The Influence of Oxide Content on the Properties of Fly Ash/Slag Geopolymer Mortars Activated with NaOH

The actual study is an attempt to analyze the influence of the main oxides on the behavior of heat cured fly ash/ slag blend geopolymer mortars activated with sodium hydroxide (NaOH). Fly ash and slag were decomposed into oxides and analyzed in oxide basis. Polynomial models for mortar flow workability and compressive strength were built based on 40 design points with different; oxide ratios, water content, NaOH levels and curing temperatures normalized appropriately. The same data were also modelled and analyzed in Design Expert package program Response Surface method using the historical data feature. The models show to be very stable as the error values are several orders of magnitude smaller compared to the respective coefficients. It was observed that main oxides such as CaO, MgO and SiO2 play an important role on the compressive strength of the mortars. On the other hand, both the methods used to build the models resulted in same equations, which indicates the consistency between the two approaches.