Geopolymerization behavior of ferrochrome slag and fly ash blends

This study highlights on the development of blended geopolymer cement by utilization of two industrial wastes namely ferrochrome slag (FCS) and fly ash. Geopolymer cement with 100 wt% FCS is considered as control batch. Then FCS is gradually replaced by introducing fly ash. The result obtained by isothermal conduction calorimetry shows that higher heat of reaction with intensified peak in slag rich specimens. The appearance of SiOSi/Al bond vibration at lower frequency in slag dominated reaction indicates the structural alteration and formation of new calcium and magnesium rich gel. The main reaction product in blended geopolymer samples is identified as N-A-S-H and C,M-A-S-H (where, N = Na2O, A = Al2O3, C = CaO, M = MgO, S = SiO2, H = H2O) based heterogeneous hydrated gel with varying Si/Al, and Na/Ca ratios. Higher compressive strength is attained in slag based reference sample due to its higher degree of reaction, formation of more gel phases and development of compact microstructure.