Brazilian fly ash based inorganic polymers production using different alkali activator solutions

Inorganic polymers are a relatively new class of inorganic binders of elevated mechanical strength and chemical resistance which can be produced from various industrial byproducts containing alumina and silica such as fly ash, slag and kaolin. In this work, fly ash from a Brazilian thermoelectric power station at Capivari de Baixo, Santa Catarina, was used to produce the inorganic cement. Different alkaline activator solutions were used in order to study their influence on the properties of the produced inorganic polymers. The results demonstrated that this fly ash is a viable starting material for the production of inorganic binders with compression strength higher than 40 MPa. It has been observed that the compression strength increased with increasing curing time of up to 28 days. Phase analysis by X-ray diffraction analysis revealed the formation of new zeolithic phases during the polymerization process. The polymerization process was also confirmed by modifications of the binding structure, as indicated by altered and new absorption bands observed by infrared spectroscopy. Furthermore, it has been found that physical properties, such as density and porosity, not only varied for different activator solutions, but also with curing time.