Thermal and mechanical properties of ultra-high performance concrete incorporated with microencapsulated phase change material

Abstract

A novel structural–functional integrated concrete (MPCM-UHPC) with excellent mechanical properties and thermal storage capacity was developed by incorporating microencapsulated phase change material (MPCM) into ultra-high performance concrete (UHPC). The indoor tests were performed to determine the thermal performance of MPCM-UHPC. Mechanical properties and autogenous shrinkage strain of MPCM-UHPC were evaluated. The microstructure, thermal stability, chemical structure and crystal structure of the composite material were investigated by mercury intrusion porosimetry (MIP), scanning electron microscope (SEM), thermal gravimetric analyzer (TGA), Fourier transformation infrared spectroscope (FTIR) and X-ray diffraction (XRD). The results show that no chemically phenomenological interaction between MPCM and cementitious components occurs in the hydration process. However, the incorporation of MPCM increased air voids content in cementitious matrix, thus inducing harmful effect on the mechanical properties and autogenous shrinkage of MPCM-UHPC. From indoor performance test, the surface temperature of UHPC with 10 wt% MPCM was 3.9 °C lower than that of control group. Compressive tests results show that it possesses a considerable compressive strength of 78 MPa. Therefore, the MPCM-UHPC composite is a promising structural–functional integrated building material.