Laboratory evaluation of the properties of high-cured crumb rubber modified asphalt containing sulfur and polymer after the oxidative aging procedure

The crumb rubber modified asphalt (CRMA) prepared by terminal blend (TB) process with high interaction temperature (260 degrees C) and extended curing time (6 h) is called high-cured CRMA, which has the characteristics of good storage stability and easy construction. The composition of the material has an important influence on the performance of high-cured CRMA after the oxidative aging procedure. In this study, the properties of high-cured CRMA containing sulfur and styrene-butadiene-styrene (SBS) after the oxidative aging procedure were studied. All binders were aged using rolling thin film oven test and pressure aging vessel, respectively. Fluorescence microscopy tests and rheological property tests of all binders were performed. The chemical composition of all binders was monitored using Attenuated Total Reflection-Fourier Transform Infrared Spectroscopy. Fluorescence microscope observation shows that the particles of the SBS phase are significantly reduced and their distribution becomes uniform with the increase of the sulfur content in the high-cured crumb rubber hybrid binder before aging. Besides, the SBS phase in high-cured crumb rubber hybrid binder gradually decreases and the distribution becomes more uniform after aging. 0.3% sulfur has a certain effect on the rutting resistance of high-cured crumb rubber hybrid binder before aging, while low sulfur content has little effect on the rutting resistance. Moreover, sulfur can retard the growth of carbonyl groups of high-cured crumb rubber hybrid binder, and improve the resistance to thermal oxidation in the rheological indexes of high-cured crumb rubber hybrid binder.