Use of calcium silicate-coated paraffin/expanded perlite materials to improve the thermal performance of cement mortar

Here we demonstrate thermal energy storage cement mortar (TESC) developed by integrating cement mortar with a calcium silicate-coated paraffin/expanded perlite based form-stable phase change material (CPEP). The thermophysical properties, microstructure and spectroscopic characterization of the CPEP and the thermal and mechanical properties of the TESC were studied. MIP and SEM results show that paraffin mixture PCM is adsorbed uniformly into the pores of expanded perlite treated by hydrochloric acid. The thermal-cycling test results indicate the good thermal stability of CPEP by the cladding of three-layer calcium silicate. Differential scanning calorimetry (DSC) results reveal that the CPEP has phase change temperature and latent heat of 24.58 °C and 88.57 J/g, respectively, and the lower phase change temperature of CPEP compared to paraffin mixture is supported by FT-IR. Moreover, the CPEP was incorporated in cement mortar at 10%, 15%, 20% and 25%, by weight of sand. It is found that the compressive strength of TESC decreases with increasing CPEP content. However, they can still be regarded as building maintenance structure materials to use. Further, the ITZ structures between CPEP and cement substrate are focused on by SEM. In addition, the thermal energy storage performance of TESCs is revealed by the results of specific heat capacity test and heating test.