Effect of aggregate shape properties on performance of porous asphalt mixture

Abstract

Aggregate shape properties can greatly influence the overall performance of asphalt mixtures. In this study, shape-controlled aggregates were fabricated and used in porous asphalt mixture (PAM) to assess the effect of aggregate shape properties on the performance of PAM. Three shapes of the aggregates were fabricated, namely cube, cylinder, and sphere. Two parameters, shape factor and sphericity index, were used to define the aggregate shape properties. Results of discrete-element method (DEM) simulation and laboratory measurements were compared to obtain a better understanding on the effect of aggregate shape on the performance of PAM. The results indicated that aggregate shape properties have notable effect on the overall performance of PAM. Spherical aggregates need only a low compaction effort to achieve the design voids-in-total-mix (VTM). For aggregates with the same shape factor, the overall mechanistic properties of PAM generally decrease with increasing sphericity of the aggregates.