Natural Sand Replacement in Concrete
Presented by:
Martins Pilegis & Andi Lusty
21st September CMIC 2012, Melbourne, Australia
The V7 Technology
Unique Crushing System
There is an autogenous crushing within the
particle cloud and on the rock bed for
both, the Barmac and V7 Crushers.
The V7 Crusher is constructed so there are
multiple impacts in the new dense material
zone.
As the material drops down from the stone
wall into an increasingly dense zone, it is
re-crushed by particle interaction as well
as hammers, being both shaped and
scrubbed.
Unique Shaping to 75μm
Shape of particles <1mm vital
•
•
•
Workability
Pumpability
Density
Cone Crusher
Barmac VSI
V7 Crusher
A Unique Separation System
•
Dust
collector
Air screen gives partial return, top-size
cut and classification.
Raw material flows from VSI → diffusion
feeder → air screen separation using the
blower.
(5) is fully returned, and (4) is partially
returned by the damper.
Top size (1) - (3) and part of (4) screened
for oversize return.
•
VSI
Wind
power
•
View showing
dispersion system
•
Diffusion feeder
Blower
100
10
90
100
80 90
10
70 80
Passing rate (%)
Passing rate (%)
Grain
size
damper
60
70
60
50 50
40
40
30
30 20
Cut screen
Product
20
Over size
(Return to VSI)
10
0
10
0
0.15
0.15
0.3
0.3
0.6
1.2
0.6
1.2
Sieve mesh (mm)
Inner structure of air screen
2.5
Sieve mesh (mm)
2.5
5
5
Unique Flexibility in Gradation
A poorly graded crusher dust becomes
even poorer after the removal of filler by
washing or dedusting.
Kayasand is evenly graded and
gradations can be changed to make
the ideal sand as a single fine aggregate
component for concrete or asphalt.
Summary of Differences
 The V7 has a more efficient crusher than other autogenous VSI’s
 The V7 has an airscreen with the ability to recirculate a variable size
of product
 The V7 can vary the gradation of the sand
 The V7 can control the minus 75 micron content of the sand
 The V7 produces a shaped particle size to 75 micron particles
 The V7 operates dry as well as quietly and dust free
Can V7 Kayasand can COMPLETELY replace natural sand in concrete?
Cardiff University Research
Key Objectives
• Primary aim to show that a manufactured sand can be
made to replace natural sand and sand blends
• Secondary aim to refine gradations to reduce cement
usage and to find new uses for rock filler in agriculture
Environmental Benefit
• If replacement is proven viable then dredging for sand
can be reduced or eliminated, and viable concrete
sands can be made in most quarries.
Manufactured sands
Manufactured sands from crusher dusts
with at least 4 gradings for each quarry
Basalt (B) – Duntilland Quarry, Holcim
Granite (G) – Glensanda Quarry, Holcim
Sandstone (S) – Gilfach Quarry, CEMEX
Limestone (L) – Taff’s Well Quarry, CEMEX
100
100
B-A
B-B
B-C
B-D
80
60
40
60
40
60
40
1
Basalt
10
S-Dust
40
L-Dust
20
0
0.01
0.1 Sieve size, mm 1
60
40
20
0
0.01
0.1
1
Granite
10
10
L-A
L-B
L-C
L-D
80
20
0
0.1
G-Dust
60
S-A
S-B
S-C
S-D
80
20
0
B-Dust
80
100
100
G-A
G-B
G-C
G-D
G-E
80
20
0.01
Percent passing, %
•
•
•
•
100
0.01
0.1
1
Sandstone
Materials:
CEM I 52.5 N, Crushed limestone 4/20 mm, Sea dredged
natural sand control (N), Mid range plasticizer WRDA 90,
manufactured sands
10
0
0.01
0.1
1
Limestone
10
Characterisation tests
New Zealand Flow Cone (NZS
3111-1986)
Observations from mixing
(finishability, ease of placement)
Particle size distribution (BS
EN 933-1)
Plastic Density
Slump
Water absorption (BS
EN 1097-6)
Fine Aggregate
Methylene Blue Value
(BS EN 933-9)
Fresh
Concrete
Air Entrainment
Hardened
Concrete
Flexural strength
–28 days
GMBV (Grace
Rapid Clay test)
Sand Equivalent
(BS EN 933-8 )
Compressive strength
–1 day
–7 days
–28 days
Manufactured sand test results
38.0
Granite Sand
B-Dust
36.0
Basalt sand
• New Zealand flow cone –
simple indirect test indicating
shape, grading and surface texture
34.0
32.0
FLOW TIME, s
30.0
• All manufactured sands fit
within the standard envelope
Sandstone sand
L-A
26.0
L-D
24.0
L-B
L-C
G-A
B-A
G-B
G-E
G-D
G-C
B-B
22.0
B-C
S-A
NS
B-D
S-B
S-D
18.0
36%
S-C
41%
VOIDS, %
46%
6
Methylene Blue
Value
5
4
3
2
1
S-FEED
S-A
S-B
S-C
S-D
L-FEED
L-A
L-B
L-C
L-D
B-FEED
B-A
B-B
B-C
B-D
0
N
G-FEED
G-A
G-B
G-C
G-D
G-E
Methylene Blue Value, g/g of sand
• MBV reduced in all
manufactured sands if
compared to feed material
0/4 mm fraction
S-Dust
G-Dust
28.0
20.0
• Methylene blue test –
indication of potential presence of clays,
Grace’s rapid clay test directly correlated
with these results
L-Dust
NZS 3121 specification
envelope
Limestone sand
Concrete, Stage 1
 Stage 1: without plasticizer, aiming for S2 slump, fixed w/c ratio for particular quarry sands
which provides S2 slump.
Cement
FA
CA
Water
350
753
1040
varies
Compressive, flexural strength and slump
70
140
Granite w/c 0.58
Basalt w/c 0.67
Limestone w/c 0.55
Sandstone w/c 0.67
60
120
50
100
40
80
30
1 day compressive
strength
Slump, mm
Compressive, flexural strength, N/mm2
Natural sand
w/c 0.48
7 day compressive
strength
28 day compressive
strength
60
28 day flexural
strength
20
40
Slump, mm
10
20
0
0
N
slump
G-A
G-B
G-C
G-D
G-E
B-A
B-B
B-C
B-D
Concrete mixes
L-A
L-B
L-C
L-D
S-A
S-B
S-C
S-D
Concrete, Stage 2
 Stage 2: Varying plasticizer dosage to achieve S2 slump, fixed w/c ratio at 0.55 for
all sands.
Cement
FA
CA
Water
Plasticizer
350
753
1040
193
varies
Compressive, flexural strength and slump for w/c 0.55
70
60
Natural
sand
Limestone
w/c 0.55
Basalt
Granite
100
Limestone
w/c 0.50
Sandstone
90
1 day compressive
strength
50
70
7 day compressive
strength
60
40
50
30
40
Slump, mm
Compressive, flexural strength N/mm2
80
28 day compressive
strength
28 day flexural
strength
30
20
20
10
10
0
0
N
G-A
G-B
G-C
G-D
G-E
B-A
B-B
B-C
B-D
L-A
L-B
L-C
L-D
L-A
0.5
L-B
0.5
L-C
0.5
L-D
0.5
S-A
S-B
S-C
S-D
Slump, mm
Primary Objective
• to show that a manufactured sand can be made to replace
natural sand and sand blends in concrete
V7 sand can COMPLETELY replace natural sands in concrete!
The Economics
V7-60 Economics (60 tph throughput)
Operating Costs
Capital Costs
•
•
•
Power = 6.7kwhr per tonne
throughput
@ 15c/kwhr = Aus $1.00
Wear parts and maint = $1.85 to
$2.80 depending on material
Typical Opex ~ $3.20 /t throughput
•
•
Typical ~ Aus $3m turnkey
installation
60tph capacity = 200ktpa+
10 yr amortisation
Typical capital rec ~ $1.50 /t throughput
V7-60 Economics (60 tph throughput)
Sand Yields
Filler (dry premium product)
•
•
•
•
Range = 75% to 85%
Typical = 80%
Depends on feed
- Crushing properties
- Filler content
Premium all in fine aggregate ~ $5.80/t
(Assuming filler has no value and full capital recovery)
15% to 30%
- Granulate – drainage = $15/t
- Road base = $20/t
- Asphalt/block plants = $20/t
- Agriculture = $20/t
Significant upside likely from filler
The economics compared
Kayasand V7-60
Dredged Sand
Washed Pit Sand
Operating Cost per
tonne sand produced
$3.00-$3.801
$7.00 to $12.003
$8.00 to $12.005
Capital Cost per tonne
per annum capacity
$301
$45 to $752
$30 to $454
Nil
High
High
High
Med
Med
Environmental Impact
Availability
1 Costs will vary depending on location and feed, these costs are typical of installations Kayasand has
completed detailed evaluations for.
2 Allowance for resource consent, dredger, wharf facilities.
3 Will vary depending on the distance off shore for dredging.
4 Allowance for resource consents and capital investment – wash-plant , filter press etc.
5 Wash plant operating costs vary depending on water, waste costs, efficiency etc.
The Environment
The Japanese Experience
•Japan banned unnecessary dredging in 1991
• Kayasand now accounts for 45% of all of their manufactured sand
•While the introduction of Kayasand has been successfully
implemented and the environment as well as the construction
industry has benefited, regulatory change was necessary
Driving Change for Environmental Gain
There is often resistance to change in any industry due to:
•
•
Vested interests (from existing sand, gravel and dredging companies)
•
•
Relatively slow adopters of proven but novel technology
Economic pressures and lack of priority (bigger problems so park this)
The environmental cost is not borne by them
Acknowledgements
Kayasand would like to acknowledge the financial and in kind support of:
The Aggregate Levy Fund for Wales
Kotobuki Engineering & Manufacturing Company (Kemco)
CEMEX
Aggregate Industries (Holcim)
Grace Construction Products
and Cardiff University’s Engineering Department for their input and supervision, in
particular Diane Gardner and Professor Bob Lark