Research On Clogging Characteristics Based On Porous Asphalt And Pervious Concrete Of Mesoscopic Structure

Due to rapid urbanization,most places are covered with impervious materials,such as cement concrete,dense-graded asphalt mixtures,etc.,which seriously affect groundwater level.At the same time,during heavy rain,flooding heavily affects vehicle traffic.Pervious roads are an effective way to minimize these problems.Pervious concrete(PC)and porous asphalt concrete(PAC)are common pervious pavement materials.At present,scholars at home and abroad focus on the permeability and anti-clogging of a single mixture,but there are relatively few comparative studies on the microstructure of these two mixtures.This study explores the permeability and clogging characteristics of pervious concrete and porous asphalt concrete from the perspective of the mesoscopic structure of the mixture.From two aspects: surface physical and chemical differences of cement paste and asphalt material and internal void structure differences,this paper mainly explains and analyzes the differences of permeability and clogging characteristics of the two kinds of mixture having the same void ratio.Differences in properties of cemented materials.First of all,through experiments to study the adhesion difference between the surfaces of the cement paste and the asphalt material and clogging materials(graded loess particles),it was found that clogging materials were more likely to adhere the surface of asphalt material.Secondly,using molecular dynamics simulation technology to simulate the microscopic adhesion behavior of plugs on the surface of hydrated calcium silicate and asphalt was used to further explain the reason for the difference in adhesion.Finally,by using laser scanner to scan the surface of the two materials and find the dielectric constant of the two materials,it was found that the surface texture of the asphalt material was smoother and the dielectric constant was lower,which indicates that the surface of the asphalt material has a larger contact area with the micro particles and is prone to generate static electricity easier to adsorb fine particles and cause the permeable mixture to clog.Differences in the void structure of the two permeable mixtures.First of all,from the selection of the gradation of the mixture to the formation of the test specimens,strict control was exercised;Secondly,through the test piece slicing and digital image processing technology,the two-dimensional void structure inside the test piece was obtained,and a method for evaluating the uniformity of the mixture was proposed.It was found that the internal void distribution of the pervious concrete was more uniform when the design void was the same.At the same time,the influence of curvature on drainage was studied.It was found that the greater the curvature of pores,the lower the drainage efficiency.Through experiments and simulation studies,it was found that the main reasons leading to the difference in permeability and clogging characteristics of pervious concrete and porous asphalt concrete at the same porosity: one was the difference in surface texture and adhesion characteristics between the asphalt material and the cement paste material;the second was that the internal void distribution of pervious concrete is more uniform than that of porous asphalt concrete.