Stereological estimation of aggregate gradation using digital image of asphalt mixture

Abstract

The gradation of asphalt concrete affects the properties of pavement significantly. It is an important parameter for the design of asphalt mixture. So the planar gradation of asphalt concrete was investigated using the digital image processing techniques in this paper. Then the planar gradation was transformed to the three dimensional gradation by stereological method. The aggregate was assumed as ellipsoidal particle in stereological conversion. And stereological coefficients of ellipsoidal particle were determined using numerical method. The results indicated that aspect ratio of aggregate affected stereological coefficients significantly. There was a good agreement between the estimated and the control gradations when the improved assumption was used. The estimated errors of proposed method were less than that of other methods. Aggregate was suggested to be assumed as ellipsoidal particle in stereological conversion. And the combined method of digital image processing and stereological conversion is a universal, fast and accurate method for gradation estimation.