气态水在沥青混合料中的扩散特性和影响因素

Diffusion Characteristics and Influencing Factors of Water Vapor in Asphalt Mixture

摘要:

为了探究水汽在沥青混合料中的扩散规律及影响因素，设计了穿透型水汽扩散试验装置，制备了7%、17%和24%这3种空隙率的沥青混合料试件，分别在25℃、30℃和40℃下进行水汽扩散试验。研究发现水汽在沥青混合料中的扩散速率随着温度的增大而增大，在较低温度下（25℃和30℃），空隙率对沥青混合料的水汽扩散速率起主导作用，在较高温度下（40℃），温度对水汽扩散速率起主导作用，2种多孔沥青混合料的水汽扩散通量和扩散系数明显高于密级配沥青混合料；水汽在沥青混合料中的积聚量随空隙率的增大而增大，随温度的增大而减小。结果表明温度和空隙率均对水汽扩散有显著性影响，且温度越高，空隙率影响越显著；空隙率越大，温度影响越显著。

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.