Mechanical Properties of Alkali Activated Slag Pastes and Determination of Optimum Values of Effective Factors

Geopolymers are alumino-silicate polymer that formed by alkali activation of Si and Al rich materials. This paper describes the effects of different alkaline solution types and concentrations, modulus of sodium silicate and sodium silicate to alkaline solution ratio on the flowability and mechanical properties of alkali activated slag and the optimum activator has been determined for the slag- based geopolymers production.Results reveal that adding the sodium silicate largely enhances the workability and compressive strength of slag-based geopolymer paste.The optimum modulus of sodium silicate and sodium silicate to alkaline solution ratio to reach the maximum strength are 2.33 and 0.4 respectively. At 91 days of curing, the compressive strength of the optimum mixture of slag- based gepolymer is about 74 % more than the compressive strength of ordinary Portland cement paste.