Comparison of the mechanically compacted dry-mix and ordinary vibrated wet-mix glass concretes after exposure to elevated temperatures

This paper presents an investigation on high temperature performance of dry-mix and wet-mix concretes using 0–100% glass aggregates to replace river sand. The thermal conductivity at room temperature and the compressive strength before and after exposure to elevated temperatures were evaluated. The dry-mix and wet-mix concretes with the content of 100% glass aggregates were examined by X-ray μCT, microhardness and SEM-BSE to explain the noticeable property improvement after exposure to 800 °C. Regardless of the casting method, the increasing content of glass aggregates reduced the thermal conductivity at room temperature and improved the compressive strength after exposure to 800 °C. This was because the surface of the glass aggregates was partially melted at 800 °C and it re-solidified after cooling, which served to enhance the bond between the glass aggregates and the cement paste. The new bonding played a role in filling up the gap between the glass aggregates and the cement paste and partially repaired the decomposition of cementitious materials after exposure to 800 °C. With a constant content of glass aggregates, the dry-mix concrete had a lower thermal conductivity at room temperature and a higher residual compressive strength after exposure to 800 °C than the wet-mix concrete. This was due to the higher initial porosity of the dry-mix concrete and the glass aggregates which were not completely attached to the cement paste, both of which would contribute to reliving the thermally induced expansion.