Study of a thermally enhanced mortar incorporating phase change materials for overheating reduction in buildings

Abstract

The use of thermal energy storage systems incorporating Phase Change Materials (PCM) as passive thermal regulators, in innovative buildings’ applications is an increasing trend and promising strategy for maintaining indoor thermal comfort while promoting buildings’ energy efficiency in a sustainable way. Incorporating PCM into mortars enhances their thermal properties but modifies physical and mechanical characteristics. This paper presents an experimental research on the microstructural, mechanical, and thermal properties of innovative cementitious mortars incorporating two different microencapsulated PCMs, targeted for low thermal mass constructions located in warm climates.The characterization was developed in three steps: microstructural evaluation using scanning electron microscopy; physical and mechanical characterization by workability, density as well as compressive and flexural strength tests; and thermal characterization through enthalpy-temperature curves, determined with differential scanning calorimetry, and the assessment of real case application to evaluate the impact over the thermal behaviour of a lightweight constructive solution with the developed mortars as inner finishing layer using the hot box heat flux metre method at steady-state conditions. Results revealed an expressive decrease in flexural and compressive strength; significant loss of latent heat capacity and variations of onset and peak melting temperatures were observed; good correlation between thermal conductivity and mean specimen temperatures were attained for the lightweight opaque building solution tested with the two different PCMs, for temperatures below and above the phase change transition zone.