Research On The Durability Performance Of Hot Recycling Asphalt Mixture With Different Content Of Reclaimed Asphalt Pavement And SBS Modified Asphalt

Hot recycling technology of asphalt pavement can improve the efficiency of resource using, reduce waste, protect environment and take minimal resource consumption to create the greatest economic and social benefits. So it has been widely used in the conservation of the asphalt pavement. Currently, hot recycling technology of asphalt pavement has not been large-scale applicated because of the doubts of its feasibility and reliability, especially the durability of hot recycling asphalt pavement. Based on this, this paper studied the durability properties of hot recycling asphalt mixture with different recycling asphalt pavement (RAP) to provide some reference for the establishment of the evaluation system and performance limits for hot recycling asphalt mixture.Firstly, this paper studied the properties of RAP. The asphalt-aggregate ratio and gradation of aged asphalt mixture were got through extracting method. In order to ensure the unimformity of RAP in the design of hot recycling asphalt mixture, we divided RAP into two tranches, which is greater than 4.75mm, and another is less than 4.75mm. Then, the performance of the aged asphalt from reclaiming method was assessed. At the same time, recycling agent has been evaluated, it is found that 3% mass of aged asphalt can recovery its performance close to the degree of new asphalt binder. Subsequently, Mashall mixuture design method was used to deign the hot recycling asphalt mixture with different content of RAP.Secondly, laboratory fatigue evalution methods were summed up and semi-circular bending test was used to assess the fatigue performance of asphalt mixture in one-level amplitude loading. Through graphics techniques, the relation between load times and crack growth length was gained. Crack growth rate and cracking energy was analyzed in this paper to evaluate the fatigue performance. It is found that the crack growth rate of hot recycling asphalt mixture was faster than that of new asphalt mixture and if the content of RAP is more, the crack growth rate is faster. Analyzing total fatigue cracking energy and single fatigue cracking energy during the process of asphalt fatigue crack, it shows that the single fatigue cracking energy of hot recycling asphalt mixture was greater than that of new asphalt mixture, but total fatigue cracking energy of hot recycling asphalt mixture was less than that of new asphalt mixture, so the fatigue performance of hot recycling asphalt mixture is not as good as new asphalt mixture.Thirdly, through the fatigue test under the multi-level amplitude load of different loading thods, the asphalt mixture performance was evaluated. Based on the results, the asphalt mixture fatigue damge index is more than 1 using Miner linear criteria, which means asphalt mixture fatigue damage was nonlinear charactristical evolving. Asphalt mixture with 30% RAP has similar or even more fatigue properties comparing with new asphalt mixture, but when the content of RAP increases, asphalt mixtue fatigue performance decreases significantly. So to ensure the mixture fatigue performance, the content of RAP should be limited.Fourthly, indirect tensile test, dynamic modulus test, dynamic creep test and semi-circular bendin test with multi freeze-thaw conditions were taken to analyze hot recycling asphalt mixture performance. Evaluating methods and RAP content influence to hot recycling asphalt mixture was researched in this paper.Finally, based on the results of fatigue and moisture damage performance evaluating results in this paper, it is suggested that the RAP content should not be more than 30% when considering the durability property of asphalt mixtue.