Recycling of existing pavement materials, and the re-use of alternative aggregates, has become an increasingly important factor in the UK for maintenance of highways. The 'linear quarry' concept of using the existing highway as a source of road-stone aggregates has gained considerable favour in recent years following the introduction of the first nationally consistent guidelines in 1999. Since that time, sustainability and environmental issues have continued to receive more attention which has resulted in the demand to consider recycling in the maintenance of a larger proportion of the primary and secondary road network. In situ and ex situ variants of cold recycling techniques are now feasible and many large and specialist contracting organisations can offer these services, with the benefit of reduced consumption of energy, fuel and materials. The report, based upon a three year programme of work, provides an end-performance based design guide and specification for cold recycled materials, no matter how they are produced, and covers a wide range of cold-mix recycled materials involving a range of binders and binder blends. Materials are classified into families, which enables materials produced with new binders or combinations of binders to be introduced with relative ease. Advice is given for a wide range of traffic conditions ranging from the lightly traffic roads to heavily trafficked trunk roads. The pavement designs utilise 1-year material properties, thus enabling slow curing materials to be used in an equivalent manner to traditional materials. The specifications and advice should facilitate more prudent use of natural resources and assist in the protection of the environment in line with Government Policy.
Abstract