高旧料掺量下热再生沥青混合料宏细观损伤断裂试验表征OA

Based on the average asphalt film thickness theory and Marshall design method,this research carries out mix design of SUP-13 hot recycled asphalt mixture(HRAM).The composition ratio of new and old materials,the synthetic oil-stone ratio of HRAM and its mesoscopic medium component(fine aggregate matrix)were determined.Then,with the help of universal testing machine(UTM)and environmental scanning electron microscope(ESEM),the semicircular bending test(SCB)of HRAM and the mesoscopic in-situ tensile fracture test(ISDT)of hot recycled fine aggregate matrix at the same temperature were designed.The load-displacement curves of SCB and ISDT tests under five high reclaimed asphalt pavement(RAP)dosages(60%,70%,80%,90%,100%)were obtained.The effect of RAP content on the fracture energy and the crack resistance index was evaluated.By recording the cracking process of the ISDT test,the mesoscopic failure mechanism of the recycled fine aggregate matrix was detected,and its crack expansion and evolution behavior were studied.The results show that increasing the RAP content contributes to an elevated failure load of HRAM,while simultaneously reducing its fracture energy and crack resistance index.Two distinct crack propagation modes,namely surface microcracking and through-cracking,are identified in thermally fine aggregate matrix.A higher RAP content is found to accelerate the evolution of through-cracks and main cracks,yet leads to a pronounced reduction in the propagation area of microcracks.