Utilization of natural and waste pozzolans as an alternative resource of geopolymer mortar

Abstract

The objective of this research was to investigate the engineering properties and mix design of geopolymer mortar made using fly ash, natural zeolite and ground granulated blast furnace slag as source material and combination of sodium hydroxide and sodium silicate as alkaline activator. To study the effect of sodium hydroxide concentration on compressive strength, three different sodium hydroxide solutions (8, 10 and 12 M) were used. The ratio of sodium silicate/sodium hydroxide was varied from 1.0, 2.0 to 3.0. The test results demonstrate that the compressive strength of developed geopolymer mortar increases with increase in the concentration of sodium hydroxide solution and sodium silicate content in the activator. The average maximum compressive strength was obtained when the sodium hydroxide concentration was 12 M and sodium silicate content was 3.0. At higher alkali content, the water absorption is less due to lower void spaces. The utilization of industrial waste materials such as fly ash, ground granulated blast furnace slag and natural pozzolans such as zeolite would lead to significant economic and environmental benefits in geopolymer production.