Effect Of Aggregate On Performance Of Superpave-13 Asphalt Mixture

The shape,mineral composition and processing methods of sand and gravel materials from different producing areas are different,which results in the great difference of the properties of the asphalt mixtures prepared under the same gradation,especially the warm mix asphalt mixtures.It is of scientific and engineering significance to study the influence of aggregate properties on different properties of warm mixed asphalt mixture.In order to promote the warm asphalt mixture technology quickly,this paper studied the influence of basalt aggregate from three different provinces commonly used in Suzhou area on the performance of warm asphalt Superpave mixture.To this end,the macro and micro properties of the three aggregates were tested first.Combined with fractal theory,image-Pro Plus was used to measure the aggregate shape,edge,texture,contour and other macroscopic morphology characteristics,and scanning electron microscopy was used to observe the aggregate microscopic morphology characteristics.Chemical composition and mineral composition were analyzed using X-ray diffraction techniques;At the same time,the three basalt aggregates were used to design the dual-temperature asphalt mixture,and the test pieces were prepared to test the performance of high temperature rut,water damage(Marshall residual stability,freeze-thaw splitting strength)and compared with the hot mix asphalt mixture.Finally,the correlation between aggregate and warm mix asphalt mixture is analyzed and the most significant factors affecting mixture performance are found out.The main conclusions of the study are as follows:(1)The measured data of mathematical statistical analysis show that the basalt aggregates from three different provinces have significant differences in macroscopic morphology,namely fractal dimension,roundness,plane shape and convexity,as well as in microscopic morphology,crystallinity and grain size.Its main mineral composition,physical and mechanical properties are also different.(2)The mixture mixed with double temperature mixing technology can drop about 40℃ than the commonly used hot mixing,but its high temperature performance is not inferior to the hot mixing asphalt mixture.Compared with hot mix,its water damage resistance is slightly decreased,but it meets the requirements of the specification.The performance of double-temperature asphalt mixture is closely related to the origin of aggregate.(3)The dynamic stability,residual stability and freeze-thaw splitting strength ratio of asphalt mixture have a linear increase relationship with fractal dimension and convexity,and a linear decrease relationship with roundness,and an approximate quadratic parabola relationship with plane shape.The aggregate crushing value and abrasion value are inversely correlated with the high temperature performance and water damage resistance of the mixture.Principal component analysis and multiple linear regression analysis show that the fractal dimension and convexity of aggregates have the greatest influence on the volume index of mixtures.Fractal dimension roundness and mineral composition have the most significant effect on the dynamic stability of the mixture.