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In the seasonal frozen regions, freeze-thaw (F-T) damage is the main pavement damage, causing a variety of poor conditions in bitumen pavement, such as cracks, pits, potholes, and slush. In previous studies, we evaluated the effect of nano hydrophobic silane silica (NHSS) on the degradation of asphalt mixture under F-T cycles, and established the damage model of NHSS modified asphalt mixture in spring-thawing season. To gain more understanding of the influence of NHSS on asphalt in spring-thawing season, NHSS modified asphalt was systematically analyzed under F-T aging process in this study. The main research objective of this paper was to investigate the deteriorating properties of NHSS modified asphalt under Freeze-thaw aging process. Within this article, the physicochemical characteristics of NHSS modified asphalt were determined by using various laboratory tests, which included basic property test, dynamic shear rheometer test (DSR), Fourier transform infrared spectroscopy test (FTIR) and thermogravimetric analysis (TGA). The results showed that the incorporation of NHSS could inhibit the F-T aging process of asphalt. Moreover, the chemical composition and thermal stability of asphalt under F-T aging process was analyzed through FITR and TGA test parameters. The results illustrated that the sulfoxide functional groups content index was more suitable for evaluating the aging degree of asphalt in the spring-thawing season and the F-T aging process had a great impact on the thermal property of NHSS modified asphalt.

This study mainly uses PFC (particle follow code) to simulate the void characteristics of permeable asphalt mixture, and uses these to simulate the silting process. Then, a tire drop test was used to evaluate the noise reduction performance of permeable asphalt concrete. Finally, a self-made ring rutting test machine was used to simulate the silting process. Through experiments, the following conclusions were obtained: 1. The critical size of the sludge particle size is 0.3 mm–0.6 mm. 2. The quality of the water-permeable asphalt concrete specimens increased by 13% before and after silting, and the porosity of the specimens finally decreased from about 20% to about 8%. The water-permeable function only retained less than 20% of the original, and the water-permeable function was basically lost. 3. By measuring the road noise detection, it was found that the road noise is directly proportional to the degree of blockage of the permeable road. Compared with the original road with a perfect permeable function, the road noise of the completely blocked road increased by about 4 decibels. This study reveals the silting process of permeable asphalt mixture and the key particle size of the silt, which is of great significance for the detection, cleaning and maintenance of permeable asphalt pavements.

Dynamic water scouring damage is the main cause of pavement structure damage, and the main reason for dynamic water scouring damage is the rapid change of pore water pressure caused by vehicle load. Numerical simulation is a commonly used pore water pressure test technology, but its accuracy is not high, and the test data are very different to actual values. In this study, a pore water pressure test method is designed, which has the advantages of less disturbance to the pavement structure and the measured data are closer to the true pore water pressure value of the pavement structure. Measurement data show that the pore water pressure gradually increases with increasing vehicle speed, and the pore water pressure response time becomes shorter. The pore water pressure response time is greater than vehicle loading time. Moreover, the phenomenon of periodic decay of pore water pressure with time is analyzed based on hydrodynamic water hammer theory. The empirical formula of maximum positive pressure with speed and the empirical formula of Abp at different speeds were obtained.