Evaluation of Thermal Performance of Cork Impregnated with Phase Change Material in Cement Composite

Abstract

Rising CO2 emissions from the building sector, responsible for over 40% of global energy consumption, significantly contribute to climate change. The high energy demand, driven by population growth and using heating, ventilation and air conditioning (HVAC)system, is a major source of CO2 emissions. Phase Change Materials (PCMs), known for their high latent heat and heat absorption/release during phase changes, enhance energy efficiency. However, challenges like leakage in cement composites limit PCM use in construction. Encapsulation technologies and Shape Stabilized PCMs (SSPCMs) using porous materials have been explored to address these issues. This study aims to enhance PCM application by utilizing cork granules as shape-stabilizing materials, using their low thermal conductivity and density. Existing studies have demonstrated cork's positive thermal performance in cement composites. In this study, parafol 20z and paraffin wax were utilized with melting temperatures of 35°C and 46°C, respectively. Cork and PCMs were impregnated to produce thermal storage aggregates (TESAs), with 100% substitution of sand in the mortar. Various experiments were conducted to evaluate the mechanical and thermal properties of the fabricated mortar. Despite noticeable reductions in strength and increasement in absorption rate in specimens with applied TESAs, the values remained within acceptable ranges. Specimens with TESA demonstrated significant improvement in thermal performance compared to control specimens. This enhancement is attributed to the heat absorption through latent heat storage within the PCMs in cork, particularly causing heat transfer delay at the melting points of each PCMs. The proposed research could contribute to sustainable construction practices, reducing CO2 emissions.