Field experience of cold mix asphalt during 15 years

In the days of concern about high energy consumption and global warming, all sectors of our society are scrutinised for potential savings of energy. One potential area for energy saving in the road construction sector is to make asphalt without heating the aggregates which is the current practice when making hot mix asphalt. Bitumen emulsions have been used to make cold mix asphalt, but uncertainties about the quality of the constructions have limited a wider use. Twenty years ago, an extensive development took place to improve cold mix asphalt to make it more sustainable. In the current paper, the development of an improved technology for the manufacture of cold asphalts using emulsions is described. The technique was used to produce a number of test roads to demonstrate performance. Several of the roads have now been in service for more than 15 years. The roads have been evaluated by sampling and analysis. It is shown that the roads have sustained excellently throughout the years and an evaluation of binders recovered from the roads show remarkably little ageing in spite of high void content of the asphalt.