Influence of additives on the hydration, pore chemistry and phase assemblage of ferrite-rich steel slag-based cement clinker

Electric arc furnace slag (EAFs) was used as an alternative material for alite-ferrite (C 3 S-C 4 AF) clinker synthesis. Successful synthesis achieved 26 wt.% and 70 wt.% of C 4 AF and C 3 S, that was used for hydration investigation. The combined effect of triisopropanolamine (TIPA) and gypsum on the hydration kinetics, pore solution, and phase assemblage on the synthesized cement was investigated by using advanced characterization methods. The results showed the addition of gypsum delayed the hydration of C 4 AF, reduced the Fe concentration in the pore solution and altered the formation of hydrogarnet in the presence of TIPA. Whereas, in absence of gypsum and presence of 250 ppm of TIPA, Fe content in the pore solution increased, the hydration of C 4 AF was enhanced, leading to formation of hydrogarnet and improving strength of the mortar. Lastly, the results show the effect of TIPA on ferrite hydration is dependent on the proportions of C 3 S, C 4 AF, and gypsum in cement. • EAF slag (15%) can be used as alternative raw material in synthesizing C 3 S (70-wt%)-C 4 AF (26-wt%) cement clinker. • TIPA addition increases concentration of Fe, Ca, S, and Al ions in the pore solution in the early hours of hydration. • Gypsum addition hindered the dissolution of C 4 AF and the formation of siliceous hydrogarnet both with and without TIPA. • TIPA dosage of 250 ppm was optimal for this cement system.