Phase change materials embedded in expanded clay aggregates to develop energy storage concrete: a review

Thermal energy storage (TES) based on phase change materials (PCM) is an effective strategy to reduce energy consumption in buildings. The efficient implementation of TES in building through PCMs, requires modification of their thermal performance, appropriate design and evaluation of their thermal and economic efficiency. One major challenge in the application of PCMs is the selection of high-performance and environmental-friendly supporting materials to overcome the most critical drawback of PCMs (solid-to-liquid transition and resulting leakage). This review focuses on expanded clay (EC) lightweight aggregate (LWA), as one of the promising supporting materials for development of form-stabilized PCM (FSPCM) in the lightweight concrete (LWC) industry. The large specific surface area and porous structure of expanded clay can maintain considerable amount of PCM. In addition, mechanical properties and compatibility with various PCMs make EC a suitable carrier. A detailed review of available researches is presented to elucidate the properties of PCMs embedded in EC for thermally efficient cement-based concrete. Various combinations of EC with the most used PCMs, thermal and mechanical properties of matrices containing PCM-EC, strategies to improve the efficiency of PCM performance, and finally the impact of PCM-EC based concretes on the thermal comfort of buildings are critically summarized.