Roads and Works Conference
Materials for Unsealed Roads –
Developments in testing, additive/blending
protocols and its place in Asset management
Rod Ellis
August 2012
Introduction
• Local Government Research and Development Scheme 2009 2012
• Trialing new techniques for improving the composition of material
used for unsealed roads
Outcomes
• Results of the 3 trial sites monitored over 3 years
• Protocol in the assessment process and decision making for
material selection
• Monitoring forms and process
• Whole of life considerations
Purpose
• To better understand what makes a good material for unsealed
roads (before it is used)
• To acknowledge the large volumes of material used in unsealed
road construction and to attempt to become smarter by introducing
some science to compliment practical experience
• Acknowledge some Councils Works Managers will not have years
of local experience so setting up a framework and knowledge base
to assist good decisions in material selection and treatment is
critical for future success
Trial Process
• Pit Material testing against ARRB specifications
• Assess options to improved material properties
– Blending
– Additives
– Adapting works practices
• Examine Whole of Life benefits of various treatments
• Setup and monitor trial sites
• Recording findings and reporting
Adelaide Hills Councils
• Dolomite and Monarto
Material
• Polycom in sections
• Monarto, slightly finer
grading ,less loose
material and wear
Goyder
• Drews Pit – 5 sections
• Polycom, Lime, Import material, bag lime in
sections, untreated
• Imported material to PM specification higher loose material and windrow
development
• Lime not effective for low PI material
• Polycom seemed to work with the fines to
reduce windrow development and loose
material.
Loxton Waikerie
• Lowbank Road
• Dustcheck use to reduce dust
• No observable dust reduction
• Less rutting, windrow generation and loose
material where additive used
Pit Material
• Key Learning 1
Local Government need to recognise the difference between
commercial products for base course, sub base course and material
from pits for sealed roads to those attributes which contribute to a
good wearing
surface for unsealed roads.
100
90
Percent Finer
80
Unsealed Road
70
60
50
40
30
Sealed Road
20
10
0
0.01
0.1
1
Particle Size (mm)
10
100
Key Learnings
Where we want to get to
Key Learning
•
Key Learning 2
•
•
•
Improve raw material before using additives
Clear specification for grading and plasticity
Pit operators need to blend stone, gravel and fines in
proportion to develop acceptable material
The Thirds Rule
100
90
80
Percent Finer
70
60
50
40
30
20
10
0
0.01
0.1
1
10
Particle size mm
0.5mm
10mm
100
Blending at the Pit
Use of testing information
10
50
10
230
500
450
Sandy clays
Clayey gravels
D
50
10
Slippery
400
50
38
Shrinkage Product
More Clayey
350
300
250
E
A
C
Good
Erodible
Ravels
200
Silts
150
Silty gravels
100
Sands
50
Sandy gravels
B
Corrugates and ravels
0
0
2
4
6
8
10
12
14
16
18
20
22
24
26
28
30
32
34
36
38
40
Grading Coefficient
More Gravel
42
44
46
48
Key Learning
Key Learning 3
•
•
•
Properties in the pit will be different on the road.
Select the right equipment to suit the material
Test post compaction from the road to determine
compliance to grading and Plasticity
When to Grid Roll/Rock bust
When to crush and raw feed composition
Blending on the Road Bed
Additives
» Key Learning 4
» For Drews Pit material at Goyder in hindsight the
use of lime was inappropriate, however lime/fly ash
may be an alternative in future trials.
» Key Learning 5
» Polycom needs fines in the material to work.
Further monitoring is recommended for each
Council to determine if there is longer term benefits.
After 2 years of monitoring there are positive
indicators.
Monitoring
• The monitoring methodology used was deliberately made simple to
allow Councils field staff. In all cases the field record sheets were
designed to allow for a systematic and consistent approach to record
keeping
• The visual assessment observed Dust, Corrugation, Potholes and
Loose Material on a course rating of LOW, MEDIUM and HIGH.
• The site measurement assessment consisted of:
– depth of rutting depth (mm)
– window height (depth) mm
– loose material (kg/0.5m2)
– Corrugations (depth mm, spacing (m))
Monitoring
Monitoring
Key Learning 6
Dust assessment discernment is very difficult visually. The extent of
humidity at time of assessment i.e. overcast, clear or recent rain needs
to be recorded.
Key Learning 7
While visual assessment of loose material may not be discernible, the
measurement of windrow height and loose material are more
indicative.
Key Learning 8
Trial sites should be left without maintenance grading interventions if
possible to develop a longer term trend of deterioration. Several
Councils undertook grading operation during the trial period.
Typical results
WHOLE OF LIFE
WHOLE OF LIFE
Protocol for Unsealed Road Performance
Protocol for Unsealed Road Performance
Application to the wider local government
Promotion
Roads Conference and SALGSOA groups
Get other Councils involved
Kingston and Kangaroo Island are planning trials
Support
Tonkin/ARRB through Rod Ellis and Bob Andrews
Tools
– Grading Assessment Tools
– Material performance Charts
– WOL Spreadsheets
– Field Trial monitoring forms
– Reporting Framework
Upskilling
Relating to Asset Management
47700 km of sheeted roads over 45 rural Councils
$1.1 Billion Dollar asset in sheeted roads across the state
$51 Million dollar annual re-sheeting across the state
$1.1 Million dollar average re-sheeting /rural Council
Road Hierarchies
Asset Life linked to service standards and associated
costs
example
Rate
Resheet
percent
resheet *percent
life
life*per
cent
cat1
35000
25
875000
12
300
cat2
28000
20
560000
15
300
cat3a
22000
15
330000
25
375
cat3b
18000
25
450000
30
750
cat3c
15000
15
225000
35
525
100
2440000
Ave
Resheet
$ 24,400.00
2250
Ave
Life
22.5
Life Extension
Impact across the state
example
Saving for
State with
each extra
year life
average/Cou
ncil (assume
45 Councils)
Average
Saving
for
Council
Percen
t
saving
km in the State
$$/km
Value of States
sheeted roads
Avera
ge life
Total Annual
Resheeting
Cost for State
47678
24400
1,163,332,586
22.5
51,703,670
47678
24400
1,163,332,586
23.5
49,503,514
2,200,156
1,100,078
48,892
4%
47678
24400
1,163,332,586
24.5
47,482,963
4,220,708
1,055,177
93,794
9%
47678
24400
1,163,332,586
25.5
45,620,886
6,082,785
1,013,797
135,173
13%
47678
24400
1,163,332,586
26.5
43,899,343
7,804,328
975,541
173,430
18%
1,148,970
Life extension
Hypothetically how can 4 year increase life be achieved
example based on percentages in previous slide
life
life
comment
cat1
12
15
Improve Material Properties
cat2
15
19
Improve Material Properties
cat3a
25
28
both material and service level
cat3b
30
35
both material and service level
cat3c
35
40
Review service levels
22.5
26.5
4 years increase in life
AVERAGE
Benefit to Asset Management
An Average 4 year life increase across network can result in
$175,000/annum/Council less re sheeting (18% saving)
Average for 45 Councils/annum
$1,400,000.00
Annual resheeting cost
$1,200,000.00
$1,000,000.00
$800,000.00
av/Council
$600,000.00
Saving
$400,000.00
$200,000.00
$22.5
23.5
24.5
Ave Life
25.5
26.5
Shift from this
To this