The Preparation Of Phase Change Thermal Storage Aggregate And Effect On The Performance Of Concrete

With the widening of human activities range and the improvement of people’s material conditions, it have been an important research direction that how to heighten energy efficiency and comfortableness of the buildings in extreme weather conditions(desert, plateau and cold, etc.). The subject put forward to prepare a kind of phase change thermal storage aggregate that used fatty acid eutectics as media and porous materials as matrix by superficial encapsulation and a shell-making method.Meanwhile, the effect of aggregate on properties of concrete was investigated. The concrete materials that merged he structure and temperature regulating function can be realized by using the phase change thermal storage aggregate instead of normal aggregate, which laid the foundation to solve the problems of housing and living under extreme climate.Fatty acid eutectics were prepared by studying the thermal physical properties and the properties of energy storing of the fatty acids and their multicomponent eutectics. A fatty acid eutectic was selected whose phase change temperature was 31.14℃ and phase change latent heat was 166.63J/g. The fatty acid eutectic had more excellent thermal stability by thermocycling and FT-IR tests. Seven weight percent graphite was added to the PCMs for the improvement of thermal conductivity to make it increased by193%.With the ceramsite and diatomite as the carrier, two kinds of phase change thermal storage aggregate with stable performance were prepared by soaking adsorption and encapsulation & shell making technology.The results showed that the flowability of concrete with the same mix proportion,the compressive strength and thermal conductivity decreased with increasing of the two types of phase change thermal storage aggregate. The compressive strength of the phase change thermal storage concrete less affected for several thermocyclings. It was found that the incorporation of phase change thermal storage aggregate can not only reduce the temperature peak, but also delay the time to reach the peak temperature. The temperature peak of concrete can cut down 5.2 ℃ in the maximum extent and the maximum delay time of reaching the peak temperature of concrete was 8.5h.In addition,the effect of regulating temperature for concrete with phase change thermal storage aggregate of different proportions can be discussed by the self-made experimental devices. The results indicated that the concrete panels by total substitution of normal aggregate for phase change thermal storage aggregate can reduce the maximum of the average temperature of the enclosed space 5.94℃ in the heating process and went up the final average temperature 5.26℃ in the cooling process. Therefore, it was useful that mixing into the phase change thermal storage aggregate to control the early-age hydration temperature rise of concrete and regulate the stability of internaltemperature of the buildings in the long-term use process.