The influence of stone crushing processes on aggregate shape properties

Aggregate shape properties have a direct influence on the behaviour of pavement materials. The crushing process is the main factor responsible for generating these shape properties; however, there has hardly been any effort directed toward optimising the performance of pavement materials by altering the crushing techniques to produce aggregate particles with desired shape properties. The aim of this research is to analyse how the crushing process influences aggregate shape properties. Form, angularity and surface texture of five coarse and five fine aggregates, from three different quarries, were evaluated by means of digital image processing and were categorised by two different classification systems. The jaw crusher produced coarse aggregates with a better combination of sphericity and angularity during the first crushing stage. Fine aggregates produced by cone crushers in the final crushing stages were more elongated, but had a greater angularity than fine aggregates produced by the primary jaw crusher.