Study on performance of recycled asphalt mixture based on blending state analysis of virgin and aged asphalt

The blending state of virgin and aged asphalt is one of the key factors that influence the cracking resistance and fatigue performance of recycled asphalt mixtures. In this paper, the complex modulus of the virgin and aged double-layered asphalt samples was measured by DSR experiments, and the degree of blending (DOB) was calculated based on the complex modulus. The cracking resistance and fatigue performance of the mixture prepared under different blending conditions were tested and related to the DOB to obtain a prediction model. Results showed that the DOB and the complex modulus G* increased with blending time and temperature. The blending effect of modified asphalt was not as good as 70-pen asphalt. The contribution of blending time and temperature to DOB was 40% and 50%, respectively. The influence of DOB on cracking resistance and fatigue performance of recycled asphalt mixtures was consistent with DSR test. Good correlations between DOB, cracking resistance and fatigue performance were observed, which were 79.14% and 82.82%, respectively. Based on the DOB model, optimal blending temperature and blending time could be found according to the softening point difference between virgin and aged asphalt.