Analysis of distribution properties of coarse aggregates in HMA based on delaunay triangulation

Abstract

To investigate the microstructure of asphalt concrete,a new method was proposed to analyze the distribution properties of coarse aggregates.Based on the digital image processing and computational geometry,delaunay triangulation method was used to generate the centroid of the coarse aggregates which square sieve size larger than 2.36mm.Then,coarse aggregate-asphalt bind area ratio(A1/A2) for each delaunay triangle was calculated by statistics theory.The A1/A2 varies with different gradations,therefore,it can be used to represent the local character of the hot mixture asphalt(HMA) microstructure.According to the statistic analysis,it indicates that the total mass and each graded mass of the coarse aggregates both significantly influence the microstructural character of HMA.The central tendency and skewness of A1/A2 is helpful to judge the dense degree of the coarse aggregate skeleton,and the nonparametric tests can further provide the possibility of classifying the microstructure of the HMA.By comparing three different gradations,such as stone matrix asphalt(SMA),open graded friction course(OGFC),and superpave(SUP),it shows SMA has the largest dense degree of coarse aggregates distribution,and SUP appears the least dense degree characteristic.Furthermore,SMA and OGFC have similar type of microstructure while SUP's type is different from others.