Research on strength formation mechanism and noise reduction characteristics of waste rubber powder micro-surfacing

The application and promotion of the traditional micro-surfacing is limited by the defects of high noise and poor wear resistance. In order to improve the adhesive strength and noise reduction properties of the micro-surfacing, an attempt was made to add waste rubber powder (WRP) in dry form to the micro-surfacing. Firstly, the mixtures were prepared by orthogonal tests taking into account the number of rubber powder grades, rubber powder dosages, asphalt-aggregate ratio and gradation. The microscopic strength formation mechanism at the micro-surfacing of the waste rubber powder was investigated by means of Scanning Electron Microscope (SEM). Secondly, the effect of waste rubber powder (WRP) on the modification of asphalt mastic was investigated with the Dynamic Shear Rheometer (DSR), both as unaged and after short-term ageing. Finally, the effect of waste rubber powder on the performance improvement and noise reduction characteristics of the micro-surfacing was analyzed through road performance tests, and to establish the correlation between microstructure and road performance. The results showed that 2% of 40-mesh rubber powder mixed with 8% asphalt-aggregate ratio of medium grade MS-3 micro-surfacing mixture, the densest structure of the slurry. Significantly improved high-temperature and ageing performance at the micro-surfacing reduced noise generation and suppressed noise transmission, but no significant improvement in water stability performance. The waste rubber powder enhances the strength of the micro-surfacing by interweaving with cement hydration products and asphalt mortar. It also optimizes the inter-aggregate embedding and void characteristics, and has an excellent noise reduction effect.