Evolution of aggregate surface texture due to tyre-polishing

Three kinds of aggregates were polished by genuine pneumatic rubber tyres. The initial states of surface texture and dynamic friction coefficient were measured and their developments in polishing process were monitored. The characterizations of height distribution and power spectral density of aggregate surface texture were estimated. The changes of micro-texture were also investigated based on a fractal filtering method with sound theoretical backgrounds of rubber friction on rough surfaces. Global height reduction and differential removal of mineral component are observed in polishing process. It is concluded that the tyre-polishing action plays the critical roles in the micro-scale texture, and the evolution of friction of aggregate is governed by the micro-texture changes due to the differential removal of mineral component.