Properties of alkali-activated ground granulated blast furnace slag blended with ferronickel slag

Abstract

This study aims to investigate the feasibility of using ferronickel slag (FNS) blended with ground granulated blast furnace slag (GGBS) to produce alkali-activated cements (AACs). Sodium silicate (Na2SiO3) and sodium hydroxide (NaOH) are used to activate the GGBS/FNS blends with mass ratio varying from 100:0 to 40:60. The setting time, flexural and compressive strengths, autogenous shrinkage and drying shrinkage are investigated to examine the effect of FNS content. The reaction products and pore structure of hardened AACs are characterized using X-ray powder diffraction (XRD), Fourier transform infrared spectroscopy (FTIR) and mercury intrusion porosimetry (MIP). The results show that blending FNS below 40% does not significantly influence the initial and final setting times; however, blending 60% FNS prolongs the setting times and causes a great reduction of mechanical strengths. For the sodium silicate activated AACs, the increase of FNS content in blends results in increased autogenous and drying shrinkage, as well as the total porosity. For the NaOH activated AACs, the autogenous and drying shrinkage are both reduced with the addition of FNS, while the total porosity is increased.