Influence of various parameters on strength and absorption properties of fly ash based geopolymer concrete designed by Taguchi method

Abstract

The paper presents the influence of various parameters on compressive strength and water absorption properties of fly ash based geopolymer concrete mixtures optimized by Taguchi method. A total of sixteen mixtures were evaluated considering the effect of inclusion of ordinary Portland cement as fly ash replacement, different molarities of sodium hydroxide solution and different curing temperatures. Analysis of variance was employed to study their influence on compressive strength and water absorption. Also, using multiple regression analysis, mathematical models were developed for both the properties followed by their confirmation test results.Results show that maximum 7days compressive strength of 64.39MPa and minimum water absorption of 3.04% was obtained for fly ash based geopolymer concrete with the considered parameters. The inclusion of additional calcium (in form of OPC as fly ash replacement) was found to influence the compressive strength and water absorption properties most significantly. The best parametric combinations for both the properties were also obtained using Signal-to-Noise ratio graphs. Microstructure properties were also examined using Scanning Electron Microscopy, Energy Dispersive Spectroscopy and X-ray Diffraction analysis which confirmed more compact and less permeable matrix for the optimized mixture.