Strength Properties of Alkali Activated Fly Ash

Abstract

Fly ash is a by-product of burning pulverized coal in electricity generation plants, whose pozzolanic properties enables it to (containing aluminous and siliceous materials) develop cementitious properties upon the addition of water. Activation of fly ash via alkali enhances its cementitious properties. In this paper, the compaction, strength and durability properties of fly ash activated with NaOH solution (0.5M, 1M and 2M), lime and cement (0, 2.5, 5, 7.5 and 10% of dry weights) have been deter-mined. The OMC of alkali-activated fly ash is reduced whereas the MDD is found to increase with increasing alkali content. The effect on unconfined compressive strength is also studied with increasing geo-polymer concentration, lime and cement content for different curing period (0, 3, 7, 15, 30 and 60 days). The unconfined com-pressive strength improves with increase in lime, cement and NaOH content. Amelio-ration of strength properties also accentuate with curing time for alkali activated fly ash specimens. The compendium of this work can be further extended to expand the application domain of fly ash as a construction material under severe environmental conditions.