LAUSR

Bitumen emulsion sprays have an important part to play in the achievement of durable, efficient road pavement construction. Clearly, spraying of bond coats or tack coats at the interface of the bound layers should improve the likelihood of full bond and of resistance to the entry of water through the layers, both of which are needed to meet the design objectives and for the pavement to continue to function properly. BS 594987 recommends bond coats, which are typically polymer modified bitumen emulsion, as best practice and their use is prevalent for the whole range of paved areas in the UK. Recent work examines the effect of different rates of spread of bitumen emulsion sprays on interlayer adhesion and permeability, and attempts to ascertain whether there are optimum quantities to obtain the desired effects.