Caracterização de resíduos de rochas pegmatíticas e gnáissicas segundo potencial reativo, índices físicos e resistência mecânica

Abstract

Mining is an economic activity of an extractive character and fundamental as a basis for various production chains such as: chemical, pharmaceutical, civil construction and many others. While promoting wealth and consumer goods, this activity is potentially harmful to the environment if it is improperly disposed, generating negative environmental impacts. Since Rio Grande do Norte is a state that holds mining as one of its main economic activities and the civil construction industry that demands a high volume of inputs, the present work proposes to analyze mining residues of two species of crystalline rocks (pegmatites and gneisses) from two mining companies. These residues were characterized petrographically, according to their reactive potential to the Alkali-aggregate reaction, according to physical indexes (absorption, porosity and specific mass) and mechanical resistance (simple compression resistance using Schmidt's sclerometer test) with a view to the use for aggregates for concrete. It was verified that two samples of pegmatites obtained good results according to both reactivity, physical indexes and mechanical resistance. However, other samples of pegmatite obtained good values, according to their physical indexes and mechanical resistance. A sample of gneiss presented a reactive potential to the norm, but it standed out in relation to the mechanical resistance and physical indices. Therefore, it is concluded that it is necessary to expand the understanding of such samples through complementary tests such as expansion tests with mortar bars, for example.