| Based on the National Natural Science Fund project of China(51508063),aiming at the problems of thermal stability and urban heat island effect of asphalt pavement under high temperature,a new type of composite phase change materials(PCMs)was developed according to phase change theory.Then,PCMs were blended with asphalt mortar to form eomposite phase ehange heat storage asphalt mortar,and the technical performance of and mechanism of temperature regulation of heat storage asphalt mortar was studied.Firstly,PEG/SiO2 FS-PCMs were successfully prepared by sol-gel method.The results show that PEG/SiO2 FS-PCMs possess commendable thermal and chemical stability,and the phase change enthalpy is as high as 116.4 J/g.After several thermal cycles,the heat storage performance and chemical structure are still stable,and the thermal conductivity of PEG/SiO2 FS-PCMs is also significantly higher,which improves the sensitivity of thermal response,implying that PEG/SiO2 FS-PCMs can be used for heat storage and temperature control in asphalt pavement.Then,PEG/SiO2 FS-PCMs particles were mixed into asphalt mortar with different mass ratios,and the effects of PEG/SiO2 FS-PCMs on the technical properties of asphalt mortar were investigated by heat storage performance,temperature sensitivity,rheological properties,aging resistance and microstructure characterization tests,respectively.The results show that there is no chemical reaction between PCMs particles and asphalt mortar,as a result,PCMs particles can still play a good role of phase change heat storage in asphalt mortar and reduce the temperature sensitivity of asphalt mortar.In addition,PCMs particles can significantly enhance the rheological properties of asphalt mortar at high temperature,and enhance the high temperature stabilitym,and effectively improve the thermal oxygen aging resistance of asphalt mortar.Finally,the phase change heat transfer model of thermal storage asphalt mortar was established by using Fluent software.The results show that the heat transfer mode of PEG/SiO2 FS-PCMs is mainly heat conduction in the initial stage of melting.With the passage of heating melting time,natural convection gradually dominates the heat transfer mode,and heat transfer mode is mainly heat conduction in the solidification process.The cooling test shows that the peak temperature of asphalt mortar with 30%PEG/SiO2 FS-PCMs is the lowest and the maximum cooling range is 8.8?,which demonstrates that the PEG/SiO2 FS-PCMs in asphalt mortar can still play its phase change heat storage characteristics,absorb external heat,reduce the heating rate of asphalt mortar,and play a good role in heat storage and temperature regulation... |
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