Volume 5, Issue 1 (January 1977)
Concept and Test Method for a Unified Characterization of the Geometric Irregularity of Aggregate Particles
The paper describes a concept by which the geometric irregularity (shape, angularity, and surface texture) of aggregate particles is unified and expressed quantitatively by basic and volumetric characteristics that are related to the physical properties of individual particles as well as to the packing behavior of particles in bulk. A test method, the pouring test, was developed for bulk measurements of these characteristics by a fast, simple, and practical procedure. Tests were made on 22 types of aggregate with six sizes of each. It was found that the new geometric parameters can reflect and explain the discernible irregularity of a wide range of aggregate types and sizes. The parameters were highly correlated with the packing specific gravity, asphalt requirement of the particles, optimum asphalt content, and maximum stability of graded bituminous mixtures. The parameters successfully provided physical explanations to marginal and unexpected behavior of unconventional aggregates, while conventional test indexes failed to provide an appropriate explanation.