engleski

The effect of alkali activator on the development of mechanical properties of fly ash based geopolymer

The alkali activation of fly ash is a physical-chemical process of mixing fly ash with alkaline activators in order to produce materials with high mechanical properties - geopolymers. Three types of geopolymers were synthesized. The same fly ash was used in all the samples, but the alkali activator has been changed: water glass (sample A), sodium hydroxide (sample B) and combination of water glass and sodium hydroxide (sample C). After preparation, all samples were thermally cured in the laboratory oven at the temperature of 85 °C for 24 hours. Mechanical strengths were measured after 3, 7 and 28 days, and during that period of 28 days all the samples were hermetically sealed and stored at room temperature. The results obtained indicate that, geopolymer, synthesized by mixing fly ash with the combination of water glass and sodium hydroxide as alkaline activator, developed the highest compressive strengths during all period of interest, about 21.23 MPa at the age of 3 days and 21.28 MPa at the age of 7 days, which then reached 22.52 MPa after 28 days of curing at room temperature.

geopolymers ; alkali activator ; compressive strengths

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