Testing and evaluation for long-term skid resistance of asphalt pavement composite seal using texture characteristics

As a common means to improve the skid resistance of asphalt pavement, chip seal is widely used for road surface treatment and preventive maintenance. As the aggregate is progressively dislodged under repeated wheel loads, continuous loss of the surface texture characteristics occurs, and its skid resistance increasingly declines. Therefore, it is necessary to further refine the process of chip seal. In addition, in order to scientifically evaluate its performance and accurately predict the deterioration, the relationship between the surface texture characteristics and the skid resistance needs to be quantitatively established. In this paper, a composite seal structure was proposed by applying sand-containing fog seal layer on top of chip seal. Firstly, four seal schemes (i.e., 3–5 mm chip seal, 5–9.5 mm chip seal, 3–5 mm composite seal and 5–9.5 mm composite seal) were designed and loaded by a four-wheel rotary accelerated abrader. Secondly, the skid resistance indexes of each scheme were investigated under different abrasion times using pendulum meter and sand patch method. In this process, the three-dimensional texture characteristic parameters (i.e., Ssk, Spd, Spc, Vmp and Vmc) of the specimen surface were also obtained by laser scanning. Finally, by analyzing the data, the relationship between the seal texture characteristic parameter and the skid resistance index was established, and the decay law prediction model of the skid resistance for four seal schemes was derived. It is found that the pendulum value and texture depth of the seal decreased with the increase of abrasion times, but the composite chip seal can reduce the decreasing rate of skid resistance index. Sq, Spd, Spc and Vmc showed good synergistic decay laws with the British pendulum number (BPN) and mean texture depth (MTD), among which Spc had the best correlation and can be used as an parameter to characterize the skid resistance of the seal. The relationship and decay prediction model established in this paper can be used to characterize the skid resistance of chip seal and predict the decay law of the skid resistance.