Compressive Strength Assessment of Geopolymer Composites by a Phenomenological Model

Fly ash based geopolymer composite cubes were cast using class F fly ash, ground granulated blast furnace slag (GGBFS) as binders. The fluid-to-binder ratio was varied keeping all other parameters constant. The geopolymer composites were cured in different conditions. The composites were tested for compression at different ages. It is interesting to note that the variation of the strength with various fluid-to-binder ratios is unique irrespective of combination of materials, curing conditions, fluid content, and molarity of the fluid. The strength data generated was generalized to arrive at a phenomenological model. The model represents an unique pattern of strength development for the series of composite materials. The validity of the model was examined with an independent set of experimental data generated by the authors and Rangan. It was found that the predicted strengths were in line with the experimental strengths having a percentage error less than 6.0. The model is effective in re-proportioning of geopolymer composites in the field.