Concern about protection of the environment and energy savings has led to a growth of interest in the use of cold-mix materials made with bitumen emulsions for use in the construction of road pavements. The report reviews the current state of the art in Europe and the USA to identify promising materials and associated technology, and to evaluate environmental and economic factors. It also describes trials of cold-mix materials provided by the UK industry and presents results of structural performance tests on cores of `grave emulsion' obtained from roads in Ireland. The UK trials showed that cold-mix materials can be mixed in hot-mix plants, paver-laid and roller compacted without difficulty. Although the materials did not yield performance test results equivalent to those of conventional hot-mix used in road construction the growing interest of the industry is expected to result in improvements in the near future. Dense graded Type 1 emulsified asphalt used in the US can develop structural properties equivalent to those of asphalt concrete and has performed well in parts of the USA, but it would not appear to be suitable for climatic conditions in the UK. `Grave emulsion', however, has proved successful in Ireland for the structural layers of major routes and tests on cores show that it develops structural properties similar to those expected of conventional hot-mix. It also requires less energy to manufacture than hot-mix materials. (A)
Samenvatting