Abstract

This study presents the development of a one-part phosphate-activated geopolymer foam based on fayalite flotation residue from the copper industry. The solid activator consisted of triple superphosphate, enabling a dry-mix binder that requires only water addition prior to use. Foamed materials were characterized by XRD, FTIR, Mössbauer spectroscopy, DSC-TG, hot-stage microscopy, SEM-EDX and physical and mechanical testing. The foaming of the geopolymer reduced the densities between 0.753 and 2.15 g/cm3, relative porosities up to 73.6%, and compressive strengths ranging from 1.4 to 28.8 MPa. The foamed geopolymer maintained dimensional stability up to about 1000 °C. The thermal conductivity coefficient measured on large-sized specimen blocks was 0.099 W/mK at a density of 0.753 g/cm3. These results demonstrate that fayalite slag can be effectively utilized as a precursor for sustainable geopolymer foams combining low thermal conductivity, high thermal stability, and the utilization of industrial by-products.

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