Phase Change Material (PCM) Supported on Basaltic Aggregate for Cementitious Mortars as a Thermal Coating

Population growth, high ambient temperatures, and longer warm periods have led to increased energy consumption related to heating and cooling systems. The building envelope plays a fundamental role in the performance of such systems to reduce heat transfer into buildings. This study evaluated the effect of incorporating phase change materials (PCMs), namely Glauber’s salt and calcium chloride hexahydrate, into a cement-based mortar. The PCMs were impregnated into basalt aggregate used as a supporting medium and encapsulated. The physicochemical, mechanical, and thermal properties of the mortars were characterized before and after PCM incorporation. The mortars with PCMs exhibited reductions in thermal conductivity of 48% and 53%, thermal diffusivity of 40% and 45%, and volumetric heat capacity of 17% and 24%, respectively, as determined according to ASTM D5334. Thermal performance was evaluated using hot-box equipment, demonstrating a reduction in the temperature fluctuation of up to 2.865 °C and average reductions in maximum temperature peaks of 0.3106 °C. Compressive strength revealed reductions of 61% and 76% relative to the reference mortar for each modified mortar. PCM-modified mortars satisfied the minimum requirements established for non-structural rendering applications and exhibited a substantial improvement in overall thermal performance. These results suggest their potential use as passive coating materials for thermal management in buildings.