Abstract: “Curing conditions as well as type and content of silica in raw mixture seem to be very important in both producing quality as well as stability of red-mud-based geopolymers. The influence of amorphous SiO2 along with the other components of raw mixture was studied in this paper. The presence of amorphous silica turned to be a very important factor influencing the strength of red-mud-based geopolymers. The results confirm that the compressive strength of geopolymers increases (up to 41MPa) with the presence of amorphous silica in raw mixture up to the certain point (50 wt %). Excessive content of amorphous silica causes sharp decrease in strength. Microstructure analysis confirms the existence of homogenous structure. The presence of gluing geopolymer phase is also detectable by various techniques.”

Keywords: compressive strength, geopolymers, red mud, volcanic tuff