Aggregate Surface Texture Influences on Asphaltic Concrete Skid Resistance

Abstract

<p>For asphaltic concrete surface courses, the surface texture of the exposed coarse aggregate in the key factor influencing the skid resistance performance of the pavement. With time, this surface texture is altered by the dynamic, interactive processes of polishing, wear or abrasion and weathering. In this study, four types of aggregate which are available in Ontario - traprock, limestone, steel slag and blast furnace slag - were subjected to these processes in order to evaluate their surface texture characteristics. The study was completed in terms of both quantitative analyses of laboratory samples and qualitative analyses of field and laboratory samples. Two major aspects were surface texture evaluation using the scanning electron microscopy, and the simulation of weathering influences on skid resistance. Both chemical and x-ray diffraction analyses were completed to support the evaluation.</p> <p>From the study, two new concepts - positive and negative rejuvenating processes and Potential Rejuvenating Value (PRV) - were developed. Steel slag, with a relatively high PSV, low AAV and potential negative rejuvenation was found to be the most desirable aggregate in terms of skid resistance performance.</p>