Performance Research Of Warm Mix Asphalt With High Content Of RAP

The asphalt pavement is prone to failure due to the effect of the vehicle load and external climate.The maintenance of the road surface has become the research point of road construction.The warm mix asphalt(WMA)recycling technology combines the advantages of hot recycling technology and cold recycling technology.The application of the WMA recycling technology not only reduces energy consumption,and environmental pollution,avoids the secondary aging of the asphalt but also has good pavement performance,which has become an important research direction of current asphalt pavement.At present,the research on the WMA recycling technology is still limited,especially lack of the research on the WMA recycling technology with high content RAP.There are many problems with the warm mix recycled asphalt mixture such as the lower utilization rate of RAP and the poor water stability and fatigue resistance.Thus,the stability,fatigue resistance,and the optimum RAP high contents of the warm mix recycled asphalt mixture were investigated in this paper.Firstly,the aging and regeneration mechanism of asphalt was explained,and RAP is tested to determine its aging degree.Then,the raw material was detected and meet the standard.The SMC rejuvenator and 10%optimum content of the warm mix rejuvenator were determined by the experimental analysis of the ductility,softening point,and viscosity of the aging asphalt in RAP.The Marshall design method was used to determine the optimum asphalt content of the warm mix recycled asphalt mixtures.On this basis,the high-and-low temperature performance,water stability,and water temperature stability of asphalt mixtures were utilized.The results showed that the high-temperature performance of warm mix recycled asphalt mixture improved with the increase of RAP content while the low-temperature performance and the water stability decreased.In addition,the water stability of the asphalt mixture was lower than the specification standard when the RAP content is 60%.The water temperature stability of the warm-mix recycled asphalt decreased with the increase of RAP content but which were better than those of hot-mix asphalt.In the end,the fatigue resistance of WMA under different stress ratios(0.4,0.6,0.8)with different high RAP contents was analyzed,and the relevant fatigue prediction model was established to analyze the fatigue damage process of the warm mix recycled asphalt mixture.The results showed that the fitting curves of the logarithm of fatigue life between the stress ratio of recycled asphalt mixtures with different RAP contents showed a linear relationship.Moreover,the fatigue life prediction models of warm mix recycled asphalt mixtures with different RAP contents under different stress ratios were established.To sum up,the mix proportion,road performance,and durability of the warm mix recycled asphalt mixtures with 30%,40%,50%,and 60%RAP content were investigated in this study.It provides a reference for the practical engineering application of the warm mix recycled asphalt mixtures containing high content RAP.