Research On Low Temperature Anti-cracking Performance Of Aged Asphalt Mixture Based On SCB

Asphalt pavements begin to produce a variety of pavement problems after the using of years,mainly due to the aging of asphalt mixtures.Aging leads to easy to produce cracks of asphalt pavement,in order to further study the crack resistance of asphalt mixture in low temperature environment;the short-term aging and long-term aging of asphalt mixture,as well as asphalt,aging time and aging temperature are considered comprehensively,and the impact of aging on low temperature crack resistance of asphalt mixture is evaluated by 6 aging methods.According to the temperature in Anhui in winter,four temperature gradients were set in the test,namely 0 °C,-5 °C,-10 °C,-20 °C;at different temperatures,the low temperature performance of the asphalt mixture will also be different.Meanwhile,adding an appropriate amount of fiber can play a positive role in the low temperature performance of the asphalt mixture and reduce the expansion of cracks;the low temperature crack resistance test of the asphalt mixture is carried out,by adding 3commonly used fibers respectively,namely lignin fiber,polyester fiber and basalt fiber,and the applicability and economic suggestions of each fiber are given.Through the experiment,the conclusions reached are as follows:(1)Asphalt mixtures with different aging methods,the degree of aging is deepened in turn: unaging control group,asphalt aging asphalt mixture,135 °C short-term aging asphalt mixture,155 °C short-term aging asphalt mixture,long-term aging 5d asphalt mixture,long-term aging 10 d asphalt mixture.(2)Temperature has a greater impact on the low temperature crack resistance of asphalt mixture,at 0 °C,-5 °C,short-term aging asphalt mixture,long-term aging asphalt mixture with the deepening of aging,the peak load becomes larger,the fracture energy becomes smaller;and with the further reduction of temperature,the deeper the aging degree,the smaller the peak load and fracture energy.(3)The fiber has a significant effect on improving the low-temperature crack resistance of the asphalt mixture,and the peak load and fracture energy of the asphalt mixture are improved to varying degrees after the fiber is added.Among them,basalt fiber has the widest application range and the best effect;lignin fiber has poor effect at-20 °C,and the performance is poor under long-term aging;polyester fiber has a limited improvement effect and is a cost-effective fiber.(4)In the evaluation index,the peak load is easily affected by other factors,the fluctuation is very large,and the repeatability of the test results is not high;the vertical displacement requires high accuracy;the fracture energy is more comprehensively evaluated the low-temperature crack resistance of the asphalt mixture specimen,which is the best of the three evaluation indicators.(5)Through SEM observation,it is found that the aging process makes the asphalt mixture prone to microcracks;with the deepening of the aging degree,the microcracks have a tendency to continue to expand,and the wave velocity of the aging asphalt mixture can also partially reflect the changes in the microcracks inside the asphalt mixture.Figure [27] Table [16] Reference [81]...