Effect of high alumina-based solid waste on efflorescence behavior of alkali-activated steel slag

Abstract

• Preparation of high strength alkali-activated materials by steel slag coupled with SFCC catalyst. • Addition of SFCC catalyst solves the efflorescence of alkali-activated steel slag materials. • The gel composition under different ratios of SFCC catalyst and steel slag are analyzed. In this paper, the influences of efflorescence on the property of alkali-activated steel slag materials were investigated, and the (Spent Fluid Cracking Catalytic) SFCC catalyst was used as an additive to control efflorescence. The property and microstructure of alkali activated cementitious materials synthesized with different raw materials composition was characterized by XRD, FTIR, TG and SEM-EDS. The efflorescence degree of different products was also evaluated. The C S H was mainly formed during the alkali-activated steel slag, which is difficult to adsorb the alkali metal ions, resulting in the serious efflorescence and a reduction of compressive strength. As the addition of SFCC catalyst increased, more N -A S H gels formed and adsorbed alkali metal ions, while inhibiting the efflorescence and its effect on mechanical property. In addition, the [AlO 4 ] − contained in the N(C)-A S H exhibit stronger adsorption properties for calcium ions than for sodium ions. This study not only proposed a new method of synergistic utilization of steel slag and waste SFCC catalyst, but also provided a further understanding of efflorescence, which is conducive to the collaborative high-value utilization of a variety of solid wastes, and effectively solves the problem of steel slag and SFCC catalyst stockpiling.