Microscopic and dynamic rheological characteristics of crumb rubber modified asphalt

A test for crumb rubber modified asphalt containing 20% crumb rubber particles (30 mesh) was performed using a scanning electron microscope (SEM). The experimental results indicate that the crumb rubber particles are evenly distributed in the asphalt. Shear rate sweep and shear-temperature sweep tests on the crumb rubber modified asphalt at −20–80 °C using a dynamic shear rheology (DSR) instrument, were carried out. The tests show that the complex modulus decreases with increasing temperature; at equivalent temperature, higher load frequencies lead to a larger complex modulus, and this value increasingly decreases as the temperature increases; the phase angle increases with temperature and decreases as the load frequency increases. It can be concluded that the rutting resistance limiting temperature of crumb rubber modified asphalt is 78 °C, and the anti-fatigue limiting temperature is 16 °C, which shows that the asphalt has preferable rutting resistance characteristics at high temperature, as well as anti-fatigue characteristics. In addition, the complex modulus master curve at different temperatures was plotted according to the time temperature equivalence principle, which allows the study of the dynamic state behavior of crumb rubber modified asphalt at a wide range of load frequency.