Siltation behavior characterization and evaluation of permeable asphalt mixture based on computed tomography method

Abstract

The pavement surface sediments are continuously transported into the pore structure of permeable pavement under hydraulic power, resulting in the loss of permeability function. Obtaining the siltation behavior of the permeable asphalt mixture is the key and foundation to achieving siltation prevention and control technology for permeable asphalt pavement. In this paper, a self-developed laboratory accelerated siltation test was designed, and X-ray diffraction (XRD), computed tomography (CT) experiments, intrinsic frequency tests were employed to explore the siltation behavior of permeable asphalt mixture. The test results reveal that the density of pavement surface sediments is approximately 15.2 g/m2 per day, and pavement surface rainwater contains 27.6% clay minerals, which exhibits induration consolidation property with dry-wet cycles. The blockage behavior caused by sand particles is 7.5% higher than that caused by clay. For the siltation contribution of permeable asphalt mixture, sand particles account for 81%, clay particles represent 7%, and the induration consolidation contributes 12% of the siltation. CT test results indicate that the lower 1/3 of permeable asphalt mixture is silted up with continuous adhesive deposition of clay. The dry-wet cycle is one of the key factors of hardening blockage, the hardening blockage primarily experiences three stages: stagnation and hardening, erosion and collapse, and deposition blockage. Intrinsic frequency test explores that the intrinsic frequency of permeable asphalt pavement is between 14,000 Hz and 15,000 Hz, and the intrinsic frequency of pavement surface sediment is 3968.83 Hz. The intrinsic frequency of pavement increases continuously with the transportation of surface sediment, and there is a good correlation between the siltation degree and intrinsic frequency of permeable asphalt mixture.