Caracterização geológica-geotécnica de duas jazidas utilizadas para construção civil localizadas no batólito de Pelotas/RS

Abstract

The present research aim the geological-geotechnical characterization of two deposits of granite rock, JA Silveira quarry and SBS quarry, located in different facies of Pelotas batholith. The JA Silveira quarry is located in the center of the batholith, in the Complexo Granítico-Gnáissico Pinheiro Machado, characterized by rocks predominantly granodiorítica and monzogranítica. The SBS quarry is located on the edge of the batholith, in the Capão do Leão formation, characterized by sienogranites. The study was based on macroscopic and microscopic compositional analysis of rocky masses, structural analysis and geotechnical characterization tests. The macroscopic analysis was performed at the Laboratory of Petrography and the microscopic analysis was performed at the Laboratory of Microscopy, both at the Universidade Federal do Pampa. The geotechnical characterization tests were performed at the Laboratory of Materials in Construction Civil at the Universidade Federal de Santa Maria. A correlation was made between the rocks of the two quarries and explanations were established for the results of geotechnical tests based on geological knowledge. The monzogranite is composed mainly of quartz (45%) and plagioclase (40%), has a faneritic texture and massive structure, while the sienogranite is composed mainly of alkaline feldspar (45%), has phanerite texture and massive structure to foliate. The aggregates of the JA Silveira quarry presented higher density and lower results of absorption, abrasion, shock loss, crushing and sanity, due to its granulometric composition with greater hardness and tenacity of its minerals, greater rock compactness and absence of microstructures. The aggregates of the SBS quarry presented greater lamellarity of the particles and its performance in the tests can be explained as a function of a foliation that acts as a plane of weakness in the aggregates. The aggregates of both quarries have potential for use as coating, ornamental rock and crushed stones, and can be used for concrete and paving works. The aggregates of the JA Silveira quarry obtained satisfactory results in the mechanical and chemical tests, being able to be used for larger works, such as railway ballasts and foundations. Through the interaction between the methods of petrographic analysis and geotechnical characterization tests, it was able to establish a correlation between the two deposits using geological knowledge as a form of technological control, establishing an optimization of use for the different types of aggregates.