Effect of aggregate shape on the surface properties of flexible pavement

Abstract

One of the most important properties of flexible pavements in terms of tire-pavement interface is surface texture. The texture of a pavement surface and its ability to resist polishing effect of traffic is of prime importance in providing skidding resistance. Pavement surface texture greatly contributes to tire-pavement skid resistance which has a direct effect on traffic operation and safety particularly at high speeds. Doubtless, there exists a close relationship between pavement surface texture and aggregate angularity within the wearing course. This paper is aimed to determine the effect of aggregate shape on the surface properties of Hot Mix Asphalt (HMA). Two different mineralogical types of aggregate (basalt and limestone) have been crushed with impact, jaw and roll type of crushers. Various types of aggregate with different shapes have been mixed with 50/70 penetration grade bitumen to form dense graded mixtures. Test methods related with the evaluation of shape and texture characteristics have been utilized to characterize the geometrical properties of aggregates. The texture and friction properties of asphalt slabs have been evaluated by means of sand patch test, 3D laser scanner and dynamic friction tester respectively.