Design And Performance Evaluation Of Grouting Asphalt Pavement With Low Heat Absorbing Ability

The high heat absorption characteristic of asphalt pavement leads to high pavement temperature in summer,which is easy to cause a series of pavement high-temperature distresses.As a result,after material composition optimization,a grouting asphalt pavement with low heat absorbing ability was designed based on thermal resistance and thermal reflection technologies,so as to reduce the heat absorption and temperature of pavement structure.In this paper,four matrix asphalt mixtures with different air voids contents（21%,24%,27%and 30%）were designed,and their road performances were evaluated by dynamic creep,immersion Marshall,low-temperature bending and semicircular bending fatigue tests.The results show that increasing the air voids contents of matrix asphalt mixture could enhance its high temperature performance and water stability,and reduce its low temperature performance and fatigue performance when the applied stress ratio higher than 0.35.Thermal resistance grouting asphalt mixture was prepared by using grouting material with low thermal conductivity The mesoscopic heat transfer model of grouting asphalt mixture were established through CT scanning.After that the effects of thermal conductivity of grouting material and void characteristics of matrix asphalt mixture on heat transfer performances of grouting asphalt mixture were analyzed.The results show that decreasing the thermal conductivity of grouting material and increasing air voids contents of matrix asphalt mixture could effectively reduce the equivalent thermal conductivity of mixture.Reflective grouting material was prepared by using magnesium phosphate cement as binder and reflection matrix material,and then Ti O₂was added as reflection reinforce.The color characteristic,mechanical strength,reflectance and bond property were tested.The possibility of practical application of thermal reflection grouting asphalt mixture was evaluated by wear resistance test,slip resistance test,visual effect test and cooling effect test.The results show that thermal reflection grouting material had good wear resistance,reflection effect and bonding strength.When Ti O₂ content was 20%,the reflectance of grouting material could reach 61.64%.Aa a result,the maximum surface temperature of the grouting asphalt mixture reduced by 20.2℃,and it had excellent cooling durability.According to the pavement temperature field model,the heat flux and temperature distribution in the pavement were investigated when grouting asphalt mixture with low heat absorbing ability was applied on the top layer.The results show that the thermal reflection and thermal resistance structures reduced the heat absorption of the pavement surface and the top layer respectively.Therefore,asphalt pavement with low heat absorbing ability had the most significant cooling effect at the depth of4cm.Compared with traditional asphalt pavement,the heat flux and maximum temperature of the asphalt structure reduced by 48.3%and 13.1℃at the depth of 4cm respectively,and the model results were verified by an indoor irradiation test.