湿度-尾气共同作用对沥青混合料抗滑性能的影响

Effect of Humidity-tail Gas Combined Action on Skid-resistance Performance of Asphalt Mixture

摘要:

基于尾气排放在隧道沥青路面表面形成油膜进而导致路面抗滑性能快速衰减的工程背景，探究了湿度-尾气共同作用下沥青混合料抗滑性能的衰减规律及尾气油膜的形成机理。采用恒温恒湿养护箱及自制尾气处理系统对三种沥青混合料车辙板试件进行了不同湿度-尾气组合作用的模拟，并测试试件摆值用于表征试件的抗滑性能。除此之外，对有水（无水）尾气-沥青界面进行了分子动力学模拟，用以探究尾气油膜形成的微观机理。结果表明，在相对干燥和完全潮湿条件下，随着尾气处理时间的增长三种沥青混合料试件摆值呈现线性下降趋势，完全潮湿条件下尾气处理1h后OGFC混合料抗滑性能衰减幅度较其余两种混合料低近30%，OGFC混合料具有优异的抗滑性，并且在湿度-尾气共同作用下还具有良好的抗滑耐久性。尾气油膜导致的沥青混合料抗滑性能衰减难以自然消散且具有累积效应，是导致沥青混合料抗滑性能快速衰减的主要原因。尾气油膜主要形成在尾气排放后冷却的过程中，水分子主要存在于尾气分子附近0~5?范围内填充尾气分子间空隙，其自身较强的极性能够吸引尾气分子并有助于尾气在沥青分子表面的吸附。

Abstract:

Based on the engineering background that the vehicle exhaust emission forms oil film on the surface of tunnel asphalt pavement， which leads to the rapid attenuation of pavement skid-resistance performance， the attenuation law of asphalt mixture skid-resistance performance under the combined action of humidity and tail gas and the formation mechanism of tail gas oil film are explored. Using constant temperature and humidity curing box and self-made exhaust gas treatment system， the combined effect of different humidity and tail gas on three kinds of asphalt mixture rut plate specimens was simulated， and the British pendulum number （BPN） was used to characterize the skid-resistance performance of the specimens. In addition， molecular dynamics simulation was carried out on the water （anhydrous） tail gas - asphalt interface to explore the micro mechanism of tail gas oil film formation. The results show that the British pendulum number of three asphalt mixtures shows a linear downward trend with the increase of tail gas treatment time under relatively dry and completely moist conditions. After tail gas treatment for 1h under completely moist conditions， the attenuation range of skid-resistance performance of OGFC mixture is nearly 30% lower than that of the other two mixtures. OGFC mixture has better skid-resistance performance， and has good skid-resistance durability under the combined action of humidity and tail gas. The skid-resistance performance of asphalt mixture caused by tail gas oil film is difficult to dissipate naturally and has cumulative effect. Tail gas oil film is the main reason for the rapid attenuation of skid-resistance performance of asphalt mixtures. The tail gas oil film is mainly formed in the process of cooling after the tail gas is discharged. Water molecules mainly exist in the range of 0~5 ? near the tail gas molecules， filling the gap between tail gas molecules. Its strong polarity can attract tail gas molecules and contribute to the adsorption of tail gas on the surface of asphalt molecules.