Experimental And Simulation Study On Cracking Behavior Of Asphalt Rubber Mixture

Purpose: Considering the common situation of asphalt pavement cracking and some problems existing in the design of asphalt pavement,this study aims to use the SCB test and modeling analysis of cracking behavior of asphalt rubber mixture to deepen the understanding of cracking behavior of asphalt rubber mixture and improve the implement and development of SCB in the design specification.Methodology: The study applied several different methodologies to conduct the research of cracking behavior of asphalt rubber mixture.First,based on Superpave,the study designed two different bituminous mixture with different air voids(4%,6%)to be the research subjects.Second,the paper used the measurement of SPT dynamic modulus and studied the dynamic modulus of various asphalt rubber mixture of different aging time,temperature,and air voids.Through time/ temperature conversing and Sigmoidal function fitting,a master curve of dynamic modulus of asphalt mixture has been built.Third,through conversing dynamic modulus to relaxation modulus,the study calculated the viscosity parameter of asphalt rubber mixture.Fourth,based on SCS test,the fracture energy and fracture toughness in a different condition of the aging time were studied in this research.At last,the study analyzed the SCB cracking behavior of asphalt rubber mixture through XFEM(eXtended Finite Element Method)modeling.The main conclusions are as follows:(1)The viscosity index of asphalt rubber 3.58Pa·s,aggregate structure gradation of HMAR-16 in Texas regulation,the amount of asphalt,rubber asphalt mixture 5.7%are chosen for the Superpave design,the performance index of the designed mixture can meet the requirements of design standard;(2)Aging time and temperature have a significant influence on the dynamic modulus of asphalt rubber mixture,the specific performance is: the longer the aging of rubber asphalt mixture dynamic modulus value is greater,the higher the temperature,the dynamic modulus of asphalt mixture of rubber is smaller;(3)The dynamic modulus values at different reference temperatures can be obtained by establishing the dynamic modulus master curve to reduce unnecessary tests;(4)The dynamic modulus and the relaxation modulus contain the information of the viscoelastic material of rubber asphalt mixture,and the generalized Maxwell viscoelastic parameters can be obtained by the method of dynamic modulus test;(5)Fracture energy is a reliable method to evaluate the cracking performance of asphalt mixture;(6)With the aging time,the anti-cracking performance of rubber asphalt mixture is poor;temperature is low,the rubber asphalt mixture has higher modulus,the anti-crack performance of high-temperature condition is good,but the condition is more likely in the low-temperature brittle fracture;(7)Through the SCB test and SCB virtual simulation test,we can evaluate the crack resistance of rubber asphalt mixture by SCB fracture energy;(8)Through the comparison of SCB test and SCB test,it is found that the method of combining XFEM with viscoelastic material parameters can simulate the cracking behavior of rubber asphalt mixture,and it has a high degree of coincidence.