Roads and Works Conference

Rod Ellis

August 2012

Materials for Unsealed Roads – Developments in testing, additive/blending protocols and its

place in Asset management

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.

0

10

20

30

40

50

60

70

80

90

100

0.01 0.1 1 10 100

Particle Size (mm)

Pe

rce

nt

Fin

er

Sealed Road

Unsealed Road

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

0

10

20

30

40

50

60

70

80

90

100

0.01 0.1 1 10 100

Particle size mm

Per

cen

t F

iner

0.5mm 10mm

Blending at the Pit

Use of testing information

1050

10230

5010

5038

0

50

100

150

200

250

300

350

400

450

500

0 2 4 6 8 10 12 14 16 18 20 22 24 26 28 30 32 34 36 38 40 42 44 46 48

Grading Coefficient

Shr

inka

ge P

rodu

ct

D Slippery

AErodible

CRavels

EGood

BCorrugates and ravels

Sandy clays

Silts

Clayey gravels

Silty gravels

Sandy gravelsSands

1050

10230

5010

5038

0

50

100

150

200

250

300

350

400

450

500

0 2 4 6 8 10 12 14 16 18 20 22 24 26 28 30 32 34 36 38 40 42 44 46 48

Grading Coefficient

Shr

inka

ge P

rodu

ct

D Slippery

AErodible

CRavels

EGood

BCorrugates and ravels

Sandy clays

Silts

Clayey gravels

Silty gravels

Sandy gravelsSands

Mor

e C

laye

y

More Gravel

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

 Rate Resheet percent resheet *percent life

life*percent

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   2250

   Ave Resheet $ 24,400.00

Ave Life 22.5

Asset Life linked to service standards and associated costs

example

Life Extension

Impact across the state

example

km in the State $$/kmValue of States sheeted roads

Average life

Total Annual Resheeting

Cost for State

Saving for State with each extra

year life

average/Council

(assume 45 Councils)

Average Saving

for Council

Percent

saving

47678 24400 1,163,332,586 22.5 51,703,670   1,148,970    

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%

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 28both material and service level

cat3b 30 35both material and service level

cat3c 35 40 Review service levels

AVERAGE 22.5 26.5 4 years increase in life

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

$-

$200,000.00

$400,000.00

$600,000.00

$800,000.00

$1,000,000.00

$1,200,000.00

$1,400,000.00

22.5 23.5 24.5 25.5 26.5

Ave Life

Ann

ual r

eshe

eting

cos

t

av/Council

Saving

Shift from this

To this