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Accurate Asphalt & Road Repairs Nominated for Award

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Accurate Asphalt & Road Repairs is nominated for the AUSTAB Awards for Excellence in Category 3 – Innovation or Excellence in Sustainability, June 2015.

This nomination was a result of the innovative method and technology used in March 2015 on the RMS contract for the New England Highway near Murrurundi in New South Wales.

The contract consisted of:

  • Full service in-situ stabilisation of existing pavement material including pre-milling, spreading and incorporating additive as nominated at the respective sites, compaction and trimming to provide a heavily bound pavement of UCS > 4MPa, meeting the ride requirements of RMS R75.
  • Final trimming including saw cutting centre lines and edge lines at 120mm depth 48hours after trimming, with pavement to be returned to existing levels and cross fall.
  • Removal of excess spoil associated with trimming.
  • Sealing of stabilised pavement in accordance with RMS R106.
  • Line marking in accordance with RMS R141 and R142.

The total area of work required to be stabilised is:

  • Site 1 New England HWY at Liverpool Range 11,500m2
  • Site 2 New England HWY at Kankool 29,300m2

Operating Environment

Stage #1 of the project involved the in-situ stabilisation of 11,500m2 @ 380mm with 3% 60/40 Slag/Lime on the southbound lane of New England Highway at Liverpool Range.

The Client provided preliminary core testing results at tender that indicated the presence of some bound pavement layers in limited sections of the work area. To mitigate these bound layers and to improve overall in-situ mixing AARR included the use of a 2M Metrecut Profiler to pre-mill the top layer of the entire work area.

Following the normal process for pre-milling AARR crews began to mill the top section of the pavement, with the intention of then running the stabilisers to the full-depth. However the stabilisers were unable to cut through the bottom layer due to the pavement’s excessive hardness. As a result the operating strategy had to be amended to include pre-milling and side-casting of the top layer, pre-milling of the bottom layer, replacement of side-cast material and then stabilising to full-depth. The excessive hardness of the pavement to full depth was found throughout the work area in contradiction to the qualitative assessment of the core testing provided.

The excessive pavement hardness experienced throughout the work area resulted in unexpected time delays, increased difficultly with heavy traffic flows through the work area as a result of the side-cast material and significant damage to profiling and stabilising plant teeth and blocks.

Challenge & Innovation

Prior to commencing Stage #2 of the project a de-briefing meeting was held to assess the impact the excessive pavement hardness had had on our operational strategy. It was clear that this unexpected factor had caused significant challenges during Stage #1.

It was identified that pavement hardness was now a significant factor for Stage #2. The additive rate was also to be increased to 5% 60/40 Slag/Lime further highlighting the need for efficiencies.

How could an excessively hard pavement through to full-depth be pre-milled to ensure efficient in-situ mixing?

Conventional Approach

The conventional approach to this challenge involves pre-milling and side-casting of the top layer, pre-milling of the bottom layer, replacement of side-cast material and then stabilising to full-depth. The disadvantages of this approach are that it is costly, time consuming to contractor, client and public, would create traffic control issues on this site and expose more material than necessary to the open environment.

Innovative Approach

After considering the drawbacks of the conventional approach the operations team carefully researched what other plant options might be available to pre-mill the pavement to fulldepth in one pass. It was discovered that there are surface mining machines used primarily in mining operations that have significantly higher power and cutting depth than a conventional road profiler.

After consulting with a number of industry experts AARR procured a 1,000HP Wirtgen Surface Miner that could profile to a depth of 600mm in one pass to a width of 2.5m.

This was the first time a Surface Miner had been used on the RMS road network in NSW.

Results

The innovative approach adopted by AARR in utilising the Surface Miner to pre-mill Stage #2 to full-depth generated a number of important benefits for the industry.

Economic – mitigation of excessive pavement hardness to full-depth, reduction in project time, improved in-situ mixing to full-depth, reduction in delay costs to commercial transport enterprises.

Social – reduced road closure time for the public, industry and the RMS on a major arterial road of the State.

Environmental - mitigation of traffic control restrictions, increased work area on-site due to not having to side-cast thus greatly improving site safety, reduction in material exposure to the open environment (i.e. dust, sediment etc)

Our Location

Accurate Asphalt & Road Repairs

66 Kalaroo Rd Redhead
NSW 2290, Australia

Phone: +(61) 02 4942- 6100

Fax: +(61) 02 4942- 6111

Email: office@accurateasphalt.com.au

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