Investigation on thermal and physical properties of geopolymer phase change energy storage concrete with paraffin microcapsules

Phase change energy storage concrete (PCMC), as an eco‐friendly building material, is gradually being promoted and applied in engineering. In the study, paraffin microcapsules (PM) were used to replace the standard sand in equal volume, and the effects of different PM replacement amounts on the performance of geopolymer phase change energy storage concrete (GPCMC) were studied. The performance indicators studied mainly include apparent density, latent heat, specific heat capacity, thermal conductivity, compressive strength, compactness, microstructure, and phase composition. The results indicate that GPCMC's apparent density decreases progressively with higher levels of PM replacement amount. Increasing PM replacement amount will enhance the latent heat and specific heat capacity of GPCMC and reduce the thermal conductivity of GPCMC. PM lowers the compressive strength of GPCMC at various ages and diminishes the ultrasonic velocity and compactness of GPCMC. The microstructures of GPCMC become looser with the increasing PM replacement amount, and GPCMC's microstructures gradually become dense and uniform with extending curing age. The kinds of hydration products in GPCMC remain unchanged by PM, nor does PM participate in chemical reactions, but it does have an inhibitory effect on the polymerization reaction of GPCMC.