Geology, Geotechnical Characteristics and Industrial Application of Miocene Clay Deposits at Wadi El Natrun Area-Egypt
Clay deposits are widely distributed in many geological formations. In Egypt, they occur around Nile valley and Delta as well as in the Eastern and Western Desert. Miocene clay deposits are widely exposed especially at the east of Western Desert. Most of these occurrences were geologically studied, assessed for application in many industries.
In Egypt, conventional clay brick, which produced from clay with high firing temperature is the most common construction materials used for the historical and traditional buildings for a long time. So the clay bricks industry consumes a significant amount of energy and releases a large quantity of gases to the atmosphere leading to environmental and economic problems. Also, the accumulation of unmanaged wastes has resulted in an increase environmental concern. The stabilized clay bricks are an unfired clay bricks produced from mixture of clay, stabilizing materials and wastes. The current study evaluates the feasibility of using waste materials electric arc furnace slag (EAF slag), calcrete dust (CD) for production of stabilized clay bricks. One of the possible remedies is the use of waste material, having a chemical composition similar to that of natural clay or shale, to replace a percentage of the raw material. There are two-fold benefits can achieve; economic benefits (reduction in raw material and energy required) and environmental benefits (due to placement of waste in a sound, inert and useful medium and reduction of gases emission).
Experimental investigations were carried out to explore the effect of wastes addition in different clay-based mixes at different ratios. Cement, gypseous hydrated lime and sands were added in the studied formulations. These mixes contained clay (50%), sand (25, 20, 15%), gypseous hydrated lime (15 wt. %), Portland cement (5, 10 wt.%), calcrete dust (5, 10 wt.%), and electric arc furnace slag (5,10 wt.%). The ingredients of each mix were molded in a cylindrical metal mold under compression of 100kg/cm2 then cured in a plastic container for 14, 28, and 60 days. The laboratory made specimens were mineralogical identified using X-ray diffraction technique and microstructure analysis was studied using Scanning Electron Microscopy. In addition, physical and mechanical properties were measured according to the Egyptian Standard Specification (ESS), 2005 and evaluated in accordance with the Egyptian code for the building by the stabilized and compressed earth soil (ECBS, 2016) to ensure the quality and impact of the made unfired clay specimens. Also, the durability of the cured specimens against collapsibility in water was assessed and enhanced by using silicon and acrylic –based paints. The results show that the pozzolanic reaction and cation exchange played an important role in particles agglomeration and stabilization. Also, the addition of EAF slag as an additive material enhances the durability of stabilized clay specimens more than the addition of calcrete dust.