Performance Enhancement of Fly Ash-Based Self Compacting Geopolymer Concrete Using Pre-heating Technique

The conventional approach for activating geopolymer concrete is to heat the concrete for a specified period after casting. This attribute has significantly impacted construction activities and energy consumption, restricting fly ash based geopolymer concrete to the precast industry only. This paper aims to provide an alternate curing technique for fly ash based self-compacting geopolymer concrete other than post-casting heating of the elements. This limitation of post-casting heating of elements can be addressed by altering the mixing process of self-compacting geopolymer concrete. The modified fly ash-based self-compacting geopolymer concrete is termed as reformed geopolymer concrete (RGC) in this study. This modification is introduced by heating the binders and activator solutions initially before mixing with the aggregates, and the modified specimens show superior results than post-casting heated geopolymer concrete (PHGC) and control (self-compacting) cement concrete (CCC) specimens. The mechanical strength (compressive, flexural and split tensile), fire resistance capacity, acid attack resistance, and water absorption are also improved in the case of reformed geopolymer concrete (RGC) as compared to PHGC and CCC. The RGC shows nearly 31% and 33% more compressive strength than PHGC and CCC respectively. Also, the energy consumed for the preparation of RGC is as low as 99% from the PHGC specimens, hence making it more economical, less time-consuming and practical to use for construction purposes. The microstructural analysis (SEM, XRD) also shows that RGC has less unreacted fly ash than PHGC hence confirming the reason behind the enhanced properties of preheated self-compacting geopolymer concrete (RGC) in this investigation.