Paving the way for wider use of recycled materials
NEW research, funded by WRAP (the Waste & Resources Action Programme) and supported by Tarmac, is being carried out to test the performance of hydraulically bound materials (HBMs) using recycled aggregates, for use in road construction.
The research was outlined at the fifth international conference on the use of waste and secondary materials in pavement engineering, which took place last month at Liverpool John Moore’s University.
Designed to test the performance of HBMs in situ, the research is being managed as a collaborative effort by Tarmac, Scott Wilson Pavement Engineering and TRL, and will involve comprehensive field and laboratory trials. The work is scheduled to be completed by March 2007.
Speaking at the event, John Barritt, aggregates technical advisor at WRAP, said: ‘Since the Highways Agency included hydraulically bound mixtures in its specification for highway works for the first time in 2004, the highways industry has been busy developing recipes for sub-bases and bases using recycled materials bound together using hydraulic binders, including industrial by-products such as slag or pfa.
‘However, to date, the industry has had only limited ability to predict and measure performance data on applications for HBM and this is holding back take-up of this potentially highly sustainable construction material.
‘The research we are now funding will address this, allowing client organizations and their designers to specify HBM more confidently across a wider range of applications. This research will help industry by encouraging the use of recycled and secondary aggregates and helping to conserve finite primary materials.’
As part of the field trials, HBM will be used to provide a rigid sub-base and base layer for a heavily-trafficked quarry road at a Tarmac site in Essex. Dr Howard Robinson, Tarmac’s head of product development, explained: ‘By testing the performance of HBM in situ under heavy slow-moving traffic, we should be able to produce reliable independent performance data to enhance confidence and to help develop specifications for these materials.
‘Of particular interest, we expect to be able to show that recycled and marginal-quality materials can be used in the production of HBM. In doing so, this could help to elevate the use of recycled and secondary aggregates into higher-specification materials.’
