A series of Recycled Road seminars is presenting a solid case to local authorities and their contractors about the benefits of recycled and secondary aggregates. With workshops running until March, the Waste and Resources Action Programme (WRAP) has teamed up with the Transport Research Laboratory (TRL) and the Building Research Establishment (BRE),with the aim of giving practical information and advice on their use.
Suitable for use in a wide range of applications in highway maintenance and new construction - from cycle paths and haunching on minor rural roads through to major reconstruction of principal roads in urban areas - recycled and secondary aggregates can bring a number of benefits. Stimulating uptake, however, means addressing some major misconceptions, including the belief that specifications constitute a major obstacle to using recycled materials.
According to David O'Farrell, technical director of Capita Symonds, however, this is increasingly not the case. The most commonly used specification, the Highways Agency's Specification for Highway Works, is updated regularly and has seen considerable changes which expand the potential for using recycled materials and set clear guidelines for in-situ recycling.
Introduced last year, the new European Standards (BS-ENs) for aggregates apply equally to primary, recycled and secondary aggregates and WRAP's recently issued Quality Protocol for the production of recycled and are also helping to ensure that these materials are, and are seen to be, fit for purpose.
In a series of studies presented by Dr Murray Reid of TRS, the perception that recycled and secondary aggregates will deliver inferior handling or performance characteristics is shown not to be the case.
In the M25 Junction 12 to 15 widening project, for example, using recycled aggregates helped contractor Balfour Beatty Civil Engineering to meet a tight deadline which required earthworks to continue throughout the winter. Locally available fill materials were moisture susceptible, but the coarse grained, free-draining recycled aggregates worked well in the wetter conditions. They were also cheaper than the equivalent free-draining primary aggregates.
Staffordshire Highways, a partnership of design and construction contractors working for Staffordshire County Council, will be delivering direct cost savings of about 40% in two projects due for 2005 by using GFA, a hydraulically bound material consisting of coarse aggregate, often asphalt planings, bound with about 12% pulverised-fuel ash (PFA) and 3% lime or cement.
From a policy perspective, local authorities are also under pressure to build sustainability into their procurement practices and in terms of specifying recycled content procurement for highways maintenance and construction the business case has never been more compelling. As well as clear financial benefits, there can be the positive contribution towards best value, recycling and wider sustainable development targets.
According to Steve Biczysko, technical services manager of Atkins Highways & Transportation, many of the technical issues surrounding greater recycling and reuse in highways work have been resolved over the last decade.
Where the effort does have to be put in is in the procurement process and the logistical planning. Moving forward from guidance published by WRAP in July 2004, The Big Picture: specifying recycled in local authority contracts for highways maintenance: Good Practice, senior consultant Katherine Adams and Gilli Hobbs, director of BRE's