Synthesis and characterization of cement clinker based on Tunisian dam sediments

Abstract

Siltation is a permanent threat to the operation of dams since it reduces its storage capacity. In Tunisia, the annual siltation of dams is estimated at 22 Mm3 / year. Sediments currently cover 20% of the total capacity of the reservoirs, which could be a national water security issue in the years to come. Considering that sediments contain the oxides, SiO2. Al2O3. Fe2O3 and CaO, as main chemical constituents, a partial replacement of the raw materials in the cement production is suggested. This work concerns dam sediments from different regions in Tunisia. Characterisation results show that studied sediments are suitable for a beneficial reuse in the clinker production. However, according to the chemical composition, the incorporation rate of sediments in the raw mix varies from one sediment to another but still relatively important, ranging between 9 and 27 wt%. The characterization of produced clinkers show that mineralogy depends on minor oxides contents, especially SO3. MgO and equivalent Na2O. It has been proven that it is possible to substitute natural materials with 27.4 %SS sediment. The obtained clinker is characterized by the presence of M1 C3S and orthorhombic C3A. The high free lime content associated to incomplete alite formation can be surmounted by increasing slightly the clinkerization temperature.