The influence of low alkaline activator on the compressive strength and workability of geopolymer concrete

Abstract

This paper presents the results of research on geopolymer concrete using a reasonably low alkaline activator. The key objective concerning this research is to investigate whether a low alkaline activator is still qualified to produce a concrete compressive strength that fulfills the structural requirements. The experimental program is carried out by making geopolymer concrete specimens, where the variables reviewed represented the amount of alkaline activator (4% and 5%), the ratio of alkaline activator to fly ash (AAS/FA) was 0.35, 0.4, 0.5, 0.6. The treatment temperatures of the specimens were room temperature (33°C) and 60°C. The experimental results of the compressive strength test have shown that the compressive strength of low alkaline geopolymer activator concrete still meets the requirements as a structural material (i.e. Indonesian Concrete Code). The weight of the resulting specimen is included in the category of normal weight concrete. The workability of geopolymer concrete with low alkaline activator tends to be better if the ratio AAS/FA also increases, but the compressive strength of concrete tends to decrease.