Diffusion Characteristics and Influencing Factors of Water Vapor in Asphalt Mixture

Abstract:

In order to explore the diffusion law and influencing factors of water vapor in asphalt mixture， a penetration water vapor diffusion test device was designed， and three types of asphalt mixtures with porosities of 7%， 17%， and 24% were prepared. Water vapor diffusion tests were conducted at 25℃， 30℃， and 40℃， respectively. The results show that the diffusivity of water vapor in asphalt mixture increases with the increase of temperature. The porosity plays a dominant role in the diffusion of water vapor in asphalt mixture at a lower temperature （25℃ and 30℃）， and temperature plays a dominant role at a higher temperature （40℃）. The diffusivity of two porous asphalt mixtures is obviously higher than that of dense asphalt mixture. The amount of water vapor accumulation in asphalt mixture increases with the increase of porosity and decreases with the increase of temperature. The TSR decreases with the increase of water vapor accumulation. The results indicate that both porosity and temperature have a significant effect on diffusivity， and the higher the temperature， the more significant the effect of porosity on the diffusivity. The higher the porosity， the more significant the effect of temperature on diffusivity. The water stability of dense asphalt mixture is more affected by water vapor diffusion.