Optimization of fly-ash based geopolymer composition for composite bricks manufacturing

FACUNDO VALLE; ARIEL STOCCHI; JUAN MORÁN; EXEQUIEL S. RODRIGUEZ

Mar del Plata

Simposio; XVI Simposio Latinoamericano de Polímeros, SLAP2018; 2018

Universidad Nacional de Mar del Plata

Fly ash is an industrial waste that can be used to replace Portland cement in concrete manufacturing1. In Argentina, fly ash is a by-product of coal-fired thermal power plants, like San Nicolás AES power plant, located near Paraná River. However, it can only partially replace Portland cement (up to 30%) due to the fact that the pozzolanic reaction of fly ash consumes part of the Ca(OH)2 from Portland cement hydration. Nonetheless, fly ash has a new promising application as an alternative source for making geopolymer, a new binder roughly comparable to hydrated Portland cement in appearance, reactivity and properties. Geo-polymerization occurs when aluminosilicate materials are alkali-activated, giving a three-dimensional structure. Since fly ash composition changes considerably depending on its source, the activation solution has to be optimized in order to improve mechanical properties of the geopolymer. In this work, the activation solution based on NaOH and Na2SiO3 was optimized by measuring flexural and compressive properties of the resulting geopolymer. The final goal of the project is to obtain construction bricks made 100% with waste by-products, with mechanical properties comparable to commercial Portlant cement based bricks.