The potential use of silico-manganese slag into cementitious materials

Abstract

Silico-manganese (SiMn) slag, a by-product of steel alloying is produced by carbothermic reduction in submerged electric arc furnace. Around 1.2 to 1.4 ton slag is generated in per ton of SiMn alloy production. The majority of the produced slag is simply dumped as it has no such value added use except land filling. The chemical content of SiMn slag resembles with blast furnace slag except high MnO. In the present work attempt has been made to use SiMn slag in Portland slag cement (PSC). To increase the glass content and to improve the reactivity, the molten slag is water quenched. Rapidly cooled granulated slag has been utilized as a component of Portland cement. A reference sample is prepared with granulated blast furnace slag (GBFS), and granulated SiMn slag (GSS) is gradually added to replace the GBFS. Calorimetry result shows that addition of granulated SiMn slag (GSS) slows down the initial reactivity but accelerates at later stage with the appearance of a new flat peak. A significant strength gain is observed during 7 to 28 days curing with GSS incorporation and it reaches to comparable strength of reference sample. The major hydrated phases detected in XRD are Portlandite, C-S-H and CA-H. Along this calcium manganese oxide hydrate is formed by GSS hydration and detected in GSS rich cement.