EFFECT OF GEOMETRIC IRREGULARITY OF AGGREGATES ON THE PROPERTIES AND BEHAVIOR OF BITUMINOUS CONCRETE

Abstract

The geometric irregularity (GI) of aggregate particles has a major effect on the physical properties and mechanical behavior of bituminous paving mixtures. Many test procedures and quality criteria have been adopted to evaluate and control these geometric factors for the use of aggregates as mixture ingredients, most of which have historically been qualitative and subjective. However, several tests were developed in the 1960s to measure the combined geometric properties of aggregate particles in bulk. Although mainly empirical, they provide a practical tool for bituminous concrete technology. A more recent development is the packing volume concept, by which the GI of aggregate particles is unified and expressed quantitatively through basic volumetric parameters related both to the physical properties of individual particles and to the packing behavior of particles in bulk. A test procedure, the pouring test, was developed for the fast, simple, and practical bulk measurement of these parameters. The packing volume concept and the pouring test have already been applied to aggregate and bituminous mixture technology. This paper, which presents a continuation of the research effort on this subject, describes a comprehensive quantitative study on the GI of a wide range of aggregate types and its influence on the properties and behavior of actual bituminous paving mixtures.