Mitigation of the potential alkali–silica reaction of FNS using ground FNS as a supplementary binder

Abstract

Alkali-silica reactivity of granulated ferronickel slag (FNS) aggregate was evaluated by accelerated mortar bar tests. The test results showed noticeable expansions of the samples containing 50% FNS aggregate due to potential alkali silica reaction (ASR). On the other hand, finely ground FNS (GFNS) exhibited pozzolanic property in the studies of compressive strength development, thermogravimetric analysis and X-ray diffraction (XRD) analysis. Therefore, GFNS was used as a partial replacement of cement to study its effect on the reduction of ASR. It was found that the use of GFNS by at least 30% of cement replacement reduced the 10-day and 21-day mortar bar expansions below the allowable limits. The consumption of portlandite by the pozzolanic reaction of GFNS is considered as the primary reason for reduction of expansion. The ASR mitigation process of GFNS was further confirmed by scanning electron microscopy (SEM) images and energy dispersive x-ray spectroscopy (EDS) of the reaction product.