Optimizing Ternary-blended Geopolymers with Multi-response Surface Analysis

© 2016, Springer Science+Business Media Dordrecht. Geopolymers, also known as alkali-activated pozzolan cements, have been recently gaining attention as an alternative binder for concrete because of its potential to lower the environmental impact of construction, to utilize waste as raw materials of alumino-silicates, and to enhance the material performance. In this study, engineering properties of lightweight geopolymer-based material produced from the ternary blend of red mud (RM) waste, rice husk ash (RHA) and diatomaceous earth (DE) are optimized with statistical multi-response surface method. Using the augmented simplex lattice mixture design, ten mix proportions of RM, RHA and DE were prepared and mixed with 15 % (by weight of the solid) water glass solution to produce the specimens. After 28 days of curing at room temperature, these specimens were tested for compressive strength (MPa), volumetric weight (kg/m3), and water absorption (kg/m3) including the mass loss (%), volumetric shrinkage (%) and change in compressive strength (%) when subjected to an elevated temperature of 1000 °C. By using the desirability function approach on multiple responses, the optimum ternary blend was found to be 14.5 % RM, 67.2 % RHA and 18.3 % DE to obtain the desirable engineering properties of a lightweight heat resistant material. Using this mix proportion, confirmatory runs were also done and the experimental values were found to be in good agreement with the predicted values