Full-service
Everything required to build the pavement from start to finish, self-delivered and handed over complete.
- Pre-milling, spreading, mixing
- Compaction, trimming and rolling
- Seal coat or asphalt
- One contract, one site supervisor
Services / Stabilisation methods
In-situ stabilisation
In-situ stabilisation rehabilitates a road by recycling the existing pavement in place.
What it is
The surface and base are pulverised, a binder is mixed through, and the layer is moisture-conditioned, compacted, trimmed and sealed.
A worn pavement becomes a stronger one, without excavating the old material and carting it away.
It is usually around half the cost of full reconstruction, much faster, and far less disruptive, because it removes most of the truck movements a dig-out needs. For a council with a rehabilitation backlog and a fixed budget, it is the method that treats the most network per dollar.
Accurate has been doing it since 2009, holds the top-tier Transport for NSW Z1 prequalification for full-service in-situ stabilisation, and has stabilised more than 27 million square metres of NSW pavement.
Value & Efficiency
Same ground. Lower costs.
In-situ stabilisation reuses the material already in the ground, so there is no new material to import and no spoil to cart away. Less transport, less handling and a single mobilisation of plant make it a faster, more cost-effective way to rebuild a road.
Traditional approach
More transport. Higher costs. Longer program.
Import material
New gravel carted in from the quarry, load by load.
Export waste
The old pavement dug out and trucked away as spoil.
More plant and labour
Extra trucks, excavators and crew on site for longer.
Increased costs
Haulage, tipping and program time all add to the price.
In-situ stabilisation
Less movement. A smarter solution.
Reuse existing material
Stabilise on site, with nothing imported and nothing carted away.
Lower transport costs
Fewer truck movements, less haulage and less disruption to traffic.
Faster delivery
One pass of the recycler, compacted and back under traffic sooner.
The process
Eight steps, one crew
Every job is different, but the sequence is consistent.
Test pits or cores to establish what's actually there: depth of granular material, subgrade type, moisture. Where a client has a pavement design, we work to it. Where they don't, we'll recommend a binder and depth based on the material and the traffic.
Where the existing seal or asphalt is too thick to mix through, or the level needs to come down, the surface is profiled first. On the New England Highway near Murrurundi, Accurate used a 120-tonne surface miner for this step, the first such use in the industry, and cut a six-week job to two.
Powder binders (lime, cement, ground slag, fly ash, or blends) are spread by a calibrated spreader truck at the specified rate. Typical application is 2–5% by mass, depending on the material and target strength.
A Wirtgen or Bomag stabiliser pulverises the pavement and mixes the binder through to the specified depth, commonly 200mm to 350mm. Water is added through the mixing chamber or a following water cart to bring the layer to optimum moisture content.
Padfoot roller for the initial compaction, then smooth-drum and multi-tyre rollers to density.
Grader to final level and crossfall. On heavily bound pavements, trimming happens within the binder's working time, before it sets.
The surface is rolled tight and cured, usually under a prime or bitumen emulsion seal, while the binder gains strength.
A spray seal or asphalt wearing course completes the job. Asphalt is laid by Accurate's own crew; spray sealing is delivered by Accurate's sealing partner under the same contract, so the client still has one contractor and one point of accountability.
When it's the right method
The right call when
In-situ stabilisation suits a pavement where the existing material is worth keeping but isn't performing: cracking, rutting, potholing, or failing under traffic loads it wasn't built for. It's normally adopted to improve strength and durability and to reduce the moisture sensitivity of poor-quality materials.
- The existing pavement has enough material to recycle, typically 150mm or more of granular base
- The subgrade is sound, or can be made sound with lime treatment
- The failure is structural (the base has lost strength) rather than surface-only (a reseal would fix it)
- Access, haulage or landfill costs make dig-out uneconomic
- Traffic disruption needs to be kept short
Binders
Which one, when
The binder is the decision that determines everything else. Accurate's crews are experienced with the full range and have an understanding of the various binder applications suitable for each individual project.
Hydrated lime / quicklime
- Best for
- Clay subgrades, wet material, reactive soils
- Typical rate
- 2–4%
- Notes
- Slow reaction. Dries and de-plasticises clay. The Mullaway Point job.
Slag/lime blends (70/30, 50/50, 40/60)
- Best for
- Granular base courses on council and state roads
- Typical rate
- 3–5%
- Notes
- The workhorse blend in NSW. Slower set than cement, less shrinkage cracking, high final strength. Most of Accurate's Wollongong work.
GP cement
- Best for
- Granular bases needing fast strength gain
- Typical rate
- 2–4%
- Notes
- Quick set, high early strength. Higher shrinkage risk; managed with construction joints and prompt sealing.
Fly ash blends
- Best for
- Pozzolanic reaction with lime on granular material
- Typical rate
- 3–5%
- Notes
- Cost-effective; slower strength gain.
Dry polymer
- Best for
- Unsealed roads, haul roads, dust control
- Typical rate
- Varies
- Notes
- Water-resistant. See Dry Polymer Binders.
The benefits
The results
- Recycles and reuses the existing pavement material
- Less disruption to traffic: days, not weeks
- Minimal or no site excavation, and none of the cost that goes with it
- New quarried material reduced or not required
- Landfill costs reduced or eliminated
- Little or no haulage: no unsuitable material carted out, no new material carted in
- Dries wet soils so construction can continue
- Shorter completion time
- A stabilised pavement needs less future maintenance than an unmodified one
- Reduced permeability and better serviceability in wet conditions
Experience
What it looks like in practice
Mid CoastIn-Situ StabilisationThe Bucketts Way, Krambach
Upper HunterIn-Situ StabilisationNew England Highway, near Murrurundi
SydneyIn-Situ StabilisationPort Botany, Sydney
Central WestHeavy PatchingNewell Highway, Trewilga
New EnglandIn-Situ StabilisationNorth Star Road
IllawarraIn-Situ StabilisationHarry Graham Drive
HunterIn-Situ StabilisationMarshall Avenue, Metford
Mid North CoastIn-Situ StabilisationMullaway Point
Why Accurate
Twenty-five years of it
Based in Newcastle. For a stabilisation crew, with the plant self-contained and the material already on site, that means the Hunter, Central Coast and Mid North Coast are all a morning's mobilisation away.
Z1 prequalified
Z1 prequalified and AustStab accredited, with ISO 9001, 14001 and 45001.
Owned plant
Owned Wirtgen and Bomag plant and two spreader trucks, maintained in-house.
Our own crews
Crews who've dealt with stiff clay in the Illawarra, reactive subgrade on the Newell, and a live highway at Murrurundi.
How we work with you
Full-service and part-service
Flexible ways to engage Accurate, depending on your project requirements.
Part-service
Plant and crew for the stabilisation step itself, working to your programme with your own resources alongside.
- Stabiliser, spreader truck and water cart
- Operators who know the plant
- Your compaction, trimming and surfacing
- The specialist step, on your dates
Best suited for
Where it earns its place.
- 01Local governmentCouncils / ShiresRehabilitation programmes: two to three times the length of road for the same spend as reconstruction.
- 02Government & state infrastructureTfNSW / State roadsHeavily bound highway work, to UCS above 4 MPa and R75 ride requirements.
- 03Civil & head contractorsInfrastructure / CivilPart-service plant and crew for the stabilisation step, on your programme.
FAQs
Common questions.
01When is in-situ stabilisation not the right method?
It's less suitable where the pavement is too thin to recycle, where there are shallow services that limit mixing depth, or where the material is contaminated. In those cases we'll tell you, and usually propose deep-lift patching or reconstruction instead.
02How deep can you stabilise?
A Wirtgen or Bomag stabiliser pulverises the pavement and mixes the binder through to the specified depth, commonly 200mm to 350mm.
03What do modified, lightly bound and heavily bound mean?
Under Austroads, a stabilised layer below about 1 MPa unconfined compressive strength (UCS) is modified; 1–4 MPa is lightly bound; above 4 MPa is heavily bound and designed as a bound layer.
Enquiries, tender requests or specifications
Enquire about your next in-situ stabilisation project
Call (02) 4942 6100 or send the road and the problem.
Contact Info
- (02) 4942 6100
- quotes@accuratestabilising.com.au
- 66 Kalaroo Rd, Redhead NSW 2290
- Mon–Fri 7:00am – 5:00pm