Study On Adhesion Of Asphalt-Aggregate And Diffusion Process Of Water In Asphalt

Water damage of asphalt pavement is one of the main forms of its early disease.The occurrence of water damage on asphalt pavement leads to the emergence of loose,pits and other diseases on the road surface,which leads to the decline in the performance of asphalt pavement and the shortening of life span and directly endangers the safety of travel.The water damage of asphalt mixture consists of two parts,that is,the cohesion failure caused by the infiltration of water into the asphalt and adhesion damage caused by the water intrusion into the asphalt-aggregate interface.However,the cohesion failure and adhesion failure exist and interact with each other at the same time,which increases the complexity of the research.Therefore,the mechanism of water damage of asphalt pavement has not yet reached a consensus.In this paper,aiming at the problem of asphalt mixture water damage,the mechanism of asphalt-aggregate adhesion mechanism and the diffusion process of water in asphalt was studied to further explore the anti-water damage of asphalt aggregate system performance.Firstly,the factors influencing the adhesion of asphalt-aggregate system were reviewed in this paper.The main influencing factors were asphalt composition,aggregate composition,aggregate surface structure,aggregate cleanliness and water.The adhesion of three kinds of asphalt and three kinds of aggregates were studied by photoelectric colorimetric method.The results showed that there were different adhesion properties between different asphalt and different aggregates.The adhesion and desorption properties of oxides and asphalts were studied by the improved SHRP net adsorption method.The results showed that the contribution of metal oxides to the adhesion of asphalt-aggregate system was greater,while the contribution of silica to adhesion is smaller.Secondly,the adhesion work under anhydrous condition of asphalt-aggregate and the stripping work of asphalt-aggregate system under water condition into asphalt-water-aggregate system were studied by means of contact angle method.Based on the surface energy theory,the water damage resistance of different asphalts and stones were evaluated.The results showed that the better the wettability of the water and the aggregate was,the worse the water resistance of the asphalt and the aggregate was for the same kind of asphalt.For the same kind of aggregate,the better the wettability of water and asphalt was,the worse the resistance to water damage of the asphalt-aggregate system was.Finally,the diffusion process of water in different asphalt was analyzed by infrared spectroscopy.The effects of temperature,pressure and aging of asphalt on the diffusion process were studied.Based on the analysis of the asphalt water sensitive components and the surface morphology of the asphalt before and after soaking,it was to reveal the mechanism of water penetration into asphalt.The results showed that the infrared spectroscopy could be used to observe the diffusion process of water in asphalt.And the water in the asphalt diffusion process could be divided into two stages: rapid diffusion stage and slow growth stage;and it could be calculated the water in the asphalt diffusion rate remained at 10-14 level and the number of 10-13 in the fast diffusion stage;Based on the analysis of the influencing factors,the resistance to water diffusion of three kinds of asphalt was as follows: Karamay 90#> CNOOC 90# > SK 90#.Based on the analysis of the asphalt water sensitive components and the surface morphology of the asphalt before and after water saturation,a diffusion reaction model was proposed to explain the diffusion process of water in asphalt.