Evaluating thermal storage capability of recycled construction materials: an experimental approach

Granular materials like sand have gained importance in thermal storage applications due to their stability and cost-effectiveness. However, excessive usage of sand can pose environmental issues. This study investigates recycled construction materials such as glass, asphalt, ceramic, and concrete as alternatives to natural sand for low-temperature TES applications. The materials were processed to similar grain sizes and evaluated for their chemical, thermophysical, and thermal storage properties through a six-hour charging cycle at 60 °C. XRF analysis revealed significant compositions, including high oxygen and silicon content in concrete and sand, respectively. Results indicate that sand with 0.189 W/m K recorded the highest thermal conductivity compared with concrete 0.172 W/m K, glass 0.131 W/m K, ceramic 0.159 W/m K and asphalt 0.159 W/m K. A higher specific heat capacity was observed in concrete at 755 J/kg K, followed by asphalt at 732 J/kg K, glass at 708 J/kg K, and sand at 688 J/kg K. However, ceramic is categorized for a lower specific heat capacity of 682 J/kg K. Absolute density evaluation indicates that sand is the densest material with 2662 kg/m³, contrary to concrete 2480 kg/m³, glass 2421 kg/m³, ceramic 2285 kg/m³, and asphalt 2436 kg/m³. More to the point, the Ragone plot for specific power and energy highlighted that ceramic has a rapid energy release and concrete demonstrated sustained energy storage capabilities. Volumetric power and energy density assessments indicated sand's outstanding performance. However, concrete registered a superior thermal storage among recycled materials. The results highlight that recycled materials, specifically concrete can be used for thermal storage applications like water heating in poor communities.