Evaluation of geotechnical properties of Cretaceous sandstone, Western Desert, Egypt

The Western Desert, Egypt, mostly covered by clastic sedimentary rocks ranging in age from Lower Cretaceous to the Quaternary. Taref Formation of Nubian Group constitutes one of Cretaceous succession; it consists mainly of yellowish, pale red, pink, and white massive and cross-bedded sandstone in fining-upward cyclic manner. The petrographical parameters and mechanical properties of these clastic rocks must be integrated to better understand their geotechnical behavior. Mineralogically, it composes quartz, feldspars, and rock fragments, with an average value of 97.9, 1.2, and 0.9 %, respectively. Accordingly, Taref Sandstone can be classified as quartz arenite. The roundness of grains are dominated by sub-angular, sub-rounded, angular, rounded, very angular, and well rounded with an average value of 36, 25, 17, 9, 7, and 6 %. Its dry density (gamma d, g/cm(3)) varies from 1.65 to 1.87 g/cm(3) that indicates Taref Sandstone classified as dense-very dense sandstone. Porosity (n%) ranges from 9.41 to 13.59 % that means that it ranges from medium to high porous sandstone. The dry uniaxial unconfined compressive strength (UCSdry) and point load strength index (IS50) values indicated that its compressive strength rages from moderately strength to very high strength and both of them are closely related. The porosity (n%) of Taref Sandstone has a significant correlation with mostly its physical and mechanical properties of the studied sandstone. Through matching correlation data among these parameters, it was clearly indicated that both porosity (n%) and dry density (gamma d) had been considered as the major parameters influencing other physical and mechanical properties of the studied Cretaceous sandstone samples.