Preparation Of Phase Change Microcapsule For Snow Melting And Research On Performance Of Phase Change Asphalt And Mixture

The icy pavement in the northern regions in cold weather has seriously affected the safety of transportation on the road,which may cause huge dangers to the normal operation of the national economy.Considering the problem of pavement freezing,a new methord was proposed to autometically adjust the temperature of asphalt pavement.In this paper,phase change microcapsules were developed and added into the asphalt pavement,where the energy can be stored when the ambient temperature is higher than the phase change temperature and the latent heat can be released at lower temperatures through phase change process.As a result,the cooling process of the pavement can be delayed and the ice on the surface may be melt autometically.In this paper,in-situ polymerization method was used to prepare the microcapsules in which tetradecane wae used as the phase change core material and urea-melamine-formaldehyde resin was fabricated as the shell material.This materials can store energy and release latent heat under low temperature conditions.The effects of different emulsification process,wall material composition and wall forming conditions were studied through scanning electron microscope(SEM),laser particle size analyzer,differential scanning calorimeter(DSC)and thermogravimetric analyzer(TG)under which the morphology,particle size,latent heat and thermal stability of microcapsules were investigated As a result,the best methord was determined to fabricate this microcapsules.Under this process condition,the morphology result showed that the microcapsule particles were regular and uniform and the surface was smooth,DSC test result showed its latent heat value of was up to 119J/g.The laser particle size analyzer showed the particle size of the microcapsules was concentrated at 10?m?20?m.The microcapsules obtained under the optimal preparation process conditions were added to the asphalt in stirring way to prepare phase-change asphalt.The chemical composition,three major indexes and rheological properties were analyzed which shown that the performance of phase change asphalt has not changed significantly compared with the general asphalt,microcapsules and asphalt did not chemically react,the microcapsule shell material has good sealing performance,only a small part of the core material leaked and entered into the asphalt which becomed a lightweight component in asphalt.After the preparation of phase change asphalt,the phase change asphalt mixture was also prepared to analyze its thermophysical properties.Based on the transient plate heat source method,the unsteady state thermal conductivity method and DSC indirect measurement method,the thermal conductivity,thermal diffusivity and specific heat capacity of the phase change asphalt mixture were investigated.The results showed that the thermal conductivity and specific heat capacity of the phase-change asphalt mixture were abruptly changed in the phase-change temperature domain,The thermal diffusivity of the phase-change asphalt mixture was also slightly higher than that of the ordinary asphalt mixture.The change of thermal parameters indicated that the phase-change asphalt mixture had good temperature regulation characteristics in the corresponding temperature range.Temperature adjustment test under outdoor and indoor conditions was investigated and the temperature adjusting ability of phase change asphalt mixture in winter low temperature was evaluated.The effect of temperature delaying can be found due to the release of latent heat during the temperature decreased.In the actual snowfal,the rutting board with microcapsules can reduce the adhesion of the snow with surfacelayer.At the end of this paper,the road performance research of the phase change asphalt mixture was carried out.The research showed that the performance of the phase change asphalt mixture was good,the microcapsules did not have much adverse effect on its performance.