Floorings based on geopolymers: Optimization of mixture composition

Geopolymer-based alternatives to concrete have been mentioned very frequently in the last decade as they conform the topical environmental saving efforts. Utilization of byproducts or waste material make them even more attractive from this point of view. However, the process of a design is not the same like in case of well known concretes which means. it might be difficult to reach the properties desired. This paper therefore aims at the optimization of a geopolymer composition to reach sufficient 7-day compressive strength. Being composed of metashale, water glass, siliceous sand and water, the mixture proposed is supposed to be used in floorings applications. As the optimization technique, the modified downhill simplex method was applied, being tailored to specifics of the mixture design. Proving its effectiveness, the demanded 7-day compressive strength (25.0 MPa) was achieved after the first optimization step (27.8 MPa, due to an combination with an empirical design that exploited authors’ experience to set the initial simplex closer to the optimum zone. In the end of the research presented, analytical formulas of the composition were proposed that are supposed to guarantee that the required 7-day compressive strength will be achieved.