In-situ carbonation of alkali activated fly ash geopolymer

This research work investigates the effect of in-situ carbonation on the properties and geopolymerization of alkali-activated fly ash mortars. The mortars were prepared from fly ash, sodium silicate, sodium hydroxide and different amounts of sodium bicarbonate. CO2 produced by the decomposition of sodium bicarbonate during curing, was utilized for the fast and improved development of the geopolymer properties. After curing the samples were characterized by TGA-DTA, XRD, FT-IR and SEM in order to understand the effect of carbonation on the thermal behavior, phase composition, degree of polymerization and microstructure of samples. Geopolymers with 2 wt% of sodium bicarbonate shows higher compressive strength and Young’s modulus compared to the sample without sodium bicarbonate. The thermal conductivity was found higher for carbonated geopolymer, whereas samples without carbonation show least conductivity.