Split tensile strength of OPC-based geopolymers: Application of DOE method in evaluating the effect of production parameters and their optimum condition

In the present study, Taguchi method as a design of experiment (DOE) method was implemented to design split tensile strength tests of geopolymer produced by ordinary Portland cement (OPC) as an aluminosilicate source. Six main parameters including NaOH concentration, water glass to NaOH weight ratio, alkali activator to cement weight ratio, oven curing temperature, oven curing time and water curing regime each at four different levels were considered for examinations. A total number of 32 experiments were performed according to the L32 array which was proposed by the method. Analysis of the experimental results through ANOVA revealed that the specimen with NaOH concentration of 14 M, water glass to NaOH weight ratio equals to 1.5, alkali activator to cement weight ratio of 0.35, and curing at room temperature for 28 days was potential of highest strength (7.73±2.01 MPa) in the considered procedure. Based on achievements, it was shown that split tensile strength of Portland cement-based geopolymers could be suitably designed by Taguchi method.