The Application Of Phase Change Material In The Semi-flexible Pavement

Asphalt pavement use more and more widely and asphalt pavements as a heat source tothe atmosphere emits radiation, causing severe urban heat island effect. Therefore, we needmeasures to reduce the urban heat island effect. Because of the great reflection rate,semi-flexile pavement becomes a bargain-hunting hot pavement. We mix a kind of a phasechange material in the semi-flexible pavement, so we can control temperature more active andeffective.On basis of temperature requirements of the phase change materials for semi-flexiblemixture, PEG2000is selected at45.2℃, and by DSC test the phase change enthalpy is138.9J/g. To solve the leakage problem of the phase change material, the shape-stabilized phasechange material is made by Sol-Gel approach and physical adsorption. In Sol-Gel reaction,when TEOS-water ratio is1:8, the reaction temperature is80℃,the silane coupling agentcontent is10%of the content of TEOS, the content of PEG2000is80%,the dying temperatureis60℃,the performance of the SiO₂/PEG2000is best. By DSC test characterization, thephase change temperature of the shape-stabilized phase change material is44.9℃; the phasechange enthalpy is99.8J/g. In the preferred case of adsorption, diatomaceous earth/PEG2000and activated carbon/PEG2000in the mass fraction is33%and46%. The phase changetemperature are46.77%、47.69and the phase change enthalpy are44.82J/g,49.10J/g.Because the SiO₂created by Sol-gel haves greater phase change enthalpy, we close theSiO₂/PEG2000preparation for the phase change semi-flexible mixture.Because the SiO₂created by Sol-gel is amorphous substance, so we wrap theshape-stabilized phase change material by emulsified asphalt. Cement, water, sand, bulkingagents, polymer emulsion and phase change material as raw material product phase-changecement mortar. The16%content of the shape-stabilized phase change material is preferred byfluidity, compressive and flexural strength of7d.OGFC as the maternal asphalt mixture,phase-change cement mortar is poured the maternal asphalt mixture so that Phase ChangeSemi-flexible Pavement is formed. The performance test of the shape-stabilized phase changematerial in semi-flexible mixture indicates that the composite shape-stabilized phase changematerial affects at low temperature performance, water stable performance of asphalt mixture and high-temperature performance and they meet the current specifications for asphaltpavement requirements. Thermostats indoor simulation experiment concludes that thedifference in temperature between the phase change semi-flexible pavement and the AC-13asphalt mixture is4.4℃.According to near-Earth atmospheric heat balance state, we analysehow the temperature change on the road surface affects the active radiation and convectionheat transfer.So we can evaluate the effect of the phase change semi-flexible pavementreducing the urban heat island effect.