Research on the Low-carbon Cementitious Materials: Effect of Triisopropanolamine on the Hydration of Phosphorous Slag and Steel Slag

Cement, phosphorous slag (PS), and steel slag (SS) were used to prepare low-carbon cementitious materials, and triisopropanolamine (TIPA) was used to improve the mechanical properties by controlling the hydration process. The experimental results show that, by using 0.06% TIPA, the compressive strength of cement containing 60% PS or 60% SS could be enhanced by 12% or 18% at 28 d. The presence of TIPA significantly affected the hydration process of PS and SS in cement. In the early stage, TIPA accelerated the dissolution of Al in PS, and the formation of carboaluminate hydrate was facilitated, which could induce the hydration; TIPA promoted the dissolution of Fe in SS, and the formation of Fe-monocarbonate, which was precipitated on the surface of SS, resulting in the postponement of hydration, especially for the high SS content. In the later stage, under the continuous solubilization effect of TIPA, the hydration of PS and SS could refine the pore structure. It was noted that compared with portland cement, the carbon emissions of cement-PS-TIPA and cement-SS-TIPA was reduced by 52% and 49%, respectively.