ABSTRACT
The process of manufacture of bituminous materials involves three stages. Firstly, the aggregates must be proportioned to give the required grading; secondly, the aggregates must be dried and heated; and thirdly, the correct amount of binder must be added to the aggregate and mixed to thoroughly coat the aggregate particles and produce a homogeneous material. There are a very large number of bituminous mixtures that vary according to density, bitumen content, bitumen grade, aggregate size and aggregate grading. Under BS EN 13108, bituminous mixtures are classified according to the grading of the aggregate, their upper sieve size (maximum nominal aggregate size), the intended use of the material and the binder used in the mixture. Asphalt concretes are characterised by relatively low binder content and a continuously graded aggregate. They rely on the packing and interlock of the aggregate particles for their strength and stiffness.
