Thermal storage cementitious materials containing SiO2-coated cenosphere@bio-based PCMs: Microstructural, mechanical, and thermal properties

Abstract

Integration of phase change materials (PCMs) into buildings contributes to mitigating indoor temperature fluctuations, offering opportunities for alleviating energy crisis. However, prevalent PCM integration methods commonly suffer from shortcomings in mechanical properties, compatibility, and environmental sustainability, restricting their applications. This study developed a novel shape-stabilized PCM (SSPCM) using cenospheres from coal-fired power waste and bio-based PCMs from vegetable oil by-products, subsequently sealed with silica coatings to inhibit PCM leakage and improve thermal stability, termed as SCS@PCM, exhibiting melting enthalpy up to 103.9 J/g. SCS@PCM was then integrated into cement mortars by replacing fine sand to fabricate thermal storage cement-based materials (TSCM), followed by assessments of their microstructural, mechanical, and thermal properties. The results showed that the silica coating helps to lowrer adverse impact of SCS@PCM on the compressive strength and thermal conductivity of TSCM. TSCM containing 30.0 vol% SCS@PCM reached a 28-day compressive strength of 45.3 MPa, exhibiting only a 17.4 % reduction compared to the control group, notably less than reductions observed for other SSPCMs reported in literature. Moreover, integration of SCS@PCM improved thermal storage capacities and decreased thermal fluctuation rates of TSCM, evidenced by a 4.7 ℃ decrease in peak temperature at dosage of 30.0 vol%. This study endeavors to develop an eco-friendly TSCM with excellent thermal and mechanical properties, providing insights for applications in improving the thermal regulation and energy efficiency in building roofs.