Preparation and performance evaluation of rubber powder-polyurethane composite modified cold patch asphalt and cold patch asphalt mixture

Considering the unfavorable stability and insufficient strength of cold patch mixtures used in pavement pothole repair at an early age, 80 mesh waste rubber powder and polyurethane were selected for composite modification of #70 base asphalt, in which the contents of the two modifiers were determined through parallel tests with basic performance indexes of asphalt being employed as the criteria for evaluation. The modified asphalt was diluted with XSJ-1, a self-made composite diluent, and the preparation process of cold patch asphalt, as well as the cold patch asphalt formula, were defined. Based on DSR, DSC and FTIR tests, the performance of the composite modified cold patch asphalt was evaluated, and the modification mechanism was analyzed. The cohesion, strength, high-temperature stability, and moisture susceptibility of the cold patch asphalt mixture were evaluated with two types of commercially available cold patch asphalt mixtures as the comparison. The outcomes demonstrate that the qualities of waste rubber powder/polyurethane composite modified cold patch asphalt are significantly superior to those of single modified cold patch asphalt. The viscosity of cold patch asphalt is remarkably influenced by the quantity of diluent employed. It is recommended that base asphalt contain 10 % and 7 %, respectively, of waste rubber powder and polyurethane with a diluent of 25 %. The initial strength and formed strength of the composite modified cold patch mixture were considerably higher than those of the control cold patch mixtures, and the time needed to reach the formed strength was shortened by 2 days.