Improved foamed glass using carbonated recycled concrete powder as a foaming agent

A novel foaming agent derived from carbonated recycled concrete powder (CRCP) has been employed to produce foamed glass as an alternative to commercial CaCO₃. Three sintering temperatures (750, 800, and 850°C) and five dosages (1%, 2%, 3%, 5%, and 9%) were conducted for two foaming agents (CRCP and CaCO₃). The results demonstrated that the CRCP samples perform better than those produced with CaCO₃ as the foaming agent. This can be attributed to the more uniform pore structure observed through scanning electron microscopy and X-ray computed tomography analysis, and enhanced micro-mechanical strength determined by nanoindentation testing. The CRCP exhibited a moderate gas generation process, accompanied by the decomposition residues that facilitated enhanced crystalline formation within the matrix, ultimately resulting in improved performance. The findings unveiled the underlying mechanism behind the disparity in foaming properties between the two agents and highlighted the potential opportunities for waste material substitution in this industry.