes
place over a long period of time.
iii) For all additives, the CBR of treated soil
increases with increasing quantity of additive and
no peak value is observed.
iv) For all soils tested, the lime-RHA additives were
not able to achieve the highest CBR achieved by
lime additive.
This is more pronounced in the
case of soil C which is very suitable to lime
stabilisation.
These observations conform to the findings of UCS in section
5.2.2a with the only exception of CBR not having a peak
value at an optimum quantity of lime-RHA additive.
5.2.3 Effect of delay in compaction on the strength of
lime-RHA treated soils
The results presented in Table 4.8 have shown that delay in
compaction of lime and lime-RHA treated soil decreases the
148
strength of these mixes.
This is more pronounced as the
time elapsed since mixing is increased. This can be
explained by the fact that delay in compaction allows some
cementitous bonds to occur and resist the applied compactive
effort. The final density achieved will, therefore, be
lower and a loss in strength will occur.
The results presented in Table 4.8 have also revealed that,
in lime and lime-RHA stabilisation, the losses in strength
due to delay in compaction were not great and almost
similar. This implies that the rate of reaction in lime-RHA
stabilisation is relatively slow and somewhat similar to
lime stabilisation. Accordingly, the time constraints in
respect of compaction, including delays caused by plant
breakdown, etc and the effects of rain are not so critical.
5.2.4 Effect of lime-RHA additives on the shear strength
parameters of soils
A perusal of Table 4.10 reveals the general increase in the
shear strength parameters (cohesion and angle of internal
friction) of the soil both with respect to the proportion
and percentage of additives. With increase in lime content,
the parameters increase for a given percentage; also for a
given proportion, as the percentage of total additive
increases, an increase in the parameters is observed in
almost all cases. It can also be seen that the cohesion and
149
angle
of
internal
friction
of
soil
stabilised
with
8%
content of 1:1 lime-RHA additive were higher than those with
4% lime additive. This confirms the belief that RHA has a
role in strength development of lime-RHA stabilisation.
The results presented in Table 4.10 also show that shear
strength parameters increase with increasing curing time.
As the shear strength of a soil is determined by its
parameters and effective normal stress (ie T= C + cfn tan 0),
it can easily be seen that the abovementioned observations
are applicable to the effect of lime-RHA additives on the
shear strength of soils. These observations conform to the
findings with respect to CBR and UCS (sections 5.2.2a and
5.2.2b) which are, more or less, measures of the combined
effects of cohesion and internal friction of a soil.
Accordingly, it can be stated that the increase in strength
(UCS, CBR and shear strength) due to lime-RHA stabilisation
is caused by the increase in both the angle of internal
friction and cohesion of the stabilised soil.
The increase in the angle of internal friction could be
attributed to the formation of bigger size particles (ie,
aggregation of clay particles) due to the cation exchange
reactions, whereas cohesion is increased mainly by the
formation of calcium silicate gel due to the reaction of
lime with pozzolanic components of soil and RHA. This gel
150
gradually crystalises
into well defined calcium
silicate
hydrate micro-crystals which can interlock mechanically and
cause the development of interparticle bonds.
5.2.5 Discussion of the results of the XRD analysis of
lime-RHA stabilised soils
A computer analysis for the d spacings and intensities of
the peaks on each X-ray diffraction chart was used in
identifying the compounds that existed in the various
samples examined.
The XRD chart of the untreated Soil C, as shown in Figure
4.26, exhibits peaks at d spacings of 4.26, 3.343, 2.458,
2.282, 2.128 and 1.817 A° indicating the presence of Quartz
(Si02). Peaks exhibited at d spacings of 7.18, 4.48, 3.58,
2.565 and 2.386 A° indicate the presence of Kaolinite
(Aluminium Silicate Hydroxide). The analysis also shows low
peaks at d spacings of 9.95 and 4.97 A° indicating the
presence of Muscovite (Potassium Aluminium Silicate
Hydroxide).
Similarly the XRD chart of the untreated Soil A, as shown in
Figure 4.25, exhibits peaks at d spacings of 4.26, 3.343,
2.282 and 2.128 A° indicating the presence of Quartz. The
chart also shows peaks at d spacings of 7.18, 4.48, 3.58,
2.565 and 2.502 A° indicating the presence of Kaolinite.
151
The XRD chart of the lime-RHA treated Soil A, as shown in
Figure 4.27, exhibits peaks similar to that of the control
sample of the untreated Soil A indicating the presence of
Quartz and Kaolinite. This chart has proved inconclusive in
showing the nature of lime-RHA hydration product. Possible
existence of Calcium Silicate Hydrate compounds could be
hindered by the presence of Calcite (Calcium Carbonate) in
the sample. This presence could be attributed to the effect
of atmospheric carbon dioxide on the thin dispersion of fine
material. The Calcite can be identified by the intensities
and peaks shown at d spacings of 3.86, 3.035, 2.285, 2.095,
1.913 and 1.875 A°.
Figure 4.28 shows the XRD chart of the lime-RHA treated Soil
C. It can be clearly seen that the treated soil retained
some of the details of the original structure. Quartz can
be easily identified by the peaks at d spacings of 4.26,
3.343, 2.458, 2.282, 2.128 and 1.817 A°. Kaolinite and
Muscovite disappeared and were replaced by Illite (another
form of Potassium Aluminium Silicate Hydroxide). The Illite
was identified by the peaks shown at d spacings of 10.30,
4.49 and 2.583 A° whereas Calcite was identified by the
peaks at d spacings of 3.035 and 2.285 A°.
Again, the XRD analysis has proved inconclusive in
identifying the lime-RHA hydration products. No indication
of the presence of calcium silicate hydrate and calcium
aluminate hydrate appeared.
152
5.2.6
Discussion of the results of the SEM examination of
lime-RHA stabilised Soils
The scanning electron micrograph of the fracture surface of
the untreated Soil A, as shown in Figure 4.21, has clearly
indicated that upon fracturing of the specimen, several
areas of the matrix exhibited extensive cracking. Cracks
can be seen at the top and bottom of the centre of the
micrograph. It can also be seen that the matrix exhibited
poor bonding and considerable amount of microporosity. Such
porosity can be seen in the centre and at the bottom right
of the micrograph.
Figure 4.22 shows the fracture surface topography of the
untreated Soil C (Clay). It indicates a relatively smooth
textured surface although areas with some associated
microporosity appear in the centre and the right side of the
micrograph.
In comparison, the micrograph of the fracture surface of
lime-RHA treated Soil A, as shown in Figure 4.23, indicates
that the surface of the treated soil retained some details
of the original texture. Areas with associated
microporosity can clearly be seen at the top and the bottom
of the micrograph. However, patches of amorphous
components, which are presumably the non crystalline
lime-RHA reaction products, can be seen in the micrograph.
153
Figure 4.24
indicates that such amorphous components are
also shown to cover the fracture surface of lime-RHA treated
Soil C, particularly in areas shown at the lower left corner
of the micrograph. The rope-like fibres shown in the upper
portion of the micrograph are presumably some plant growth
contamination in the soil.
It has to be noted that comparison of micromorphological
results has an apparent limitation because of the small
number of micrographs usually published and the
correspondingly small area represented by these micrographs,
which might not be representative of the structure. The
description of the features given here are, somewhat,
subjective. Consequently, speculations on the origin of
strength and other properties, when based on these
observations have limited validity.
5.2.7 Effect of lime-RHA additives on the Atterberg
limits and linear shrinkage of soils
It can be observed from Table 4.6 that liquid limit and
plastic limit of lime-RHA treated soils increase with the
increase of additive quantity with one notable exception
where the very high liquid limit of soil C decreases with
the increase of additive quantity. However, the plasticity
154
index and linear shrinkage of all treated soils decrease
with the increase in additive quantity. These effects are
more pronounced as the amount of lime in the lime-RHA
additive is increased.
These effects could be attributed to the combined action of
the partial replacement of plastic soil particles with the
abrasive non-plastic particles of RHA, and the ionic
exchange between lime and the clay minerals of soils.
It can also be observed from Table 4.6 that liquid limit,
plastic limit, plasticity index and linear shrinkage of
treated soil after a curing period of 28 days are almost
equal to those after a curing period of 7 days. This can be
explained by the fact that the reactions responsible for
reducing plasticity and shrinkage (ie, cation exchange)
occur during a short period of time and mostly in the first
7 days of the curing time and the RHA does not react with
soils as was discussed in sections 5.1.2 and 5.1.3.
A perusal of Figures 4.5 and 4.7 reveals that lime-RHA
additives could not attain the results achieved by 4% lime
additive. Hence, their use to modify the plasticity and
shrinkage of soils could be restricted to a lower level of
achievement. However, their limited role in this context
(ie, to replace 2-3% lime additive in modifying plasticity
and shrinkage of soils) could be justified by the amount of
155
lime saving they can achieve.
This will be discussed in the
following section.
5.2.8 Implications of lime savings
By examining Figure 4.30 it can be deduced that the UCS of
2% lime treated soil A can be achieved by 2.72% of 1:1
lime-RHA additive (ie 1.36% lime + 1.36% RHA). The lime
saving is therefore equal to 2 - 1.36 = 0.64% and the ratio
of RHA required to lime saved is 1.36/0.64 = 2.12.
Therefore 1:1 lime-RHA additive is not economically feasible
to replace the 2% lime stabilisation unless the cost of lime
is equal to or greater than 2.12 times the cost of RHA.
Table 5.3 has been derived in a similar manner utilising
Figures 4.3, 4.5 and 4.7 and applying the same calculations
for the various values of strength, shrinkage and plasticity
for each case of soil treatment.
From Table 5.3 it can be deduced that:
i) At a low level of achievement, RHA has a
significant role in the lime-RHA soil
stabilisation.
156
ii)
1:1
lime-RHA
additive
tends
to
be
the
most
economical mixture of all lime-RHA additives used.
iii) Lime-RHA additives are more efficient for strength
improvement of soils than for reduction of
plasticity and shrinkage.
iv) Lime-RHA additives are more efficient in
stabilising low cohesion soils than in stabilising
clays.
v) 1:1 lime-RHA additive cannot be recommended for
improvement of soil strength unless the cost of
lime is at least three times the cost of RHA.
However, for modifying the plasticity, the cost of
lime must be at least 5-6 times the cost of RHA.
5.2.9
Effect of lime-RHA additives on the behaviour of
soils under the action of repeated dynamic load
Soils (A, B and C) treated with 3% content of 1:1 lime-RHA
additives were found to have UCS equal to or greater than
those of 2% lime treated soils, (see Figure 4.3). To find
whether or not the behaviour of these treatments under the
action of repeated dynamic loads are consistent with
157
strength findings, it was decided to compare the pavements
having 2% lime treated soil D and 3% content of 1:1 lime-RHA
treated soil D with the control pavement of untreated soil
D.
The various measurements of deflections of the three
pavements, shown in Tables 4.15, 4.16 and 4.17, reveal that:
i) For any point on the grid, where measurements were
taken, the deflection of the three pavements
increased with the increase in number of loads
applied.
ii) As the number of total load applications to the
pavements increases, the actual deflection per
single load applied decreases, indicating the
pavement stiffness has increased (see Table 5.2).
iii) The maximum deflections for the various number of
load cycles occurred close to wheel contact area
and particularly under the wheel edge (ie point eH
on the grid) for all cases.
iv) For any number of load cycles the deflections, at
any point on the grid, of the lime and lime-RHA
treated pavements were less than the deflection of
the untreated pavement. This indicates that lime
158
and lime-RHA additives increase the stiffness and
reduce the compressibility of soils.
The deflection of the lime-RHA treated pavement
after any number of load applications was less
than the deflection of the lime treated pavement
at most points on the grid and all points within
the wheel contact area.
The maximum deflection of the lime-RHA treated
pavement after 50,000 load cycles was less than
the maximum deflection of the lime treated
pavement (7.2mm for 2% lime treated pavement and
7.0mm for 3% content of 1:1 lime-RHA treated
pavement). This signifies the positive role of
RHA as a pozzolan in lime-RHA additive, in
improving the stiffness of a soil and reducing its
compressibility. This is consistent with the
findings of strength in sections 5.2.2 and 5.2.4
and may imply that the lengthy and costly repeated
load test is less significant than the economical
and simple UCS test as a tool for the selection
and design of lime-RHA soil stabilisation.
A perusal of Tables 4.15, 4.16 and 4.17 reveals
that, for all pavements, there were downward
movements of all points on the grid where
159
measurements
were
taken
and
the
permanent
deformations of the three pavements were caused by
the densification of the pavements rather than by
any shear failure of these pavements (see also
Figures 4.14, 4.15 and 4.16).
vii) A visual assessment of the surface of all
pavements showed that no fatigue cracks or
shrinkage cracks were developed and the pavements
were intact and sound at the conclusion of the
test.
In general, the observations derived from the results of the
repeated dynamic load test have demonstrated that 1:1
lime-RHA additive is effective and efficient in improving
the behaviour of soils under the action of repeated loads.
5.3 Cement-RHA Additives
5.3.1 Effect of various cement-RHA additives on
compaction characteristics of soils
It has been observed that when cement-RHA additives are
added to the soils A, B and C, the maximum dry densities
decrease and the optimum moisture contents increase (see
Tables 4.3a to 4.3c). These effects are more pronounced as
the quantity of RHA in the additives is increased. The
160
increase
in
OMC
is due
to
the water
required
for the
hydration of cement as well as to assist flocculation of the
clay clods. Additional water also is required for wetting
the large surface area of the fine RHA particles or is
absorbed by the fine particles of RHA as mentioned in
sections 5.1.1 and 5.2.1.
The decrease in densities of all treated soils was mainly
due to the partial replacement of soil with lighter
cement-RHA additives (specific gravities for 1:1, 1:2, 1:3
and 1:4 proportions are 2.465, 2.24, 2.127 and 2.06
respectively). As stated above, the decrease in density is
more pronounced as the quantity of the lighter constituent
(ie RHA) in the additives is increased. The decrease in
density could also be influenced by the increase in porosity
due to the addition of cement-RHA additives which in turn
could be attributed either to the rapid development of
bonds, between particles, which resist compaction effort or
to the morphology of RHA particles itself (see section
5.1.1). The porosity of values were calculated by a method
similar to that specified in sections 5.1.1 and 5.2.1 and
are presented in Appendix B.
The increase in OMC of a soil due to treatment by cement-RHA
additives can be utilised in improving the workability of
wet soils. Any adverse effect on strength due to increase
in porosity or reduction in density is unlikely to occur due
161
to the expected substantial gain in strength of treated soil
because of the cementing action of cement-RHA additives.
5.3.2 Effect of cement-RHA additives on the strength
properties of soils
5.3.2a Effect on UCS
It can be seen from Table 4.5 that:
i) For a given quantity of additive as cement content
in the additive increases the strength at all
ages, for all treated soil, increases. This is
consistent with the case of cement-RHA pastes
(section 4.5.3) and implies that the strength
development is dominated by the hydration
reactions of cement rather than by the pozzolanic
reaction between the released lime (from the
hydration of cement) and the RHA and clay
particles of the soils.
ii) For all additives and all curing periods there is
continuous increase in strength with increasing
quantity of additive. No peak value of strength
was observed. These are consistent with the
findings above.
162
iii)
As curing time increases the strength of treated
soil increases. The rates of strength development
of soils treated with cement-RHA additives are
slower than those of cement treated soils. Rates
of strength development, as ratios of 7 days
strength to 90 days strength, and 28 days strength
to 90 days strength for various treated soils are
derived from Tables 4.5 and presented in Tables
5.4 and 5.5. From these Tables, it can be easily
seen that RHA is acting somewhat as a retarder and
hence may have some favourable effect on the
workability of cement-RHA soil stabilisation.
This effect will be further examined in the later
discussion on the effect of delay in compaction on
strength of treated soils (section 5.3.3).
From Figure 4.4, it can be seen that the UCS of soils
treated with 4% content of 1:1, 1:2 and 1:3 cement-RHA
additives are greater than those of 2%, 1.3% and 1% cement
treatment. This indicates that RHA is acting as a pozzolan
and has a role in strength development of cement-RHA soil
stabilisation. This is consistent with the findings of
section 5.2.2a. The effectiveness of this role is
investigated in section 5.3.7.
163
5.3.2b
Effect on CBR
It can be seen from Tables 4.12 and 4.14 that:
i) CBR increases with increasing curing time or
decrease in the amount of RHA in the additive.
ii) There is a continuous increase in CBR due to
increase in the additive quantity in almost all
cases and no peak value for CBR is observed.
Implication of cement saving cannot be derived from the CBR
values as some of these values are greater than 100 and
considered meaningless in accordance with the discussion of
the appropriateness of the test in section 3.4.4.
5.3.3 Effect of delay in compaction on the strength of
cement-RHA treated soils
The results presented in Table 4.9 show that a loss in
strength occurs if the compaction of cement or cement-RHA
treated soil is delayed. The loss in strength is more
pronounced as the time elapsed since mixing is increased.
The delay in compaction of cement treated soil A was so
critical that 30% to 70% of strength was lost due to 2 - 6
hours delay in compaction. However, this loss in strength
was decreased by using cement-RHA additives. The decrease
164
in the loss of strength is more pronounced as the amount of
RHA in the additive is increased.
This could be attributed to the fact that the RHA acts as a
retarder in slowing the rate of strength development of
cement-RHA treated soils (see section 5.3.2a).
The loss in strength due to delay in compaction of
cement-RHA treated soil is significantly less than that of
cement treated soil. Accordingly, the time constraints in
respect of compaction, including delays caused by plant
breakdown, etc, and the effects of rain are not so critical.
5.3.4 Effect of cement-RHA additives on the shear
strength parameters of soils
A perusal of Table 4.11 reveals that:
i) For a given additive, shear strength parameters
increase with increase in additive quantity.
ii) For a given quantity of additive, the shear
strength parameters increase with decrease in RHA
content in the additive.
iii) Shear strength parameters increase with increase
in curing time in almost all cases.
165
As the
shear
strength
of
a
soil
is determined
by
its
parameters and normal stress (ie V = C + Cntan 0) , it can
easily be seen that the above mentioned observations are
applicable to the effect of cement-RHA additives on the
shear strength of soils. These observations conform to the
findings for CBR and UCS (sections 5.3 2a and 5.3.2b) which
are, more or less, measures of the combined effects of
cohesion and internal friction of a soil. Accordingly, it
can be stated that the increase in strength (UCS, shear
strength and CBR) of cement-RHA stabilised soil is
influenced by the increase in both its internal friction and
cohesion.
As discussed in section 5.2.4, the increase in the angle of
internal friction could be attributed to the formation of
bigger size particles (ie aggregation of clay particles) due
to the cation exchange reactions of the clay minerals of the
soil with the lime released from the hydration reactions of
cement in the additive. The cohesion is increased mainly by
the formation of cementitous material (calcium silicate and
aluminate hydrates as in concrete) due to the hydration
reactions of the cement with the water in the soil. These
reactions release hydrated lime (about 30% by mass of added
cement) which can cause secondary reactions with RHA and
clay particles within the soil. The secondary reactions
produce cementitous products similar to those of the
hydration reactions of the cement. These cementitous
166
products gradually crystalise and interlock mechanically to
increase the cohesion.
5.3.5 Effect of cement-RHA additives on the Atterberg
limits and linear shrinkage of soils
It can be seen from Table 4.7 that liquid limit and plastic
limit of cement-RHA treated soils increase with the increase
of additive quantity with one notable exception where the
very high liquid limit of soil C decreases with the increase
of additive quantity. However, the plasticity index and
linear shrinkage of all treated soils decrease with the
increase in additive quantity. These effects are more
pronounced as the amount of RHA in the cement-RHA additive
is decreased.
These effects could be attributed to the combined action of
the partial replacement of plastic soil particles with the
abrasive non-plastic particles of RHA, and the cation
exchange reactions of clay minerals in the soil with the
released lime from the hydration reactions of cement.
It can also be seen from Table 4.7 that liquid limit,
plastic limit, plasticity index and linear shrinkage of
treated soils after a curing period of 28 days are almost
equal to those after a curing period of 7 days. This
implies that the reactions responsible for reducing
167
plasticity and shrinkage (cation exchange) occur during a
short period of time and mainly in the first 7 days and that
RHA does not react with soil. All of these observations are
consistent with those of lime-RHA additives as discussed in
section 5.2.6.
Figures 4.6 and 4.8 indicate that, for modifying the
plasticity and the shrinkage of soils, the replacement of
cement with cement-RHA additives should be restricted to an
upper limit of cement additive of 4%. However, this limited
role has to be justified by the amount of cement that can be
saved.
5.3.6 Implications of cement saving
By examining Figure 4.4a it can be deduced that the UCS of
2% cement treated soil A can be achieved by 3.3% content of
1:2 cement-RHA additive (ie 1.1% cement + 2.2% RHA). The
cement saving is therefore equal to 2 - 1.1 = 0.9% and the
ratio of RHA required to cement saved is 2.2/0.9 = 2.44.
Therefore 1:2 cement-RHA additive is not economically
feasible to replace the 2% of cement in stabilising soil A
unless the cost of cement is equal to or greater than 2.44
times the cost of RHA.
Table 5.6 has been derived in a similar manner, utilising
Figures 4.4, 4.6 and 4.8 and applying the same calculations
168
for the various values of strength, plasticity and shrinkage
for each case of soil treatment.
From Table 5.6, it can be deduced that:
i) At a low level of achievement, RHA has a
significant role in cement-RHA soil stabilisation.
ii) 1:1 cement-RHA additive tends to be the most
economical
used.
mixture
of
all
cement-RHA
additives
The additive tends to be less economical as
the RHA content in the additive increases.
iii) Cement-RHA additives are more efficient in
improving the properties of low cohesion soils
than in improving the properties of clays.
iv) Cement-RHA additives are not efficient in
achieving
the
plasticity
and
shrinkage
of
4%
cement soil stabilisation.
v) 1:2 cement-RHA additives can be recommended for
replacing 2% cement in modifying the strength of
low cohesion
soils
provided
that
the
cost of
cement is equal to or greater than, 2.4 times the
cost of RHA.
For higher levels of achievement
169
(ie, strength of 4% cement stabilised soil) or to
achieve the plasticity and shrinkage achieved with
2% cement stabilised soil, the cement-RHA additive
is not economical unless the cost of cement is
equal to or greater than 4 times the cost of RHA.
vi) 1:3 and 1:4 cement-RHA additives are not efficient
and cannot be recommended to be used in soil
stabilisation.
5.3.7 Effect of cement-RHA additive on the behaviour of
soils under the action of repeated dynamic load
In section 5.3.2a, it was found that RHA acted as a pozzolan
and has a role in strength development of cement-RHA
stabilisation. To inspect the effectiveness of this role in
improving the behaviour of soils under the action of
repeated dynamic loads, it was decided to compare the
pavements containing 1.5% cement treated soil D and 3%
content of 1:1 cement-RHA treated soil D with the control
pavement of untreated soil D.
The various measurements of surface deflection for the three
pavements, shown in Tables 4.15, 4.18 and 4.19 reveal that:
i) For any point on the grid, where measurements were
taken, the surface deflection in all three
170
pavements increased with the increase in number of
load applications.
ii) As the number of total load applications to the
pavements increases, the actual deflection per
single load applied decreases, indicating that the
pavement stiffness had increased (see Table 5.7).
iii) The maximum deflections for the various number of
load cycles occurred close to wheel contact area
(ie point Gd and eH on the grid).
iv) For any number of load cycles, the deflections, at
any point on the grid, of the cement and
cement-RHA treated pavements were less than the
deflection of the untreated pavement. This
indicates that cement and cement-RHA additives
increase the stiffness and reduce the
compressibility of soils.
v) The maximum deflection of the 3% content of 1:1
cement-RHA treated pavement after 50,000 load
cycles was equal to 2.91mm, which was slightly
less than the maximum deflection of the 1.5%
cement treated pavement which was equal to 2.96mm.
However, the role of RHA as a pozzolan in
cement-RHA additive for improving the stiffness of
171
a soil and reducing its compressibility could be
more significant had the curing period (7 days)
and the age of the pavement at time of test (7
days) been greater.
vi) For all pavements, most of the points where
measurements were taken, exhibited a downward
movement and the permanent deformations of the
pavements were caused by the densification of the
pavements rather than by any shear failure of
these pavements. The upward movements of the
points at the edges of the grid of the cement
treated pavement, as shown in Figure 4.17, are
probably caused by an incorrect initial
measurement reading at zero load cycle at these
points.
vii) A visual assessment of the surface of all
pavements showed that no fatigue cracks or
shrinkage cracks were developed and the pavements
were intact and sound at the conclusion of the
test.
In general, the observations derived from the results of the
repeated dynamic load test have demonstrated that 1:1
cement-RHA additive is effective, but not very efficient, in
improving the behaviour of soils under the action of
repeated loads.
172
Table 5.1
Soil
A
B
C
Effect of RHA additive on the grading of soils.
Grading of
untreated
soil
% passing
Grading of
RHA
% passing
Grading of
soil +
8% RHA
% passing
Grading of
Max. density
curve
% passing
19mm
100
100
100
100
95mm
73
100
75
70
4.75mm
36
100
41
50
2.36mm
22
100
28
35
425pm
15
60
19
15
75pm
8
17
9
6
13.5pm
4
12.5
5
3
4.75mm
100
100
100
100
2.36mm
85
100
86.2
90
42 5pm
43
60
44
30
75pm
24
17
23
13
13.5pm
17
12.5
17
5
2.36mm
100
100
100
100
425pm
95
60
83
42
75pm
71
17
67
18
13.5pn
53
12.5
50
8
Sieve
size
173
Table 5.2a
Progressive
total of
loads applied
50
500
5,000
50,000
Deflection per load as number of load
applications increases at point eH of 3% 1:1
lime-RHA treated pavement.
No. of loads
applied
Deflection due
to loads
applied
(mm)
Average deflection
due to one load
application
(mm)
50
450
4,500
45,000
5.85
6.75-5.85
6.45-6.75
7.00-6.75
0.117
0.0018
-6.6 x 10~ 5 *
5.55 x 10" 7
Error in reading
Table 5.2b
Progressive
total of
loads applied
50
500
5,000
50,000
Deflection per load as number of load
applications increases at point eH of 2% lime
treated pavement.
No. of loads
applied
Deflection due
to loads
applied
(mm)
Average deflection
due to one load
application
(mm)
50
450
4,500
45,000
5.95
6.90-5.95
7.12-6.90
7.20-7.12
0.119
0.002
4.88 x IO - 5
1.77 x IO" 6
174
Table 5.2c
Progressive
total of
loads applied
50
500
5,000
50,000
Table 5.2d
Progressive
total of
loads applied
50
500
5,000
50,000
Deflection per load as number of load
applications increases at point eH of untreated
pavement.
No. of loads
applied
Deflection due
to loads
applied
(mm)
Average deflection
due to one load
application
(mm)
50
450
4,500
45,000
3.12
4.25-3.12
6.97-4.25
8.95-6.97
0.062
0.0025
0.0006
0.0004
Deflection per load as number of load
applications increases at point eH on the grid
of 8% RHA treated pavement.
No. of loads
applied
Deflection due
to loads
applied
(mm)
Average deflection
due to one load
application
(mm)
50
450
4,500
45,000
3.40
4.25-3.40
7.00-4.25
8.20-7.00
0.068
1.88 x IO - 3
6.11 x 10~ 4
2.66 x 1 0 - 5
175
Table 5.3
Ratio of RHA required to lime saved or
identical economic cost ratio of lime to RHA.
Level of
Achievements
UCS of 2% lime
treated soil
UCS of 4% lime
treated soil
Plasticity index of
2% lime treated soil
Plasticity index of
4% lime treated soil
Linear shrinkage of 2%
lime treated soil
Linear shrinkage of 4%
lime treated soil
N/A
Soil
Lime:RHA
1:3
Lime:RHA
1:4
A
2.12
2.15
N/A
N/A
B
3.44
3.24
N/A
N/A
C
3.0
6
13
A
3
N/A
N/A
N/A
B
N/A
N/A
N/A
N/A
C
3
N/A
N/A
A
5.66
22.9
9
16
B
5.66
10
9
N/A
C
N/A
N/A
36
A
N/A
N/A
N/A
N/A
B
3
N/A
N/A
N/A
C
N/A
N/A
N/A
A
3
2.63
3
4.88
B
3
4.04
9
N/A
C
7
7.30
10.33
A
N/A
N/A
N/A
N/A
B
4
N/A
N/A
N/A
C
N/A
N/A
N/A
No lime saving could occur.
Additive is not tested.
LimesRHA Lime:RHA
1:2
1:1
176
Table 5.4
^^.Additives
Soils^v^
Ratios of strength at 7 days to strength at 90
days of soils treated with 8% content of
various additives.
Cement
Cement:RHA
1:1
Cement:RHA
1:2
Cement:RHA
1:3
Cement:RHA
1:4
A
.65
-
.56
.55
.55
B
.54
-
.44
.40
.58
C
.68
.81
.78
.70
-
Table 5.5
Ratios of strength at 28 days to strength at 90
days of soils treated with 8% content of
various additives.
Cement
Cement:RHA
1:1
Cement:RHA
1:2
Cement:RHA
1:3
Cement:RHA
1:4
A
.93
-
.74
.74
.74
B
.89
-
.72
.70
.79
C
.85
.85
.90
.86
-
^•v. Additives
Soils^-^.
177
Table 5.6
Ratio of RHA required to cement saved or
identical economic cost ratio of cement to RHA.
Level of
Achievements
Soil
Cement:RB7 . Cement:RHA Cement:RHA
1:1
1:2
1:3
Cement:RHA
1:4
A
2.44
5
N/A
B
2.29
2.71
N/A
10
45
A
4.01
N/A
N/A
B
2.81
2.65
N/A
N/A
N/A
A
4.04
N/A
N/A
B
4.04
9
N/A
5.55
9
A
N/A
N/A
N/A
B
N/A
N/A
N/A
N/A
N/A
A
4.04
N/A
N/A
B
N/A
N/A
N/A
4.04
6.65
A
N/A
N/A
N/A
B
N/A
N/A
N/A
N/A
N/A
UCS of 2% cement
treated soil
C
UCS of 4% cement
treated soil
C
Plasticity index of
2% cement treated soil
C
Plasticity index of
4% cement treated soil
C
Linear shrinkage of 2%
cement treated soil
C
Linear shrinkage of 4%
cement treated soil
C
N/A
5.66
7
4
15
3
15
N O cement saving could occur.
Additive is not tested.
178
Table 5.7a
Progressive
total of
loads applied
50
500
5,000
50,000
Table 5.7b
Progressive
total of
loads applied
50
500
5,000
50,000
Table 5.7c
Progressive
total of
loads applied
50
500
5,000
50,000
Deflection per load as number of load
applications increases at point eH on the
grid of untreated pavement.
No. of loads
applied
Deflection due
to loads
applied
(mm)
Deflection due
to one load
application
(mm)
50
450
4,500
45,000
3.12
4.25-3.12
6.97-4.25
8.95-6.97
0.062
0.0025
0.0006
0.0004
Deflection per load as number of load
applications increases at point eH on the
grid of 1.5% cement treated soil.
No. of loads
applied
Deflection due
to loads
applied
(mm)
Deflection due
to one load
application
(mm)
50
450
4,500
45,000
1.30
2.23-1.30
2.53-2.23
2.96-2.53
0.026
0.002
6.66 x 10~ 5
9.55 x IO" 6
Deflection per load as number of load
applications increases at point dG on the
grid of the 3% content of 1:1 cement-RHA
treated soil.
No. of loads
applied
Deflection due
to loads
applied
(mm)
Average deflection
due to one load
application
(mm)
50
450
4,500
45,000
2.04
2.55-2.04
2.82-2.55
8.95-6.97
0.040
0.0011
6 x IO -5
2 x 10 -6
179
Chapter VI
EXPERIMENTAL INVESTIGATIONS USING
GRANULATED BLAST FURNACE SLAG (GBFS)
6.1 Scope of Chapter
This chapter covers the experimental research used to
determine the behaviour of granulated blast furnace slag in
relation to its use in soil stabilisation. It sets the
objectives of this research, describes the materials used
and details the programme and procedures of testing. It
also gives the results of all the various tests used.
6.2 Objectives of Research
The main objectives of the research reported in this chapter
have been as follows:
a) To examine the influence of granulated blast
furnace slag, as a single additive to soils on
various properties of a range of soils.
b) To study the effects of lime-GBFS and cement-GBFS
additives on the properties of soils.
180
6.3
Materials
6.3.1 Blast Furnace Slag (GBFS)
The slag used was a sample of granulated blast furnace slag
produced in Port Kembla, NSW, and delivered in 200 litre
drums to the Department of Civil and Mining Engineering,
University of Wollongong.
The specific gravity of the sample was 2.86 and the grading
was as follows:
% passing 2.36mm 100
% passing 425pm
% passing 75pm
% passing 13.5pm
50
5
2
The chemical analysis of the sample was as follows:
Si02 31.7%
A1203
Fe203
CaO
MgO
Na20
k20
Loss on ignition
14.0%
2.6%
40.5%
5.80%
0.18%
0.42%
1.04%
181
6.3.2
Cement
'Kandos' commercial grade, ordinary portland cement was used
conforming to Australian Standards (AS1315) as specified in
section 4.3.2.
6.3.3 Lime
'Blue Circle' commercial grade, hydrated lime was used,
conforming to Australian Standards (AS1672) as specified in
section 4.3.3.
6.3.4 Soils
Four different soils were selected for stabilisation and
tested in this investigation.
soils A, B, C and D.
These soils are designated as
Description and properties of these
soils have been given in Chapter 4 (section 4.3.4 and Table
4.1) .
6.4 Testing regime
GBFS varies according to the iron content of the ore, the
proportions and constituents of fluxing stone and coke fed
into
the
furnace
solidification of
and
the
the
liquid
conditions
slag.
of
cooling
and
The variations
are
182
reflected in the physical and chemical composition of GBFS
with particular emphasis on the ratio of lime to silica and
the
sulphur
content.
The
relative
contents
of
these
materials affect the pozzolanic reaction of GBFS with lime
and cement.
Consequently, it was decided that testing be
carried out, in a sequence similar to that in Chapter 4
(section 4.4), to determine the:
i) Reactivity of GBFS (ie, the optimum ratio of lime
or cement to GBFS).
ii) Effect of lime, GBFS and cement individual
additives on the engineering properties of soils
A,B and C.
iii) Effect of lime-GBFS and cement-GBFS additivies at
their
optimum
and
practical
ratios
on
the
properties of soils A,B and C.
iv) Behaviour of GBFS, lime, cement, lime-GBFS and
cement-GBFS stabilised soil D under the action of
repeated dynamic loads.
Testing was carried out in accordance with methods described
in Chapter 3.
183
6.5
Optimum ratios of lime or cement to GBFS
The unconfined compressive strength test was selected to
investigate the degree of reactivity of GBFS in lime-GBFS
and cement-GBFS compacted specimens and specifically to
determine the optimum ratios of lime and cement to GBFS.
Dry mixtures of lime-GBFS and cement-GBFS were prepared,
proportioned by weight and mixed. The ratio of lime to GBFS
and cement to GBFS was in the range of 1:1 and 1:10. Two
series of compacted specimens were then prepared at OMC
using standard compaction test equipment. All specimens
were cured and tested in a manner similar to that specified
in Chapter 4 (section 4.5).
The results of the UCS tests on the lime-GBFS specimens are
presented in Figure 6.1, whereas those of cement-GBFS
specimens are presented in Figure 6.2.
Figure 6.1 indicates that for both curing periods (28 and 90
days), the optimum ratio of lime to GBFS is the ratio 1:2
whereas Figure 6.2 shows that there is no optimum ratio of
cement to GBFS. This result indicates that the strength of
cement-GBFS specimens is dominated by the hydration
reactions of cement rather than by the pozzolanic reaction
between the released lime and the GBFS.
184
6.6
Treatment of soils with various additives
Various additives, namely GBFS, lime, lime-GBFS, cement,
cement-GBFS were used individually to stabilise the soils
(A, B & C) . The various quantities of additives were 2%,
4%, 6% and 8% of the total weight of the dry soil and
additive. The ratio of lime to GBFS for each quantity of
additive was varied as 1:1, 1:2, 1:3 and 1:4. Although the
ratio 1:2 was found to be the optimum ratio of lime to GBFS
(section 6.5), the values 1:1, 1:3 and 1:4 were also
considered to be within the practical range.
The initial testing indicated that no optimum ratio of
cement to GBFS occurs (section 6.5). In the test series the
values 1:1, 1:2, 1:3 and 1:4 were considered to be within
the practical range and were also used for comparison.
6.7 Testing of stabilised soils
6.7.1 Compaction characteristics
The optimum moisture contents and the maximum dry densities
of soils stabilised with various additives and various
quantities (section 6.6) were determined in accordance with
standard compaction test T120. The test results are
presented in Tables 6.1 and 6.2.
185
6.7.2
Unconfined compressive strength
Three series of specimens of soils stabilised with the
various additions and various quantities (section 6.6) were
prepared and compacted to their maximum dry densities at
their OMC using the standard compaction test equipment.
All
specimens were then cured and tested in a manner similar to
that described in Chapter 4 (section 4.7.2).
The results of specimens cured for 7, 28 and 90 days are
shown in Tables
6.3
and
6.4, whereas
the 90 days test
results are shown in Figures 6.3 and 6.4.
6.7.3 Linear shrinkage
The linear shrinkage of all mixes was determined in
accordance with test method T113 using materials collected
from unconfined compressive strength crushed specimens which
had been previously cured for 7 and 28 days.
moulding
and
testing techniques were
Preparation,
identical to those
specified in Chapter 4 (section 4.7.3).
The results of the 7 and 28 days tests are presented in
Tables 6.5
and 6.6, whereas the results of the 28 days
curing period are shown in Figures 6.5 and 6.6.
186
6.7.4
Atterberg Limits
Plastic limit, liquid limit and plasticity index of all
mixes were determined in accordance with test methods T108
and
T109
using
compressive
materials
strength
crushed
collected
specimens
previously cured for 7 and 28 days.
from
unconfined
which
had
been
Preparation, curing and
testing procedures were identical to those shown in Chapter
4 (section 4.7.4).
Liquid limit, plastic limit and plasticity index of the
various treatments after the curing periods of 7 and 28 days
are given in Tables 6.5 and 6.6 where as the results of the
plasticity index for the 28 days curing period are given in
Figures 6.7 and 6.8.
6.7.5 Effect of delay in compaction on the strength of
stabilised soils
This part of the investigation was limited to some selected
mixes.
Its main role
the effect
of
delay
stabilised soils.
was to determine the general trend of
in
compaction
on
the
strength
of
Samples of dry soil A were mixed with
cement and cement-GBFS additives.
The ratio of cement to
GBFS was varied as 1:2 and 1:4, whereas the quantity of
additives used in each case was 8% of the total dry weight
of the treated soil.
187
Samples
of
dry
soil
C
also
were mixed
with
lime
and
lime-GBFS additives. The ratio of lime to GBFS was varied
as 1:1 and 1:3, whereas the quantity of additives used in
each case was 8% of the total dry weight of the treated
soil.
Water was added and every mix was put in a covered metal
container and maintained at its OMC during the delay
periods. At the conclusion of the various delay periods (2
hours, 4 hours, 6 hours and 24 hours) the various mixtures
were immediately compacted using the standard compaction
test equipment. The speciemns were cured and tested in a
way similar to that described in Chapter 4 (section 4.7.5).
At the conclusion of the 90 days curing period the specimens
were subjected to unconfined compression. The strength of
these specimens is given in Tables 6.7 and 6.8. The losses
in strength due to delays in compaction, expressed as
percentage of strength of undelayed compaction specimens,
also are given in Tables 6.7 and 6.8 and shown in Figures
6.9 and 6.10.
6.7.6 Effect of various additives on the shear strength
parameters of soils
The undrained triaxial compression test was carried out on
selected stabilised mixes to determine whether or not the
188
increase in UCS of stabilised mixes was associated with an
increase in cohesion, angle of internal friction or both.
The tests were carried out in accordance with Australian
Standards Test Method AS1289.F4.1.
Samples of dry soil B were mixed with cement and cement-GBFS
additives. The ratio of cement to GBFS was varied as 1:2
and 1:3. The quantities of additives in each case were 4%
and 8% of total dry weight of the treated soil.
Samples of dry soil C were mixed with lime and lime-GBFS
additives. The ratio of lime to GBFS was varied as 1:1 and
1:3. The quantities of additives in each case were 4% and
8% of the total dry weight of the treated soil.
Water was added and every mix was compacted at its OMC using
standard compaction test equipment. Preparation, curing and
testing of samples were identical to those described in
Chapter 4 (section 4.7.6).
Values of cohesion (C) and angle of internal friction (0) of
the various mixes are given in Tables 6.9 and 6.10.
189
6.7.7
Effect of various additives on the CBR value of
soils
The CBR test in this part of the investigation was limited
to some selected mixes.
Its main role was to determine the
general trend of the effect of various additives on the CBR
property of soils and to confirm results derived from the
UCS test.
Dry samples of soil A and B were mixed with GBFS, lime and
lime-GBFS additives.
The ratio of lime to GBFS and cement
to GBFS was varied as 1:2
and
1:3.
The quantities of
additives in each case were 4% and 8% of the total dry
weight of treated soil.
Cement at the rate of 2% of total
dry weight of treated soil, also was used for comparison.
Further, dry samples of soil C were prepared and mixed with
GBFS, lime, lime-GBFS and cement-GBFS additives.
The ratio
of lime to GBFS and cement to GBFS, in this case, was varied
as 1:1 and 1:2 whereas the quantities of additives in each
case were 4% and 8% of total dry weight of treated soil.
Cement at the rates of 4% and 8% of total dry weight of
treated soil, also was used for comparison.
Water was added and all mixes were compacted at their OMC in
accordance with the standard procedures of the CBR test with
the
exception
of
using
a
special
split
CBR
mould
to
190
facilitate specimen extraction for the purpose of curing.
All specimens were cured and tested in a manner similar to
that described in Chapter 4 (section 4.7.7).
The CBR values of the various mixes for the various curing
times are presented in Tables 6.11 to 6.13, and the results
of the 90 days curing period are shown in Figures 6.11 to
6.13.
6.7.8 Repeated dynamic load test
The test in this part of the investigation was conducted on
three pavements.
Soil D stabilised with GBFS, lime-GBFS and
cement-GBFS
additives
pavements.
The ratio of lime to GBFS and cement to GBFS
used was
formed
the
base
course
of
these
1:1, whereas the quantity of additives used was
8%, 3% and 3% respectively and expressed as percentage of
the total dry weight of the treated soil.
The sub-base of all pavements consisted of beach sand from
the Illawarra region.
Particle size distribution of sand
was as given in section 4.7.8a.
Placement of pavement materials, compaction of sub-base and
base courses and assembling of test rig were carried out in
a manner similar to that described in section 4.7.8a.
191
After the pavements had been constructed and the test rig
assembled, zero readings were taken at the grid points at
which deflections were to be measured.
The pavements were
covered by a damp cloth and cured for 7 days.
At the
conclusion of the curing period the GBFS and the lime-GBFS
treated pavements were each subjected to 50,000 cycles of
42kN load applications, at a uniform rate of one load cycle
per second.
The cement-GBFS treated pavement was intended
to be subjected to one million 42kN load applications, but
because of a major breakdown in the test facility the test
was concluded at 250,000 load applications.
Deflection readings were taken at intervals during the load
application for the three pavements.
In total, 385 readings
were taken of the deflections of the three pavements at
various intervals during the tests and at various positions
on the pavements.
in a tabular
The results of the deflections are given
form in Tables 6.14 to 6.16.
Figures 6.14 to
6.16 show the deflections of pavements after the various
intervals at the cross sections of the maximum deflections.
6.7.9 Scanning Electron Microscopy
It was considered that limited testing of some of the soil
mixes would be sufficient for determining the morphology of
the GBFS pozzolanic reaction products in soil stabilisation.
192
Samples of lime-GBFS treated Soil A and lime-GBFS treated
Soil C were made available for examination in a Hitachi S450
Scanning Electron Microscope.
The ratio of lime to GBFS in each case was 1:1 whereas the
quantity of lime-GBFS additive was 8% of the total dry
weight
of
the
treated
soil.
Preparation,
curing
and
examining of samples were identical to those described in
Chapter 4 (section 4.7.9).
Scanning electron micrographs of the lime-GBFS stabilised
Soil A and lime-GBFS stabilised Soil C are shown in Figures
6.17 and 6.18.
6.7.10 Powder X-ray Diffraction Analysis
X-ray diffraction patterns were determined for the soil
mixes used in the preceding Scanning Electron Microscopy
examination.
Preparation, curing and testing of specimens
were carried out in a way similar to that specified in
Chapter 4 (section 4.7.10).
The X-ray diffraction patterns determined for the lime-GBFS
treated soils A and C are shown in Figures 6.19 and 6.20.
193
T A B L E 6.1a
ADDITIVE
Compaction characteristics of lime, G B F S and LimeG B F S stabilised soil A
OMC
(%)
(%)
MDD
gm/cm 3
LIME
0%
2%
4%
6%
8%
LIME.GBFS 1:1
13.00
14.50
16.00
16.50
17.00
1.83
1.82
1.77
1.74
1.73
0%
2%
4%
6%
8%
13.00
14.50
15.50
16.00
16.50
1.83
1.82
1.79
1.77
1.77
0%
2%
4%
6%
8%
LIME:GBFS 1:3
13.00
14.50
15.00
15.75
16.00
1.83
1.82
1.81
1.79
1.79
0%
2%
4%
6%
8%
LIME:GBFS 1:4
13.00
14.50
14.90
15.50
15.00
1.83
1.82
1.82
1.80
1.80
0%
2%
4%
6%
8%
13.00
14.50
14.50
14.70
14.70
1.83
1.82
1.82
1.82
1.83
0%
2%
4%
6%
8%
13.00
14.00
14.50
14.70
14.70
1.83
1.84
1.84
1.85
1.85
LIME.GBFS 1:2
GBFS
194
T A B L E 6.1b
ADDITIVE
Compaction characteristics of lime, G B F S and lime-GBFS
stabilised soil B
OMC
(%)
(%)
MDD
gm/cm 3
LIME
0%
2%
4%
6%
8%
LIME:GBFS 1:1
15.00
16.00
16.50
17.00
18.00
1.82
1.81
1.78
1.75
1.73
0%
2%
4%
6%
8%
15.00
15.50
16.00
16.50
17.50
1.82
1.82
1.81
1.78
1.77
0%
2%
4%
6%
8%
LIME:GBFS 1:3
15.00
15.50
16.00
16.00
17.00
1.82
1.83
1.82
1.82
1.82
0%
2%
4%
6%
8%
LIME:GBFS 1:4
15.00
16.00
16.00
16.00
16.00
1.82
1.82
1.83
1.83
1.84
0%
2%
4%
6%
8%
15.00
15.50
16.00
16.00
16.00
1.82
1.82
1.83
1.84
1.84
0%
2%
4%
6%
8%
15.00
15.50
15.50
15.70
15.70
1.82
1.83
1.84
1.84
1.85
LIME:GBFS 1:2
GBFS
195
T A B L E 6.1c
ADDITIVE
Compaction characteristics of lime, G B F S and lime-GBFS
stabilised soil C
OMC
(%)
(%)
MDD
gm/cm 3
LIME
0%
2%
4%
6%
8%
22.00
23.00
24.00
24.50
25.00
1.32
1.32
1.31
1.30
1.29
22.00
22.50
23.00
23.00
23.00
1.32
1.32
1.32
1.31
1.31
22.00
22.00
22.50
22.50
23.50
1.32
1.32
1.32
1.32
1.32
0%
2%
4%
6%
8%
22.00
22.00
22.00
21.50
20.00
1.32
1.32
1.32
1.32
1.33
0%
2%
4%
6%
8%
22.00
22.00
21.00
20.50
20.00
1.32
1.32
1.32
1.32
1.33
LIME:GBFS 1:1
0%
2%
4%
6%
8%
LIME:GBFS 1:2
0%
2%
4%
6%
8%
LIME:GBFS 1:3
GBFS
196
T A B L E 6.2a
ADDITIVE
Compaction characteristics of cement, G B F S and
cement-GBFS stabilised soil A
(%)
OMC
(%)
MDD
gm/cm 3
CEMENT
0%
2%
4%
6%
8%
CEMENT:GBFS 1:1
13.00
14.00
14.50
15.50
16.50
1.83
1.85
1.85
1.85
1.85
13.00
14.00
14.50
15.00
15.70
1.83
1.83
1.84
1.85
1.85
0%
2%
4%
6%
8%
CEMENT:GBFS 1:3
13.00
14.00
14.50
14.50
14.70
1.83
1.83
1.84
1.84
1.84
0%
2%
4%
6%
8%
CEMENT:GBFS 1:4
13.00
14.00
14.50
14.50
14.70
1.83
1.83
1.84
1.85
1.85
0%
2%
4%
6%
8%
13.00
14.30
14.70
14.70
14.90
1.83
1.83
1.83
1.84
1.84
0%
2%
4%
6%
8%
13.00
14.00
14.50
14.70
14.70
1.83
1.84
1.84
1.85
1.85
0%
2%
4%
6%
8%
CEMENT:GBFS 1:2
GBFS
197
TABLE 6.2b
ADDITIVE
Compaction characteristics of cement, GBFS and
cement-GBFS stabilised soil B
OMC
(%)
(%)
MDD
gm/cm 3
CEMENT
0%
2%
4%
6%
8%
CEMENT:GBFS 1:1
15.00
15.50
16.50
17.00
17.50
1.82
1.82
1.84
1.84
1.84
15.00
15.50
16.00
16.50
17.00
1.82
1.83
1.84
1.84
1.84
15.00
15.50
16.00
16.00
16.50
1.82
1.83
1.84
1.84
1.85
15.00
15.50
16.00
15.70
15.70
1.82
1.83
1.84
1.84
1.85
0%
2%
4%
6%
8%
15.00
15.50
16.50
15.70
15.70
1.82
1.83
1.84
1.85
1.85
0%
2%
4%
6%
8%
15.00
15.50
15.50
15.70
15.70
1.82
1.84
1.85
1.85
1.85
0%
2%
4%
6%
8%
CEMENT:GBFS 1:2
0%
2%
4%
6%
8%
CEMENT.GBFS 1:3
0%
2%
4%
6%
8%
CEMENT:GBFS 1:4
GBFS
198
T A B L E 6.2c
ADDITIVE
Compaction characteristics of cement, G B F S and
cement-GBFS stabilised soil C
(%)
OMC
(%)
MDD
gm/cm 3
CEMENT
0%
2%
4%
6%
8%
CEMENT:GBFS 1:1
22.00
23.00
24.50
25.00
26.00
1.32
1.34
1.35
1.39
1.40
22.00
22.00
23.00
24.00
25.00
1.32
1.33
1.34
1.37
1.37
22.00
22.00
22.50
23.00
23.50
1.32
1.33
1.34
1.36
1.36
0%
2%
4%
6%
8%
22.00
22.00
22.00
22.50
23.00
1.32
1.33
1.33
1.34
1.34
0%
2%
4%
6%
8%
22.00
22.00
21.00
20.50
20.00
1.32
1.32
1.32
1.32
1.33
0%
2%
4%
6%
8%
CEMENT:GBFS 1:2
0%
2%
4%
6%
8%
CEMENT:GBFS 1:3
GBFS
199
TABLE 6.3a
U C S (MPa) of lime, GBFS and lime-GBFS stabilised soil
A.
ADDITIVE (%)
7
CURING (DAYS)
90
28
LIME
0%
2%
4%
6%
8%
LIME:GBFS 1:1
0.33
0.43
0.46
0.43
0.41
0.33
0.55
0.76
0.73
0.70
0.33
0.69
1.00
0.95
0.90
0%
2%
4%
6%
8%
0.33
0.41
0.46
0.48
0.40
0.33
0.44
0.72
0.79
0.79
0.33
0.54
0.86
0.95
0.90
0.33
0.39
0.50
0.67
0.57
0.33
0.43
0.57
0.85
0.85
0.33
0.46
0.75
0.92
0.94
0%
2%
4%
6%
8%
LIME:GBFS 1:4
0.33
0.39
0.39
0.39
0.57
0.33
0.40
0.47
0.56
0.80
0.33
0.44
0.51
0.61
0.70
0%
2%
4%
6%
8%
0.33
0.36
0.39
0.39
0.35
0.33
0.38
0.39
0.50
0.51
0.33
0.40
0.51
0.58
0.67
0%
2%
4%
6%
8%
0.33
0.34
0.36
0.38
0.40
0.33
0.36
0.37
0.38
0.41
0.33
0.36
0.36
0.39
0.40
LIME:GBFS 1:2
0%
2%
4%
6%
8%
LIME:GBFS 1:3
GBFS
200
TABLE 6.3b
ADDITIVE
U C S (MPa) of lime, GBFS and lime-GBFS stabilised soil
B.
(%)
7
C U R I N G (DAYS)
28
90
LIME
0%
2%
4%
6%
8%
0.26
0.32
0.34
0.28
0.27
0.26
0.40
0.42
0.38
0.36
0.26
0.50
0.57
0.50
0.45
0%
2%
4%
6%
8%
0.26
0.30
0.32
0.32
0.30
0.26
0.37
0.39
0.35
0.36
0.26
0.44
0.55
0.53
0.44
0.26
0.28
0.30
0.31
0.31
0.26
0.30
0.32
0.35
0.36
0.26
0.34
0.40
0.50
0.51
0%
2%
4%
6%
8%
LIME:GBFS 1:4
0.26
0.27
0.28
0.29
0.29
0.26
0.30
0.30
0.29
0.33
0.26
0.32
0.32
0.36
0.38
0%
2%
4%
6%
8%
0.26
0.26
0.26
0.26
0.31
0.26
0.26
0.26
0.28
0.32
0.26
0.29
0.28
0.30
0.35
0%
2%
4%
6%
8%
0.26
0.26
0.26
0.27
0.28
0.26
0.26
0.26
0.27
0.28
0.26
0.26
0.26
0.27
0.29
LIME-.GBFS 1:1
LIME:GBFS 1:2
0%
2%
4%
6%
8%
LIME:GBFS 1:3
GBFS
201
TABLE 6.3c
ADDITIVE
U C S (MPa) of lime, GBFS and lime-GBFS stabilised soil
C.
(%)
7
C U R I N G (DAYS)
90
28
LIME
0%
2%
4%
6%
8%
LIME:GBFS 1:1
0.21
0.25
0.34
0.43
0.41
0.21
0.30
0.41
0.51
0.50
0.21
0.33
0.44
0.56
0.55
0%
2%
4%
6%
8%
0.21
0.22
0.25
0.30
0.30
0.21
0.25
0.30
0.36
0.37
0.21
0.28
0.35
0.42
0.43
0.21
0.22
0.24
0.27
0.27
0.21
0.26
0.29
0.34
0.34
0.21
0.28
0.32
0.37
0.38
0%
2%
4%
6%
8%
0.21
0.22
0.24
0.26
0.28
0.21
0.24
0.27
0.30
0.32
0.21
0.25
0.29
0.33
0.35
0%
2%
4%
6%
8%
0.21
0.21
0.23
0.23
0.24
0.21
0.21
0.23
0.24
0.25
0.21
0.21
0.23
0.25
0.25
LIME:GBFS 1:2
0%
2%
4%
6%
8%
LIME:GBFS 1:3
GBFS
202
TABLE 6.4a
ADDITIVE
U C S (MPa) of cement, GBFS and cement-GBFS
stabilised soil A
(%)
7
CURING (DAYS)
90
28
CEMENT
0%
2%
4%
6%
8%
CEMENT:GBFS 1:1
0.33
1.26
1.75
2.45
3.00
0.33
1.95
2.70
3.50
4.30
0.33
2.00
3.15
4.00
4.60
0.33
0.60
1.41
1.41
1.58
0.33
0.80
1.69
1.95
1.96
0.33
1.00
2.15
2.35
2.50
0.33
0.45
0.85
0.92
1.00
0.33
0.50
1.10
1.25
1.37
0.33
0.59
1.43
1.50
1.64
0.33
0.42
0.75
0.90
0.99
0.33
0.45
0.90
1.20
1.35
0.33
0.45
0.90
1.30
1.62
0%
2%
4%
6%
8%
0.33
0.39
0.47
0.75
0.85
0.33
0.40
0.49
0.75
0.95
0.33
0.40
0.71
1.10
1.32
0%
2%
4%
6%
8%
0.33
0.34
0.36
0.38
0.40
0.33
0.36
0.37
0.38
0.41
0.33
0.36
0.36
0.38
0.40
0%
2%
4%
6%
8%
CEMENT:GBFS 1:2
0%
2%
4%
6%
8%
CEMENT:GBFS 1:3
0%
2%
4%
6%
8%
CEMENT:GBFS 1:4
GBFS
203
TABLE 6.4b
ADDITIVE
U C S (MPa) cement, G B F S and cement-GBFS stabilised
soil B.
(%)
7
C U R I N G (DAYS)
28
90
CEMENT
0%
2%
4%
6%
8%
CEMENT:GBFS 1:1
0.26
0.43
0.62
0.90
1.40
0.26
0.67
1.02
1.50
2.30
0.26
0.74
1.15
1.70
2.57
0.26
0.30
0.52
0.62
0.75
0.26
0.42
0.73
0.82
1.02
0.26
0.50
0.85
1.00
1.20
0.26
0.33
0.40
0.60
0.61
0.26
0.38
0.50
0.65
0.75
0.26
0.42
0.54
0.75
0.95
0.26
0.33
0.41
0.50
0.51
0.26
0.33
0.41
0.51
0.55
0.26
0.33
0.42
0.60
0.65
0%
2%
4%
6%
8%
0.26
0.27
0.28
0.29
0.40
0.26
0.30
0.35
0.47
0.50
0.26
0.30
0.37
0.47
0.55
0%
2%
4%
6%
8%
0.26
0.26
0.26
0.27
0.28
0.26
0.26
0.26
0.27
0.28
0.26
0.26
0.26
0.27
0.28
0%
2%
4%
6%
8%
CEMENT:GBFS 1:2
0%
2%
4%
6%
8%
CEMENT:GBFS 1:3
0%
2%
4%
6%
8%
CEMENT:GBFS 1:4
GBFS
204
TABLE 6.4c
ADDITIVE
U C S (MPa) of cement, GBFS and cement-GBFS
stabilised soil C.
(%)
7
C U R I N G (DAYS)
28
90
CEMENT
0%
2%
4%
6%
8%
CEMENT:GBFS 1:1
0.21
0.25
0.32
0.42
0.48
0.21
0.32
0.41
0.52
0.60
0.21
0.35
0.46
0.58
0.70
0.21
0.23
0.29
0.39
0.42
0.21
0.25
0.33
0.43
0.44
0.21
0.29
0.40
0.54
0.60
0.21
0.23
0.27
0.34
0.38
0.21
0.27
0.33
0.38
0.38
0.21
0.27
0.36
0.44
0.42
0%
2%
4%
6%
8%
0.21
0.22
0.26
0.32
0.32
0.21
0.26
0.32
0.35
0.35
0.21
0.28
0.34
0.40
0.38
0%
2%
4%
6%
8%
0.21
0.21
0.23
0.23
0.27
0.21
0.21
0.27
0.29
0.30
0.21
0.21
0.29
0.31
0.33
0%
2%
4%
6%
8%
CEMENT:GBFS 1:2
0%
2%
4%
6%
8%
CEMENT:GBFS 1:3
GBFS
1C<
205
MH
0
JS
o>
o o o o in
m in © o r~
o o o in o
in m o r» o
o in o o o
m p» in o m
o o m in in
m o r- r- CM
o in o o in
in r- o o CN
ro PO CM t-H
o
PO PO PO rH rH
ro ro ro C N iH
PO ^« PO CM CN
PO PO Tf Tf Tf
ooooo
ooooo
o o m m o
o o o o o
o o o m o
ooooo
o m m o o
o o o o o
o o in o m
o o o o o
o o m o in
OS US rH O
a\ vo ^* P O ro
as vo in TJ-
as r- vo vo vo
os oo r» r-- vo
os cs oo co r-
ooooo
ooooo
o o o o o
o o o in o
o o o o o
o in o o o
o o o o o
o o o o o
O O O O O
o o in o o
Tf o ro in as
CN ro P O ro ro
"•f C* CN PO CO
CN CN P O ro ro
"tlOHlfllO
CN CM ro ro ro
f vo as ro Tf
CM CM CM ro ro
^< in in in in
CM CN CM CM CM
o o o o o
© © m m ©
ooooo
ooooo
ooooo
o o m o o
o o o o o
o o in o m
O O O O O
O O O O O
o in o in in
•dp
(8
u
PO <-H © ©
o
U
a
c
•H
TJ
C
IB
a
•P
•H
DAYS CURING
UNIT
rH
O O O O O
O
ooo
ooo
CO
CN
rH
•dP
PH
f
rH
ooooo
ooooo
PO
o eu cu
TT
M
0)
+J
ro co rH os as
ro vo r» co CN
rH
ro PO ^* Tf ^*
PO PO PO PO ^*
PO in P » co CM
ro PO PO P O ^*
PO Tf f- rH CM
PO PO PO ^* ^*
ro T»* vo o o
ro ro ro ^* ^*
PO ^* ^* PO PO
PO P O P O P O ro
U
A
W
o o o in m
o o o o o
o o o o in
o o m o in
O o m O O
in in m m r-
m in CM in CM
in o r-« o m
o in in o
in t»- r» ©
rocONHO
PO PO PO <-< rH
ro ^* ro ro rH
ro ro ro ^* ^*
o o o o o
o o o o o
ooooo
o o m o o
O O O O O
O O O O O
O O O O O
O O O O O
•dP
c
0
to
8
'dP
rH
fl
W
fc.
PS
a
w
fc.
ea
u
M
OB
o o o o o
o o o o o
mionoo
ooooo
ooooo
os vo in f CN
os vo vo in n*
oi co vo in P O
CM CO vo vo ro
Os OS OS OD CO
o o o
o o o
ooooo
ooooo
ooooo
ooooo
ooooo
ooooo
ooooo
ooooo
O O O O O
CN CM PO PO PO
Tf VO Ol Tf CO
CN CM CM PO PO
TT VO CO O VO
CN CM CN ro ro
o o o o o
o o in o o
n**inoiH
ooooo
ooooo
O O O O O
O O O O O
H3
DAYS CURING
P.L
I
H11
H
rt* o PO in o
CN ro ro PO ^*
••j* as CN PO vo
o o o o o
^* m m m in
CM CM CM CM CM
r»
o o o o o
o o o o o
•3
o
flJH
M-l -H
ooooo
ooooo
ooooo
ooooo
PO VO CO O «f
PO PO PO ^* ^*
PO vo co as CN
ro P O ro ro ^*
PO If) CO CO o
PO ro ro P O ^*
fO PO PO PO Tf
PO Tf Tf VO OS
ro ro P O P O PO
ro •«• Tf ro ro
ro P O ro ro P O
dP dP dP dP dP
© CN ^< VO 00
dP dP dP dP dP
O CM IS" VO CO
dP dP dP dP dP
O CN "«f VO CO
dP dP dP dP dP
O CM Tf vo 00
dP dP dP dP dP
O CN Tf VO 00
dP dP dP dP dP
rH
CM
ro
"3*
rH
rH
rH
fc,
fc.
fc,
CQ
CQ
CQ
U
••
Ed
&
H
o
65
O CN f vo 03
w 0
fc. w
dP
W
w
u
fc.
>
ra
0) H H
I
fc]
EH
S
H
H
a
a
<
aa
aa
rH
•
o
©
U
•H
•U
•H
u
m in in CN CN
in o o o in
ro <-t o o o PO PO CN rH o
o
fc.
S
H
••
fc]
a
H
•a
a
H
J
W
fc,
CQ
206
•M
0
0)
ei
fl
n
CO
m © o m ©
r» © in CM o
m © © © ©
r» m o m ©
o m © © m
m r» m o CM
r~ r- m CM t-
m © o © o
r» m m m m
N N H H H
CM CM CN rH rH
ro CM CM CM rH
CM CM CM CM <-H
CM CM CM CM CN
© © o © ©
o o o o o
© © o © ©
© © o © ©
O O O O O
© o m © m
o o o o o
o o o o ©
o o © m o
O O O O ©
O O O O ©
O O P O H H O
co vo T T P O ro
co P~ vo m Tf
co oo r» vo m
co co r- vo vo
00 CO 00 CO 00
© O O O O
o © o o o
o o o o ©
o o o © o
o o o o o
o o o o o
o o o o o
© © © ©
o o o o m
Tf .H ro m oo
CN ro ro ro PO
«f vo os © ro
Tf m vo r» co
TT Tf m vo r-
Tf Tf m m vo
o o o o o
o © o © o
Tf m m m m
CN CM CM PO PO
CM CM CM CM CM
CN CM CM CM CM
CM CM CM CN CM
CN CM CM CM CM
O O O O O
O O O © o
O O O O ©
© © © © ©
o o o © o
O O O O O
O O O O O
© © © ©
o o o o o
o o o o o
tf Tf vo a>
PO PO PO ro PO
CN CM CN PO VO
CN CN CM CN CM
ro ro ro PO ro
CM CN CN CM CN
ro ro PO PO PO
CN CN CN CN CM
CN ro ro ro ro
ro ro ro ro ro
PO PO PO PO PO
m m m o m
m © © o ©
r» m m © m
m © m m ©
m m o © o
m m o m m
m m m m m
r- CM r-» m CM
r»- m r» r- m
r» r» in in in
r» r~ m r» r>
[» CM CM CM CM
CM I-H © o
N P f i H H O
CM CM rH ©
CM CM CN i-H rH
CM CN CM rH rH
CN CM CM CN CM
O O O O O
O O O O ©
O O O O ©
CO CO CO CO CO
CO CO 00 00 00
© © © ©
in in in ©
•dP
VJ
in
r» CM r~ m CN
( N H O O O
m m o m m
•a
•H
n
M
z
fl
•H
H
OS
H
© O O O O
cn
"g
fl
tn
CO
CM
JJ
rH
•H
•dP
CU
©
© © © m o
&
M
JS
O © O O
O
© o m o ©
M
0)
JJ
0)
JJ
•dP
G
0
tfl
JS
CO
•dP
U
rl
I
JJ
•H
TJ
TJ
fl
CM
o
EH
M
© © © © o
O O O O O
MD
PO P O PO PO ro
o
©
© O O O ©
© o o o ©
© © © ©
oo m ro CM CM
o m o o in
oo m m TT ro
O O O O O
co vo vo m Tf
© m m © ©
oo vo m m m
o o o o o
o o o o o
© © © ©
© in o o
O O O O O
© © o © ©
© m m © ©
Tf r> rH Tf VO
rr vo vo r» co
Tf m r-» co oo
CM CM ro ro ro
WIOCOOIH
CM CM CM CM CO
© © © © o
o o o o o
f m m vo vo
CM CM CM CM CM
CM CM CM CM CM
CM CN CM CM CM
CM CN CN CM CM
o o o o o
o o o o ©
O O O O O
o o o o o
o o o o o
O O O O O
o o o o o
o o o o o
O O O O O
© © © o ©
o o o o ©
© © o o o
©
© © © © o
DAYS CURING
P.L
cn
fc.
m
u
TJ
cI
0>
fl
w
fc.
CQ
©
m
o o o o o
r~
u
rl
•dP
rH
i
0
•P CQ
0
»H
CN CM ro ro m
ro ro
CM CN CM PO PO
ro ro PO ro ro
CN CM CM CN CN
PO PO PO
CN CM CN CN CM
PO PO PO ro PO
CN CN CO TT Tf
P O ro ro P O ro
ro ro ro ro ro
ro ro ro ro ro
dP dP dP dp dP
© CM Tf VO CO
dP dP dP dp dp
O CM ^* VO CO
dP dP dP dP dP
O CM Tf VO CO
dp dP dP dp dP
© CM Tf VO CO
dP dP dP dP dp
© CN Tf VO CO
e*> dP dP dP dp
© CN -f VO CO
CM
ro
CN CN Tf VO CO
«H 0
fcJ CO
rH
dp
w
oa
>
H
EH
I
©
o o o o ©
w
a
a
<
aa
a.
a.
rH
rH
rH
rH
cn
cn
fc,
CQ
cn
fc.
CQ
••
Ed
fc.
CQ
fc,
CQ
fcl
u
u
X
••
Cd
••
Ed
a
a
H
H
M
Ed
a
H
a
H
cn
fc,
EQ
o
207
VJ
Oi
•dP
A
VJ
•a
o o o o o
© © © o o
o o o o o
P- CN • Tf Tf
rH rH 09
t- Tf rH as 03
rH rH rH
© © o o o
o o o o o
m n H H
O O O O O
O O O O O
m r» r» ro co
in ro CM CN rH
© © © o ©
© o o o o
© ©
A
cn
© ©
o o o o o
o o o o ©
r-» m CN © os
O O O O ©
© © © O ©
M f l * N O
rH rH rH rH
rH rH rH rH rH
rH rH rH rH rH
© © © O O
© O O O O
© © O O O
© © © © ©
m o © m
m Tf ro CM CM
m CM Tf as vo
m Tf ro CM CM
O
O
m
m
O O O O O
O O O O O
© © © © ©
o o o o o
o o o o o
o o o o o
m r» co as rH
m P~ oo co co
m [•«• co r» r»
m VO VO VO VO
m vo vo r- oo
Tf Tf Tf Tf m
^ * ^ * ^ * T f ,ef
Tf Tf Tf ^* ^*
^* Tf Tf Tf Tf
Tf Tf Tf Tf Tf
O
o
o o o o ©
• o o o ©
o
© © © © ©
• o o o o
o
o o o o ©
• o o o o
I-H co r» r- vo
© co © in CM
rH CO co r- t-»
© VO rH as vo
IH as as co co
HMOKllfl
©
. . . .
o Tf m IH vo
H co r» M O
© © © © m
© © © © r»
o o o o o
o m © © ©
o o o o ©
© o m © ©
r-»
CM
r- ro rH os oo
r» Tf
© © © © ©
o o in in in
M n d H O l
© © © © ©
© © m m ©
[-»r» vo m m
t-H
rH
i-H rH rH
rH rH rH rH
rH rH rH rH
rH rH rH rH rH
O O O O O
O O O O O
O O O O O
O O O O O
O O O O O
o o o o o
o o o o o
m © co as m
innn
m vo vo ro co
O O O O O
© O O O ©
m © os vo CM
m CO CN CM rH
m
m CM TfCT>VO
m Tf ro CM CM
m --H co m CN
m m Tf Tf Tf
© © © © o
o o o o ©
© o o o o
© © m © o
o o o o ©
o o o o ©
o o o o ©
© © © o ©
o o o o ©
o © © © ©
m m vo vo vo
O O O O O
o o o o ©
p» r» vo m f
l-H
CQ
M
fl
0)
c
•H
TJ
C
fl
CQ
JJ
•H
DAYS CURING
UNIT
•H
09
CN
a
•dP
JS
J
VJ
0)
JJ
•dP
•H
0)
J:
JJ
VJ
JS
c
0
cn
CD
QJ
>
•H
JJ
•H
•dP
VJ
EH
M
oz
en
cn
fc,
ea
u
*>
rH
•dp
•4
0
JJ u
0
OJH
D-l -H
U 0
cd cn
©
o o o o o
o
o o © o o
• o o o ©
o . . . .
© r» m as m
oo m Tf
o © © © o
•© © © ©
.H
© co
o o o o ©
Tf CM CM CM
MS
DAYS CURING
P.L
TJi
C
fl
© © © ©
•H
TJ
TJ
fl
ea
u
CM
O O O
© © ©
m CM co
-«f *f ro
CU
01
U
fc,
m o r^ © Tf
O
©
o
m
m r» co © CM
m vo r» os as
**«*nm
^* ^* ••f **f ^*
o
o o o o o
•© o © ©
o
o o o o o
•o m o o
<"» . . . .
o P» vo as PH ^. vo m m
dP dP dP dP dP
O CN Tf vo CO
dP
u
m
•
vo
0)
H
a
W
EH
<
M
a
a
m vo vo r» t-»
^*
o
o o o o o
• o o o ©
o
o o o o o
• o o © o
r—i
f—s
.
.
.
© co © m
.
CM
© CM ro *-H r»
rH 00 C» P- vo
rH 00 p» r> vo
dP dP dp dP dP
O CN Tf vo 00
dP dP dP dP dP
© CM Tf VO CO
dP dP dP dP dP
© CM Tf VO CO
rH
CM
ro
rH
rH
rH
cn
fc,
cn
fc,
cn
CQ
CQ
CQ
U
••
U
Ed
a
rH oo co r-> r»
^*
Ed
a
M
a
M
rH
Ed
H
rH
a
H
.
*rf*
.
^*
.
.
dP dP dP dP dP
O CN Tf VO CO
rH
Ed
^*
© p» f CM as
rH as as os as
a.
>
M
EH
o
o o o o ©
• o o o o
o m m CM co
in vo vo vo vo
^* ^* ^* ^* ^*
cn
fc,
CQ
208
cu
Oi
VJ
fl
—:
o o o m ©
m © m CM ©
PO <H o o o
o m © © o
m r- o o m
f l H H H O
o m m o ©
m P» CM m ©
© © o © m
m m © o CM
o m m © o
m p- CN m m
o m © © m
m p» © © CM
PO CM CM i-H rH
PO PO PO CM rH
ro ro ro
ro ro Tf Tf Tf
o o o o o
o o o o o
o^ m rH o o
o o o o o
© © m o o
O O O O O
o o o o o
© © © o o
© o © o in
o o o o o
o o o o o
o o o o o
o © m © m
OS VO Tf CO rH
cn c^ vo Tf
O"! CO P- •* CN
os co p» vo ro
OS OS CO 00 P*
© © © ©
© © m o
o o o o o
o o o o o
O O O O O
© © © © m
Tf rH Tf CO ©
CM PO PO PO Tf
*t as rH in os
Tf P» © Tf CO
CM CM PO PO PO
o o o o o
o o o o o
Tf m as rn m
© o o o ©
© © m © m
•f m m m m
ro ro
CM CM CM CM CM
o o o o o
o o o © o
© o o o o
© © o o o
o o © © o
© o o o o
ro oo r-* oo cr*
ro ro "3* Tf Tf
PO P» Ol rH rH
PO PO PO Tf Tf
ro vo p> os rH
ro ro P O P O Tf
© © m o m
in in r» in CM
PO rH o © ©
o m © m o
m c- © r- m
f l H H O O
o m m o m
© © o © ©
o © o © o
as vo CM o o
A
cn
•dP
VJ
VJ
fl
0)
z
e
as
•H
TJ
n
soz
e
cn
A
>H
n
2
JJ
00
CN
rH
Oi
•dP
M
&
VJ
JJ
CM
%
0
A
JJ
C
0
IS
0)
•4
•dP
r4
.5
JJ
•H
rl
VJ
TJ
TJ
fl
cn
A
en
fc,
a
u
EH
H
az
Z
©
o
CM CM PO PO PO
CM C M C M
o o o o ©
© © © © o
PO m P» co IH
o o o o o
o o o o o
o o o o o
© © © o ©
PO PO VO P» CO
PO PO PO PO Tf
ro ro ro ro ro
ro ^* ^ ro ro
ro ro ro PO PO
in CM CN © P»
o m © m o
m CM © p» o
o in m o in
m CM r- © r-
o m m o o
m r- P» o ©
C 1 H H H O
PO CN CM rH rH
ro ro
PO PO PO Tf Tf
© © © © ©
o o o o m
© O O O O
o o o o o
o o o o ©
o © o o o
O O O O O
o o o o ©
o o o o o
o © © o ©
01lOlflfl*H
Ol P> p» m rH
as oo co vo P O
as 03 oo
OS OS 0\ CO 00
O O O O ©
© © © © m
o o o o o
o o o o ©
o o o o o
o o o o o
^* OS © PO pro ro ro
>»f p» as
«*f in in in in
CM ro Tf Tf Tf
•* o PO vo co
CM PO PO PO PO
o o o o o
o o o © o
Tf m co © Tf
CM C N
CM CM CM PO PO
CM CN CN ro ro
CM CM CM CN CM
O O O O ©
O O O O O
© O O O O
o o o o o
o o o o o
o o o o ©
© o © o ©
o o o o o
O O O O O
o o o o ©
ro vo p- co oi
PO PO Tf Tf Tf
PO VO CO o ©
PO PO PO ^* ^*
ro vo p» oo oo
PO PO PO PO PO
o o o o ©
© © o o ©
PO m P* co co
ro ro ro ro ro
ro ro vo p* oo
ro ro ro ro ro
PO Tf Tf ro ro
ro ro ro ro ro
dP dP dP dP dp
O CN Tf VO 00
dP dP dP dp dP
O CN Tf VO 00
dP dP dP dP dP
© CM Tf VO CO
dP dP dp dP dP
O CM Tf VO 00
dp dP dP dP dP
O CM Tf VO CO
dP dP dP dP dP
O CN Tf VO CO
rH
aa
rH
CM
ro
a.
rH
•a
rH
Tf
a.
rH
cn
fc,
CQ
©
CM CN
P»
Tf
z
M
DAYS CUR
P.L
a0)
o o o
o o ©
Tf ro vo z
CM ro Tf
VJ
cn
•dp
fc,
BQ
CJ
I
JJ
TJ
e
CN
rH
CM
o © o o ©
o o o o o
»f o m m m
CM
m
© o o o o
© © © © ©
r-
JJ
c
•dP
rH
1) <
<«
0
H
JJ •H
0 0
tv en
•W
1-1 «w
fc]0
dP
cn
fl
vo
I
IO
I
Ed
>
M
EH
EH
H
z
a
Z
Ed
Ed
cn
Eh
CQ
U••
EH
Z
Ed
Q
<
a
a
cn
fc,
CQ
O• •
Ed
u
Ed
U
••
cn
fc.
CQ
U
EH
&J
Z
Ed
Z
Ed
cn
a
a
a
Eh
CQ
Ed
U
Ed
U
Ed
U
o
209
J3
cn
in in in m ©
P- P» CM CM O
•d
VJ
rl
z
H
OS
CM © o o
m m m o o
p- p> CM © ©
©
m m o o o
r- P» m m m
m o m o m
p» m CM © r-
m m m m ©
p- P» p» CM ©
m © © © ©
p» m m m m
CM CM CN CM ~J
CN CN CN CN CM
«N CM CM CM CM
© © © © ©
o
0 0o
0 3o
0 0o
0 0o
00
EH
o o o o o
o o o o ©
M
o o o o o
o o o o ©
o o o o o
o o m © m
© o o o o
© m o m ©
o © © © ©
© o m o o
00 PO CM *H ©
00 Tl* PO CM tH
co r~ VO VO in
C0P«P»VOVO
CO CO p» p» p»
o o o ©
o o o o
o o © o o
o © o o o
o o o o o
o o m o m
© © © o o
o o o o o
o o o o o
o o o o o
© © © © ©
Tf rH PO VO
CM PO PO PO
Tf OS rH PO vo
CM CN PO PO PO
Tf m vo 09 as
CM CM CN CM CN
Tf m vo vo 03
CM CM CM CN CM
^* Tf m vo P»
CM CM CM CM CM
>* in in in in
CM CM CM CM CN
o o o o ©
o o o o o
o o o o ©
© o o o o
O O O O O
O O O O ©
O O O O O
© m © m ©
© © o o ©
o o o o ©
O O O O O
CM Tf m r^ o
PO PO PO ro ^*
CM PO
Tf m rPO PO PO PO PO
CM CN PO Tf m
CM CN ro ro Tf
PO PO PO PO PO ro ro PO PO PO
CN CM
ro ro Tf
ro ro ro ro ro
CM ro ro ro ro
ro ro ro ro ro
m o o o o
p» o m m o
in © © in in
p> m © P» P»
N H H O O
m © o o ©
p» m m m ©
m o m m m
m m m m m
p» m CM P» CM
CNCMCNrHtH
P» CM CM CM CM
CMCMCMCMCM
O O O O O
O O O O ©
oomTfCNO
O O O O O
O O © © O
coininTfCM
© © o o ©
o o o o o
O O O O O
o o o o o
o o o o o
o o o o o
o o o o o
co vo vo in TT
oo
CO p- VD VO VO
CO CO CO CO GO
© © © o o
o o o © ©
o o o o ©
© © © © ©
© o o © ©
© © © © o
o o o o o
o o o o o
© © © © o
o o o o ©
o o o o o
^* P» OS PO 03
CM CM CM PO PO
•a* P» oo rH *r
CN CM CN PO PO
Tf VO P- O CM
CM CM CN PO PO
Tt* m
ooooo
o
oo
CM o
CM o
PO m VO
ooooo
oo
oo
PO m vo
CN
CM o
© o o o o
o o o o ©
PO PO PO PO PO
dP dP dP dP dP
O CN ^" VO 00
DOB
UHD
cn
CO
CN
rl
•dP
CU
VJ
cn
•d
M
CM rH O O
©
m m © o m
p» p» m m CM
CN rH rH rH rH
o © o o o
ooooo
rl
oz
o © © ©
P-
o
vo m Tf
Z
M
OS
D
UJ
as ©
ooooo
Tf m P» oo co
CM CN CM CM CN
CM CM CM CN CN
O O O O O
O O O O O
O O O O O
o o o o o
© © © © ©
ooooo
CM CM PO CN CN
PO PO PO PO P0
dP dP dP dP dP
© CM Tf vo 00
P»
CN CM CM CM PO
•o
cncu
I
•dP
PO PO PO PO PO
CM CM ro m vo
PO PO PO PO PO
P0 PO PO PO PO
CN CN PO Tf Tf
P0 PO PO PO PO
dP dp dP dP dP
O CM Tf VO 03
dP oP tiP dP dP
O CM Tf VO 00
dP dP dP dP dP
© CN Tf VO 03
dP dP dP dP dP
O CN Tf vo 00
CN
CM
ro Tf Tf
P0
c
n
Ed
>
H
EH
H
Q
Q
H
Z
<
U
Ed
ad
E
cn
cn
cn
cn
Eh
CQ
Eh
CQ
Eh
CQ
U
EH
U
••
Eh
CQ
O
••
Z
Ed
EH
a
Z
Ed
Ed
U
a
Ed
U
EH
Z
Ed
a
Ed
U
o
EH
Z
Ed
cn
a
Eh
CQ
Ed
U
U
210
0)
en
VJ
S
•a
JS
cn
•dP
JVJ
9
1
H
O O O O O
o o o m o
o o m P» m
o o o o o
o o o o ©
o m m m o
p- CM CO VO VO
rH rH
p» Tf © oo p»
MneiHOl
rH rH rH
I-H rH rH rH
O O O O O
O O O O O
m o o PO CT>
O O O O O
O © O O ©
m co m r» Tf
m PO CM rH
m CO CM rH rH
O O O O O
o o o o ©
O O O O O
o o o o o
r- VO Tf CM rH
rH rH rH rH rH
p> r» vo m Tf
O O O O O
o o © © ©
o o o o o
Ifl^lflOH
in Tf ro CN CM
tn VO VO CM P»
m Tf ro ro CN
o o o o ©
© o o o o
m o m CM co
© o o o o
o o o o o
o o o o o
o o o o o
o o o © o
o o o o o
o o o o o
inifiiopos
m vo p> p» P-
m VO VO VO VO
m vo vo p» oo
Tf Tf Tf Tf Tf
rH rH rH rH rH
O
•p
z
H
SH
OS M
DH
OE
U
D
"Ei2
fl
CO
•VJ
o o o o o
m in Tf Tf ro
cn
<
•p
Q
00
CM
.aJ
Oi
J
o o o o o
o o o o o
m P» os o o
M
CU•dP
Tf Tf •* m m
Tf Tf Tf Tf Tf
Tf -3* ^, ^* ^*
Tf Tf Tf Tf Tf*
J
•dP
J
o
o o o o o
• o o o ©
©
o P- o> PO as
H M O I O W
o
o o o o o
• o o o o
o
o o o © o
• o. o. o. o.
r*i
o
o o o o o
• o o o ©
©
rn co r- vo vo
o © CN m co
HfflCOPIfl
CD • • • •
O CM CM 00 ro
i-H OS CO P» P»
o © © m ©
o m o P» m
o o o o ©
o © o o o
O O O O O
o o o o ©
o o o o o
o o o o o
o o o o ©
© © m m ©
r- C M
tH rH
r>*oosr>
p- m ro .H oi
rH rH rH rH
C- VO Tf CN rH
rH rH rH rH rH
p» p- vo in in
iH rH rH
o o o o ©
o o m o o
m oo m p» TT
O O O O O
o o o o ©
O O O O O
o o o © o
mr-PHto
O O O O O
o © © o o
m rH oo m CM
in f ro ro CM
m
© o o o o
© o o o o
m m vo vo vo
© o o o o
o o o o o
m m m vo vo
o o © o o
© © © © o
m vo vo P> P>
•rf ^* Tf Tf TJ*
Tf Tf Tf Tf Tf
Tf Tf Tf Tf Tf
o
o o o o o
• o o o ©
©
O O O O ©
© © © ©
©
il
VJ
J0)
J
JJ
<
$
X.
JJ
©
. . . .
ro rH Tf iH
o
© © © o ©
• o o o ©
© . . . .
© VO t-H OS VO
rH OS OS 00 CO
e
0
CO
0)
VJ
>
A
cn
JJ
'dP
JVJ
TJ
c*i vo vo
rH rH rH rH rH
"8
en
fa
CQ
CJ5
1
JJ
&J
H
HQJZ
5
a
1
u
TJ
B
fl
en
fa
m
u*
O
Z
H
OS
D
UJ
cno,•dP
O © O
O
O O O ©
m
PO CM PO
os
m PO CM rH
m rO CM rH rH
O O O O O
O O O O O
© o o o o
o o m o ©
in vo vo o
©
m ro ro VO rH
m Tf ro CM CM
m
"•** Tf Tf
Tt* •* Tf in m
in in in P » P Tf Tf Tf Tf Tf
o
o o o o o
• o o o o
o
o o o o o
• o o o ©
©
© © © © ©
• O O O O
O OS rH rO Ol
rH P» p- vo m
O PO rH Tf rH
rH 00 P» VO VO
O CO Cl CN PiH oo r» P » vo
©
• • • •
O CM CM P- CM
I-H os co r» r»
©
• . . .
o P- »f CN Q".
rH as as as co
dP dP dp dp dP
O CM "f VO 00
dP dP dp dP dp
O CM Tf VO 00
dP dP dP dP dP
© CN ^" VO CO
dP dP dP dP dP
O CM Tf VO CO
dP dP dP dP dP
O CM Tf vo CO
ro
Sx
<<
Q
JJ
*>
c
0)
§0
VJ
O
O
j
•dP
J
u
©
. . . .
o
....
• o o o o
0
0 H0
wai en
W <M
fa 0
.-»
dP
0
IO
a
VO
M
&J
.a
rH
cn
cn
en
Eh
Eh
Eh
EH
O
»•
&J
Z
a
Ed
U
EH
H
Q
Q
Cd
(3
<
&J
•a
rH
C•ffl
H
Z
H
0)
J3
CN
CQ
c
n
Cd
>
rH
rH
CO
U••
Cfl
Z
Ed
z
Ed
cn
a
Cd
a
Ed
a
Ed
Eh
CQ
U
U
U
O
Ed
211
T A B L E 6.7
Effect of delay in compaction on the U C S of cement and
cement-GBFS stabilised soil A.
Additive %
Time elapsed
Since mixing
90 days
U C S (MPa)
loss in
strength
%
8% CEMENT
0.00 hours
2.00 hours
4.00 hours
6.00 hours
4.60
3.22
2.34
1.47
0.00
30.00
49.00
68.00
0.00 hours
2.00 hours
4.00 hours
6.00 hours
1.64
1.24
1.05
0.67
0.00
24.00
36.00
59.00
0.00 hours
2.00 hours
4.00 hours
6.00 hours
1.32
1.05
0.84
0.56
0.00
20.00
34.00
57.50
8%CEMENT:SUVG1:2
8%CEMENT:SLAG1:4
212
T A B L E 6.8
Additive %
Effect of delay in compaction on the U C S of lime and
lime-GBFS stabilised soil C
Time elapsed
since mixing
90 days
U C S (MPa)
loss in
strength
%
8 % LIME
0.00 hours
2.00 hours
4.00 hours
6.00 hours
24.00 hours
0.55
0.52
0.51
0.51
0.48
0.00
5.45
7.27
7.27
12.72
0.00 hours
2.00 hours
4.00 hours
6.00 hours
24.00 hours
0.43
0.41
0.39
0.37
0.36
0.00
4.65
9.30
13.95
16.27
0.00 hours
2.00 hours
4.00 hours
6.00 hours
24.00 hours
0.35
0.32
0.30
0.30
0.30
0.00
8.57
14.28
14.28
14.28
8%LIME:SLAG1:1
8%LIME:SLAG1:3
213
T A B L E 6.9a
Effect of lime and lime-GBFS additives on the shear
strength parameters of Soil B.
ADDITIVES
Lime
7 DAYS CURING
0%
4%
8%
0 (degrees)
C (MPa)
28 D A Y S C U R I N G
0 (degrees) C (MPa)
19.00
29.00
32.00
0.08
0.10
0.16
19.00
32.00
37.00
0.08
0.13
0.21
Lime: GBFS
1:1
19.00
25.00
31.00
0.08
0.10
0.10
7.00
25.00
34.00
0.08
0.10
0.12
Lime: GBFS
0%
4%
8%
1:3
0%
4%
8%
19.00
22.00
26.00
0.08
0.08
0.10
19.00
24.00
27.00
0.08
0.10
0.10
T A B L E 6.9b
Effect of lime and lime-GBFS additives on the shear
strength parameters of Soil C.
7 DAYS CURING
ADDITIVES
Lime
0%
4%
6%
Lime-.GBFS
1:1
0%
4%
8%
Lime:GBFS
28 DAYS CURING
0 (degrees) C (MPa)
0 (degrees)
C (MPa)
7.00
30.00
28.00
0.08
0.16
0.23
7.00
35.00
33.00
0.08
0.17
0.22
7.00
20.00
28.00
0.08
0.11
0.14
7.00
22.50
33.00
0.08
0.12
0.18
7.00
12.00
20.00
0.08
0.10
0.11
7.00
14.00
22.00
0.08
0.11
0.13
1:3
0%
4%
8%
214
T A B L E 6.10
Effect of cement and cement-GBFS additives on the
shear strength parameters of soil B.
7 DAYS CURING
ADDITIVES
Cement
0%
4%
6%
CementGBFS
1:2
0%
4%
8%
CementGBFS
28 D A Y S C U R I N G
0 (degrees) C (MPa)
0 (degrees)
C (MPa)
19.00
36.50
44.00
0.08
0.11
0.16
19.00
47.00
50.00
0.08
0.19
0.29
19.00
28.00
29.00
0.08
0.13
0.14
19.00
47.00
48.50
0.08
0.23
0.25
19.00
24.00
26.00
0.08
0.10
0.12
19.00
38.00
46.50
0.08
0.18
0.23
1:3
0%
4%
8%
215
T A B L E 6.11
Effect of various additives and curing time on the C B R of
stabilised soil A.
CBR
28 Days
90 Days
55
75
72
55
81
76
55
69
80
55
71
84
0%
4%
8%
55
65
70
55
67
79
0%
4%
8%
55
60
65
55
62
66
0%
2%
55
102
55
110
55
80
99
55
80
105
55
70
101
55
70
98
ADDITIVES (%)
LIME
0%
4%
8%
LIME:GBFS1:2
0%
4%
8%
LIME.GBFS 1:3
GBFS
CEMENT
CEMENT:GBFS1:2
0%
4%
8%
CEMENT:GBFS1:3
0%
4%
8%
216
T A B L E 6.12
Effect of various additives and curing time on the C B R of
stabilised soil B.
ADDITIVES (%)
LIME
CBR
28 Days
90 Days
30
40
37
30
43
41
30
38
45
30
41
50
0%
4%
8%
30
36
42
30
36
43
0%
4%
8%
30
35
40
30
36
42
0%
2%
30
99
30
100
30
56
100
30
60
105
30
49
100
30
60
102
0%
4%
8%
LIME.GBFS 1:2
0%
4%
8%
LIME:GBFS1:3
GBFS
CEMENT
CEMENT:GBFS1:2
0%
4%
8%
CEMENT:GBFS1:3
0%
4%
8%
217
T A B L E 6.13
Effect of various additives and curing time on the C B R of
stabilised soil C.
CBR
28 Days
90 Days
19
31
55
19
32
60
19
27
32
19
30
35
0%
4%
8%
19
25
32
19
27
35
0%
4%
8%
19
23
28
19
24
30
19
32
51
19
35
56
19
20
36
19
22
46
19
20
30
19
22
36
ADDITIVES (%)
LIME
0%
4%
8%
LIME:GBFS1:1
0%
4%
8%
LIME:GBFS1:2
GBFS
CEMENT
0%
2%
8%
CEMENT:GBFS1:1
0%
4%
8%
CEMENT:GBFS1:2
0%
4%
8%
218
TABLE 6.14
No. of Load
Applications
Permanent deformations of 3 % content of 1:1 Cement:GBFS
treated pavement (mm)
Row/Column a
b
c
d
e
f
g
5000
50000
250000
E
1.80
0.10
1.35
-0.70 0.78
-1.40 1.00
0.80 2.20
1.15 1.50
1.00 1.00
2.75 2.00
-0.20 0.02
-0.25 0.57
0.00 0.27
5000
50000
250000
F
1.72
1.76
2.17
0.70
1.28
1.57
1.42
2.10
2.80
1.28 1.55
2.15 2.05
2.22 2.50
0.21
1.31
1.51
0.17
1.30
1.42
G
1.37
1.87
1.87
0.51
1.16
1.24
0.89
1.66
2.60
1.00 0.99
1.09 1.80
2.07 2.04
1.25
1.75
0.50
-0.52
0.35
0.72
H
1.31
1.16
0.50
1.07
0.95
1.70
2.42
2.32
2.72
1.70 1.32
1.87 1.55
2.30 2.15
-0.57 5.15
0.73 5.01
0.03 5.81
I
0.40
0.38
0.12
-1.10 -1.20
0.30 0.45
0.38 0.45
3.98 2.75
1.26 1.85
1.36 1.83
-0.40 0,83
0.18 0.00
-1.52 0.18
5000
50000
250000
5000
50000
250000
5000
50000
250000
219
TABLE 6.15
No. of Load
Applications
50
500
5000
50000
50
500
5000
50000
50
500
5000
50000
50
500
5000
50000
50
500
5000
50000
Permanent deformations of 3 % content of 1:1 lime:GBFS
treated pavement (mm)
Row/Column a
b
c
d
e
E
0.30
-0.70
-0.70
-0.85
0.39
0.60
0.65
0.70
1.51
2.23
3.25
3.83
1.50
2.02
2.36
2.53
3.00
3.22
3.80
4.29
1.15
1.35
1.51
1.65
0.30
0.34
0.80
-0.32
F
0.40 0.50
1.30 0.68
0.00 1.02
-0.50 1.55
2.89
3.43
4.00
4.30
2.09
3.43
3.66
3.77
2.29
3.48
3.11
4.52
1.30
2.75
2.99
3.27
0.50
0.91
0.95
-1.05
0.41
0.58
0.54 1.11
0.90 1.51
-1.16 1.71
4.00
5.18
5.38
5.55
2.89
3.63
4.00
4.30
3.50
4.70
5.12
5.65
1.00
1.28
1.90
2.33
0.36
0.60
1.00
-0.55
0.60 0.80
1.00 0.96
0.30 1.00
-0.50 1.44
3.36
4.00
5.09
5.55
3.11
4.15
4.26
4.72
3.89
4.53
4.99
6.00
1.40
1.65
2.65
3.05
0.60
0.73
0.80
0.00
0.70
0.80
1.10
1.35
1.30
2.80
2.80
3.17
2.30
3.18
3.40
3.62
0.66
0.90
1.00
1.10
0.20
0.28
0.25
-0.47
G
H
I
0.20
0.75
0.00
-0.40
0.20
0.28
0.00
-0.80
f
g
220
TABLE 6.16
No. of Load
Applications
50
500
5000
50000
50
500
5000
50000
50
500
5000
50000
50
500
5000
50000
50
500
5000
50000
Permanent deformations of 8 % G B F S treated pavement (mm)
Row/Column a
b
c
d
e
f
g
E
1.10
0.80
1.65
0.00
-0.44
0.15
-0.40
0.40
0.83
1.88
2.58
3.08
1.99
2.13
3.24
5.39
2.36
4.02
4.96
6.76
1.75
0.85
2.65
3.45
-0.18
0.32
0.32
0.51
F
0.30 -0.30 1.70
0.48
1.33 3.10
0.60 2.43 4.15
-0.22 2.69 5.08
2.25
1.18
4.38
4.88
3.63
3.83
4.63
6.63
1.45
2.94
3.45
3.35
-0.04
0.06
0.56
0.66
G
0.35
0.45
2.10
2.20
0.95
1.67
1.74
2.75
1.87
2.82
4.97
5.42
2.41
3.58
5.11
5.21
3.44
4.26
5.26
6.26
1.10
2.45
3.80
3.70
-0.08
-0.05
0.38
0.40
H
-0.05
0.25
0.20
-0.45
-0.05
1.09
2.13
3.05
2.85
5.10
5.38
5.55
3.30
5.40
6.00
6.40
4.35
5.70
6.20
6.70
1.20
1.20
2.80
3.30
0.00
0.00
0.10
0.25
0.50
1.20
1.10
0.60
0.44
1.53
1.22
1.38
0.74
1.72
2.10
2.42
0.53
2.03
3.90
3.38
0.50
1.50
2.60
3.41
1.45
0.40
0.20
0.30
0.12
1.32
0.67
0.92
I
W>
221
CO
z
LU
o
co
Q
O
•
LU
Q.
CO
CO
LL
CQ
LU
O
CO
•5
i
IU
L_
o
CO
o
D
CO
O
LL
H
o
z
DC
D
O
Q
CO
CM
u
UJ
IO
z
cc
ID
o
•vat
222
CO
CO
><
Q
O
0)
B
o
UJ
LU
CL
co
CO
(DO
g |i
L_ Z
LU
LU
O
LL
o
CO
o
CO
LL
s
h-
CO
a
o
h-
z
DC
M M
a
hZ
UJ
2
UJ
o
LL
CO
£Q
o
g
b
CO
CM
H
<
H
cr
o
UJ
2
z
DC
3
O
rs ,. •
223
o
-J
o
o
CO
Q
UJ
CO
-J
CO
Q
UJ
CO
-J
CQ
I
g
CO
co
(£>
o
CO
g
55
LL
LL
o«5 CO
CQ
-j
CQCOg
O
oi<y
co^g
Ocoo-
CO
Q
UJ
CO
-J
CQ
l<
CO
00
3 U- tn
CD
C0Oi=
2
LULU g
SCO ^
JJ "
O
EL-J
^lil§
CJ2
:
LL
o
iq
O
Tt; q
cvj T-;
O O O O
o
111
224
O
_J
o
8
CO
Q
UJ
CO
_J
Q
UJ
CO
CQ
m
i<
CO
CO
o
CQ
-<*
<D"
CD
g
LL
LL
IO
-*
»
<N
T-
ddo'dcicJod
O
<*C0
CQ
CQ CO
1
h- LU
O
Z CO O)
JfjOQ
S
H
£8
co&a.
^zec
(D^g
OUJ
ELO
•J
o
CO
Q
LU
CO
-J
CQ
£
CO
«t
CD
LL
225
O
_J
o
CO
D
CO
-J
CQ
-J
m
g
CO
o
IO
CD
to
LO
CO
LL
g
LL
ui 3
3s
CD
I
UJ $Q
O =J oo
gmcM
z j5 »
CC
co a
coQ
cc CQ LU
<
OflL
yjujo
-Jjoc
io «tf Q
<oco
U. o
§
Q
UJ
CO
CQ
CO
-O
IO
CO
UL
r%&
226
M
r.
<
h-
Q
cr
o
_l
5
>-
CO
ui
co
3
m
IU
0>
s
iu 8:
a
O ©
o
CO
a
>
ha —
H
Z
D
<
«0
UL
UJ
>
CO
IL
a a
-j
i-: is
CQ
2
2
UI UI
2
X
DJ UI
u o
\ \
m
O
(0
CD
(D
o
.. »•
•.J.I
I
g
a
K
a
z
£ { i
o1
u.
o
.#
a
•»»
IL
CO
o
&
CO
ea
cd
hQ
i- o
«•
z z
O
<
UI
UI
S UI
£
IU
LL
) J
W W ' -
LL
H -co
So
UiQ CO
OUJ
LL 22
Q
o -j
CQ 00
UJ
CM
p"
a CO D
<
X
CO
Q
I
cc z
< UJ
UJ UJ
CC
UJ
CL
a
oz
<D *S
co</) cc
LL CD
D
a
CQ
8
Q
UJ
CO
-J
CQ
CO
JQ
CO
CO
£!
UL
^^"7
227
O
O
O
CO
Q
LU
CO
-J
CO
a
LU
co
-j
CO
<
8
ID
CO
g
o
LL
h-.
CO
g
U.
>co
UJ -J
_JCO
1
-J
Oui -
O
w ~ SP
CO
D
Q CQ CM
•fc- |*>
M
>COQ
m
ofeoc
CO
-J
CQ
<UlO
£
h- CO Q
""13 DC
CO -*
CO
rfcn
CO
r^
<d
<2
LL
"IV
228
<
O
-J
O
CO
8
o
a
LU
UJ
to
co
CQ
_j
CQ
to
co
CD
CO
o
CO
CO
<2
<2
LL
LL
j— -J
™
i—
ZO
LUCO
CQ
2
u
CQ ~
Bte.
ZCOO
"~lL O
H Z
(TJ
couj*y
-Jm cc
S*
Eg
Q
UJ
92
_J
CQ
to
JO
oo
CO
LL
llf
229
w
2<
z
CO
UJ
,
UJ
O
LL
ca
o
~OC0
<LLQ
•«.
hZ
UJ
UJ
_j O ui
CO ~j
LL Q d
o
co
O3CQ
hUjF
OlCO
LUOg
CO
u.
m
GJ
"Is
H H
Z Z
UJ
O oS
UJ
2
2
UJ
00
UJ
CO
o o
o
I +
0
0 0 0 0 0 0 0 0
i - N ( f J - * K ) ( D N 0 O
1
1
1
1
1
1
1
I
230
UJ
--J-J
<Oco
UJ CO Q
QOUJ
U. CO
=j
O UJ CQ
O I
CO
LU
LL
UL
UJ
O
LL
CQ
o £O
T—
QLL
0 9=
O otf
O
o
T—
10
1
1
r-
o
CSJ
1
Ill
231
s
o
o
(0
u00
•3
iii
S
to
u.
m
Z Q
UJ
o
9
iii
2
iu
2
Uj CD
2(5
<3
H =d O
O w CO
H UJ u_
OO
UJ
OD
LL oe$
Li-
iu CO
LL
"
00
o£
Q.
r-»UJ 0
T
1
o
CO 1
UJ
Z 3
05
LL -J
OO
U1
232
£co
C5LU 9
Pr^ co
2(5CQ<
LLZOS
h- UJ LL.
to
II
H
OO O o
DC
g
CC
LU
LL od cn cr
LU
LL
o CL
wco LU O
IZ
l hCO LL
LU
CM ca
CD
LL
Z D
oo
a
_j
m
2
0
V
o
<
?
UI
U_
j
a> H
.
O
Vurf-
>H*
*tZ
<
D
a
UJ
N
u.
D3
>
H
O
a
<
2
+
W
«
%
40
•3
iii
2
-j
{
III
2
-i
1
233
CO
LU t
O Q
co~Q
LL <
CQ „
CD CO
CO
>-
HLL
UJ CQ
ICDO<H
f
.LL
|— O
«J
H LU
LL
06
-J
LL
O
O
LU CO
DC
CO
to
Q
O
cr
LU
UJ LL O CL
LU
co cn X CD
CO
z
CD
cc
CD_
UJ
U 1 O O
£
m
o
iii
0»
&
o
iii
2
LU
2
234
•
•
i
**
X
CO UJ
LL
CQ
3
00
5
2
.g
>
z
co
x> fc
o
o
UJ
(0 CO
-J
OCQ
o
o
o
o
10
¥>
i
LL
CQ UJ
3
O ill
1o
o
z
O
»
, 3
o
a
^ LU
CL
CO CO
-J
LO CQ
°o
f
V
a
tf {
>
8
CO
I
UJ
CL
03
LLf*
"^.
•a
a
T-
CO
o
g
o
LL
s
I
E
e
z
o
5
tr
O
u.
ui
a
x
fcfc
§2g
QCOcQ
&<3
cc
g O CO
D
LL
O
LU
ccQ cc
O I cc
LL
LU
UI
Q < j-co
ULUJ
UJ LL
< -J
Z
X
<
O cc
a
a
I
a
a.
CC
UJ
CC L U <
IO
h- -J
235
FIG.6.17 - Scanning electron micrograph of the fracture
surface of Soil A stabilised with 8% content
of 1:1 lime-GBFS additive after 7 days
accelerated curing
236
FIG.6.18 - Scanning electron micrograph of the fracture
surface of Soil C stabilised with 8% content
of 1:1 lime-GBFS additive after 7 days
accelerated curing
237
f !• ra
>\™
/. <-»
- <JSJ
t
<n>
J
a-«
a-n
O-«J
. g-bs
9-U
VS
• » • *
0-3
i
O'K
fl'SS
%
0-3
z
ars
a-is
r <rv
s r\>
l
ri>
m*
«..-.-\>3—\
- rtf
6-Slr
• D-»
t-C"^"
o-o
— = ^ .
• 0-3r
T3
03
(0
•H
iH
•H
rQ
CD
>
• o-iy
(0 •rH
•P +•>
a-o>
cn•H
o-K
< TJ
Q-1C
us
0-JE
OSJ
o-ve
o-tr
0-5
(TIE
rot
ra
rn
o-iz
m>
«•-?
f^P)) •CT°0
^ l ^ ^ O ^
73
ra
rH
•rH
CM cn
0 w
c
O •H
4-1 1 rH
0 CD 3
OD CO
g 0
•rH
c
U -H TJ
0) 0)
+J rH 4->
+J .« (fl
(0 rH rH
a 0}
4H rH
0
c
0
<D
U
+J O
+J c rd
•H
o-n
o-i:
t^yxmo) *Q?S
u«
1-H
SMI
J'll
I'll
0 5i
31^\0
>o>
•H
T3 <#> r00
rH
>
(0 rC a)
rH +J +J
1 •H MH
X ,5 ra
o-fi
/
0
u
(fl •P (fl
SH
>1
4-1 c ra
M-l o
U T3
o-n
rn
\
(
501
(Tl
g.
oi
«i
0 7
•) S
6
H
238
o-s>
rrt
1
r«
a-a
•OMJ
• a-*.?
*0?S
»•«
r vis
"y
<
J
O-iS
|-0-K
•• a-ts
- ra
a-as
i
. .*
-»_
o-vt
rl*
Tl
CU
tn
m
f
. art
•H (13
ot*
<r2>
• <riv
rQ >
ra -H
P P
tn -H
•a
J
VJ>
0?S
• V.t
O-lf
r«
o-ss
o-»c
•ott
rlt
VIS
ta
•H
•H UJ c
0 CM •rH
Di
W CQ rH
O 3
4H I O
0 Q)
CIS
Oil
'00^
r
ws
«'«
OUZ
CK
rH r H TJ
0)
d)
•) -52
<
CH
0"lZ
m
>c.
•9-1!
Oil
o-ti
I'll
0'5I
0 51
o-vt
71^\y\\oro>\
g
C -H
• 0'tl
- J:I
. <rn
P •• ra
•H
ra »H Ou
ra
Pd. a)
UH iH
>1
Cu O 03
ra
O
4H
W0 O T )
•H P
TJ <c
#> r00
O 03
>i
n
ra -P co
ra .C 03
C "
SH P P
0
I -H <4H
x 5 <a
o
o-oi
^
*
„X
0".
SO
ol
u
01
• III
l'*i
H
CM
Chapter VII
DISCUSSION AND ANALYSIS OF RESULTS CONCERNING GBFS
7.1 GBFS as a single additive to soils
7.1.1 Effect of GBFS additive on compaction
characteristics of soil
It can be observed from Table 6.1 that when GBFS is added to
soils A, B and C, the maximum dry density of these soils is
increased. This can be explained by the fact that the
addition of GBFS to soils A, B and C has significantly
improved the grading of these soils (see Table 7.1) and
reduced the porosity of their compacted specimens (as shown
in Appendix B).
The effect of addition of GBFS to soils A, B and C on their
OMC is related to the comparative fineness of GBFS and the
soils. As shown in Table 6.1 when GBFS is added to the
soils A, B and C the OMC of soil C decreases whereas the OMC
of soil A and soil B increases. This is due to the fact
that GBFS is coarser than soil C and hence it decreases the
particle surface area of this soil and subsequently
decreases the water demand in compaction. Conversely, GBFS
is finer that soil A and soil B and hence it increases the
240
particle
surface
area
of
these
soils
increases the water demand in compaction.
and
subsequently
The increase in
OMC is more pronounced in the case of coarser soil
(soil A)
where the increase in fineness due to the addition of GBFS
is more significant.
GBFS as a single additive to soils, therefore, can be
utilised in improving the workability of wet soils (ie,
gravel, sand soils).
it can also be used in improving the
grading and increasing the density of soils and subsequently
favourably
affecting
the
strength
properties
of
treated
soils.
7.1.2 Effect of GBFS additive on the strength properties
of soils
7.1.2a Effect on UCS
It has been observed from Table 6.3 and Figure 6.3 that GBFS
as a single additive to soils A, B and C increases the UCS
of these soils.
This can be attributed to reduction in
porosity and increase in density of the compacted specimens
of these treated soils.
It can also be observed from Tables
6.3 that the UCS of GBFS treated soils A and B may not
result in strength changes with the variation of curing
time.
This implies that strength development reactions had
not taken place between these soils and any constituent of
241
GBFS during the various curing times.
However, the slight
increase in UCS of GBFS treated soil C with the increase in
curing time may indicate a reaction between this heavy clay
soil and the free lime in the GBFS.
7.1.2b Effect on CBR
Tables 6.11 to 6.13 and Figures 6.11 to 6.13 show that the
CBR values of treated soils A, B and C increase with the
increase in the quantity of GBFS additive.
This could be
attributed to the decrease in compressibility caused by the
increase in density and the decrease in porosity of these
treated soils (see section 7.1.1).
Unlike the UCS test results, the CBR values of all treated
soils exhibited a slight increase with increase in curing
time.
However, this may not be meaningful in an engineering
context
in
the
light
of
precision,
accuracy
and
repeatability of the test.
7.1.3 Effect of GBFS additive on the Atterberg limits
and linear shrinkage of soils.
Atterberg limits and linear shrinkage tests have exhibited
some scattered results as shown in Table 6.5.
Liquid limit
and plastic limit of GBFS treated soil A show a very slight
increase with the increase of GBFS quantity whereas liquid
242
limit and plastic limit of GBFS treated soil B do not vary
from those of untreated soil. Tables 6.5a and 6.5b indicate
that GBFS has no significant effect on the plasticity and
linear shrinkage of low cohesion soils (ie soil A & soil B)
whereas Table 6.5c shows that GBFS as a single additive to
soils has a remarkable effect on the plasticity and linear
shrinkage of cohesive soils (ie soil C) . Table 6.5c shows
that plastic limit of GBFS treated soil C increases with the
increase of GBFS quantity whereas liquid limit, plasticity
index and linear shrinkage decrease with the increase in
GBFS quantity.
These effects are due to the partial replacement of high
plastic particles of soil C with the low plasticity GBFS
particles. The effects could also be attributed to the
action of free lime in the GBFS on the clay particles which
may explain the slight reduction in plasticity index of GBFS
treated soil occuring with curing time. This is consistent
with the findings for UCS tests in section 7.1.2a.
Although the effects of GBFS on the plasticity and linear
shrinkage of cohesive soils are remarkable, they are
inferior to those which occur by the addition of lime or
cement to these soils.
For example, the linear shrinkage of 8% GBFS treated Soil C
is almost comparable to the linear shrinkage achieved by the
243
addition of 1% lime or 1% cement to this soil (see Figures
6.5c and 6.6c).
From Figures 6.7c and 6.8c, it can also be
deduced that the addition of 6-7% GBFS to soil C is required
to achieve the plasticity index achieved by the addition of
1% cement or 1% lime to the soil.
The use of GBFS as a single additive to soils to modify
their plasticity and shrinkage properties is, therefore, not
efficient.
7.1.4 Effect of GBFS additive on the behaviour of soils
under the action of repeated dynamic load.
The various measurements of deflections for both pavements
(the untreated soil D and the 8% GBFS treated soil D) shown
in Tables 4.15 and 6.16 reveal that:
i) For any point on the grid, where measurements were
taken, the deflection increased with the increase in
number of load applications.
ii) As the number of total load applications to the
pavements increased, the actual deflection per single
load
applied
decreased,
indicating
stiffness had increased (see Table 7.2).
that
pavement
244
iii) The maximum values of deflection for the various number
of load cycles occurred close to the wheel contact area
and particularly under the wheel edge.
iv) For any number of load cycles the deflections at almost
all measuring points on the grid for the GBFS treated
pavement were less than the corresponding deflection
for the
untreated
pavement.
The maximum value of
deflection for the GBFS treated pavement after 50,000
load
cycles
was
less
than
the
maximum
deflection for the untreated pavement
GBFS
treated
pavement).
pavement
and
8.95mm
value
of
(6.7mm for 8%
for
untreated
This signifies the positive role of GBFS in
improving the stiffness of a soil and reducing its
compressibility by increasing the density and reducing
porosity as was indicated in section 7.1.1.
7.2 Lime-GBFS Additives
7.2.1 Effect of lime-GBFS additives on compaction
characteristics of soils
It can be observed from Table 6.1 that when 1:1 lime-GBFS
additive is added to the soils A, B and C, the maximum dry
density of these soils is decreased.
dominant
effect
gravity = 2.35).
of
the
light
weight
This is due to the
of
lime
(specific
As the quantity of GBFS in the additive
245
increases, the maximum dry density of the treated soils
increases. This is due to the fact that GBFS is heavier
than lime (specific gravity = 2.86) and GBFS tends to
improve the particle size distribution of the treated soils
and reduce the porosity of the compacted specimens (see
Table 7.1 and Appendix B) . Table 6.1 also shows that when
lime-GBFS additives are added to soil A and soil B, the OMC
of these soils increases. This is more pronounced as the
quantity of GBFS in the additive is decreased. This implies
that the increase in OMC is dominated by the hydration
effect of lime rather than by the quantity of water required
to wet the increased surface area of the soil particles.
Table 6. lc shows that the OMC of treated soil C increases
due to the addition of 1:1 lime-GBFS. This can be
attributed to the dominant effect of lime hydration.
However, as the quantity of GBFS in the additive increases,
the effect of GBFS, again, becomes more dominant than the
effect of lime and tends to decrease the OMC of treated soil
C due to the fact that GBFS is coarser than this soil (see
Table 7.1) and hence it decreases its particle surface area.
Lime-GBFS additives, therefore, can be utilised for
improving the workability of wet soils (gravel, sand etc.).
They also can be used as mechanical stabilisers for
improving the grading and increasing the density of soils,
246
which may
favourably
affect
the
strength
properties
of
treated soils.
7.2.2 Effect of lime-GBFS additives on the strength
properties of soils
7.2.2a Effect on UCS
A perusal of Table 6.3 shows that:
i) For a given quantity of additive, as GBFS in the
additive decreases, the strength at all ages for all
treated soils increases.
treated
soils
additive.
was
The highest strength for all
achieved
by
using
1:1
lime-GBFS
This is not consistent with the case of
lime-GBFS specimens
(section 6.5.3) and implies that
lime reacts more readily with soils than with GBFS.
sufficient quantity of lime
A
(initial consumption of
lime, ICL) may be consumed in increasing the pH value
of soils to a stage (pH = 12.4) at which reactions take
place between the lime and the clay minerals and other
pozzolans
to
produce
hydrated
calcium
silicate
and
calcium aluminate gels.
ii) As the curing time increases, the strengths of treated
soils increase which implies that pozzolanic reactions
take place over a long time.
247
For
all
additives,
the
strength
of
treated
soil
increases with increasing quantity of additive, up to a
peak value,then decreases with the continuous increase
in the quantity of additive, similar to that in the
case of lime stabilisation.
The quantity of additive,
at which a peak value of strength occurs, tends to
increase
additive.
with
decreasing
amount
of
lime
in
the
This conforms to the previous finding that
lime reacts more readily with soil than with GBFS.
For all soils tested, the lime-GBFS additives were not
able to achieve the highest strength achieved by lime
additive.
This is more pronounced in the case of soil
C which, as a heavy clay, is very suitable to lime
stabilisation.
This denotes that lime-GBFS additives
are more efficient in modifying the strength of non
cohesive soils than they are in modifying the strength
of cohesive soils.
Figure 6.3 shows that the UCS of soils treated with 4%
content of 1:1, 1:2 and 1:3 lime-GBFS additives are
greater
than
stabilisation.
pozzolan,
in
those
of
2%,
1.3%
and
1%
lime
This signifies the role of GBFS, as a
the
stabilised soils.
strength
development
of
lime-GBFS
The effectiveness of this role will
be examined further in section 7.2.7.
248
7.2.2b
Effect on CBR
From Tables 6.11 to 6.13 and Figures 6.11 to 6.13, it can be
observed that:
i) For all additives, the CBR of all treated soils
increases with increasing quantity of additive and/or
curing time.
ii) For a given quantity of additive, as the amount of GBFS
in the additive decreases, the CBR value of all treated
soil increases.
iii) In the case of soil C, which as a heavy clay is very
suitable to lime stabilisation, the lime-GBFS additives
were not able to achieve the highest CBR value achieved
by lime additive.
This, also, is consistent with the
findings for UCS in section 7.2.2a.
However, the 1:2
lime to GBFS additive, at an additive quantity of 8%,
was
able
to
achieve
higher
CBR
values
than
those
achieved by 2.6% lime in the case of soil A and soil B.
This implies once more that:
a) lime-GBFS additives are more suitable for modifying
the strength of non cohesive soils than they are
for modifying the strength of cohesive soils.
249
b)
GBFS is a pozzolan and has a role in the strength
development of lime-GBFS soil stabilisation.
The observations described in (i) and (ii) are
consistent with the findings for UCS in section 7.2.2a.
7.2.3 Effect of delay in compaction on the strength of
lime-GBFS treated soils
It can be seen from Table 6.8 that delay in compaction of
lime and lime-GBFS treated soils decreases the strength of
these mixes.
This is more pronounced as the time elapsed
since mixing is increased.
The results presented in Table 6.8 have also shown that in
lime and lime-GBFS stabilisation, the losses in strength due
to delay in compaction were not great and almost equal.
This
implies
that
the
rate
of
reaction
in
lime-GBFS
stabilisation is relatively slow and somewhat similar to
lime stabilisation.
respect of
Accordingly, the time constraints in
compaction, including
delays caused by plant
breakdown, etc, and the effect of rain are not so critical.
These observations are consistent with the findings for
lime-RHA additives which are explained in Chapter 5 (section
5.2.3) .
250
7.2.4
Effect
of
lime-GBFS
additives
on
the
shear
strength parameters of soils
It has been observed, as shown in Table 6.9, that in almost
all cases, the shear strength parameters (cohesion and angle
of internal friction) of the soil increase with increasing
quantity of additive and/or decreasing amount of GBFS in the
additive.
For a given proportion of lime to GBFS, as the quantity of
additive
increases,
observed
in
an
all cases.
increase
in
the
parameters
is
It can also be seen that the
cohesion and angle of internal friction of soil B stabilised
with 8% content of 1:1 lime-GBFS were higher than those with
4% lime additive.
In the case of soil C, the cohesion and
angle of internal friction achieved by 8% content of 1:1
lime-GBFS additive were somewhat similar to those achieved
by 4% lime additive.
These observations are consistent with
the findings for UCS and CBR in section 7.2.2a and 7.2.2b.
Table 6.9 also shows that shear strength parameters increase
with increasing curing time.
This confirms the belief that
GBFS is a pozzolan and its reaction with lime takes place
over a long time.
As shear strength of a soil is determined by its parameters
and effective normal stress (ie r = C +rntan 0), it can
251
easily be seen that the above mentioned observations are
applicable to the effect of lime-GBFS additives on the shear
strength of soils. As previously stated, these observations
conform to the findings for CBR and UCS which are, more or
less, measures of the combined effects of cohesion and
internal friction of a soil. Accordingly, it can be stated
that the increase in strength {UCS, CBR and shear strength)
due to lime-GBFS stabilisation is caused by the increase in
both the angle of internal friction and cohesion of the
stabilised soil. The reasons behind this increase were
discussed in Chapter 5 (section 5.2.4).
7.2.5 Discussion of the results of the XRD analysis of
lime-GBFS stabilised soils
A comparison of the XRD chart of lime-GBFS treated Soil A,
as shown in Figure 6.19, with the XRD chart of the untreated
soil (Figure 4.25) reveals that the peaks pattern in both
cases are almost similar with the exception of the presence
of Calcite (CaC03) in the treated sample. This was
identified by the existence of several peaks at d spacings
of 2.285, 2.095, 1.913 and 1.875 A°.
The XRD chart of lime-GBFS treated Soil C, as shown in
Figure 6.20, has also indicated the presence of Calcite in
the treated soil. This can be identified by the peaks shown
at d spacings of 3.035, 2.285, 2.095, 1.913 and 1.875 A°.
252
It was
also
shown
that the treated
soil retained
some
details of the original structure of the untreated soil
(ie, Quartz) whereas some other details such as Kaolinite
disappeared.
The XRD charts of lime-GBFS treated Soils A and C have not
indicated the existence of any form of calcium silicate
hydrate or calcium aluminate hydrate.
Possible existence of
such compounds could be hindered by the presence of Calcite
in the samples.
The presence of Calcite could be attributed
to the effect of atmospheric carbon dioxide on the thin
dispersion of the fine material.
The XRD analysis has
proved inconclusive in providing information on the nature
of
the
hydration
products
of
the
lime-GBFS
soil
stabilisation.
7.2.6 Discussion of the results of the SEM examination
of lime-GBFS stabilised soils
The scanning electron micrograph of the fracture surface of
the lime-GBFS treated Soil A as shown in Figure 6.17 reveals
a rough texture with few cracks and microporosities.
This
indicates that the surface of the treated soil retained some
details of the surface of the untreated soil (see Figure
4.21).
However,
these
cracks
and
microporosities
are
smaller in number and size than those shown for untreated
soil in Figure 4.21.
253
Figure 6.17 also reveals a considerable crystalline reaction
product, presumably calcium silicate hydrate, which can be
seen at the bottom
left of the micrograph.
Few other
patches of amorphous reaction products can be seen covering
some areas and filling some of the microporosities in the
fracture surface.
The micrograph of the lime-GBFS treated Soil C as shown in
Figure
6.18
amorphous
reveals
a massive
components
which
and even distribution of
are
presumably
the
non
crystalline reaction products.
The description of the features of both micrographs given in
this
section
are
some
what
subjective.
Consequently,
speculations on the origin of strength and other properties
when
based
Hence,
on
this
observation
the
SEM
proved
identifying
the
hydration
have
inconclusive
products
limited
in
of
validity.
comparing
lime-GBFS
and
soil
stabilisation.
7.2.7 Effect of lime-GBFS additives on the Atterberg
limits and linear shrinkage of soils
A perusal of Table 6.5 reveals that:
Liquid limit and plastic limit of lime-GBFS treated soils
increase with the increase of additive quantity with one
254
notable exception where the very high liquid limit of soil C
decreases with the increase in additive quantity.
However,
the plasticity index and linear shrinkage of all treated
soils
decrease
with
the
increase
in
additive
quantity.
These effects are more pronounced as the amount of GBFS in
the lime-GBFS is decreased.
These effects could be referred to the combined action of
the partial replacement of plastic soil particles with the
GBFS
particles
of,
relatively,
low
plasticity
and
ion
exchange between the lime and the clay minerals of soils.
Table
6.5
also
shows that
liquid
limit, plastic
limit,
plasticity index and linear shrinkage of treated soils after
a curing period of 28 days are almost equal to those after a
curing period of 7 days.
This can be explained by the fact
that the reactions responsible for reducing plasticity and
shrinkage (ie cation exchange) occur during a short period
of time and mostly in the first 7 days of the curing time,
and that GBFS does not react with soils as was discussed in
section 7.1.2.
A perusal of Figures 6.5 and 6.7 reveals that lime-GBFS
additives could not attain the results achieved by 4% lime
additive.
Hence, their use to modify the plasticity and
shrinkage of soils could be restricted to a lower level of
achievement.
However, their limited role in this context
255
(ie to replace 2-3% lime additive in modifying plasticity
and shrinkage of soils) could be justified by the amount of
lime saving they can achieve.
The observations presented in this section are almost
identical
to
the
findings
for
lime-RHA
additives
as
discussed in Chapter 5 (section 5.2.7).
7.2.8 Implications of lime savings
Figure 6.3a indicates that the UCS of 2% lime treated soil A
can be achieved by 3.6% content of 1:2 lime-GBFS additive
(ie, 1.2% lime + 2.4% GBFS).
The lime saving is therefore
equal to 2-1.2 = 0 . 8 % and the ratio of GBFS required to lime
saved is 2.4/0.8 = 3.
not
economically
Therefore 1:2 lime-GBFS additive is
feasible
to
replace
the
2%
lime
stabilisation unless the cost of lime is equal to or greater
than 3 times the cost of GBFS.
Table 7.3 has been derived in a similar manner utilising
Figures 6.3, 6.5 and 6.7 and applying the same calculations
for the various values of UCS, shrinkage and plasticity for
each case of soil treatment.
From Table 7.3, it can be deduced that:
256
i)
1:1 lime-GBFS additive tends to be the most economical
additive of
all lime-GBFS
additives
tested.
These
additives tend to be less economical as the quantity of
GBFS in the additive increases.
ii) Lime-GBFS additives are more efficient in stabilising
non
cohesive
soils
(soil
A
and
soil
B)
than
in
stabilising clays.
iii) All of the tested lime-GBFS additives are not
recommended for replacing 4% lime in stabilising soils.
iv) 1:1 lime-GBFS can not be recommended for replacing 2%
lime in modifying strength, plasticity and shrinkage of
clays (soil C) unless the cost of lime is 6-7 times the
cost of GBFS.
However, this economic cost ratio tends
to decrease as the treated soil tends to be coarser
(identical cost ratios for increasing the strength of
soil A and soil B are 2.25 and 4.68 respectively).
7.2.9 Effect of lime-GBFS additive on the behaviour of
soils under the action of repeated dynamic load
The results of the laboratory tests used in this research
indicate
that
lime-GBFS
additives, particularly
that
of
proportion 1:1, can be used in soil stabilisation to modify
workability, strength, plasticity and shrinkage of soils.
257
To find whether or not the behaviour of these treatments
under the action of repeated dynamic loads is consistent
with the finding for the various laboratory tests, it was
decided to compare the pavements having 2% lime treated soil
D and 3% content of 1:1 lime-GBFS treated soil D with the
control
pavement
of
untreated
soil
D.
The
various
measurements of surface deflections of the three pavements,
shown in Tables 4.15, 4.16 and 6.15, reveal that:
i) For any point on the grid, where measurements were
taken, the surface deflection of the three pavements
increased
with
the
increase
in
number
of
load
applications.
ii) As the number of total load applications to the
pavements increases, the actual deflection per single
load applied decreases, indicating that the pavement
stiffness has increased ( see Table 7.4.).
iii) The maximum deflections for the various number of load
cycles
occur
close
to
wheel
contact
area
and
particularly under the wheel edge (ie, point eH on the
grid) for all cases.
iv) For any number of load cycles the deflection, at any
point on the grid, of the lime-GBFS treated pavement
258
was less than the deflection of the untreated pavement.
This indicates that lime-GBFS additive increases the
stiffness and reduces the compressibility of soils.
The deflection of the lime-GBFS treated pavement after
any number of load applications was less than the
deflection of the lime treated pavement at all points
on the grid. The maximum value of deflection of
lime-GBFS treated pavement after 50,000 load cycles was
less than the maximum value of deflection of the lime
treated pavement (7.2mm for 2% lime treated pavement
and 6.0mm for 3% content of 1:1 lime-GBFS treated
pavement). This signifies the positive role of GBFS,
as a pozzolan in lime-GBFS additive, for improving the
stiffness of a soil and reducing its compressibility
and is consistent with the findings for strength in
sections 7.2.2 and 7.2.4.
Perusal of Figures 4.14, 4.15 and 6.15 reveals that,
for all pavements, there were downward movements of all
points on the grid where measurements were taken, and
the permanent deformations of the three pavements were
caused by the densification of the pavements rather
than by any shear failure of these pavements (see also
Figures 4.20, 4.21 and 6.18).
259
vii) A visual assessment of the surface of all pavements
showed that no fatigue cracks or shrinkage cracks were
developed and the pavements were intact and sound at
the conclusion of the test.
In general the observations derived from the results of
the repeated dynamic load test have demonstrated that
1:1 lime-GBFS additive is effective and efficient in
improving the behaviour of soils under the action of
repeated loads.
The observations desribed in (i) to (vii) are almost
identical to the findings for lime-RHA additives as
shown in Chapter 5 (section 5.2.9).
7.3 Cement-GBFS Additives
7.3.1 Effect of various cement-GBFS additives on
compaction characteristics
A perusal of Table 6.2 reveals that when cement-GBFS
additives are added to soils A, B and C, the maximum dry
density and the optimum moisture content of these soils
increase.
pronounced
decreased.
The increase in OMC of the treated soils is more
as
the
This
quantity
implies
of
GBFS
in the
that
the
increase
dominated by the hydration reactions of cement.
additive
in
OMC
is
is
In the case
260
of soils A and B, additional water is required for wetting
the increased surface area of the soil particles due to the
addition of GBFS (GBFS is finer than both soils, as shown in
Table 7.1).
The increase in maximum dry densities of all treated soils
was mainly due to the partial replacement of soil with
heavier cement-GBFS additives (specific gravity for 1:1 to
1:4 proportions are 3.0, 2.95, 2.93 and 2.916 respectively.
The increase in dry densities could also be influenced by
the improvement in grading and the reduction in porosity of
all
treated
additives.
soils
due
to
the
additon
of
cement-GBFS
The porosity values were calculated by a method
similar to that specified in section 5.1.1 and 5.2.1 and are
presented in Appendix B.
Cement GBFS additives, therefore, can be used to enhance the
workability
of wet
soils.
They
can
also
be
used
for
improving the grading, reducing porosity and increasing the
density of soils which may affect favourably the strength
properties of these soils.
7.3.2 Effect of cement GBFS additives on the strength
properties of soils
7.3.2a Effect on UCS
It has been observed, as shown from Table 6.4, that:
261
For a given quantity of additive, as cement content in
the additive increases the strength, of treated soils,
increases consistent with the case of cement-GBFS
specimens (section 6.5.3). This implies that the
strength development is dominated by the hydration
reactions of cement rather than by the pozzolanic
V
reactions of the GBFS.
For all additives there is continuous increase in
strength of treated soils, with increasing quantity of
additive. No peak value of strength was observed.
This is consistent with the findings stated above.
As curing time increases the strength of treated soils
increases. The rates of strength development of soils
(A and B) treated with cement-GBFS additives are
slightly slower than those of cement treated soils.
Rates of strength development, as ratios of 28 days
strength to 90 days strength, for various treated soils
are derived from Table 6.4 and presented in Table 7.5.
From this Table, it can be seen that GBFS is acting
somewhat as a weak retarder and hence may not have a
significant effect on the workability of cement-GBFS
soil stabilisation. This effect will be further
examined in the later discussion on the effect of delay
in compaction on strength of treated soils (section
7.3.3) .
262
iv)
From Figure 6.4c, for example, it can be seen that the
UCS of soil C treated with 4% content of 1:1, 1:2 and
El:3 cement-GBFS additives are greater than those of 2%
content of 1:3 and 1% cement treatment of soil C. This
indicates that GBFS has a role in strength development
of cement-GBFS soil stabilisation. The effectiveness
of this role is investigated in section 7.3.7.
7.3.2b Effect on CBR
The results presented in Table 6.11 to 6.13 and Figures 6.11
to 6.13 show that:
i) For a given quantity of additive, as the amount of GBFS
in the additive decreases, the CBR value of all treated
soil increases.
ii) For all additives, the CBR of treated soils increases
with increasing quantity of additive and no peak value
is observed.
iii) As the curing time increases, the CBR of all treated
soil increases.
iv) In the case of soil C, which as an organic clay is not
suitable for cement stabilisation, the 1:1 cement-GBFS
additive, at an additive quantity of 8%, was able to
263
achieve a higher CBR value than that achieved by 4%
cement treatment (see Figure 6.13). This clearly
indicates that cement can be partially replaced by GBFS
and that GBFS has a role in the strength development of
cement-GBFS stabilisation of organic clays. The
effectiveness of this role in the stabilisaton of soil
A and soil B and the implication of cement saving in
these cases cannot be derived from the CBR values as
some of these values are greater than 100 and
considered meaningless in accordance with the
discussion of the appropriateness of the test in
section 3.4.4.
The observations described in (i) to (iii) are
consistent with the findings for UCS in section 7.3.2a.
7.3.3
Effect of delay in compaction on the strength of
cement-GBFS treated soils
The results presented in Table 6.7 show that a loss in
strength occurs if the compaction of cement or cement-GBFS
treated soil is delayed. The loss in strength is more
pronounced as the time elapsed since mixing is increased.
The delay in compaction of cement treated soil A was
critical, resulting in 30% to 70% loss of strength due to
2-6 hours delay in compaction. However, this loss in
264
strength
was
additives.
reduced
slightly
by
using
cement-GBFS
The decrease in the loss of strength is more
pronounced
as
the
amount
of
GBFS
in
the
additive
is
increased.
This could be attributed to the fact that GBFS
acts as a weak retarder in slowing the rate of strength
development
7.3.2a).
of
cement-GBFS
treated
soils
(see
section
The loss in strength due to delay in compaction of
cement-GBFS treated soil is 16% - 30% less than that of
cement treated soil.
respect of
Accordingly, the time constraints in
compaction, including delays caused by plant
breakdown, etc, and the effects of rain are less critical.
These observations are consistent with the findings for
lime-RHA, cement-RHA and lime-GBFS additives as described in
sections 5.2.3, 5.3.3 and 7.2.3.
7.3.4 Effect of cement-GBFS on the shear strength
parameters of soils
It has been observed, as shown in Table 6.10, that the shear
strength
parameters
friction) of
quantity of
the
(cohesion
treated
soil
and
increase
additive, curing time and/or
amount of cement in the additive.
stated
that
angle
the
increase
in
of
with
internal
increasing
increasing the
Accordingly, it can be
strength
of
cement-GBFS
stabilised soil is influenced by the increase in both its
cohesion and angle of internal friction.
265
This
is
consistent
with
the
findings
for
lime-RHA,
cement-RHA and lime-GBFS additives as discussed in Chapter 5
and 7 (sections 5.2.4, 5.3.4 and 7.2.4).
7.3.5 Effect of cement-GBFS additives on the Atterberg
limits and linear shrinkage of soils
It can be observed, as shown from Table 6.6, that:
i) Liquid limit and plastic limit of cement GBFS treated
soils increase with the increase of additive quantity
with one notable exception where the very high liquid
limit of soil C decreases with increase of additive
quantity.
ii) The plasticity index and linear shrinkage of all
treated soils decrease with the increase in additive
quantity.
amount
of
These effects are more pronounced as the
GBFS
in
the
cement-GBFS
additive
is
decreased.
iii) It can also be seen from Table 6.6 that liquid limit,
plastic limit and plasticity index of treated soils (A,
B and C) after a curing period of 28 days vary slightly
from those after a curing period of 7 days.
266
iv)
The linear shrinkage of treated soils A and B tends to
increase slightly with the increase in curing time due
to the prolonged hydraulic reactions of GBFS stimulated
by the effect of cement.
An inspection of Figures 6.6
and 6.8 reveals that, with respect to linear shrinkage
and plasticity index, cement-GBFS cannot attain the
results achieved by 4% cement additive (except for the
linear shrinkage of treated soil C) .
Hence their use
to modify the plasticity and shrinkage of soils could
be restricted
to this level of cement replacement.
However, their limited role has to be justified by the
amont of cement saving they can achieve.
The observations described in (i, ii and iii) are consistent
with the findings for lime-GBFS additives as discussed in
section 7.2.6.
7.3.6 Implications of cement saving
Figure 6.4c indicates that the UCS of 2% cement treated soil
C
can
be
achieved
by
3.1%
content
of
additive (ie, 1.55% cement + 1.55% GBFS).
1:1
cement-GBFS
The cement saving
is therefore, equal to 2-1.55 = 0.45% and the ratio of GBFS
required to cement saved is 1.55/0.45 = 3.44.
Therefore 1:1
cement-GBFS additive is not economically feasible to replace
the 2% cement additive in stabilising soil C unless the
total cost of cement is equal to or greater than 3.44 times
267
the total cost of GBFS (ie, material, mixing and separate
storage costs).
Table 7.6 has been derived in a similar manner, utilising
Figures 6.4, 6.6 and 6.8 and applying the same calculations
for the various values of strength, plasticity index and
linear shrinkage for each case of soil treatment.
From Table 7.6, it can be deduced that:
i) 1:1 cement-GBFS is the most economical additive of all
cement-GBFS additives used.
These additive tend to be
less economical as the quantity of GBFS in the additive
increases.
ii) 1:2, 1:3 and 1:4 cement-GBFS additives are not
efficient and can not be recommended to be used in soil
stabilisation.
iii) 1:1 cement-GBFS additive is not efficient in modifying
plasticity and shrinkage properties
of
low cohesion
soils nor is it efficient in modifying the strength of
crushed rocks (gravel-sand-silt, soils).
iv) 1:1 cement-GBFS additive can be recommended for
replacing
2-4%
cement
additive
in
modifying
the
strength, plasticity and shrinkage of clays provided
268
that the cost of cement is equal to, or greater than,
2-4 times the cost of GBFS.
v) 1:1 cement-GBFS additive also can be recommended for
replacing 2% cement additive in modifying the strength
of sand-silt soils provided that the cost of cement is
equal to or greater than five times the cost of GBFS.
7.3.7 Effect of cement-GBFS on the behaviour of soils
under the action of repeated dynamic load
In section 7.3.2a and 7.3.2b it was found that GBFS acted as
a
pozzolan
and
cement-GBFS
has
soil
a
role
in
strength
stabilisation.
development
To
inspect
of
the
effectiveness of this role in improving the behaviour of
soils under the action of repeated dynamic loads, it was
decided to
compare the pavements
containing
1.5%
cement
treated soil D and 3% content of 1:1 cement-GBFS treated
soil D with the control pavement of untreated soil D.
The various measurements of surface deflection for the three
pavements, shown in Tables 4.15, 4.18 and 6.14 reveal that:
i) For any point on the grid, where measurements were
taken, the surface deflection in all three pavements
increased
with
applications.
the
increase
in
number
of
load
269
ii)
As
the
number
of
total
load
applications
to
the
pavements decreased, the actual deflection per single
load applied decreased, indicating that the stiffness
had increased (see Table 7.7).
iii) The maximum deflection for the various number of load
cycles occurred close to wheel contact area (ie, point
eH and dH on the grid).
iv) For any number of load cycles, the values of
deflection,
at
any
point
on
the
grid,
of
the
cement-GBFS treated pavement were less than the values
of
deflection
indicates
that
of
the
untreated
cement-GBFS
pavement.
additive
This
increases
the
stiffness and reduces the compressibility of soils.
v) The maximum deflection of the 3% cement-GBFS treated
pavement after 250,000 load cycles was equal to 2.3mm.
This was less than the maximum deflection of the 1.5%
cement treated pavement after 50000 load cycles, which
was equal to 2.96mm.
This signifies the role of GBFS
in cement-GBFS additive in increasing the density and
stiffness and reducing the compressibility of soils.
vi) Figure 6.16 reveals that most of the points on the 3%
1:1 cement-GBFS treated pavement, where measurements
were
taken,
exhibited
a
downward
movement
and
the
270
deflection
was
caused
by
the
densification
pavement rather than by any shear failure.
consistent
with
the
findings
for
all
of
the
This is
treated
and
untreated pavements as discussed in sections 5.2.9 and
7.2.9.
vii) A visual assessment of the surface of the 3% content of
1:1 cement-GBFS treated pavement showed that no fatigue
cracks
or
shrinkage
cracks were
developed
and
the
pavement was intact and sound at the conclusion of the
test.
In general, the observations derived from the results
of the repeated dynamic load test have demonstrated
that
1:1
cement-GBFS
additive
is
an
effective
and
efficient stabiliser in improving the behaviour of soil
under the action of repeated dynamic loads.
The observations described in this section are almost
similar to the findings of lime-GBFS additives as described
in section 7.2.9.
271
Table 7.1
soil
Effect of G B F S additive on the grading of soils
sieve size
Grading of
soil
Grading of
GBFS
% passing
% passing
Grading of
soil + 8%
GBFS
% passing
Grading of
max density
curve
% passing
A
19mm
9.5mm
4.75mm
2.36mm
425pm
75pm
13.5pm
100
73
36
22
15
8
4
100
100
100
100
50
5
2
100
75
41
28
17
7.5
3.5
100
70
50
35
15
6
3
B
4.75mm
2.36mm
425pm
75pm
13.5^m
100
85
43
24
17
100
100
50
5
2
100
86
43.5
22.5
15.5
100
90
30
13
5
2.36mm
425pm
75pm
13.5pm
100
95
71
53
100
50
5
2
100
91
66
49
100
42
18
8
C
272
Table 7.2
Deflection per load as number of load increases at point of maximum
deflection on the grid (ie point eH) of the 8 % G B F S treated pavement
Progressive total
of loads applied
N o of loads
applied
Deflection due
Average deflection
loads applied (mm) due to one load
application (mm)
50
500
5,000
50,000
50
450
4,500
45,000
4.35
5.70-4.35
6.20-5.70
6.70-6.20
.087
0.003
1.11 x10-4
1.11 X10-5
273
Table 7.3
Ratio of G B F S required to lime saved or identical economic cost ratio of
lime to G B F S
Level of achievement
Soil
lime.GBFS
1:1
lime.GBFS
1:2
lime:GBFS
1:3
lime:GBFS
1:4
2.25
4.68
3
NA
NA
NA
NA
NA
C
6.6
6.6
13.69
U C S of 4 % lime treated A
soil
B
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
C
NA
6.7
4.0
NA
50
7.55
Plasticity index of 4 %
A
NA
NA
NA
NA
lime treated soil
B
NA
NA
NA
NA
C
NA
NA
NA
Linear shrinkage of 2% A
B
lime treated soil
NA
NA
NA
NA
30
NA
5.69
6.86
9.0
Linear shrinkage of 4 % A
NA
NA
NA
NA
B
NA
NA
NA
NA
C
NA
NA
NA
U C S of 2 % lime treated A
soil
B
C
Plasticity index of 2 %
lime treated soil
A
B
C
lime treated soil
—NA
Additive is not tested
N o lime could be saved
NA
NA
274
Table 7.4a
Deflection per load as number of load applications increases at point eH
on the grid of the pavement containing 3 % lime-GBFS treated soil D
Progressive total
of load applications
No. of load
applications
Deflection due to
load applications
(mm)
50
450
4,500
45,000
50
500
5,000
50,000
Table 7.4b
3.89
4.53 - 3.89
4.99 - 4.53
6.00 - 4.99
No. of load
applications
Deflection due to
load applications
(mm)
50
500
5,000
50,000
50
450
4,500
45,000
5.95
6.90 - 5.95
7.12-6.90
7.20-7.12
Average deflection
due to one load
application (mm)
0.119
.002
4.88x10-5
1.77x10-6
Deflection per load as number of load applications increases at point eH
on the grid of the untreated pavement
Progressive total
of load applications
No. of load
applications
Deflection due to
load applications
(mm)
50
500
5,000
50,000
.0778
.0014
.0001
2.24x10-5
Deflection per load as number of load applications increases at point eH
on the grid of the pavement containing 2 % lime treated soil D
Progressive total
of load applications
Table 7.4c
Average deflection
due to one load
application (mm)
50
450
4,500
45,000
3.12
4.15-3.12
6.97 - 4.25
8.95 - 6.97
Average deflection
due to one load
application (mm)
.062
.0025
.0006
.0004
275
Table 7.5
Ratio of U C S at 28 days to U C S at 90 days for soils treated with 8 %
content of cement and cement-GBFS additives
Additives
Cement
CementGBFS
1:1
CementGBFS
1:2
CementGBFS
1:3
.93
.89
.857
.85
.784
.73
.835
.68
.90
.83
.84
.92
Soils
A
B
C
276
Table 7.6
Ratio of G B F S required to cement saved or identical economic cost ratio
of cement to G B F S
Level of achievement
Soil
Cement.GBFS
Cement.GBFS
Cement:GBFS Cement.GBFS
1:1
1:2
1:3
1:4
U C S of 2 % cement
treated soil
A
B
C
19
4.64
3.44
NA
NA
3.42
NA
NA
1.41
NA
NA
U C S of 4 % cement
treated soil
A
B
C
NA
NA
1.58
NA
NA
NA
NA
NA
NA
NA
NA
Plasticity index of 2 %
cement treated soil
A
B
C
5.20
NA
4.12
9.79
NA
21.58
6.07
NA
21.95
7.92
NA
Plasticity index of 4 %
cement treated soil
A
B
C
NA
NA
1.98
NA
NA
NA
NA
NA
NA
NA
NA
Linear shrinkage of 2 % A
cement treated soil
B
C
NA
NA
3.15
NA
NA
20.27
30
NA
9.0
NA
NA
Linear shrinkage of 4 % A
cement treated soil
B
C
NA
NA
2.27
NA
NA
NA
NA
NA
NA
NA
NA
NA
—
N o cement saving could occur
Additive is not tested
277
Table 7.7a
Deflection per load as number of load applications increases at point
eH on the grid of the untreated pavement
Progressive total
of load applications
50
500
5,000
50,000
Table 7.7b
50
500
5,000
50,000
Average deflection
due to one load
application ( m m )
50
450
4,500
45,000
3.12
4.25-3.12
6.97 - 4.25
8.95 - 6.97
.062
.0025
.0006
.0004
No. of load
applications
Deflection due to
load applications
(mm)
Average deflection
due to one load
application ( m m )
50
450
4,500
45,000
1.30
2.23 -1.30
2.53 - 2.23
2.96 - 2.53
0.26
.002
6.66x10-5
9.55x10-6
Deflection per load as number of load applications increases at point
d H on the grid of the pavement containing 3 % content of 1:1 cementG B F S treated soil D
Progressive total
of load applications
5,000
50,000
250,000
Deflection due to
load applications
(mm)
Deflection per load as number of load applications increases at point
eH on the grid of the pavement containing 1.5% cement treated soil D
Progressive total
of load applications
Table 7.7c
No. of load
applications
No. of load
applications
Deflection due to
load applications
(mm)
Average deflection
due to one load
application (mm)
5,000
45,000
200,000
1.70
1.87-1.7
2.3 -1.87
3.4x10-4
3.77x10-6
2.15x10-6
278
Chapter VIII
DISCUSSION OF ECONOMIC FEASIBILITY OF THE APPLICATIONS OF
RHA AND GBFS TO SOIL STABILISATION
8.1 Introduction
Chapters 4 to 7 report the studies of a number of additives,
involving RHA and GBFS, for soil stabilisation. Technical
performance details have been specified where possible, and
indications of the type of situation in which these
additives might or might not be appropriate are presented.
However, it must be emphasized that an Engineer's choice
between alternative additives cannot be made solely on the
basis of technical considerations. RHA and GBFS additives
may suffer unreasonably in competition with lime and cement
additives because consumers are usually geared to the
preferred use of primary materials. This preference for
primary supplies is not due to the inferiority of
by-products (ie, RHA and GBFS) but could result from the
prejudice, habit and the maintenance of status of industry
ingrained in our materials use practice.
The use of RHA and GBFS additives in soil stabilisation,
therefore, may not be justified unless RHA and GBFS are
available in large quantities at a particular location at
low competitive cost. This cost may constitute the major
279
factor in deciding which of the technically and socially
acceptable alternatives should be used.
Section 8.2 to
8.10 present the comparative costs of RHA, GBFS, lime and
cement used in this research and investigate the economic
feasibility
of
using
RHA
and
GBFS
additives
in
soil
stabilisation in NSW.
8.2 Availability Of RHA
The major rice growing area is primarily centred in the
Riverina area, where the Ricegrowers Co-Operative Limited
produces an annual crop of close to one million tonnes of
paddy rice, resulting
in
160,000
tonnes of
rice hulls.
Smaller quantities of rice hulls, of the order of 6,000
tonnes/year
Burdekin
and
delta,
1,000
tonnes/year,
Queensland
and
the
are
produced
Northern
in the
Territory,
respectively.
Currently, approximately 20,000 tonnes/year of rice hulls
from the Riverina area are burnt in controlled combustion
furnaces at Griffith producing around 1,000 tonnes/annum of
low carbon (grey ash) and 3,000 tonnes/annum of high carbon
(black ash) rice hull ash (no controlled burning of the
Queensland and Northern Territory rice hulls is currently in
operation).
The ashes are produced under strict quality
control to comply with exacting requirements of the steel
280
and refractory industries which comprise the major market.
As a result
of
this
strict
quality
control, the
ashes
currently attract high revenue.
At present 60% of the rice hulls from the Riverina are
disposed of by field burning.
It is planned (52) to install
incineration or power generation facilities at all mills
(Echuca,
Deniliquin,
Griffith) within
Coleambally,
five years, which
Leeton,
should
Yenda
and
ensure that,
progressively, up to 30,000 tonnes/annum of low carbon ash
will become available.
This ash, which would normally be
used as landfill, as a soil ameliorant for sandy soils or as
a substitute
for lime in soils, should become available
locally at low cost.
Currently, the grey ash is sold at $250/tonne whereas the
black
ash which was
used
in this
research
is
sold at
$380/tonne F.O.T. Ex Biocon, Griffith.
The price of black ash, therefore, is approximately equal
2.5 times the price of lime or cement at any place in NSW,
particularly at Finley RTA Works Office, NSW (the closest
RTA Works Office to Griffith) where lime and cement are
currently delivered in bags and bulk at $130-150/tonne.
281
8.3
Economic feasibility of RHA as a single additive
to Soils
It was stated in section 5.1.2a and 5.1.2b that RHA,
technically, is not suitable to impart significant strength
to soils.
However, it was also stated in section 5.1.3 that
RHA cannot be
recommended
to be used
in modifying
the
plasticity and shrinkage properties of soils unless the cost
of lime or cement is 5-6 times the cost of RHA.
This
condition could not be met as shown in the previous section
which indicates beyond any question that RHA used in this
research cannot, currently, be recommended to be used in
replacement of lime or cement in soil stabilisation in NSW.
8.4 Economic feasibility of Lime-RHA additives to
Soils
It has been shown in Section 5.2.8 that 1:1 lime-RHA
additive tends to be the most economical additive of all
lime-RHA additives tested
in this research and that 1:1
lime-RHA additive is not recommended to be used in improving
the strength of soils unless the price of lime is at least 3
times the price of RHA.
It was also shown in section 5.2.7
that 1:1 lime-RHA additive can be recommended to be used in
modifying the plasticity and shrinkage properties of soils
provided that the cost of lime is at least 5-6 times the
cost of RHA.
282
Section 8.2 clearly shows that both conditions, which enable
1:1 lime-RHA to be economically implemented in increasing
the
strength
and
modifying
the
stability of soils, are not met.
plasticity
and
volume
Consequently, it can be
determined that 1:1 lime-RHA additive and subsequently all
other lime-RHA additives are not, at present, economically
feasible to be used in soil stabilisation in NSW.
8.5 Economic feasibility of Cement-RHA additives to
Soil
Section 5.3.7 has indicated that 1:1 cement-RHA additive
tends to be the most economical additive of all cement-RHA
additives
tested
additives
can
be
in
this
research
recommended
for
and
that
cement-RHA
replacing
2%
cement
additive for increasing the strength of low cohesion soils
provided that the cost of cement is equal to, or greater
than, 2.4 times the cost of RHA.
It was also shown in
section 5.3.7 that the cost of cement should equal at least
4 times the cost of RHA to enable cement-RHA additive to be
implemented, economically, in modifying the plasticity and
shrinkage
properties
of
soils
or
achieving
a
strength
comparable to that achieved with 4% cement additive.
The fact that the cost of cement is not 4 times the cost of
RHA but rather 2.5 times less than the cost of RHA dictates
283
that cement-RHA additives cannot, at present, be recommended
to be used in soil stabilisation in NSW.
8.6 Summary
The current high cost of RHA in NSW has rendered this
material unsuitable to be used as a single additive to soils
or
in
combination
stabilisation.
with
lime
or
cement
in
the
soil
However, Biocon is currently investigating
larger furnaces that will produce grey ash at rate of up to
3 tonnes per hour or 15000 tonnes per annum.
It is assumed
that the cost of this grey ash will be as low as $50/tonne
bulk ex. rice mill.
This assumption suggests a role for
grey ash in soil stabilisation particularly if it proved,
after testing, to be a better soil stabiliser than black
ash.
8.7 Availability of GBFS
Iron and steel making has been a part of Australia's history
and
development
since
the
first
established at Mittagong, NSW in 1848.
blast
furnace
was
The scope and thrust
of the slag industry has been significantly changed in the
late
1980's
with
the
construction
of
new
granulation
facilities at No. 2 and 5 Furnaces, Port Kembla and No.3
Furnace, Newcastle.
These new facilities have taken the
284
process from the basic form which is still currently in use
at No.4 Furnace, Port Kembla, which has minimal controls on
flow rates, pressure, temperature, automatic dewatering and
automatic sampling (55).
The three steel production centres at Port Kembla, Newcastle
and Whyalla generated more than 3.2 million tonnes of total
iron and steel making slag in 1989 (54) of which Port Kembla
works, as the largest steel making centre in Australia (4.0
million tonnes per annum) produced more than 420,000 tonnes
of GBFS.
This GBFS is currently marketed by Australian Steel Mill
Services Pty Ltd, Port Kembla, NSW, and sold at $6.00 to
$10.00 per tonne depending on the quantity of material
ordered. This price is F.O.T. Ex Port Kembla and is
approximately /14 times the cost of lime or cement ($130 $140 per tonne) at any place within a distance of 300km from
Port Kembla.
8.8 Economic feasibility of GBFS as single additive to
Soils
Section 7.1.2a and section 7.1.3 indicate that GBFS as a
single additive to soils has a remarkable effect on
strength, plasticity and shrinkage properties of cohesive
285
soils.
However, these sections also show that the effects
of GBFS on the properties of soils are inferior to those
occurring due to the addition of lime or cement additives to
soils and that GBFS as a single additive to soils is not an
efficient stabiliser unless the cost of lime or cement is
between 6-9 times the cost of GBFS.
This condition is met as is clearly shown in section 8.7.
Hence GBFS as single additive to soils can be recommended
for use in modifying strength, plasticity and shrinkage
properties of cohesive soils in locations where the cost of
GBFS does not exceed 140/6 = $23.33 (ie where haulage rate
does not exceed 23.33 - 10.00 = $13.33 (per tonne). If x km
is the haulage distance in excess of 40kms, then the haulage
rate can be calculated by using the equation provided by RTA
NSW: Haulage rate = 9.32 + 0.2612 x and therefore the
haulage distance in excess of 40kms will equal to 15.35km.
This indicates that GBFS as a single additive to soils can
be recommended to be used in modifying strength, plasticity
and shrinkage properties of cohesive soils in locations
within a distance of 55kms from Port Kembla or similar GBFS
production plant.
286
8.9
Economic
feasibility
of Lime-GBFS
additives to
Soils
It has been shown in section 7.2.8 that 1:1 lime-GBFS
additive tends to be the most economical additive of all
lime-GBFS additives investigated in this research.
also
been
recommended
shown
that
1:1
for replacing
lime-GBFS
additive
2% lime additive
It has
can
be
in modifying
strength, plasticity and shrinkage of clays (soils) provided
that the cost of lime is 6-7 times the cost of GBFS.
This condition is satisfied at the place of production in
Port Kembla and can also be met in any location within a
distance of 55km from Port Kembla or similar production
plant as was shown in section 8.8.
Section 7.2.8 has also indicated that 1:1 lime-GBFS additive
can be used for replacing 2% lime additive in increasing the
strength of low cohesion soils provided that the cost of
lime is 4.68 and 2.25 times the cost of GBFS depending on
the nature of stabilised soils (4.68 times for sand-silt
soils and 2.25 times for gravel-sand soils).
In a way similar to that specified in section 8.8, it can be
proved that these requirements can be satisfied in locations
where hauling distance from Port Kembla or any other similar
287
GBFS production plant does not exceed 80-200km depending on
nature of soils
(80km for sand-silt soils and 200km for
gravel-sand soils).
8.10 Economic feasibility of Cement-GBFS additives to
Soils
It has been shown in section 7.3.7 that 1:1 cement-GBFS
additive is the most economical additive of all cement-GBFS
additives used in this investigation.
It has also been
shown that 1:1 cement-GBFS additive can be recommended for
replacing
2-4%
cement
additive
in
modifying
strength,
plasticity and shrinkage properties of clays provided that
the cost of cement is equal to or greater than 2-4 times the
cost of GBFS.
It was also shown in section 7.3.7 that 1:1
cement-GBFS additives can be recommended for replacing 2%
cement additive in modifying the strength of sand-silt soils
provided that the cost of cement is equal to or greater than
4.65 times that the cost of GBFS.
In a way similar to that specified in section 8.8, it can be
proved that the economic requirements for the above stated
applications can be satisfied and 1:1 cement-GBFS additive
is
economically
feasible
to
be
used
in
some
soil
stabilisation applications where hauling distance, of GBFS,
does not exceed 80-230km depending on nature of soils and
288
purpose of stabilisation (230km for increasing strength and
modifying plasticity and shrinkage of clays and 80km for
increasing strength of sand-silt soils).
289
Chapter IX
RECOMMENDED DESIGN PROCEDURES
9.1 Introduction
The design of lime-pozzolan and cement-pozzolan additive
stabilisation, as with other types of soil stabilisation, is
largely a matter of selecting and proportioning materials to
obtain the desired properties in the finished construction.
The overall objective for the additive soil stabilisation is
to determine an economical blend of soil and additive that
yeilds a mix having sufficient workability, strength,
durability and volume stability.
When stabilising with cement or lime, the amount of lime or
cement required obviously depends on the objectives of
stabilisation and properties required. Decisions as to
whether it would be advantageous to use RHA and GBFS, as
single additives or in combination with lime or cement, must
be taken with economy in mind. Since a given objective,
such as a specified plasticity index, can be achieved by a
variety of additives, the composition of the preferred mix
may be chosen because of its economy.
290
Chapters 4 to 8 examined, technically and economically, the
best ratios of lime or cement to RHA and GBFS produced in
NSW.
They also determined the amount of additives required
to be added to four selected soils to obtain certain desired
properties.
Soil properties vary from point to point. The properties of
RHA
and
GBFS
also
vary
according
indicated in section 4.4 and 6.4.
that proportions
and
amounts of
to
many
factors
as
These variations imply
additives
used
in this
investigation may not be appropriate to be implemented in
every soil stabilisation work.
This dictates that each
individual problem must be analysed on its own merits before
the design can be accomplished.
The problem of choosing the
proper additive may cause an inexperienced individual to
become confused by the many alternatives available for use.
For
this
reason,
the
following
design
procedures
are
suggested to be carried out before an attempt is made to
choose an additive.
9.2 Mix design procedures of Lime-RHA Soil
stabilisation
The essential elements of the mix design procedures of
lime-RHA soil stabilisation are listed below:
291
i)
Define the objective of treatment and determine a
specific value of the desired property (ie, CBR,
UCS, Ip, etc.) using job specifications, pavement
design or structural analysis.
ii) Determine the minimum quantity of lime which
achieves the desired specific value of soil
property. A plot of lime content versus strength
or any other desired property for three to four
lime contents should be sufficient to enable a
reasonable deduction of this minimum quantity of
lime (see Figure 9.1a).
iii) Plot this minimum quantity of lime as point M on
the abscissa of Figure 9.1b. If there is any
additional cost in involving RHA in the process of
soil stabilisation (ie, additional equipment, men,
etc.) this cost should be converted to an
equivalent lime quantity, deduction from point M
giving point N on the abscissa.
iv) From point N draw a straight line of actual cost
ratio, the slope of which corresponds to the ratio
of cost of lime to the cost of RHA delivered to
the site.
292
v)
Determine the optimum ratio of lime to RHA by
testing the UCS of lime-RHA pastes with at least
three different proportions.
The ratios of lime
to RHA of 1:1, 1:2 and 1:3 are usually sufficient
to enable an optimum ratio to be determined.
vi) Consider the optimum ratio also to be the best
economic ratio if RHA is needed to, significantly,
improve
soil.
the
particle
size
distribution
of
the
Otherwise, the mix of best economic ratio
can be considered as that mix which has a slightly
higher
lime
content
than
that
of
the
mix
of
optimum ratio.
vii) From point 0 draw two straight lines representing
the optimum ratio and the best economic ratio of
lime to RHA.
viii) Points above the line of actual cost ratio
indicate the uneconomical additives.
Hence the
feasible quantities of RHA (as single additive to
soils) are limited to the range indicated on the
ordinate below point D, from which selection may
be made by testing the specified property.
The
feasible lime-RHA mixtures are also limited to a
fairly narrow range
(ie,
the triangular
area
293
bounded
by
the
lines
of
optimum
ratio,
best
economic ratio and the actual cost ratio) from
which selection may be made by testing directly
the specified property.
9.3 Mix design procedures for Lime-GBFS, Cement-GBFS
and Cement-RHA Soil stabilisation
The design procedures for lime-GBFS, cement-GBFS and
cement-RHA soil stabilisation are similar to those of
lime-RHA specified in section 9.2. However, it must be
emphasised that no optimum ratio of cement to GBFS and RHA
can be determined. The ratio of 1:1 can be reasonably
considered as the best economic ratio of these mixes.
294
FIG.9.1 - DETERMINATION OF THE COMPOSITION OF THE PREFERRED
MIX IN A LIME-RHA SOIL STABILISATION
>i
+J
u
Specific value of desired
property of soil
CU
o
u
a.
o
cn
FIG.9.la
TS
CU
U
•rH
CO
CU
Q
c
•H
99-
4%
6%
8%
Lime additive (% of total dry weight)
•rH
CU
>1
TJ
(0
FIG.9.lb
o
-p
o
dP
CU
>
•H
+J
•H
TJ
TJ
rtJ
<
nc
os
2%
4%
6%
8%
Lime additive (% total dry weight)
295
Chapter X
CONCLUSIONS
Based on the preceeding experimental and economical
investigations, the following conclusions have been drawn:
10.1 Conclusions concerning RHA as a single additive to
Soils
RHA improves the workability of wet soils. It increases the
optimum
moisture
content
and
decreases
the maximum
dry
density of these soils.
RHA does not react chemically with soils or affect
favourably
behaviour
their
under
unconfined
the
action
compressive
of
repeated
strength
dynamic
and
loads.
However, RHA tends to decrease the CBR of soils.
RHA increases the liquid limit and plastic limit of soils.
However, the very high liquid limit of heavy clays decreases
due to the addition of RHA to these clays.
RHA improves the
volume stability of soils by decreasing their plasticity
index and linear shrinkage.
However, these decreases in
plasticity and shrinkage are not comparable to those which
occur by the addition of lime or cement to soils.
296
RHA can be recommended
for replacing
lime or cement in
modifying the plasticity and shrinkage properties of soils
provided that the cost of lime or cement is at least 5-6
times the cost of RHA.
currently
2.5
times
The cost of RHA produced in NSW is
the
cost
of
lime
or
cement
and
therefore, RHA cannot be recommended for replacing lime or
cement
in
soil
stabilisation
in NSW
unless
significant
decrease in cost of RHA can be achieved.
10.2 Conclusions concerning Lime-RHA additives
Lime-RHA additives improve the workability of wet soils.
They increase the optimum moisture content and decrease the
maximum
dry
pronounced
density
as
the
of
soils.
quantity
of
These
RHA
in
effects
the
are more
additive
is
increased.
1:2 lime-RHA ratio is the optimum ratio associated with the
highest strength of lime-RHA pastes.
However, lime reacts
more readily with soils than with RHA and hence the highest
strength of all lime-RHA treated soils has been achieved by
1:1 lime-RHA additive.
Lime-RHA additives increase the CBR, unconfined compressive
strength
and
shear
strength
of
soils.
This
is
more
297
pronounced as either the curing time, the quantity of lime
in the additive or the quantity of additive is increased.
However, the
unconfined
compressive
strength
of
treated
soils increases with increasing quantity of additive, up to
a peak value, then decreases with the continuous increase of
the quantity of additive.
The quantity of additive at which
a peak value of unconfined
compressive
strength occurs,
tends to increase with increasing amount of RHA in the
additive.
The increase in unconfined compressive strength,
CBR and shear strength of lime-RHA soil stabilisation is
caused by the increase in both the internal friction and
cohesion of the stabilised soils.
RHA acts as a pozzolan and has a role in strength
development of lime-RHA soil stabilisation.
However, the
optimum increase in strength (CBR and unconfined compressive
strength) achieved by lime-RHA additives is not comparable
to the maximum increase in strength which occurs by the
addition of lime to soils.
Delay in compaction of lime and lime-RHA stabilised soils
decreases
the
strength
of
these mixes.
This
is more
pronounced as the time elapsed since mixing is increased.
The rate
of
reaction
in
lime-RHA
soil
stabilisation
is
relatively slow and somewhat similar to lime stabilisation.
The losses in strength of lime and lime-RHA stabilised soils
298
due to delay in compaction are, consequently, low and almost
similar.
Accordingly, the time constraints in respect of
compaction are not so critical.
Lime-RHA additives improve the volume stability of soils.
They decrease the plasticity index and linear shrinkage and
increase plastic
These
effects
limit and liquid limit of these soils.
are
more
pronounced
as
the
quantity
of
additive and/or the amount of lime in the additive are
increased.
clays
However, the very high liquid limit of heavy
decreases
with
the
increase
in
additive
quantity
and/or the amount of lime in the additive.
Lime-RHA additives are more efficient for stabilising low
cohesion soils than for stabilising clays.
more
efficient
for
increasing
the
They are also
strength
than
for
modifying the plasticity and shrinkage properties of soils.
1:1 lime-RHA additive tends to be the most economical
additive of all lime-RHA additives used.
It is an effective
and efficient additive for improving the behaviour of soils
under the action of repeated dynamic loads.
1:1 lime-RHA
additive can be recommended for increasing the strength as
well as for modifying the plasticity and shrinkage of soils,
provided that the cost of lime is 3 times (for increasing
the strength) and 5-6 times (for modifying the plasticity
299
and
shrinkage)
the
cost
conditions, currently,
of
RHA
are not met
respectively.
These
in NSW and
lime-RHA
additives are not economically feasible at this time for
soil stabilisation in NSW.
10.3 Conclusions concerning Cement-RHA additives
Cement-RHA additives improve the workability of wet soils.
They increase the optimum moisture content and decrease the
maximum
dry
pronounced
density
as
the
of
soils.
quantity
of
These
RHA
effects
in
the
are more
additive
is
increased.
There is no optimum ratio of cement to RHA in cement-RHA
pastes.
The strength of these pastes increases with the
increase of quantity of cement in the mix.
Cement-RHA additives increase the CBR, Unconfined
compressive strength and shear strength of soils.
This is
more pronounced as either the curing time, the quantity of
cement
in the
increased.
additive
or the quantity
of
additive
is
The increase in unconfined compressive strength,
CBR and shear strength of cement-RHA soil stabilisation is
caused by the increase in both the internal friction and
cohesion of the stabilised soils.
300
RHA as a pozzolan has a role in strength development of
cement-RHA
retarder
soil
in
stabilisation.
slowing
down
However,
the
strength
it
acts
as a
development
and
favourably affects the workability of these mixes.
Delay in compaction of cement and cement-RHA stabilised
soils decreases the strength of these mixes.
The loss in
strength is more pronounced as the time elapsed since mixing
is increased.
The
loss
in
strength, due
to delay
in
compaction, of cement-RHA stabilised soils is significantly
less than that of cement stabilised soils.
the
amount
of
RHA
in
the
This is more
pronounced
as
additive
is
increased.
Accordingly, the time constraints in respect of
compaction of cement-RHA stabilised soils are not highly
critical.
Cement-RHA additives improve the volume stability of soils.
They decrease the plasticity index and linear shrinkage and
increase the plastic limit and liquid limit of these soils.
These
effects
are
more
pronounced
as
the
quantity
of
additive and/or the amount of cement in the additive are
increased.
clays
However, the very high liquid limit of heavy
decreases
with
the
increase
in
additive
and/or the amount of cement in the additive.
quantity
301
Cement-RHA additives are more efficient for stabilising low
cohesion soils than for stabilising clays.
more
efficient
for
increasing
the
They are also
strength
than
for
modifying the plasticity and shrinkage properties of soils.
1:1 cement-RHA additive tends to be the most economical
mixture of all cement-RHA additives used.
These additives
tend to be less economical as the amount of RHA in the
additive increases.
1:1 cement-RHA additive is an effective but not very
efficient
additive
for improving
the behaviour
under the action of repeated dynamic loads.
of soils
It is also not
efficient for replacing 4% cement additive in modifying the
plasticity and shrinkage properties of soils.
1:1 cement-RHA additive can be recommended for replacing 2%
cement additive in increasing the strength of low cohesion
soils and modifying the plasticity and shrinkage properties
of soils provided that the cost of cement is 2.4 times (for
increasing the strength of low cohesion soils) and 4 times
(for modifying the plasticity and shrinkage properties of
soils) the cost of RHA.
1:1 cement-RHA additive can also be
recommended for replacing 4% cement additive in increasing
the strength of soils provided that the cost of cement is 4
times the cost of RHA.
All of these cost requirements are
302
not, currently, met in NSW.
additive and consequently
investigated
replacing
Accordingly, 1:1 cement-RHA
all other cement-RHA
additives
in this research cannot be recommended
cement
in
soil
stabilisation
in
NSW
for
unless
significant decrease in cost of RHA can be achieved.
10.4 Conclusions concerning GBFS as a single additive to
Soils
GBFS improves the workability of wet gravel-sand soils. It
increases
the
optimum
moisture
content
of
these
soils
whereas it decreases the optimum moisture content of silts
and clays.
GBFS has no significant chemical reactions with soils.
However,
its
mechanical
porosity, increases
stabilising
the maximum
effect
reduces
dry density and
the
affects
favourably the stiffness and compressibility of soils.
GBFS
reduces the permanent deformation and improves the behaviour
of soils under the action of repeated dynamic loads.
It
also increases the CBR and unconfined compressive strength
of soils.
The increase in unconfined compressive strength
of cohesive soils is remarkable but inferior to those which
occur by the addition of lime or cement to these soils.
303
GBFS has no significant effect on the liquid limit, plastic
limit, plasticity index and linear shrinkage of low cohesion
soils. Its effect on volume stability of heavy clays is
remarkable. It increases the plastic limit and decreases
the very high liquid limit, the plasticity index and the
linear shrinkage of these heavy clays. However, these
effects on plasticity and shrinkage properties are inferior
to those which occur by the addition of lime or cement to
these soils.
GBFS, as a single additive to soils, can be recommended for
modifying strength, plasticity and shrinkage properties of
cohesive soils provided that the cost of lime or cement is
6-9 times the cost of GBFS. This condition can currently be
met in NSW within a distance of 55km from Port Kembla or
similar GBFS production plant.
10.5 Conclusions concerning Lime-GBFS additives
1:1 lime-GBFS additive improves the workability of wet
soils. It increases the optimum moisture content and
decreases the maximum dry density of soils. However, as the
quantity of GBFS in the additive increases, the effect of
GBFS gradually becomes more dominant than the effect of lime
and tends to increase the maximum dry density and decrease
304
the optimum moisture content of treated soils, particularly
clays.
1:2 lime:GBFS ratio is the optimum ratio associated with the
highest strength of lime-GBFS pastes.
However, lime reacts
more readily with soil than with GBFS and hence the highest
strength of all lime-GBFS treated soils has been achieved by
1:1 lime-GBFS additive.
Lime-GBFS additives increase the CBR, unconfined compressive
strength and the shear strength of soils.
This is more
pronounced as either the curing time, the quantity of lime
in the additive or the quantity of additive is increased.
However, the unconfined
compressive
strength
of
treated
soils increases with increasing quantity of additive, up to
a peak value, then decreases with the continuous increase in
the quantity of additive.
a peak value of
The quantity of additive at which
strength occurs tends to increase with
increasing amount of GBFS in the additive.
The increase in
CBR, unconfined compressive strength and shear strength is
caused by the increase in both the internal friction and
cohesion of stabilised soils.
GBFS, as a hydraulic cement or as a pozzolan, has a role in
strength
development
However,
the
highest
of
lime-GBFS
strength
soil
achieved
stabilisation.
by
lime-GBFS
305
additives
is not
comparable
to the maximum
increase in
strength which occurs by the addition of lime to soils.
Delay in compaction of lime and lime-GBFS stabilised soils
decreases the strength of these mixes. This is more
pronounced as the time elapsed since mixing is increased.
The rate of reaction in lime-GBFS soil stabilisation is
relatively slow and somewhat similar to lime stabilisation.
The losses in strength of lime and lime-GBFS stabilised
soils due to delay in compaction are, consequently, low and
almost similar. Accordingly, the time constraints in
respect of compaction are not so critical.
Lime-GBFS additives improve the volume stability of soils.
They decrease the plasticity index and linear shrinkage and
increase plastic limit and liquid limit of these soils.
These effects are more pronounced as the quantity of
additive and/or the amount of lime in the additive are
increased. However, the very high liquid limit of heavy
clays decreases with the increase in additive quantity
and/or the amount of lime in the additive.
Lime-GBFS additives are more efficient for stabilising low
cohesion soils than for stabilising clays.
306
Lime-GBFS additives tend to be less economical as the amount
of GBFS in the additive increases.
the most
used.
reducing
economical
It
is
the
an
Hence, 1:1 lime-GBFS is
additive of all lime-GBFS
effective
permanent
and
efficient
deformation
and
additives
additive
for
improving
the
behaviour of soils under the action of repeated dynamic
loads.
efficient
However,
all
lime-GBFS
for replacing
additives
4% lime additive
used
in
are
not
stabilising
soils.
1:1 lime-GBFS additive can be recommended for replacing 2%
lime additive in stabilising clays provided that the cost of
lime is
6.7
times
the cost of
GBFS.
It can also be
recommended for replacing 2% lime in increasing the strength
of low cohesion soils provided that the cost of lime is
2.25-4.68 times the cost of GBFS.
These cost requirements are now satisfied in NSW in
locations where hauling distance from Port Kembla or any
other similar GBFS production plant does not exceed 55-200km
depending
on
stabilisation
the
nature
of
soils
and
purpose
of
soil
(55km for stabilising gravel-sand soils and
200km for stabilising sand-silt soils).
307
10.6
Conclusions concerning Cement-GBFS additives
Cement-GBFS additives improve the workability of wet soils.
They increase the optimum moisture content and maximum dry
density of soils.
The increase in optimum moisture content
is more pronounced as the amount of cement in the additive
is increased.
There is no optimum ratio of cement to GBFS in cement-GBFS
pastes.
The strength of these pastes increases with the
increase of amount of cement in the mix.
Cement-GBFS additives increase the CBR, unconfined
compressive strength and shear strength of soils.
This is
more pronounced as either the curing time, the quantity of
cement
in the
increased.
additive
or the
quantity
of
additive
is
The increase in unconfined compressive strength,
CBR and shear strength of cement-GBFS soil stabilisation is
caused by the increase in both the internal friction and
cohesion of the stabilised soils.
GBFS, as a hydraulic cement or as a pozzolan, has a role in
strength
development
of
cement-GBFS
soil
stabilisation.
However the rates of strength development of cement-GBFS
stabilised soils are slightly slower than those of cement
stabilised soils.
GBFS, therefore, acts as a weak retarder
308
and has no significant effect on the compaction working time
of cement-GBFS stabilised soils.
Delay in compaction of cement and cement-GBFS stabilised
soils decreases the strength of these mixes.
This is more
pronounced as the time elapsed since mixing is increased.
The loss in strength, due to delay in compaction, of cement,
GBFS stabilised soils is slightly less than that of cement
stabilised soils.
This is more pronounced as the amount of
GBFS in the additive is increased.
Cement-GBFS additives improve the volume stability of soils.
They decrease the plasticity index and linear shrinkage and
increase the plastic limit and liquid limit of these soils.
These effects are more pronounced as the quality of additive
and/or the amount of cement in the additives are increased.
However, the very high liquid limit of heavy clays decreases
with the increase in additive quantity and/or the amount of
cement in the additive.
Cement-GBFS additives are not efficient for modifying the
plasticity and shrinkage properties of low cohesion soils.
1:1 cement-GBFS additive is efficient for increasing the
strength of soils and modifying the plasticity and shrinkage
properties of clays.
It is also an effective and efficient
309
additive in reducing the permanent deformation and improving
the behaviour of soils under the action of repeated dynamic
loads.
1:1 cement-GBFS additive can be recommended for replacing 24% cement additive in modifying strength, plasticity and
shrinkage properties of clays provided that the cost of
cement is equal to or greater than 2-4 times the cost of
GBFS.
1:1 cement-GBFS additive can also be recommended for
replacing 2% cement additive in modifying the strength of
sand-silt soils provided that the cost of cement is equal to
or greater than 4.65 times the cost of GBFS.
These cost
requirements can be met in NSW and 1:1 cement-GBFS additive
can be recommended
for the above stated applications in
locations where hauling distance from Port Kembla or any
similar GBFS
production plant, does not exceed
80-230km
depending on the nature of soil and purpose of stabilisation
(230km
for
increasing
the
strengh
and
modifying
the
plasticity and shrinkage of clays and 80km for increasing
the strength of sand-silt soils).
310
REFERENCES
1) Hawkes, H.E. and Webb, J.S. ,(1962) Geochemistry in
Mineral Exploration,
Harper and Row, New York.
2) Spense, R.J.S and Cook, D.J. (1983) Building
Materials in Developing Countries,
John Wiley and
Sons, New York.
3) Ingles, O.G. and Metcalf, J.B. (1972) Soil
Stabilisation
Principles
and
Practices,
Butterworths Sydney-Melbourne-Brisbane.
4) Ingles, O.G. (1978) "Soil Stabilisation The Next
One Hundred Years", Symposium on Soil Reinforcing
and
Stabilising
Techniques,
Sydney,
Australia,
pp. 365-383.
5) Davidson, W.H. and Mullin, E.F. (1962) "Use of Fly
Ash
in Road Construction
Proc.
Australian
Road
in New South Wales",
Research
Board,
1:2,
pp. 1085-1100.
6) National Association of Australian State Road
Authorities (1979).
The History and Challenge of
Road Transport, Brickfield Hill, NSW, Australia.
Kezdi, A. (1979) Stabilised Earth Roads, Elsevier
Scientific
Publishing Company, Amsterdam-Oxford-
New York.
Ingles, O.G. (1968) "Report on Survey of Use of
Soil Stabilisation in Australia", Australian Road
Research, J., 3.
pp. 58-63.
Cruickshank, J.W. (1977) "Stabilisation of Road
Pavements
- A Preliminary Survey",
Road Research, J., 7.
Australian
pp. 41-42.
Lee, I.K., Ingles, O.G. and White, W. (1983)
Geotechnical Engineering, Pitman Publishing Inc,
Marshfield, Massachusetts, USA.
Lea, F.M. (1970) The Chemistry of Cement and
Concrete, Edward Arnold (Publishers) Ltd, London.
Yamanouchi, T. (1978) "Problems of the Development
of
Soil
Stabilisation",
Reinforcing
and
Stabilising
Symposium
on
Soil
Techniques, Sydney,
Australia.
Havelin, J.E. and Khan, F. (1951) "Hydrated LimeFlyash-Fine Aggregate",
US Paten No. 2:554, 690.
14)
Minnick, L.J. and Miller, R.H. (1952) "Lime-Flyash
Compositions in Highways", Proc Highway Research
Board, pp. 511-528.
15) Davidson, D.T., Sheeler, J.B. and Delbridge, N.G.
(1958) "Reactivity of Four Types of Flyash with
Lime", Highway Research Board, Bulletin No. 193,
pp. 24-31.
16) Central Electricity Generation Board (1958)
Pulverised Fuel Ash Information, Bulletins No.
4,5,6 and 7, London.
17) Bureau of Agricultural Economics (1983) "Situation
and outlook, 1983, Rice, Australia", Government
Publishing Service, Canberra, pp. 1-10.
18) Croft, J.B. (1964) "The Pozzolanic Reactivities of
some New South Wales Flyashes and their
Application to Soil Stabilisation", Australian
Road Research Board, Proc. V2 (2), pp. 1144-1167.
19) Herzog, A. and Brock, R. (1964) "Some Factors
Influencing the Strength of Soil-Lime-Flyash
Mixtures", Australian Road Research Board, Proc
V2(2), pp. 1226-1233.
Department
of
Main
Roads,
NSW,
(1978)
"Stabilisation with Lime-flyash Mixture", Circular
No. M&R 115, Sydney, Australia.
Moulton, D., Seals, K., and Anderson, D. (1973)
"Utilisation of Ash from Coal Burning Power Plants
in Highway Construction", Highway Research Record,
No. 430, pp. 26-39.
Mehta, P.K. (1979) "Energy Resources and the
Environment - A Review of the US Cement Industry",
World Cement Technology, 9(5), pp. 144-160.
Mehta, P.K. (1976) "Energy and Industrial
Materials from Crop Residues", Resource Recovery
and Conservation, pp. 223-238.
Dave, N.G. (1981) "Pozzolanic Wastes and their
Activation to Produce Improved Lime Pozzolana
Mixtures", Second Australian Conference on
Engineering Materials, University of New South
Wales, Sydney, pp. 623-638.
Hammond, A.A. (1976) "Evaluation of Bauxite-Waste
for Cement Production in New Horizons in
Construction Materials", Envo Publishing Co Inc,
Vol 1, pp. 1159-163.
26)
Lilley,
A.
(December
1979)
"Cement
Stabilised
Materials", Civil Engineering, pp. 25-29.
27) Suwanvitaya, P. (1984) Properties and Behaviour of
Rice Husk Ash-Lime Cement, Thesis (PH.D.)
University of New South Wales.
28) Hough, J.H. and Bar, H.T. (1956) "Possible Uses
for Waste Rice Hulls", Louisiana State University,
Agricultural Experiment Station, Bulletin No. 507.
29) Rahman, M.A. (1986) "Effects of Rice Husk Ash on
Geotechnical Properties of Lateric Soil", West
Indian Journal of Engineering, Volume 11 No. 2,
pp. 18-22.
30) Lazaro, R.C. and Moh, Z.C. (1976) "Stabilisation
of Deltaic Clays with Lime-Rice Husk Ash
Admixtures", Proceedings of Second South East
Asian Conference on Soil Engineering, Singapore,
pp. 215-223.
31) Subrahmanyam, M.S., Cheran, Lee Lih and Cheran,Lee
So (December 1981) "Use of Rice Husk Ash for Soil
Stabilisation", Gological Society Malaysia,
Bulletin 14, pp. 143-151.
Rajan, B.H., Subrahmanyam, H. and Sampath Kumar,
T.S.(1982) "Research on Rice Husk Ash for
Stabilising Black Cotton Soil", Highway Research
Bulletin 17, pp. 61-75.
Dussart, Jacques. (February 1979), "Blast Furnace
and Steel Slags in France", The Australian I.M.M.
Illawarra Branch, Utilisation of Steel Plant Slags
Symposium, pp.25-34.
Lee, A.R. (1974) "Blast Furnace and Steel Slag
Production, Properties and Uses", Edward Arnold.
Prandi, E. (1965) "Traitment au Laitier Granule
des Materiaux Routieres", Ponts et Chaussees,
Bull.Liais.Labs. Routieres,.
Cohchi, M., Shiina, K. and Ohta, F., (1979)
"Effective Prevention for Weathering Expansion
Crack of Arc-Furnace Slag Concrete", The Cement
Association of Japan, Volume 33, pp. 184-188.
Sakai, M. and Miyamoto, M. (1979) "Experimental
Study on the Properties of LD Converter Slag
Concrete", Proc. of Japan Concrete Institute 1st
Conference, pp. 185-188,
38)
Hagga, Nobutake., Ohkawa, Yuichi., Michiokonno,
Kawamoto, Takayuki., Mizoguchi, Ikuo., (June 1981)
"Utilisation of Blast Furnace and Steel Slags in
Road Construction", Nippon Steel Technical Report
No. 17, pp. 73-89.
39) Kawamura, Mitsunori., Hasaba, Shigemasa, and
Torri, Kazuyuki, "Effective Utilisation of Ld
Converter Slag as a Soil Stabiliser", pp.285-296.
40) Hasaba, Shigemasa., Kawamura, Mitsunori. and
Torri, Kazuyuki, (March 1982) "Reaction Products
and Strength Charactaristics in the Stabilised
Soil using Desulfurization By-Products and Blast
Furnace Slag", Transactions of Japan Society of
Civil Engineer, Volume 14, pp.251-253.
41) Bate, I.e. (November 1972) "Slag as a Road-Base
and Stabiliser in Rhodesia", The Rhodesian
Engineer, pp. 54-58.
42) Department of Main Roads, NSW, (December 1988),
Accelerated Loading Facility Prospect Trial.
Seminar on Results and Findings.
43) Hudson, Ken., (February 1989) "Stabilisation of
Road Pavements France Autoroutes", New Zealand
Concrete Construction, pp. 3-10.
Shackel,
B.
(1975)
"A
Critical
Assessment
of
Current Test Methods and Design Criteria for
Stabilised Pavement Materials", Conference on
stabilisation and compaction, University of New
South Wales, Kensington, Australia.
Shackel, B. (1975) "The Behaviour of Stabilised
Soils under Simulated Traffic Loads", Proc. 7th
Conference Australian Road Research Board,
Vermont, Victoria, Volume 7, Part 7, pp. 18-37.
Shackel, B. (1975) "Types of Repeated Loading
Tests and Their Application to the
Characterisation of Soils and Road Making
Materials", Symposium On Repeated Loading of Soils
With Particular Reference To Road, School Of
Highway Engineering, Kensington, New South Wales,
Australia.
National Association of Australian State Road
Authorities (1986) Guide to Stabilisation in
Roadworks, Sydney, Australia.
Natt, G. and Joshi, R. (1984) "Properties of
Cement and Lime-flyash Stabilised Aggregate",
Testing and Modeling Soils and Soil Stabilisers,
Transportation Research Record 998, Washington,
DC, pp. 32-40.
49)
Rowe,
G.H.
(1985)
"Laboratory
Testing
for
Stabilisation", RRU Technical Recommendations TR7,
Road
Research
Unit,
National
Roads
Board,
Wellington, New Zealand, pp. 5-11.
50) Indian Standard for Masonary Cement (IS4098).
51) South Africa National Institute for Transport and
Research (1986) Cementitious Stabilisers in Road
Constructions,
Technical
Recommendations
for
Highways Draft TRH13, Pretoria, South Africa, pp.
1-64.
52) Klatt, P. (1991) Private Communication.
53) Jones, D.E. (1990) "Industrial slag construction
materials for the 1990's and beyond", Proc. 21st
Engineering
Nineties,
Conference
the
Illawara
on
Materials
Group,
for
Institution
Engineers, Australia, University
the
of
of Wollongong,
NSW, Australia.
54) Jones, D.E. (1990) "In the beginning-slag",
Seminar
on
slag
products
in
the
construction
industry, Australasian Slag Association, pp. 1-12.
Hanley, P.J. (1990) "Slag-towards 2000, Australian
trend", Concrete for the Nineties, International
Conference on the use of Flyash, Slag, Silica Fume
and other silceous materials in concrete, Leura,
Australia, pp. 1-11.
Department of Main Roads, NSW (now known as the
Roads and Traffic Authority, NSW)
Materials
Australia.
Testing
Manual,
Volume
(July
1,
1989).
Sydney
Appendix A
METHOD OF OPERATION OF THE FATIGUE CONTROL
PANEL USED IN THE REPEATED DYNAMIC LOAD TEST
Fatigue Control Panel
The panel is illustrated in Figure A.1 with each item numbered. Each item
is then explained briefly*
1. Supply On/Off Switch A small toggle switch in the bottom lefthand
corner of the control panel switches the mains supply to the fatigue
control panel on and off. A red light indicates the supply is on.
2. Indicator A digital indicator displays the force applied to the jack
load cell or the jack piston stroke* or an external feedback signal* It may
Indicate either the peak values or the mean or static value*
3* Meter Selection Switch A three position toggle switch selects the meter
to display load, external feedback or stroke*
6* Peak/Mean Selection Switch A three position toggle switch sets the
meter display either positive or negative peaks, or the mean value*
Note when reading static DC values the frequence switch. (7) should be
switched to DC*
7* Meter Frequency Range Switch This control adjusts the tine constant of
the meter and is used when the piston is measuring peak or mean oscillating
values*
It affects the rate of response of the meter*
It should be
switched to DC for reading static values*
84 Peak Reset Controls The peak indication may be reset manually or
automatically*
When the rotary switch is fully anti-clockwise the peak
reading circuits are reset manually with the push button*
As the switch
is rotated clockwise the peak circuits are reset automatically at
increasing frequency*
9, Monitor Sockets These 2mm terminals provide DC output signal of the
value selected for indication of the meter*
Full range of the transducer
gives lOv DC. Minimum impedance of subsequent circuit 100k ohm*
10* Zero Controls Two calibrated multi-turn lockable potentiometers adjust
the zero of the stroke and load indication and DC output signal*
11. DC Output Sockets Three sockets provide DC output signals of load and
stroke., together with a signal earth connection.
scale of the transducer.
lOv equivalent to full
Minimum impedance of subsequent circuit 100k ohm*
12. Control Selection Buttons Three push buttons set the jack to control
either load or stroke or some other variable fed to the external feedback
socket.
Care must be exercised when changing from one control mode to
another as a step may be applied to the specimen.
13, External Feedback Socket A co-axial socket beneath the external "contr
selection button1* accepts the external feedback signal*
This should be -
i
lOv may?mtim and any signal conditioning circuits must have flat frequency
i
response to 200Hz. Input impedance is 22k ohm and the feedback signal
source should have a low impedance or errors will result.
I
!
14. Mean Level Potentiometer The digital readout potentiometer controls
i
static or mean values. It can be switched so that 100% on the potentiometer is either full transducer range or 10Z of transducer range* The
push buttons give tension (+va) or compression (-ve) sign*
15. Mean Level Potentiometer Range Switch This small toggle switch sets
the mean level command potentiometer to 10S or 100Z full range.
i
i
16. Limit Load This switch is associated with control of stroke. When
switched to limit the load applied by the machine to the load cell is
limited to 0.5X (approximately) of full range*
tension and compression.
specimens*
The limit operates in
There will be some overshoot with very stiff
If the specimen will be damaged with a 57, load it will be better
use load control*
17. Valve Signal Indication A small edge meter gives an indication of
signal on the servo valve*
It may be used for observing performance or
adjusting valve bias signal.
18. Valve Bias Adjustment A screw driver operated potentiometer adjusts
valve bias signal. It may be used to set the system so that a particular
command signal gives it the exact required valve. It is normally preset
at the factory and does not require adjustment.
19. Gain Adjustment A screw driver operated control adjusts the control
loop gain under load control and external feedback. Adjustment may be
required as the gain of the system will vary with the specimen stiffness.
The control loop gain for stroke control is adjusted on the jack electronic
unit.
20. External Command Input A co-axial socket is provided for feeding
external programme signals to the jack. The scaling of these signals is 10 volts DC for - full range. The input signal may be attenuated by the
external programme attenuator control. Command signals may also be fed to
a socket at the rear of the panel.
21. External Programme Attenuator A digital readout potentiometer may be
used to attenuate the incoming externally generated programme. The
i
potentiometer reading gives percentages signal fed to the jack, i.e. 50Z on
the potentiometer (50.0) means that half the incoming voltage is applied to
the jack.
10 volts gives full transducer range*
22. Internal/External Command Selection A small toggle switch is used to
select either the internal cyclic programme from the built-in function
generator or as an alternative some external programme fed to the system
through the co-axial input socket.
!
!
-
A
23. Oscillator Waveform Selection A rotary switch selects eitherjsine "
triangular or square waveform, or ramp operation*
24* Stop/Run Switch When the switch is moved to "run" the oscillator outpu
starts to go positive from zero*
a;
c
«
c
o
u
Ai
c
o
o
fl)
3
6C
«¥«
«
>J
OM0
-l
fa
-U
c
o
a
to
to
c
-H
JJ
©
(0
o
a
i
&4
25. Preset Switch When set to the preset position this toggle switch
causes oscillator to stop when a preset count selected on the cycle counter
is reached.
26. Frequency/Rate Oscillator frequency is set on a digital readout potentiometer and a decade selection switch. This selection switch gives the
potentiometer the frequency ranges of 0 to 1 Hz, 0 to 10 Hz, or 0 to 100 Hz.
The dial is also calibrated in rate .Z Range/Millisecond for use with the
ramp facility.
27* Ramp hold Switch Enables the oscillator to produce ramp functions
positive or negative going from zero.
28, Monitor Socket A 2mm socket marked monitor enables the output waveform
of the oscillator to be displayed on an oscilloscope or similar device.
Output - lOv DC.
29. Cycle Counter A six digit preset counter records either the number of
completed cycles or the elapsed time.
Counting occurs at 0 volts positive
going. A preset number may be set on the counter by depressing the black
button raising the red perspex cover and setting the finger wheels. When
this preset number is reached the counter will stop the oscillator if the
preset switch (25) is set to preset.
Oscillator output will go to aero,
but any mean value applied (14) will remain.
30. Counter Range Switch This switch gives counter scaling factors of 1
divided by 100 and also permits the selection of timing function which
gives 1 count per second. An off opsition switches the counter off.
Maximum counting rate on the xl range is 25 Hz and in excess of 100 Hz on
the other two ranges.
In normal use a maximum counter rate of about 5 Hz
is recommended*
31. Reset Button This push button resets the counter and the divider
circuits to zero and also.resets the trip circuits.
32. Stopped Light An amber light illuminates when the counter has stopped.
33, Tripped Light An amber light illuminates when the external trip
circuits have operated.
34. External Trip Contacts When these 2mm terminals are shorted the
command attenuator signal is set to zero. This trip is reset by the reset
push button.
A pair of contacts are brought to the rear panel and may be connected to
hydraulic control circuit to stop the pump when the trip operates* Contacts
are closed when tripped.
35. Oscillator/Pump Switch This toggle switch arranges that the trip
circuit may either stop the oscillator or stop the oscillator and trip the
pump.
Procedure for Operation
The following procedure is used to operate the loading panel. Figure A.2
shows the complete panel including supplies, and switches,
1* Start the cooling pumps in the Pump "House for the oil supply motors.
2* Switch the Dartec oil pumps on in the Pump House.
3* Switch the oil supply on in the Pump House.
4. Switch the electrical supply on to the fatigue panel.
5* Start the supply of oil to the low pressure pumps,
6* After approximately 20 seconds there will be an abrupt sound which
indicates that the jack is now ready to operate. After sound switch
on jack no. 1.
7. Switch on high pressure.
8. Take out any packing or obstructions between the wheel and frame and
wheel and pavement.
9. The test is now ready to begin*
Eor Static Loading (Refer to Figure A.1)
1. Switch supply on (1)
2. Switch (3) to load
3. Switch (7) to DC
4.
Switch (8) to desired position.
The position depends on how quickly
a re reading is required.
,/yi, ...
• -, . .
_,,, j , *HVj/.ifimmw_,Vj,
,.,,
-• ,. 1 TTPiy
jEigure A . 2 - The complece operations panel for loading.
I
j 5.
Switch (6) to mean
• 6*. Calculate mean value required.
For example if Che range of loading
was from 10 kn Co 40 kn then mean value would be (10 + 40)/2 » 25
• 7*- Push load control button, (12)
8.
Calculate command input required.
9. Switch (22) to internal.
10» Select command input required (21)
11. Switch (15) to 100Z, switch (14) to (-) for compression.
12. Select mean value required (14) As the mean value is increased the
indicator display (2) will increase. The mean value (14) is increased
until the static load required appears on the display (2). Once the
load has been applied for the required duration, the load is released
by returning (14) to zero.
For Cyclic Loading
1* Switch supply on (1)
2* Switch (3) to load
3* Switch (7) to value desired to obtain peak or mean values.
4.
Set (8) as for static loading.
5.
Set (6) to mean initially.
At a later stage during the running of
the test + peak and - peak values may be desirable. All that is
required is to set (6) to either + peak or • peak and depending on (8)
the value is read.
6. Calculate mean value and command input required.
7.
Select load control (12)
8.
Switch (22) to internal.
9.
Select (23) to wave form required.
Sine wave used for test.
10. Select (24) to stop/zero.
11. Select Frequency required and set (26) accordingly.
12. Switch (15) to 100Z.
13. Switch (21) to required command input.
14. Switch (14) to (-) for compression, then turn dial to required mean
value. This applies to the first load.
15. Switch (24) to run position and cyclic loading will commence. The
counter (29) will count the number of cycles applied*
16. To unload, switch (24) to stop/zero and then return dial (14) to zero.
Appendix B
EQUIVALENT SPECIFIC GRAVITY AND CALCULATED
POROSITY OF VARIOUS MIXES
Equivalent specific gravity of the various additives used
Proportion
1:1
1:2
1:3
1:4
Lime/GBFS
2.605
2.69
2.732
2.758
Cement/GBFS
3.00
2.953
2.93
2.916
Lime/RHA
2.07
1.976
1.93
1.902
Cement/RHA
2.465
2.24
2.127
2.06
-
Additives
Cement
3.14
Lime
2.35
RHA
1.79
GBFS
2.86
Equivalent specific gravity and calculated porosity of
RHA and Lime/RHA stabilised Soil A
Additive
Specific Gravity
Porosity Of Compacted
Specimen (%)
Lime/RHA
1:1
0%
4%
8%
2.93
2.895
2.861
37.50
38.86
39.53
Lime/RHA
1:2
0%
4%
8%
2.93
2.892
2.853
37.50
39.14
39.36
Lime/RHA
1:3
0%
4%
8%
2.93
2.89
2.85
37.50
39.10
39.65
Lime/RHA
1:4
0%
4%
8%
2.93
2.888
2.847
37.50
39.40
40.63
0%
4%
8%
2.93
2.88
2.838
37.50
39.58
41.50
RHA
Equivalent specific gravity and calculated porosity of
RHA and Lime/RHA stabilised Soil B
Additive
Specific Gravity
Porosity Of Compacted
Specimen (%)
Lime/RHA
1:1
0%
4%
8%
2.86
2.828
2.7966
36.30
37.40
39.20
Lime/RHA
1:2
0%
4%
8%
2.86
2.8246
2.789
36.30
37.69
40.48
Lime/RHA
1:3
0%
4%
8%
2.86
2.822
2.785
36.30
37.63
40.39
Lime/RHA
1:4
0%
4%
8%
2.86
2.82
2.783
36.30
37.59
40.71
0%
4%
8%
2.86
2.817
2.774
36.30
37.52
40.52
RHA
Equivalent specific gravity and calculated porosity of
RHA and Lime/RHA stabilised Soil C
Additive
Specific Gravity
Porosity Of Compacted
Specimen (%)
Lime/RHA
1:1
0%
4%
8%
2.83
2.80
2.769
53.30
55.00
56.30
Lime/RHA
1:2
0%
4%
8%
2.83
2.795
2.761
53.30
54.56
55.45
Lime/RHA
1:3
0%
4%
8%
2.83
2.794
2.758
53.30
55.26
55.76
Lime/RHA
1:4
0%
4%
8%
2.83
53.30
-
-
0%
4%
8%
2.83
2.788
2.747
RHA
53.30
55.52
55.95
Equivalent specific gravity and calculated porosity of
RHA and Cement/RHA stabilised Soil A
Additive
Cement/RHA
1:1
Specific Gravity
0%
4%
8%
2.93
—
Porosity Of Compacted
Specimen (%)
37.50
~
Cement/RHA
1:2
0%
4%
8%
2.93
2.90
2.875
37.50
37.58
38.78
Cement/RHA
1:3
0%
4%
8%
2.93
2.898
2.865
37.50
37.88
39.61
Cement/RHA
1:4
0%
4%
8%
2.93
2.895
2.86
37.50
38.51
39.86
0%
4%
8%
2.93
2.88
2.838
37.50
39.58
41.50
RHA
Equivalent specific gravity and calculated porosity of
RHA and Cement/RHA stabilised Soil B
Additive
Cement/RHA
1:1
Specific Gravity
0%
4%
8%
Porosity Of Compacted
Specimen (%)
2.86
36.30
-
—
—
"
Cement/RHA
1:2
0%
4%
8%
2.86
2.835
2.810
36.30
37.21
39.50
Cement/RHA
1:3
0%
4%
8%
2.86
2.83
2.80
36.30
37.10
40.00
Cement/RHA
1:4
0%
4%
8%
2.86
2.828
2.796
36.30
37.76
40.27
0%
4%
8%
2.86
2.817
2.77
36.30
37.52
40.52
RHA
Equivalent specific gravity and calculated porosity of
RHA and Cement/RHA stabilised Soil C
Additive
Specific Gravity
Porosity Of Compacted
Specimen (%)
Cement/RHA
1:1
0%
4%
8%
2.83
2.815
2.80
53.30
53.80
55.00
Cement/RHA
1:2
0%
4%
8%
2.83
2.80
2.783
53.30
53.93
55.08
Cement/RHA
1:3
0%
4%
8%
2.83
2.80
2.774
53.30
54.28
55.29
Cement/RHA
1:4
0%
4%
8%
2.83
53.30
-
-
0%
4%
8%
2.83
2.788
2.747
RHA
53.30
55.52
55.95
Equivalent specific gravity and calculated porosity of
GBFS and Cement/GBFS stabilised Soil A
Additive
Specific Gravity
Porosity Of Compacted
Specimen (%)
Cement/GBFS
1:1
0%
4%
8%
2.93
2.933
2.935
37.50
37.26
36.96
Cement/GBFS
1:2
0%
4%
8%
2.93
2.931
2.932
37.50
37.20
37.20
Cement/GBFS
1:3
0%
4%
8%
2.93
2.93
2.93
37.50
37.20
36.80
Cement/GBFS
1:4
0%
4%
8%
2.93
2.929
2.928
37.50
37.50
37.10
0%
4%
8%
2.93
2.927
2.924
37.50
37.10
36.70
GBFS
Equivalent specific gravity and calculated porosity of
GBFS and Cement/GBFS stabilised Soil B
Additive
Specific Gravity
Porosity Of Compacted
Specimen (%)
Cement/GBFS
1:1
0%
4%
8%
2.86
2.865
2.871
36.30
35.77
35.91
Cement/GBFS
1:2
0%
4%
8%
2.86
2.864
2.867
36.30
35.70
35.40
Cement/GBFS
1:3
0%
4%
8%
2.86
2.863
2.865
36.30
35.70
35.40
Cement/GBFS
1:4
0%
4%
8%
2.86
2.862
2.864
36.30
35.70
35.40
0%
4%
8%
2.86
2.86
2.86
36.30
35.60
35.30
GBFS
Equivalent specific gravity and calculated porosity of
GBFS and Cement/GBFS stabilised Soil C
Additive
Specific Gravity
Porosity Of Compacted
Specimen (%)
Cement/GBFS
1:1
0%
4%
8%
2.83
2.837
2.844
53.30
52.70
51.80
Cement/GBFS
1:2
0%
4%
8%
2.83
2.835
2.839
53.30
52.70
52.10
Cement/GBFS
1:3
0%
4%
8%
2.83
2.834
2.838
53.30
53.00
52.70
Cement/GBFS
1:4
0%
4%
8%
2.83
53.30
-
-
0%
4%
8%
2.83
2.8312
2.8324
GBFS
53.30
53.30
53.00
Equivalent specific gravity and calculated porosity of
GBFS and Lime/GBFS stabilised Soil A
Additive
Lime/GBFS
1:1
Specific Gravity
0%
4%
8%
2.93
Porosity Of Compacted
Specimen (%)
37.50
-
_
™
—
Lime/GBFS
1:2
0%
4%
8%
2.93
2.92
2.91
37.50
38.00
38.40
Lime/GBFS
1:3
0%
4%
8%
2.93
2.922
2.914
37.50
37.70
38.20
Lime/GBFS
1:4
0%
4%
8%
2.93
2.923
2.916
37.50
37.70
37.20
0%
4%
8%
2.93
2.927
,2.924
37.50
37.10
36.70
GBFS
Equivalent specific gravity and calculated porosity of
GBFS and Lime/GBFS stabilised Soil B
Additive
Specific Gravity
Porosity Of Compacted
Specimen (%)
Lime/GBFS
1:1
0%
4%
8%
2.86
36.30
Lime/GBFS
1:2
0%
4%
8%
2.86
2.853
2.846
36.30
36.20
36.00
Lime/GBFS
1:3
0%
4%
8%
2.86
2.855
2.849
36.30
35.90
35.40
Lime/GBFS
1:4
0%
4%
8%
2.86
2.856
2.852
36.30
35.90
35.40
0%
4%
8%
2.86
2.86
2.86
36.30
35.60
35.30
GBFS
Equivalent specific gravity and calculated porosity of
GBFS and Lime/GBFS stabilised Soil C
Additive
Specific Gravity
Porosity Of Compacted
Specimen (%)
Lime/GBFS
1:1
0%
4%
8%
2.83
2.821
2.812
53.30
53.20
53.40
Lime/GBFS
1:2
0%
4%
8%
2.83
2.824
2.818
53.30
53.20
53.10
Lime/GBFS
1:3
0%
4%
8%
2.83
2.826
2.822
53.30
53.20
52.80
Lime/GBFS
1:4
0%
4%
8%
2.83
53.30
0%
4%
8%
2.83
2.8312
2.8324
53.30
53.30
53.00
GBFS