Optimal Design Of Storage And Heat Transfer Structure Of Asphalt Pavement Based On Composite Phase Change Shape-stabilized Materials

Asphalt pavement can absorb a large amount of solar radiation.Heat in the same coefficient of thermal conductivity of asphalt layer three layer structure in the free transfer and accumulation,causing the pavement temperature raise.With the increase of traffic volume,ruttinngs and other pavement diseases occur under driving load,affecting driving safety.At the same time,heat release from high-temperature asphalt road facing the atmosphere is also one of the reasons for the increasing urban heat island effect.The phase change materials store and release heat energy through the phase change process to regulate the temperature.Thermal conductive material can transfer heat to change the temperature.The combined application of the above two in asphalt pavement surface can regulate the heat from the following four aspects :(1)reduce the heat into the pavement;(2)absorb the heat entering the pavement structure;(3)prevent heat from being transmitted downward in the pavement structure;(4)accelerate the downward transfer of heat in the road surface.Based on the above four principles,two thermal induced phase change structures of asphalt pavement are designed in this paper.Using finite element software Abaqus,the mechanism of action and heat transfer of phase change materials in the designed structure were studied,and the cooling effect of different structures was verified by the temperature measuring system in the design room.A Highly oriented heat-induced phase change structure(OHI-PCS)was designed based on the three principles of preventing heat from entering the road surface,absorbing the heat entering the road surface and reducing the heat transfer efficiency.The heat transfer model calculation results show that the maximum simulated temperature of OHI-PCS decreases by 3.7℃ compared with the blank structure BS.The heat down-transfer efficiency at 18 cm was reduced by 9.2%,indicating that OHI-PCS was more effective than BS in cooling and preventing heat down-transfer.The calculation results of 3D heat transfer model and 2D heat transfer model fit well.The indoor irradiation test results are in good agreement with the model calculation results.The calculation results of rutting model show that the maximum rutting depth of OHIPCS is reduced by 53.5%.A Bidirectional Heat-Induced Phase Change Structure(BHI-PCS)was designed based on three principles: preventing heat from entering pavement,absorbing heat from pavement,and accelerating heat transfer to subgrade.The calculation results of heat transfer model show that the maximum simulated temperature of BHI-PCS decreases by 4.1℃ compared with BS.The accumulated heat was reduced by 22.1%,indicating that BHI-PCS was better than BS in cooling and reducing the accumulated heat in the road surface.The calculation results of 3D heat transfer model and 2D heat transfer model fit well.The indoor irradiation test results are in good agreement with the model calculation results.The calculation results of rutting model show that the maximum rutting depth of BHI-PCS is reduced by 46.5%.The two heat-induced phase change structures proposed in this paper can provide a new idea for preventing rutting of asphalt pavement caused by high temperature and alleviating urban heat island effect.