Investigation on storage stability and rheological properties of environment-friendly devulcanized rubber modified asphalt

Abstract

The application of conventional rubber modified asphalt was limited to its high viscosity, poor storage stability, and environmental pollution. This study proposed a preparation process of environment-friendly devulcanized rubber modified asphalt (DRMA) with superior performance. The storage stability and rheological properties of base asphalt, rubber modified asphalt (RMA), and DRMA with different modifier content were evaluated by segregation test, frequency scanning test, multiple stress creep recovery test (MSCR), linear amplitude scanning (LAS) test, and bending beam rheometer (BBR) test. Modification mechanisms of DRMA were detected by scanning electron microscope (SEM), Fourier-transform infrared spectroscopy (FTIR), and four-component analysis. Test results indicated that interaction between crumb rubber and asphalt was mainly physical and has slight chemical reaction. The swelling process of devulcanized rubber (DVR) was adequate and absorbs more light components, which was crucial to improve rheological properties. The storage stability of DRMA was less susceptible to the content of DVR. Besides the crack resistance of DRMA with 18% DVR dosage, the storage stability, high-temperature performance, fatigue resistance, and low-temperature performance of DRMA were markedly superior to that of RMA if the modifier dosage is the same. The rutting and fatigue resistance of RMA was reinforced and then weakened slightly with the increase of CR content, while that of DRMA was enhanced continuously, implying that more waste crumb rubber can be added to asphalt after devulcanization. DRMA was expected to be widely applied owing to its superior performance and environmental features.