Enhancing hydration of steel slag-based composite cementitious material: Synergistic effect of triisopropanolamine (TIPA) and sulfite/sulfate

This study enhanced the hydration of steel slag (SS) by the synergistic chemical activation of triisopropanolamine (TIPA) and sulfite/sulfate. Adding 0.2% TIPA into a cementitious material consisting of 62.5% SS and 37.5% desulfurization ash (DA) increased the 3-days and 120-days compressive strength by 9.59 times and 1.78 times, respectively. This enhancement was due to the accelerated dissolution of C2S and C2F facilitated by DA and TIPA. The complexation between TIPA and Fe accelerated the consumption of Ca2+ and SO42−, thereby promoted the generation of Fe-containing hydrates such as C2(F, A)3S3H2 and FeSO4·7H2O, significantly refining the pore structure. The TIPA-Fe complex also contributed to C-(F)-S-H gels formation, shifting hydration exothermal peak from 4.8 h to 1.1 h, with the peak value rising from 0.90 J/(g·h) to 57.07 J/(g·h). The Fe evolution even induced a colour change in the matrix. These insights contribute valuable perspectives for utilizing Fe-rich solid-wastes in cementitious materials. •TIPA and sulfite/sulfate synergy enhances the compressive strength of steel slag paste tenfold in 3 days.•TIPA accelerates C2F hydration, forming Fe-siliceous hydrogarnet and C-(F)-S-H by complexing with Fe ions.•The evolution of Fe in composition changes paste colour, possibly forming Q2(1Fe) Si in C-S-H.•Complex agent and sulfate activation efficiently utilize Fe-rich solid waste for cementitious materials preparation.