Implication of Petrography and Geochemistry on Engineering Properties of Building Stones

Abstract

Granite is a common and widely occurring type of intrusive, felsic, igneous rocks. They usually have medium to coarse grained texture. It is commonly used as dimensional stone. The quality of a dimensional stone depends of its aesthetic look, eleganceand the other characteristics, like absence of closely spaced fractures, good interlocking texture, with lesser abundance of flaky minerals, absence of alterations and minerals which are susceptible to weathering and dissolution when exposed to atmospheric conditions. Six different types of rocks were collected from various quarries, and the rock specimens were prepared for laboratory testing. Important engineering properties such as abrasive resistance, water absorption, skid resistance, modulus of rupture, uniaxial compressive strength and bulk density were determined in the laboratory. Magnetic susceptibility and natural gama radiation were measured using portable field instruments. XRD and XRF studies were also carried out in the laboratory to understand the mineralogical and geochemical characteristics. Petrographical studies were also done tounderstand the textural characteristics of rocks. Finally all the parameters were statistically analysed in order to understand their relationship. The study concludes that ferro-magnesium minerals such as pyroxenes, magnetite and garnet are greatly responsible for high magnetic susceptibility and skid resistance. These minerals are also responsible for lower water absorption characteristics. Plagioclase feldspars are more responsible for high uniaxial compressive strength. High copper content and low silica also increase the abrasive resistance and modulus of rupture.