Volume 35, Issue 2 (March 2007)
Quantification of Coarse Aggregate Surface Texture Using Image Analysis
Aggregate surface texture affects the performance of pavement and railroad track structural layers, such as the unbound aggregate base/ballast, asphalt concrete, and Portland cement concrete. A quantitative surface texture (ST) index is defined in this paper based on image analysis to measure the irregularities on the surface of coarse aggregate particles in the extent that is not characterized by the commonly used large-scale morphological descriptors, such as flatness, elongation, and angularity. Using an image analysis approach referred to as erosion and dilation, the new ST index quantifies the coarse aggregate surface irregularities at the pixel level. Samples of natural gravel and crushed aggregate were used in establishing a realistic range for the ST index independent of particle size. The effectiveness and practical applicability of the defined ST index in characterizing aggregate surface texture were evaluated by measuring surface irregularities or texture of commonly used coarse aggregate materials.