Mechanical and durability properties of alkali activated slag for sustainable concrete

Abstract

Geopolymers are cementitious binder with three dimensional structures that are formed by alkali activation of Si and Al containing raw materials such as natural and artificial pozzolans. It has been found that slag- based geopolymer binders can be synthesized by alkali activation of ground granulated blast furnace slag in presence of sodium silicate. Slag-based geopolymer binders can contribute to the reduction of environmental impact by using lesser amounts of calcium-based natural materials, lower manufacturing temperature, lower use of fuel and cost and lower greenhouse gas emissions in comparison with ordinary Portland cement binder and provides a route towards the concept of sustainable development. Materials resulting from alkali activation of slag show a wide range of workability, compressive strength and permeability. The main objectives of this work is to determine effects of alkaline solution type and concentration, modulus of sodium silicate, sodium silicate to alkaline solution ratio and natural pozzolan replacement on the mechanical properties of alkali activated slag. Results reveal that the geopolymer paste specimens containing KOH solution had higher compressive strength when compared with the concrete specimens containing NaOH solution. The optimum range for each factor is suggested based on the different effects they have on compressive strength.