Investigation of thermal and mechanical performance of composite PCM mortar incorporated with graphene nanoplatelets

Abstract

The growing need for energy-efficient and sustainable construction materials has driven research into phase change material (PCM)-incorporated cementitious composites. However, directly incorporating PCM into cementitious materials presents several challenges, including leakage and reduced mechanical strength, which hinder their practical application. To address these limitations, shape stabilization techniques have been employed to improve the integration and stability of PCM in cement-based composites. Among these approaches, composite phase change materials (CPCM) have been developed by encapsulating PCM within a stable matrix, effectively preventing leakage and enhancing mechanical performance. However, PCM still exhibits limitations such as supercooling and low thermal conductivity, which reduces its heat transfer efficiency. This study investigates the impact of graphene nanoplatelets (GNPs) on the thermal and mechanical properties of CPCM incorporated mortar. CPCM was synthesized by impregnating PCM into activated carbon and coating it with a silica shell using the sol-gel process to prevent leakage. Differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA) confirmed the thermal performance of CPCM, with enthalpies of 35.45 J/g and 33.89 J/g during melting and freezing, respectively. Mortars were prepared by replacing 50 % of fine aggregates with CPCM and incorporating GNPs at 0.05 %, 0.1 %, and 0.15 % by cement weight. While CPCM mortar exhibited a 12.78 % strength reduction, adding 0.1 % GNPs recovered 8.32 % of the lost strength. GNPs also enhanced thermal response, leading to a 1.52 °C higher temperature rise compared to reference mortar. Thus, the incorporation of GNPs significantly enhances thermal and mechanical performance of CPCM mortar, making it a promising solution for construction applications.