Measurement of aggregate texture and its influence on hot mix asphalt (HMA) permanent deformation

Aggregate shape has a significant effect on the performance of asphalt mixes. Designing well-performing asphalt pavements requires developing methods to quantify rapidly and accurately the different aggregate shape properties, and most importantly, relate these properties to performance. Aggregate texture has been identified in several studies to be the shape property that has the most significant influence on asphalt mix performance. This study presents a new procedure for measuring aggregate texture using image analysis techniques. The main advantages of this new procedure are the ability to capture the different sizes of texture elements, to separate the true texture from the color variations on the aggregate surface, and to characterize both fine and coarse aggregates. The procedure is used to measure texture for a wide range of fine and coarse aggregates, and the results are compared with the laboratory performance of asphalt mixes. The analysis shows that the procedure yields detailed information on aggregate texture in a short time. The texture measurements have very good correlation with the resistance of asphalt mixes to permanent deformation measured in the laboratory using different wheel tracking devices.