Some carbonate rocks utilized as a building material rocks, Egypt

Abstract

Studies of the geochemical, mineralogical, petrographical characteristics and the physicochemical properties were carried out on some carbonate rocks, so as to throw light on the possibility of utilizing them as a building stones. The dolomitic and dolostone rocks of Gebel Ataqa and Giran El-Ful quarries have been acquiring potential application in building and industry. Petrographically, the dolomite rocks of the Gebel Ataqa quarries are characterized by dolo-biomicrosparite and dolomitic limestone microfacies for Hassan Alaam quarry and dolosparite microfacies for Arab Contractors quarry, while those of Giran El-Ful (Abu Roash area) are mainly dolo-biomicite microfacies and dolostones. They are deposited in mixing zone environment. Mineralogically, XRD patterns indicate the dolomites of the Ataqa and Giran El-Ful quarries are non-stoichiometric. XRD with DTA revealed that the rocks of the three quarries are consisting mainly of dolomite (Ataqa quarries), calcite and ankarite (Abo Roash quarry), as the main constituents, besides quartz and halite as minor constituents. Geochemically, the normative dolomite contents in the studied rocks with an average ~ 90, ~ 35, and ~ 31% for Arab Contractors, Hassan Alaam and Giran El-Ful quarries; respectively. Thus, the dolomitization was more effective in the Cretaceous carbonates at Arab Contractors quarry than those in the Middle Eocene in Hassan Alaam and Giran El-Ful quarries. Arab Contractors have very high Mg content followed by Hassan Alaam, though impoverished in Na₂O, K₂O, Al₂O₃, Fe₂O₃, SO₃, SiO_2, TiO_2, and Cl. Giran El-Ful quarry has very high Fe₂O₃ and MgO contents; on the other hand, poor in Na₂O, K₂O, Al₂O₃, SO₃, SiO₂, TiO₂, and Cl. Sr contents indicate that the dolomite crystals were deposited in mixing zone environments. The total radioactivity measurements are ranging from 2 to 8 ppm for U and from 3 to 9 ppm for Th. The radioactivity measurements are approximately against to the background level of carbonates, and they are in the permissible limits for carbonates used in cement industries and as building stones. The dolomitic and dolostone rocks of the three quarries are proved chemically suitable for the industries relevant to crushed aggregates and lime production. Physically–mechanically examination revealed that the youngest carbonate deposits in the Middle Eocene (Hassan Alaam quarry) rocks have relatively low porosity, water absorption, and crushability, and highest compressive strength compared with those carbonate rocks of the two other quarries of Upper Cretaceous (Arab Contractors and Giran El-Ful). The petrographical, geochemical, and physical–mechanical observations recommended that the carbonates rocks of Hassan Alaam and Arab Contractors quarries in Gebel Ataqa area clearly can be used in the production of crushed aggregates to utilize in the concrete works. On the other hand, Giran El-Ful quarry can be used only in the mechanical sawing and in the production of limestone blocks.