Rock and rolling on unsealed roadsHow to make a step change in your

unsealed network – with continuous compaction behind your

grader By Paul Herbison

Table Topic

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What is continuous compaction

Defined as the use of grader attached rollers to grade and compact in one operation

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Some detail to the definition - continuous compaction the important stuff• Compact full width of the grader tyres• Overlap on each tire not hit and miss• PTR effect kneading the surface• Flexible vs ridged axle• Tyre Pressure is important 55 to 65 psi

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Where's it working now• Working from Northern Alaska to Invercargill• Americas, Canada, Alaska, Scotland, China, Fiji, Australia, last but not least NZ• All soil types• All climatic conditions• All geographic areas• From Ancient continental soils to our young soils• 1500 rollers spread over 8 countries around the world

How to make a step change in your unsealed networkWill it work on My network

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How to make a step change in your unsealed networkWhat's in it for me

So what’s in it for my network• Reduce grading cycles, users are saying up to 60%• Reduction in metal application on roads again up to 30%• 4 Track road - cars drive either side • Reduced moisture impact on road, road is sealed up again

immediately after grading• Less reactive maintenance, potholes, rutting, wash-boarding• Less complaints• Happy communities

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So Why - What does continuous compaction do to my unsealed roads

1. Stops the loss of moisture from the pavement post grading by evaporation

2. Stops the ingress of water post grading softening the surface and subgrade

3. Water doesn’t sit on the road

4. Tighter surface less dust

5. Creation of 4 track roads

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A typical Road after grading – an open surface

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Imagine a Hot Dry Day - We know from construction projects we lose between

3 and 6 percent moisture per day if we disk and dry

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Now Imagine a Wet day - I don’t think I need to draw the picture

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A road near Roundup Northern Montana USA

Same Road Same Material

Un Rolled Rolled

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Rolled

Un Rolled

A Section of Road in Southland 13500km further south

Same Results11

LTNZ - Research Report 348

Compaction requirements: Lack of compaction, or water being allowed to enter thepavement, also contributes to soft surfaces

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Keys Points

Over 1500 grader attached rollers world wide,

40+ in NZ all having the same results From Kaipara to Invercargill

Roads across the globe have totally different geological and climatic conditions and are reacting the same way to continuous compaction

What's Different

• soil types and • Aggregates• Climates• traffic loadings• Grading Techniques blades/teeth 3pass/4pass/5 pass etc

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Why

• We are controlling the moisture content in the pavement better

• Hypotheses - what we do in the first few minutes of grading controls the destiny of that road for the next few months and years - Paul Herbison

This is open for challenge – hopefully to ignite some debate

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IN Conclusion:

Continuous compaction

• works in all soil types

• Works in all geographical areas

• Controls Moisture in the pavement, stops it drying out or wetting down

• Delivers large benefits to Client and Road users alike

• Reduces potholes, corrugations, rutting, grading cycles and aggregate use

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Questions:

I have a couple

How many of the audience use continuous compaction

And

Why do you think it works

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What's the Same – The ResultsTrial section VIB roller, 3pointer, PTR, Walknroll and non rolled section6 weeks on

Less Grading

Less gravel loss4 Track Road

Less Dust

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I thought we had challenges in NZ

A road like this in china can service 10s of thousands of People

ChinaAn Unsealed roads

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China

Some Challenges.

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Finally – A cross fall and rolled

Happy Client

Reshaped road

Didn’t get arrested and thrown in jail we found out afterwards we didn’t have permission to grade this road

China

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FIJI – FHH JVSome of the challenges

Many caused by overloading21

FIJI – FHH JV

Working on it

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FIJI – FHH JVThe results

Less frequent grading required

Less potholes

Happier Communities

Less hard cutting

Happier Grader Driver

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