AGGREGATE ANGULARITY EFEFCTS ON MECHANICAL PROPERTIES OF ASPHALT CONCRETE

Abstract

Aggregates have significant influence on the serviceability and performance of flexible pavements. Estimation of the effects of the classifications of aggregate angularity on mechanical properties of asphalt concrete is understudied because of its complexity. This paper identifies the limitations of aggregate angularity and mix performance in existing studies and present experimental results of the influence of coarse aggregate angularity (CAA) on the mechanical behaviour of dense graded asphalt mixtures. Four mixtures of different classes of coarse aggregate angularity (rounded to angular) were compacted to cylindrical heights of 63, 100 and 150 mm each. Geometric characterization of the particle angularity have been evaluated using Aggregate Imaging System (AIMS). Additionally, mechanical and performance tests have been evaluated at three temperatures (25, 35 and 45 C). Principle results of the study demonstrated that tangential modulus, compressive strength, elastic, viscoelastic and viscoplastic properties are highly influence by changes in coarse aggregate angularity. The resilient stiffness modulus and recovered (elastic) creep strain however, were not significantly influenced by these changes. The influence of a particular angularity classification maybe useful to road engineers when evaluating the performance prediction of asphalt concrete.