Preparation and properties of fatty acids based thermal energy storage aggregate concrete

This paper aims to study the influence of macro-encapsulated phase change material (PCM) aggregate on the workability, mechanical strength, early age hydration temperature rise and thermal properties of cement concretes. A ternary fatty acid eutectic composed of laurie acid, myristic acid and palmitic acid was used as PCM, and diatomite and ceramsite based thermal energy storage aggregates were manufactured by using a direct impregnation treatment. The results show that the PCM has a melting temperature of 31.1 °C and latent heat of 166.6 J/g. The PCM adsorption volume in pore system reaches 28.1% and 89.8% of the total porosity for ceramsite and diatomite respectively. The addition of thermal energy storage aggregates decreases the slump at fresh status, compressive strength and thermal conductivity of concrete. Concrete incorporating 80% of thermal energy storage aggregate by volume has a compressive strength of higher than 18 MPa. Diatomite based thermal energy storage aggregate presents a better effect on controlling the early age hydration temperature rise than ceramsite based one. The incorporation of thermal energy storage aggregate significantly improves the temperature fluctuation in the testing room when exposed to a heating-cooling environment. Therefore, this developed thermal energy storage aggregate concrete has a great potential for improving the thermal comfort of buildings in severe climates.