Research On The Influence Of Aggregate Abrasion Morphology On Mechanical Properties Of Asphalt Mixture

Aggregate is major component of asphalt mixture,and its aggregate characteristics play an important role in the performance of asphalt mixture.In recent years,scholars from various countries have mostly studied the aggregate gradation,meso-skeleton structure and aggregate morphology of asphalt mixtures to explore their influence on the performance of asphalt mixture.There are still deficiencies in the analysis and research on the influence law and mechanism of aggregate morphology on the mechanical properties of asphalt mixture.This research studied the effect of aggregate abrasion morphology on the mechanical properties of asphalt mixture.The improved Los Angeles Abrasion(LAA)test was conducted in this research to acquire aggregate under the different number of abrasions.The 2nd generation of the Aggregate Imaging Measurement System(AIMS II)and 3D blue-ray scanner were utilized to evaluate the morphological characteristics of particles with high precision and capture the change in the two-dimensional and three-dimensional morphological characteristics of the abraded aggregate,and analyzing the correlation between the morphological characteristics of aggregates under the different number of abrasions.dynamic modulus test,repeated load test and uniaxial compression test,were applied using the asphalt mixtures specimen prepared by different number of rotaitions aggregates to establish a correlation between the morphological characteristics of aggregates and the parameters related to the mechanical properties of asphalt mixtures.The main conclusions are as follows:(1)This research explores the influence of different number of abrasions on aggregaterelated morphological characteristic indexes.The results show that the number of abrasions has a significant effect on the angularity index and three-dimensional sphericity of the aggregate.With the increase in number of abrasions,the angularity index decreases and the threedimensional sphericity increases.There is a good correlation between the angularity index and the three-dimensional sphericity.(2)The dynamic modulus test shows that as the frequency decreases,the amplitude of reduction in the dynamic modulus of asphalt mixture gradually increases with the increase in the number of abrasions.The amplitude of reduction in the dynamic modulus is more sensible with the temperature is higher.From the improved Christensen-Anderson-Marasteanu(CAM)model,It found that as the angularity index decreases and three-dimensional sphericity increases,the rheological parameter R increases,the equilibrium complex modulus decreases and the maximum amplitude of reduction in the equilibrium complex modulus is 36%.Aggregate abrasion morphology has a significant effect on the resistance of the asphalt mixture to deformation at high temperature.(3)The uniaxial compression test shows that under normal temperature conditions,there is no obvious correlation between the aggregate morphological characteristics and the uniaxial compressive strength of asphalt mixture,and the aggregate morphological characteristics have little effect on the strength of asphalt mixture.(4)The repeated load test shows that The flow number(FN)and the combined parameter(εp/FN)can be used as the high temperature evaluation index of asphalt mixture.Angularity index and three-dimensional sphericity have a good correlation with FN and εp/FN.As the aggregate angularity index increases,the three-dimensional sphericity decreases,FN decreases,and the εp/FN increases.Aggregate with rich angularity and shape characteristics can effectively improve the resistance of the asphalt mixture to permanent deformation at high temperature.