Influence Of Dry-wet Cycles On The Mixed Fracture Properties Of Asphalt Mixture

With the continuous promotion of highway infrastructure construction in China,highway construction has made remarkable achievements.At the same time,asphalt pavement disease has a certain impact on road service level.As one of the main disease forms,pavement cracking and other problems have been paid attention to by Chinese scholars.In order to explore the influence of rainfall and groundwater on the anti cracking performance of asphalt mixture,the influence of dry wet cycle on the fracture mode of asphalt mixture is studied in this paper.In order to accurately evaluate the change law of different fracture modes of asphalt mixture after dry wet cycle,the stress intensity factor and other indexes of asphalt mixture were analyzed by asymmetric semicircular bending test.The main contents and achievements are as follows:(1)Both the critical stress intensity factor keff and the critical fracture energy GF can reflect the anti cracking performance of asphalt mixture.The critical stress intensity factor is more suitable to be used as the index of anti cracking performance of asphalt mixture under low temperature conditions,and the critical fracture energy can more comprehensively reflect the anti cracking performance of asphalt mixture;under the joint action of vehicle load,precipitation and temperature,asphalt pavement is often in I / II mixing mode,so it should be considered Keff and GF in mixing mode are considered as indexes to evaluate the anti cracking performance of asphalt mixture.(2)Temperature,loading mode and different drying and wetting cycles have certain effects on keff and GF.Within a certain range,keff and GF can be increased by decreasing temperature;keff is the largest in pure I mode,and GF is maximum in mixed mode when me = 0.5.For the mixed mode,the minimum values of keff and GF were in the control group at 20 ?.The keff at-10 ? was the minimum at one dry wet cycle,and GF was the minimum at 24 cycles.(3)Compared with MTS criterion,gmts criterion is better than MTS criterion.-At 10 ?,the measured value of crack initiation angle first decreases and then increases with the increase of dry and wet cycles,and at 20 ?,it increases first,then decreases and then increases with the increase of dry and wet cycles.(4)The characteristics of crack propagation under different dry wet cycles are analyzed by digital image processing technology.The results show that the ability of mode I fracture to resist deformation is better than other modes under medium and low temperature conditions.Temperature has a significant effect on the size of CMOD.With the decrease of temperature,CMOD decreases significantly.The number of dry wet cycles has a significant effect on the maximum value of CMOD.With the increase of the number of dry wet cycles,the size of CMOD changes in different trends.