Research On The Influence Of Percent Air Voids And Percent Air Connected Voids On The Performance Of Asphalt Mixtures

Compared with the cement concrete pavement, the asphalt pavement has been the main form of high-type highway because of its many advantages, in the meantime water damage has becomes the main cause of early damages of asphalt pavement. The size of percent air voids and connected air voids are key factors to water can flow in and outflow pavement structure in time, therefore, there is a close relationship between percent air voids, percent air connected voids and water damage. Considering the characteristics of rainfall concentration and lager instantaneous rainfall in Hulun Buir area of Inner Mongolia and the requirement of the construction of sponge city in China, studying the effect of percent air voids, percent air connected voids on the performance of asphalt mixtures is important significance.In this paper, the experiments and researches on the five aspects of AC-13 and SMA-13 2 kinds asphalt mixtures of typical upper layer are carried out. First, by comparative analysis methods of calculation and vacuum, the method of testing maximum theoretical specific gravity of ordinary asphalt mixtures is recommended. Second, the relationship between percent air voids and percent air connected voids is further analyzed by studying the factors of affecting percent air voids and percent connected air voids, including water absorption of Marshal specimen, bulk specific gravity, asphalt aggregate ratio and water absorption of aggregate. Third, through the experiments, the effect of percent air voids on pavement performance of asphalt mixtures are studied, including anti-rutting performance and fatigue performance. During the fatigue test, load, water and percent air voids on fatigue performance are considered comprehensive by using the self-made water tank. Fourth, through vertical water seepage testing, the effect of percent air voids and percent air connected voids on water seepage performance is studied. Finally, the permeability coefficients at different slopes of 300mm×300mm×50mm specimens are determined by using the self-made transverse drainage test equipment, and the effects of percent air voids and percent air connected voids on drainage performance during different slope are discussed.Through lots of experiments and research, the percent air voids on the best anti-rutting performance and anti-fatigue performance of AC-13 and SMA-13 2 kinds of asphalt mixtures is 7% and 3.6%、3.5% and 3.2%. The minimum percent air voids and percent air connected voids of the two kinds of asphalt mixtures when water can be discharged smoothly is 7.2% and 2.8%、5.1% and 2.9%. Combined with specification and natural environment of Hulun Buir area, the measures of reducing water damage and the controlled standard of compaction degree during the construction are gave.