| The fatigue performance of asphalt pavement is the key to determining the length of road service.Rubber modified asphalt has excellent fatigue resistance,and its use in highway asphalt pavement construction not only saves resource costs and improves pavement fatigue life,but also helps to protect the ecological environment,in line with the national "dual carbon" policy.The permanent pavement of Hebei Jingde Expressway is the first to use high content rubber modified asphalt(with a content of 30%,40%,and50%)for the asphalt pavement surface layer.However,the fatigue performance of high content rubber asphalt needs further verification and in-depth research.This article relies on the scientific and technological project "Reliability Analysis and Evaluation of Semi rigid Base Permanent Asphalt Pavement" of the Hebei Provincial Department of Transportation,The fatigue characteristics of high content rubber modified asphalt and its mixtures under three different dosages were studied,and the main conclusions are as follows:(1)Using a dynamic shear rheometer,the fatigue performance of high content rubber modified asphalt(AR)was investigated.The results showed that the fatigue damage of the high content rubber modified asphalt after RTFOT was not significant in the LAS test,and the fatigue life of AR modified asphalt could be accurately distinguished after PAV aging;In the MSCR test,the creep recovery rate R0.1 cannot accurately distinguish the fatigue performance of AR modified asphalt,and R3.2 is suitable for evaluating the fatigue performance of AR modified asphalt;The time scanning index Nf50 can effectively distinguish the fatigue performance of AR modified asphalt at different dosages.The above various test results indicate that AR40(40% dosage)has the best fatigue performance.(2)Based on the permanent pavement structure of Jingde Expressway,the fatigue performance of three graded rubber modified asphalt mixtures ARHM-13(30% dosage),ARHM-20(40% dosage),and ARHM-25(50% dosage)was studied.The experimental results showed that ARHM-13 had the fastest fatigue life decay rate with increasing strain level,and ARHM-20 had the best fatigue performance under high strain conditions;The regression analysis of power function and linear function shows that the stability of ARHM-20 and ARHM-25 against continuous load is better than that of ARHM-13.(3)Exploring the effect of aging on the fatigue performance of ARHM asphalt mixture,compared with the non aging situation,after short-term aging,the fatigue life of ARHM asphalt mixture does not significantly decline,and has good fatigue performance.After long-term aging,ARHM-20(40% dosage)and ARHM-25(50% dosage)have the best fatigue performance;Using the same gradation,the effect of rubber powder content on fatigue performance was studied.The results showed that with the increase of rubber powder content,the fatigue performance of asphalt mixture improved.(4)Based on indoor fatigue test data fitting,a fatigue prediction model for high content rubber modified asphalt mixture was obtained.The adjustment coefficient K was introduced to obtain fatigue prediction models for asphalt mixtures with different rubber powder dosages.The correlation coefficients of the fatigue prediction models reached above 0.969,indicating high accuracy of the fatigue prediction model. |
