Ultra-lightweight porous materials fabrication and hazardous lead-stabilization through alkali-activation/sintering of different industrial solid wastes

Abstract

Abstract The beneficial use of alkali-activation/sintering process in the fabrication of open-celled cellular materials and lead solidification/stabilization (S/S) is the biggest challenge of the present work. Waste glass (WG), red-clay brick waste (RCBW), and lead-bearing-sludge (LBS) were used as silicate-rich-wastes in the foaming process. Porous materials with porosity ranging from 50 to 89% accompanied by low bulk density (0.73–0.27 g/cm3), low thermal conductivity (0.3–0.14 W/mK), and high compressive strength (3.4–14.2 MPa) were obtained when alkali activated WG, WG-RCBW, and WG-LBS fired at different elevated temperatures (700-900 °C). The results revealed that comparing with WG-foamed materials, the heating of WG activated by 4M-NaOH at 800 °C has resulted in the formation of foamed-glass with higher porosity, lower thermal conductivity, and lower bulk density. The use of RCBW, as a partial substituent of WG, represents the potential impact on the enhancement of foamed-material homogeneity. The dominant feature of the foamed-WG-LBS set is the formation of a porous structure with the biggest pore size and the lowest thermal conductivity. The leaching test proved that the applied alkali activation/sintering process has high efficacy on the Pb-stabilization.