Compressive Strength and Microstructural Properties of Fly Ash–Based Geopolymer Concrete: Fid-Bau Portal

Compressive Strength and Microstructural Properties of Fly Ash–Based Geopolymer Concrete

Nagalia, Gaurav / Park, Yeonho / Abolmaali, Ali / Aswath, Pranesh

This study examines the role of alkali hydroxide and its concentration on the microstructure and compression strength of fly ash–based geopolymer concrete. Geopolymer is an innovative ceramic material, composed of long chains and networks of inorganic molecules, that is used as an alternative to conventional portland cement for civil infrastructure applications. Some of the advantages of geopolymer concrete are its fast setting time, rapid strength development, and its significantly reduced carbon footprint. In this study, aluminosilicate geopolymers with different alkaline solutions [NaOH, KOH, Ba $(OH)_{2}$ , and LiOH] were prepared by mixing Class C (9.42% CaO) and Class F-fly ash (1.29% CaO). The samples were cured under different experimental conditions and then tested for compressive strength. X-ray diffraction (XRD) and scanning electron microscopy/energy dispersive spectroscopy (SEM/EDS) have been used to identify the new phases formed in the geopolymeric matrix. The results revealed that microstructural properties of fly ash particles and calcium content have a significant effect on the setting time and the compressive strength of geopolymer concrete, and the structure of the formed geopolymer is typically glasslike. The early polymerization of geopolymer concrete is dependent on the concentration of the sodium hydroxide solution (NaOH). The exclusive use of NaOH showed the highest compressive strength when compared with other combinations of alkali hydroxides.