Study On The Preparation And Road Performance Of Phase Change Asphalt And Phase Change Aggregate

Asphalt pavement has the characteristics of high blackness and strong heat absorption capacity,which is easy to produce rutting and urban "heat island effect" in high temperature in summer.In this paper,using the heat storage characteristics of phase change materials,the phase change asphalt and phase change aggregate are prepared and temperature regulating asphalt structure layer is constructed to reduce the road surface temperature actively,which provides a new idea for the development of pavement cooling technology.(1)Ethylene Glycol Distearate(EGDS),palmitic acid(PA),polyethylene glycol(PEG)and stearic acid(SA)with high transformation enthalpy and suitable transformation temperature were selected as phase change materials,and phase change asphalt was prepared by blending them into matrix asphalt according to their mass fraction of 5%,10%and 15%.Three indexes,dynamic shear rheometer(DSR),bending beam rheometer(BBR)and contact angle test were used to study the high temperature performance,low temperature performance and water damage resistance of phase change asphalt.Fourier transformation infrared(FT-IR)test was used to explore the chemical compatibility of phase change materials and asphalt.Differential scanning calorimetry(DSC)was used to test the thermophysical properties of phase change materials,and finally the storage/exothermic properties were tested.The test results are as follows:three indexes,DSR and BBR test results show that the high temperature performance of PEG10%phase change asphalt plays an obvious role in improving the low temperature rheological properties of asphalt.The effect of 10%PEG on the water damage resistance of the base asphalt is the best.When the content of PEG is 15%,the transformation enthalpy of phase change asphalt is 21.5 J/g,and the loss rate is only 20%.It can slow down the change rate of temperature.(2)According to the characteristics of cement paste which can be hardened into cement stone with compact structure,four phase change materials(EGDS,PA,PEG and SA)are selected to be directly mixed into the cement paste and poured into the mold to prepare 9.5-13.2mm phase change aggregate.Scanning electron microscope(SEM)and energy dispersive X-ray spectroscopy(EDS)were used to study the microstructure of composite phase change aggregate.FTIR and X-ray diffraction(XRD)were used to explore the compatibility between the phase change material and the matrix.TG-DSC was used to evaluate the thermal stability.DSC was used to measure the phase change enthalpy and phase change temperature,and the thermal cycle reliability,leakage stability,heat storage,release performance and strength of the composite phase change aggregate were analyzed and evaluated.The results show that the combination mode of phase change material and cement matrix is physical combination and their chemical compatibility is good.Phase change aggregate basically has no mass loss within 200℃ which has considerable phase change enthalpy and appropriate phase change temperature.It has good thermal properties,good thermal cycle stability and antileakage stability,which can slow down the change rate of asphalt pavement temperature.(3)The above selected PEG 10%phase change asphalt and PEG 10%phase change aggregate are used to replace the corresponding asphalt and mineral aggregate of the corresponding particle size in the conventional asphalt mixture to prepare all kinds of mixture test pieces.Indoor simulated light test was used to evaluate the cooling effect of the upper and lower surfaces of the test pieces.Rut test,low-temperature bending test and immersion Marshall test are used to evaluate the high-temperature stability,low-temperature crack resistance and water stability of the asphalt mixture.The results show that cooling effect and road performance of the temperature-adjusting samples of PEG phase change asphalt+PEG phase change aggregate are both better.