274 / 2022-09-20 14:30:57

Development of artificial geopolymer aggregates with thermal energy storage capacity

Phase change materials; Artificial geopolymer aggregates; Energy storage; Thermal performance; Mechanical properties

Integrating phase change materials (PCMs) into building materials has been widely used to improve the energy efficiency of buildings, for which microencapsulation and shape stabilization are considered as two most effective solutions. Various types of porous materials, including expanded graphite, expanded perlite, expanded shale, mesoporous zeolite, ceramic foam, and recycled expanded glass aggregate have been reported for such purpose. However, the cost of these porous supporting materials is usually relatively high and the mechanical properties are generally poor and their porosity is non-tunable.



In this study, artificial geopolymer aggregate (GPA) was employed as a novel PCM carrier for energy storage purpose using a vacuum impregnation technique (Fig. 1). Detailed investigations were conducted into the physical, mechanical, and thermal properties of GPA-PCM, which can be engineered through different raw material selections (e.g., slag content, water/binder ratio, and incineration bottom ash (IBA) content). It was demonstrated that increasing the IBA content is an efficient means to increase the porosity of GPA (Fig. 3), an index of the capacity to accommodate PCM. Up to 16 wt.% PCM could be absorbed into the GPA through vacuum suction (Fig. 3), resulting in a significant melting enthalpy of 24.74 J/g (Fig. 4). Besides, GPA-PCM could achieve an excellent mechanical strength greater than 53.2 MPa (Fig. 2) and a thermal conductivity of 0.510 – 0.589 W/mK (Fig. 5). The time-temperature history curves of GPA revealed that up to 10.5°C of thermal regulation was achieved due to PCM impregnation (Fig. 6). The developed GPA-PCM composites facilitate an innovative and low-carbon solution for utilizing PCMs in construction for temperature-regulating and energy-saving purpose.