Evaluating The Effect Of Hydrated Lime And Basalt Fiber On Fatigue Performance Of Asphalt Mix Under Thermal Aging Condition

Long life asphalt pavement is an important direction of road traffic development in China.However,during the process of long-term use of asphalt pavement,it will inevitably be aging due to the thermal oxygen effect of the environment.Meanwhile,fatigue cracking has become an important damage form affecting the service life of asphalt pavement on the grounds of the high strength and frequent action of vehicle load.Therefore,the anti-fatigue cracking ability of asphalt pavement under thermal aging is the crucial factor for its long-term use.In view of that,this paper,by partially substituting mineral powder and adding hydrated lime powder into the traditional matrix asphalt mixture and adding basalt fiber stabilizer,studies the influence of two kinds of admixtures on the fatigue performance of asphalt mixture under the effect of thermal aging from different scales and perspectives.The concrete research and achievements are as follows:Firstly,based on the multi-scale research method of asphalt mixture which indicates the relationship between asphalt mortar and asphalt mixture fatigue performance,medium temperature sweep and linear amplitude sweep(LAS)two methods were adopted to test the fatigue performance of asphalt materials with different admixtures in mortar scale,which was also carried out with the help of dynamic shear rheometer(DSR).It was found that hydrated lime and basalt fiber can improve the fatigue performance of aged asphalt.At the same time,considering the ductility of asphalt mortar,rutting factor and other high and low temperature performance test results,the best replacement amount of hydrated lime was 20%.Then,the fatigue test was carried out on the four asphalt mixtures,which were ordinary mineral powder filler,single lime,basalt fiber,lime and basalt fiber,by using four-point bending fatigue test method and referring to the recommended amount of lime removal in the size of mortar.Also,the fatigue damage process and results of different asphalt mixtures before and after aging were analyzed based on phenomenological method and energy dissipation method.It was observed that adding 20% hydrated lime can significantly increase the fatigue life of asphalt mixture before and after aging,and weaken the adverse effect of aging on the fatigue performance of asphalt mixture to a certain extent.What’s more,adding basalt fiber can reduce the sensitivity of fatigue performance of asphalt mixture to strain change.Ultimately,mixing two kinds of admixtures can comprehensively improve the fatigue performance of asphalt mixture under thermal aging.Eventually,the self-healing performance of four kinds of aged and unaged asphalt mixtures under different conditions was tested simply by adopting the storage healing recovery test,introducing healing gap and designing three kinds of self-healing conditions.The self-healing index based on fatigue damage rate was used to analyze the self-healing compensation ability of asphalt mixture before and after aging.It could be concluded form the results that: under the condition of high temperature induced healing,the asphalt mixture with hydrated lime shows better self-healing recovery ability.When the initial damage of the mixture is large,adding basalt fiber can effectively improve the selfhealing rate of asphalt mixture.At the same time,the self-healing situation of asphalt mixture under different conditions further verifies the gain effect of hydrated lime on the fatigue self-healing ability of aging asphalt mixture.