A study of the influence of coarse aggregate shape characteristics on permanent deformation of asphalt mixes

Abstract

The effect of aggregate shape properties such as angularity, texture, sphericity, roundness, flat and elongation on the performance of asphalt mixes have not been thoroughly investigated using direct measurement techniques. This is partly because aggregates do not have regular shapes, and it is a daunting task to accurately determine these properties. In this paper, three types of aggregates are used to produce asphalt mixes in order to study the effect of coarse aggregate shape properties on the permanent deformation. A modern three-dimensional (3-D) laser scanning device available at the Council for Scientific and Industrial Research (CSIR) in South Africa was used to directly obtained shape properties of the aggregates. Permanent deformation tests were conducted in the laboratory on three different mixes produced from the aggregates to compare performance. It was found that the three asphalt mixes have different resistance to permanent formation. The aggregates with high surface texture and angularity improve resistance to permanent deformation of the asphalt mix when compared with those with more rounded or spherical shapes.