Mechanical properties and durability of GGBS based geopolymer mortar

The main aim of this research is to examine the mechanical properties, fresh properties, and durability of geopolymer mortar by varying the ratio of fly ash and GGPS in the mix. The ratios investigated were 40% GGPS to 60% fly-ash, and 60% GGPS to 40% fly ash, with and without the inclusion of superplasticizers. The tests conducted were compressive tests on hardened mortar cubes (after 3, 7, and 28 days), slump flow, and setting time on fresh mixes. In addition, durability tests of water absorption and rapid chloride penetration were performed on the optimum mix trial. It was observed that increasing the ratio of GGBS to fly ash (60 to 40) significantly increased the compressive strength of concrete. The downside of this mix was its low viscosity which yielded a very stiff mix that failed the slump test. On the other hand, the mix with the ratio of 60% GGBS to 40% fly ash including superplasticizer resulted in an enhancement in both the compressive strength and workability. Finally, the mixes with 40% GGBS to 60% fly ash had a comparatively lower compressive strengths and unacceptable ranges of setting time and slump values. Therefore, based on the results of this research, it is recommended to increase the ratio of GGBS to fly ash in the GPC mix with the addition of a high-performance superplasticizer to maintain the workability, while maintaining the compressive strength of the mortar.