Influence of dolomite on the properties and microstructure of alkali-activated slag with and without pulverized fly ash

Abstract

In this work, dolomite or a combination of dolomite and pulverized fly ash is to substitute up to 40% of blast-furnace slag in sodium hydroxide and sodium carbonate-activated slag systems. The influence of dolomite incorporation on the strength development, flowability, setting time, pore structure, hydrated phase assemblage, and microstructure of alkali-activated slag (AAS) are studied. The results show that dolomite incorporation up to 20% or up to 40% when fly ash is present, has little detrimental effects on the compressive strength of AAS pastes. Dolomite works mainly as an inert filler in AAS systems, leading to an increased reaction of slag at early stages due to filler effect. Different from its chemical role on ordinary portland cement (OPC) systems with enhanced hydrotalcite formation, the dolomite does not substantially affect the chemistry of reacted products in AAS systems at room temperature.