Study On Temperature Control And Pavement Performance Of Composite Phase Change Material For Asphalt Concrete

Asphalt pavement has been widely used in expressways and urban roads because of its advantages of high smoothness,good comfort and low noise,but in the hot summer,asphalt pavement is easy to produce rutting,crack,lapse and other problems,which seriously affect the service performance and life of asphalt pavement.At the same time,the asphalt pavement at high temperature will release organic volatiles and heat to the environment which will affect people's living environment.In this paper,based on the heat storage theory of phase change materials,the composite phase change materials are prepared.The phase change asphalt concretes are prepared by different mixing methods,and the temperature regulation effect of reducing the heating rate and the peak temperature of the asphalt pavement is realized at high temperature.Phase change materials are added into asphalt concrete in two ways.The first kind is to prepare phase change aggregate by replacing aggregate with different proportions and equal volume and then to prepare phase change asphalt concrete.The second kind is to lapping composite phase change material into powder,and the phase change asphalt is prepared by adding it to asphalt in different proportions(into asphalt mass),and then the phase change asphalt is prepared.Phase change asphalt concrete is prepared from phase change asphalt.According to the technical requirements and construction technology of asphalt pavement engineering materials,1:1 solid-liquid paraffin and polyethylene glycol 2000(PEG2000)are selected as phase change materials,and four composite phase change materials are prepared by vacuum adsorption,including 1:1 solid-liquid paraffin-ceramsite,1:1 solid-liquid paraffin-expanded perlite,PEG2000-ceramsite and PEG2000-expanded perlite.The composite phase change materials are prepared by packaging materials with different proportions.The optimum encapsulation process is determined by thermal stability.The phase transition temperature and the enthalpy of phase change are measured by the step cooling curve,DSC and scanning electron microscope test.The PEG2000-expanded perlite phase change bitumen is prepared,and its penetration,softening point,ductility,aging property,aggregate adhesion and temperation regulation are measured,and five composite fixed phase change materials and PEG2000-expanded perlite phase change asphalt are prepared into five corresponding phase change asphalt mixtures,and their thermal conductivity,specific heat capacity,temperature regulating performance and road performance are tested.The test results show that the phase transition temperature of 1:1 solid-liquid paraffin and PEG2000 are lower than the bituminous softening point and meet the requirements.The best encapsulation process is epoxy resin,curing agent and absolute ethanol with mass ratio of 7:3:1.The thermal stability of the composite phase change material after the encapsulation is good,and the mass loss rate after the 100 phase transition is only 1.28%.With the increase of the amount of phase change materials,the needle penetration and ductility of the phase change asphalt gradually decrease,the softening point and aging property increase gradually,the adhesion properties of phase change asphalt and aggregate have hardly change,and the temperature regulating performance gradually increase.with the increase of the content of the composite phase change material,the specific heat capacity of Phase change asphalt concrete increase,the thermal conductivity reduce,the effect of temperature regulation is obvious,and the pavement performance of the phase change asphalt mixture reduce.When the content of phase change material in phase change asphalt concrete made by phase change asphalt is 15%,the water stability of the phase change asphalt concrete does not meet the requirements of the standard,but the performance of the other four kinds of phase change asphalt concretes meet the requirements of the standard.