Experimental Testing and Finite-Element Modeling to Evaluate the Effects of Aggregate Angularity on Bituminous Mixture Performance

This study evaluates the effects of aggregate angularity in bituminous mixtures. Previous studies have predominantly focused on the effects of aggregate angularity on the resistance to permanent deformation, while little work has investigated the role of aggregate angularity related to mixture volumetrics and fatigue fracture performance. To investigate the effect of aggregate angularity on mixture performance and characteristics, five mixes with different combinations of coarse and fine aggregate angularity are evaluated by performing the uniaxial static creep test and the indirect tensile fracture energy test. The asphalt pavement analyzer test is also performed with five-year field project mixtures. Fracture energy test results are then incorporated with finite-element simulations of virtual specimens produced to explore the detailed mechanisms of cracking related to the aggregate angularity. Rutting performance test results indicate that higher angularity in the mixture improves rut resistance due to better aggregate interlocking. The overall effect of angularity on the mixtures' resistance to fracture damage is positive because aggregate blends with higher angularity require more binder to meet mix design criteria, which mitigates cracking due to increased viscoelastic energy dissipation from the binder, while angular particles produce a higher stress concentration that results in potential cracks. Finite-element simulations of mixture microstructure support findings from experimental tests. DOI: 10.1061/(ASCE)MT.1943-5533.0000386. (C) 2012 American Society of Civil Engineers.