Evaluation and optimization of asphalt binder and mixture modified with high activated crumb rubber content

High-content rubberized asphalt (HCRA) is a road engineering material with favorable economic and environmental benefits. However, HCRA is still not widely used due to concerns of workability and storage stability. To improve rubber content and maintain rubberized asphalt (RA) performance, five RAs with different activated powder contents were prepared by wet process. Firstly, composite viscosity and softening point difference were used to optimize the preparation process of activated powder and RA. The dynamic shear rheometer (DSR) and bending beam rheometer (BBR) tests were carried out and the stability index was proposed to evaluate performance of HCRA. Finally, the mixture performances of HCRA, base asphalt and SBS modified asphalt were compared. The results show that the 60-mesh rubber powder with 20% waste oil is beneficial to reduce viscosity and improve compatibility of HCRA when treated by microwave for 2 mins and sheared for 5 h. As the powder content increases, RAs have excellent high and low temperature performances. Overall, the performance of HCRA binder and mixture with 60% content of rubber powder possess optimal comprehensive properties in terms of high temperature rutting resistance, cracking resistance, and moisture resistance. This study helps facilitate the incorporation of high content rubber in RA and promote its potential application in road engineering.