Research On Fatigue Resistance And Fatigue Evaluation Index Of Warm Asphalt Rubber

Warm asphalt rubber integrates the advantages of asphalt rubber and warm mixed technology,which can not only consume a lot of waste rubber tires,reduce road noise,but also maintain the same construction temperature as the ordinary hot mixed asphalt mixture.Since fatigue cracking is the main failure form of asphalt pavement,a comprehensive understanding of the fatigue behavior of warm asphalt rubber is of great significance to reveal the pavement failure mechanism,optimize the material design and extend the pavement service life,which is conducive to the further promotion of warm mixed rubber asphalt technology.In this study,different fatigue test methods were adopted,and a variety of warm mixing agents were selected.A series of fatigue performance tests were carried out on rubber asphalt binder,mortar and mixture.The effects of warm mixing agents with different action mechanisms on the fatigue characteristics of wet rubber asphalt were comprehensively investigated.At the same time,five mixing methods of warm asphalt rubber mixture were designed to explore the change of fatigue performance of the mixture under different rubber powder and addition sequence.Finally,the comprehensive comparison and mechanism analysis of the fatigue test results at different scales are carried out to evaluate the accuracy of different fatigue performance indexes.The results show that the type and addition sequence of warm mix additives have significant influence on the fatigue resistance of the mixture.Among them,the foaming warm mix additive and the chemical additive have negative effects,while the organic additive can enhance the anti-fatigue performance of asphalt mixture.The results of linear amplitude sweep test(LAS)of asphalt and shear fatigue test of mortar were consistent with the results of four-point bending fatigue test of mixtures,while the results of asphalt fatigue factor(G~*sin)test and ITFT of mixtures were deviated from the above conclusions.In this paper,LAS test,shear fatigue test of mortar and four-point bending fatigue test are recommended as the research methods of fatigue characteristics of warm asphalt rubber.