Synergistic effect of vegetable protein and silicon addition on geopolymeric foams properties

Organic–inorganic hybrid foams based on an alkali alumino-silicate matrix were prepared using different foaming methods. Firstly, silico-aluminate inorganic matrix, activated through a sodium silicate solution, was prepared at room temperature. The obtained viscous paste was expanded by means of silicon metal redox reaction in alkaline media in combination with protein-assisted foaming. The foamed systems were hardened at defined temperature and time and then characterized by FTIR, scanning electron microscopy, and compression tests. The high temperature behavior and specific surface area were also evaluated. The experimental findings highlighted that the combination of silicon metal and vegetable protein allowed tailoring hybrid foams with enhanced properties: good yield strength and thermal resistance typical of geopolymeric foam with a ductile behavior (toughness) and low density typical of organic foams.