Coarse Aggregate Surface Texture Characterization And Asphalt Mixtures Performance Research Based On Height Difference Correlation Function

The morphological characteristics of coarse aggregate play an important role in the mechanical response of the asphalt pavement under the mechanical load,and the surface texture is the key factor affecting the surface performance of the asphalt pavement.In order to fully describe the roughness of coarse aggregate,the height difference correlation function was introduced to characterize the surface texture of coarse aggregate with multi-parameters.First,utilizing the needle profiler to obtain the texture profile curve of the aggregate surface,and eliminating the error in data acquisition.Then,calculating the height difference correlation function of coarse aggregate,and fitting the curve with piecewise fitting.The self-similar feature parameters（D,ξ_∥,ξ₁）of the surface texture curve was calculated as an evaluation index to quantitatively characterize the roughness of the surface texture of the coarse aggregate.The results reveal that the surface texture of the coarse aggregate has two sections of variable dimension within a certain range but the fractal dimension is not sensitive to the roughness of the coarse aggregate.It is very limited to evaluate the surface roughness of the coarse aggregate by using the fractal dimension as an independent parameter.The horizontal cutoff wavelength ξ_∥ reflects the size of the largest microbump,which is obviously different in different kinds of aggregates.The amplitude expectation value ξ₁ can quantitatively describe the overall roughness of the aggregate.Fractal dimension D,horizontal cutoff wavelength ξ_∥ and amplitude expectation value ξ₁ can describe the surface roughness of the coarse aggregate more comprehensively.Through a large number of laboratory tests,the effect of the roughness of coarse aggregate on high temperature stability,low temperature performance,durability,and skid resistance of asphalt mixture are analyzed.The analysis results show that the increase of the roughness of coarse aggregate will result in the increase of the dynamic stability,the flexural strain,splitting strength ratio,the friction coefficient,and the decrease of the bending strength.With the increase of the roughness of coarse aggregate,the high temperature resistance to rutting,low temperature crack resistance,the ability to resist water damage and skid resistance increased.