Investigation On Sponge Characteristics Of Porous Asphalt Mixtures

The sponge characteristics of porous asphalt mixtures mainly include seepage characteristics,water holding characteristics and evaporation characteristics.However,under the influence of environment and load,the void structure is clogged,which resulting in the loss of sponge characteristics of porous asphalt pavement.Thus,it is of great significance to understand the sponge characteristics of porous asphalt mixtures and the evolution of sponge characteristics under clogging condition for the road construction of sponge city.At present,the macroscopic research method can not reveal the material migration law in the porous asphalt mixtures.The migration of moisture and clogging inside the porous asphalt mixtures is still unclear.On the other hand,computed tomography provides reliable technical support for analyzing the characteristics of multi-void asphalt mixture sponges from a mesoscopic level.Therefore,this research mainly studied the water migration law during seepage,water holding and evaporation process of porous asphalt mixtures,and their influencing factors were also discussed.What's more,the clogging process of porous asphalt mixtures was studied from a mesoscopic level.And on the basis of cloggong process,the evolution of sponges in the process of plugging was studied.The research contents and results were as follows:The point source seepage test was used to simulate the rainfall process.The water migration law of the porous asphalt mixtures was characterized by some evaluation index such as depth of seepage,the number of seepage paths and so on.The law of wetting front migration and the area of inertia influence are clearly defined.The migration law of the wet front and the inertia influence region were clarified,and the influence of location of seepage point,the number of seepage point and the void content of asphalt mixtures on the seepage characteristics was clearly difined.Based on the constant head immersion test,the water holding characteristics of porous asphalt mixture after water immersion were discussed.The distribution law of residual water in porous asphalt mixtures was clarified,and the effects of water immersion time,void ratio and temperature on water holding capacity were discussed.Based on the residual water in the voids of porous asphalt mixtures,the top surface evaporation simulation test of porous asphalt mixture was carried out to clarify the internal water evaporation characteristics of porous asphalt mixture,and the effect of void content and environmental factors on evaporation characteristics were discussed.Based on the constant head permeability test device,the porous asphalt mixtures clogging test was carried out.The evolution of void structure and clogging of porous asphalt mixture in the process of clogging were clarified,and the influence of void content and particle size on the void structure evolution and clogging degree was discussed.And on this basis,the seepage,water holding and evaporation tests were carried out on the specimens with different degrees of clogging.The water seepage performance,water-holding capability and the evaporation performance attenuation during the clogging process were preliminarily discussed,and the influence of the particle size of the clogging on the sponge characteristics was determined.This study clarifies the sponge characteristics of porous asphalt mixture and the evolution of sponge characteristics during clogging process,and provides a theoretical basis for the research of urban road sponge characteristics and its degradation mechanism.