Avaliação da influência da adição de alumina em geopolímero à base de metacaulim.

Abstract

Geopolymers constitute a class of materials that has been studied since the 50s decade, when activated alkali systems containing calcium silicate (CSH) and aluminosilicates used for constructions in the late Soviet Union were developed. Since then the studies as to this class of materials has increased intensively, either due to the excellent properties shown by them or even by the possibilities of new uses and applications. In this sense, this work aimed to evaluate the influence of the alumina addition on the mechanical properties and microstructural characteristics of the metakaolin based geopolymers. The geopolymers were synthesized from a mixture of metakaolin / alumina with a solution of sodium hydroxide by uniaxial pressing and under different conditions of synthesis and curing, such as: temperature and curing time, moisture content of the pressing mass, content and particle size of the added alumina. It was possible to verify that the curing temperature and time has an important role in the development of strength, the temperature being a significant factor, at 95%, in all conditions. The increase of the moisture content increased significantly the influence of the thick alumina content added. The incorporation of alumina to the system did not provoke any modification to the mass loss, crystallization temperature and porosity. The alumina added to the geopolymers, especially the fine alumina, favored so as to increase the mechanical strength of the obtained products acting as reinforcement in the geopolymer matrix.