Study On Multi-scales Effect For Rutting Resistance Of Asphalt Mixture In Long And Steep Slope Sections

Rutting has been one of major early diseases in asphalt pavement. It is worse in long and steep slope sections because of special longitudinal slope, which has a strong effect on traffic safety. The long and steep slope sections are unavoidable as freeway extends to mountain areas. Therefore, studying the rutting resistance performance of asphalt mixture in long and steep slope sections is not only necessary, but also urgent.The main characteristics of long and steep slope sections are large longitudinal slope and low traffic speed. This dissertation focuses on the equivalent influence of speed and temperature on the rutting resistance performance of asphalt mixture based on the time-temperature equivalent principle. The results show that the falls of speed from 80km/h to 20km/h is equal to the rises of temperature from 60℃to 72.8℃, which brings higher requests for asphalt mixture. In order to analyze the rutting formation mechanism in long and steep slope sections, spatial distribution characteristics and rutting influence law were studied by rutting investigation. Then, the conclusion is that the rutting resistance performance of asphalt mixture should be improved from three aspects: high temperature rheological behavior of asphalt mastic, reasonable filling of fine aggregates and skeleton stability of coarse aggregates. Regarding asphalt mastic as research object, the effect law of filler to asphalt ratio and temperature to the asphalt mastic's high temperature rheological behavior was studied using Superpave methods on asphalt mastic. And the rheological behavior of asphalt mastic was studied under low speed according to long and steep slope sections' characteristics. Rutting resistance performance of asphalt mixture was studied from fine aggregates filling. This study process includes three steps: Firstly, the design method of asphalt mixture which was mainly around fine aggregates filling was provided; Secondly, rutting resistance performance of asphalt mixture was studied under different fine aggregates filling effect; In the end, an optimum design method was put forward. The dissertation studied coarse aggregates skeleton formation recognition and skeleton stability using uniform test on the basis of analyzing the skeleton study progress both at home and abroad from coarse aggregates skeleton, and an optimum design method was put forward at last. The influence factors for rutting resistance performance of asphalt mixture in climbing sections were studied from multi-angles and different scales in this dissertation. The way to improve rutting resistance performance of asphalt mixture was presented, and the design method for asphalt mixture in climping sections was optimized.