Recycling of Bituminous Materials The recycling and reuse of bituminous materials is not a recent development, the first asphalt pavement recycling project being recorded in 1915 (Epps et al., 1980). Recycled (or reclaimed) asphalt pavement (RAP) material consists of aggregate and bitumen that has been removed and/or reprocessed from an Read more…
Bituminous Mixtures There are a very large number of bituminous mixtures, which vary according to density, bitumen content, bitumen grade, aggregate size and aggregate grading. Previously in the UK these mixtures used to be classified into two groups, namely ‘asphalts’ and ‘macadams’. The move to European standardisation has meant that Read more…
Durability of Bituminous Structures Durability is the ability to survive and continue to give an acceptable performance. In the case of roads, it is necessary that the structure should survive for the specified design life, although it is accepted that not all aspects of performance can be sustained for this Read more…
Strength and Failure of Bituminous Materials The Road Structure A flexible road structure consists of a number of layers of different materials. In structural terms, the purpose of the road is to distribute the applied load from the traffic to a level that the underlying subgrade can bear. The stresses Read more…
Deformation of Bituminous Materials Resistance of Bitumen to Deformation Since bitumen is a viscoelastic material, the response to an applied load depends on the size of the load, the temperature, and the duration of its application. In other words there is no simple relationship between stress and strain and it Read more…
Viscosity of Bituminous Materials Viscosity and Rheology of Binders The viscosity of a liquid is the property that retards flow, so when a force is applied to a liquid, the higher the viscosity, the slower will be its movement. The viscosity of bitumen is dependent upon both its chemical make-up Read more…
Aggregates for Bituminous Materials Aggregates make up the bulk of bituminous materials; the percentage by weight ranges from about 92% for a surface course asphalt to about 96% for a dense, heavy-duty and high-modulus base asphalt concrete. The aggregate has important effects on the strength and stiffness of bituminous mixtures. Read more…
Types of Bitumen Penetration Grade Bitumens Refinery bitumens are produced with a range of viscosities and are known as penetration grade bitumens. The term derives from the test that is used to characterise them according to hardness. The range of penetration grades for road bitumens is from 15 to 450, Read more…
Constituents of Bituminous Materials Bituminous materials consist of a graded aggregate bound together with bitumen. In addition, the mixture contains a small proportion of air. Thus bituminous materials are three-phase materials and their properties depend upon the properties of the individual phases as well as the mixture proportions. The two Read more…