Performance deterioration mechanism and improvement techniques of asphalt mixture in salty and humid environment

Abstract

To prolong the service life of asphalt pavement in coastal areas, firstly, the continuous immersion, dry-wet cycle and freeze-thaw cycle in 0% (pure water), 5% and 10% NaCl solution were selected to speed up the corrosion of salty and humid environment on asphalt mixture. The changing law of mechanical property of asphalt mixture was studied by splitting test. Then the deterioration of microstructure and road performance of asphalt mixture in salty and humid environment was tested by laboratory tests. Finally, the effects of additives such as anti-stripping agent, fiber and hydrated lime on water stability and mechanical property of asphalt mixture were studied. The test results show that the splitting strength of asphalt mixture gradually decreases with the increase of action number after treated by different ways. The method of dry-wet cycle reflects the adverse effect of salty and humid environment on the performance of asphalt mixture better. Dry-wet cycle in 10% NaCl solution for twelve times is recommended to simulate the corrosion effect of salty and humid environment. After treated by dry-wet cycle in 10% NaCl solution, the high temperature performance, low temperature crack resistance and water stability of asphalt mixture all decrease by various degrees. Especially the water stability declines seriously, which residual stability and freeze-thaw splitting strength ratio cannot meet the requirement of specification. The void ratio of asphalt mixture increases first and then stabilizes with the increase of dry-wet cycles. The chloride crystal precipitates and continues to expand in the mixture, which eventually leads to the performance deterioration of asphalt mixture. Among different additives, basalt fiber achieves best effect in combating the deterioration of asphalt mixture in salty and humid environment.