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.