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Road runners

With public sector cuts already being delivered on an unprecedented scale, we are entering an era where there is a clear expectation on all contractors to do more with less. Delivering savings through better project planning, site efficiency and management of materials will increasingly be a prerequisite of all contracts.

Better management of materials offers real scope to deliver cost, efficiency and environmental savings. But the industry has not fully capitalised on its ability to recycle and reuse aggregate from roads into new resurfacing schemes. This is an opportunity that needs to be fully exploited across national and local road networks in both sub-base and currently base and binder courses.

Getting this right will mean making intelligent decisions based on cross-network and cross-boundary availability of recycled asphalt pavement (RAP). The benefits of processing RAP material stack up, and significant cost savings can be made by using a higher content RAP. At the moment, there is usually around 20% RAP content on local roads, but there is scope in highway specifications to increase this content to 50%. Taking this approach not only saves money but it also helps to conserve virgin aggregates.

Of course, it is important to understand that thereare occasions when using recycled material is not the most sustainable solution. Clearly, hauling recycled materials over long distances is not appropriate because of the carbon and cost implications.

Reusing material on a wider scale will need greater collaboration between highways organisations, contractors and policymakers to ensure that recycled road planings from across the national network are reused and deployed on local roads. Equally, it will mean that local authorities will need to forge strategic partnerships with their neighbouring authorities to reuse recycled material across borders.

To make this transition happen, an investment is needed so that RAP can be processed in greater volumes at more sites. Ideally, it should also lead to the sharing of plant and storage facilities between councils and agencies.

Finally, we must ensure that highways engineers have greater awareness of the availability and application of recycled materials and laying techniques, so that we tackle a misconception from some quarters that recycled materials are low grade and poor quality.

We need to help break down barriers across national and local networks, and look at how materials can be recycled and reused to drive efficiency and cut costs. In an era where we have a real obligation to use natural and financial resources wisely, the ‘reduce, re-use and recycle’ mantra has never been so important.

Nick Shires is Tarmac’s national contracting director for the south east

Hot on recycling

At its high-volume asphalt facility in Hayes, Middlesex, Tarmac has successfully integrated a state-of-the-art hot recycling drum plant into its operations. The Benninghoven recycled asphalt pavement (RAP) pre-dryer is currently capable of using up to 50% of such material, and processes road planings removed from nearby areas for use onlocal roads.

Processed RAP is introduced at a constant speed to the Benninghoven system, and is dried and heated at around 120°C in a uniflow large-volume drying drum equipped with a specially developed burner. After heating, the processed asphalt is stored in an insulated buffer silo. From here it is batch weighed and introduced to a paddle mixer as required, with varying percentages depending on the mix, where it is homogenously mixed with virgin aggregates.

The hot drum recycling machinery recently processed RAP material for use on a major resurfacing project on the M25. The project, which was a partnership between Tarmac and Mouchel on behalf of the Highways Agency, achieved the highest ever reuse of RAP in a surface course material on the national highway network.

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