Fresh, strength and microstructure properties of geopolymer concrete incorporating lime and silica fume as replacement of fly ash

The need to cure fly ash-based geopolymer at elevated temperatures has limited the practicability and sustainability of the composite. Hence, there is an imminent need to find ways at which fly ash-based geopolymers can be cured at ambient conditions. This paper presents the results from the experimental investigation of the effect of lime and silica fume on the properties of geopolymer concrete cured at ambient conditions. Lime and silica fume were used as the partial replacement of fly ash as an aluminosilicate precursor and the corresponding effects on the fresh, strength and microstructure of the geopolymer concrete were investigated. The findings from this study showed that the slump and setting times of the geopolymer concrete increases with increasing silica fume content and reduces with increasing lime content. Also, the use of lime and silica fume as 7.5% and 2% respectively, replacement of fly ash yielded the highest compressive strength. Microstructural investigation showed that the combined use of lime as silica fume in GPC resulted in a densified microstructure.