Mineralogical characterization of clays moles present in the surroundings of the natural reserve of Guaratiba: west zone of the municipality of Rio de Janeiro

Abstract

The unbridled expansion of the large centers, as well as the lack of further studies, have led to the increasing occupation of irregular areas, as is the case today in the last mangrove areas of the Guaratiba nature reserve. The soft clay, which is very present on the Brazilian coast, always presents a challenge regarding the analysis of its behavior, since nearby areas with considerable soft clay thickness may present different geomechanical behavior. In order to better understand the behavior of soft arligas, as well as to deepen the studies in these areas of preservation, so important for the maintenance of the local biome, the present study deepens the knowledge about mineralogy of the soils of the West Zone of Rio de January. X - ray diffraction tests were performed at depths between 4m and 6m, from the nine samples analyzed, as well as x - ray fluorescence assays, with the purpose of complementing the mineralogical characterization of the region under study. All the tests carried out, respected the local biome, aiming at its preservation. A large variety of clay minerals, as well as non-clay minerals, quartz, feldspar and poligorsquite, were found in the samples. From the group of identified argillominerals, Illitas, Caulinitas and Vermiculitas were the most present clay minerals in the samples, with Illita being the clay mineral that contributes most to the soil behavior, since it presents more than 25% of the constituent material of the soil. The presence of low activity clay minerals, such as Illita, Chlorite, Caulinite and Mica, leads to the development of high sensitivity to grinding, as they are subject to the reduction of the liquidity limit and the resistance dented under chemical changes in the environment, such as leaching and dispersing agents.