Study On The Mortar And Composition Of Pervious Asphalt Mixture

With the rapid development of highway in China, higher and higher requirement for road-performance is put forward. Traditional dense-graded asphalt pavement has many problems which influence driving safety especially on rainy days. Meanwhile drainage asphalt pavement is one of the effective means to solve these problems. However, the composition, performance and construction technology of drainage asphalt mixture are different from dense-graded asphalt mixture. Therefore, systemic study for mortar of drainage asphalt mixture is extremely important in theoretic value and project significance for its application.In this paper, it is studied of physical and mechanical characteristics and rheological properties for different modified asphalt mortar with high viscosity composed of different asphalt binders and mineral fillers. It is found that asphalt binder is the main factor influencing the mortar properties compared to mineral filler. And different characteristics lay out of different asphalt mortar with different rate of filler to asphalt at different temperature. Meanwhile, the results of DSR and Brookfield test indicate that temperature susceptibility of asphalt mortar with high viscosity increases with the increasing of rate of filler to asphalt, and viscosity of asphalt mortar and rut factor G*/sinδboth decrease with increasing of temperature. Also it can be shown that viscosity-temperature curves satisfies power function and rut factor and temperature satisfies index function. The cone penetration test indicates that temperature susceptibility of asphalt mortar is the lowest when the rate of filler to asphalt is 1.2. Bending test results at low temperature of-10℃for mortar and mixture show that asphalt mortar is one main factor influencing the performance of mixture and low temperature performance of asphalt mortar can imply that of mixture perfectly in the rate of filler to asphalt of 1.2-1.4.Considering high void ratio and skeleton structure in drainage asphalt mixture, new test ranges for FAc and FAf are suggested adapting to the gradation of drainage asphalt mixture. Meanwhile, a new design index for mineral composition, VMA*, is introduced. Consequently, the new method for design of drainage asphalt mixture based on VMA* is put forward. Tests for influence of passing percentage to air void and effective air void have been done in the lab, and a key sieve is put forward for mineral composition design which provides reference for gradation optimizing. Besides, shape factor SFn,i of aggregate is introduced to establish the model for surface areas calculation. Finally asphalt film thickness is calculated with 3D t-model and reasonable thickness of 13μm is suggested for drainage asphalt mixture. Collecting the research findings in this paper, composition design method for drainage asphalt mixture based on VMA* is put forward by analyzing materials indices, studying asphalt mortar properties, determining aggregate composition design index, building prediction model for asphalt content and evaluating mixture performance.