Thermal and physico-mechanical evaluation of some magmatic rocks at Homrit Waggat Area, Eastern Desert, Egypt: petrography and geochemistry

Abstract

Egypt is characterized by a wide variety of granitic rocks, making it one of the most essential ten countries producing ornamental stones worldwide. The main objective of this article is to study the effect of the chemical and mineralogical variations of the granitic rocks on their thermal expansion behaviors and physico-mechanical properties for use as dimension stones. The assessment of these rocks was performed using two main parameters: the first dealt with the petrographic investigation and chemical analysis for mineralogical and geochemical characterization. The second dealt with some essential physical and mechanical properties (e.g., water absorption, bulk density, and apparent porosity, and compressive strength), and thermal behavior in terms of linear thermal expansion coefficient. Based on the petrographic description, the samples were classified into five types: syenogranite, alkali-feldspar granite, albitized granite, granodiorite, and tonalite. The mineralogical characterization exhibited variable proportions of quartz and feldspars (plagioclase and alkali-feldspar), in addition to accessory minerals such as titanite, zircon, rutile, and iron oxide-based minerals. The thermal investigation showed insignificant changes in the thermal coefficient values and the thermal strain up to 100 °C as it did not exceed 0.049%, which indicates that they can be installed in places of high-temperature conditions. The physico-mechanical properties revealed that the water absorption ranged from 0.14 to 0.52%, the bulk density ranged from 2590.42 to 2748.23 kg/m3, and the compressive strength ranged from 314.17 to 628.75 kg/cm2. These results indicate that the studied granites could be acceptable for interior (indoor) and light-duty exterior purposes such as building cladding.