Utilization of fly ash blends from pulverized coal and fluidized bed combustions in geopolymeric materials

This paper presents the utilization of fly ash obtained from fluidized bed combustion (FBC) as a source material for geopolymer. FBC-fly ash has low reactivity, and high content of CaO and CaSO4, which limits its use. To solve this problem, it was blended with reactive fly ash obtained from pulverized coal combustion (PCC). This blend powder was then used as a source material for geopolymer. Sodium hydroxide, sodium silicate and temperature curing were also used for synthesis of the geopolymer. XRD, SEM, degree of reaction, FTIR were performed on geopolymer pastes. In addition, compressive strengths of geopolymer mortars were determined. Results showed that FBC-fly ash could be used in conjunction with PCC-fly ash as source material for geopolymer. PCC-fly ash helped to increase the workability and strength of the geopolymer. Relatively high strength of 30.0 MPa was obtained with 40% content of FBC-fly ash in the blend material.