Carbon-negative heat-stored limestone calcined clay cement mortar containing form-stable phase change materials

Abstract

Heat-stored cement-based materials (HSCMs) with form-stable phase change materials (PCMs) have exhibited tremendous opportunities for energy conservation and emission reduction in buildings. In this study, a novel HSCM system was designed by incorporating form-stable PCMs into limestone calcined clay cement (LC3) mortar, in which a highly compatible form-stable PCM was constructed by the three-step method including the synthesis of red mud-based geopolymer hollow microsphere (RMHM), the impregnation of n-Octadecane (ODE) into RMHM and the surface precipitation of CaCO3. The microstructures, phase transition properties, chemical compatibility and thermal stability of the two resulting form-stable PCMs (namely ODE/RMHM and ODE/RMHM@CaCO3) were evaluated. A comparative analysis was conducted to reveal the influence mechanism of ODE/RMHM and ODE/RMHM@CaCO3 on the microstructural evolution, hydration reaction, mechanical and thermal properties of LC3 mortar. Moreover, the numerical model method confirmed the significant role of the prepared LC3-based in temperature control and energy conservation in building. In addition, the obtained LC3-based HSCM could achieve a short dynamic payback period and sequestered huge of carbon emissions for service life. In overall, this work opened up a novel path of economically feasible carbon-negative building materials with form-stable PCM.