Thermal performance and corrosion resistance of structural-functional concrete made with inorganic PCM

Over the last few years, phase change materials (PCMs) have been proved capable to improve the thermal performance of cement-based materials. However, the issues of inorganic PCM leakage and corrosion have led to apprehension. The present study aims to investigate the feasibility of using a dual-layer coating system to improve leakage and corrosion resistance of concrete made of macro-encapsulated inorganic PCM-lightweight aggregate (PCM-LWA). The coated PCM-LWA system is referred to thermal energy storage aggregate (TESA). The effect of TESA at different volume fractions on mechanical, thermal and corrosion performances of concrete were investigated. Test results indicated that the compressive strength of TESA concrete reduced by 6-9% compared to the LWA concrete. However, TESA concrete did not lose strength when subjected to thermal cycles between 15 and 40 ℃, which represents the thermal reliability of TESA system. The thermogravimetry analysis and differential scanning calorimeter test results indicated that the PCM was thermally stable and reliable. The thermal performance test demonstrated the feasibility and functionality of using TESA in concrete structures. Infrared thermography camera indicated that the surface temperature of TESA concrete was lower than that of the control mixture. The accelerated corrosion test demonstrated the significant role of the dual-layer coating system, which can reduce the leakage of PCM and avoid the detrimental impact of inorganic PCM on the corrosion of reinforcing steel. Besides, the permeability resistance of concrete was improved using TESA.