Ability of Two Dam Fine-Grained Sediments to be Used in Cement Industry as Raw Material for Clinker Production and as Pozzolanic Additional Constituent of Portland-Composite Cement

Fine-grained sediment deposition is a phenomenon that occurs at different extents in all the reservoirs. This particle accumulation has to be properly managed, in accordance with the operational needs and the environment. As an extracted and on-land managed sediment has to be considered as a waste material according to both European and French regulations, sustainable reuse options need to be investigated. One of them could be a beneficial reuse as a raw material in cement industry either as partial substitution in Portland clinker raw mix or as a supplementary cementitious material (SCM) after thermal treatment in order to activate its possible pozzolanic activity. Two dredged materials, labelled SEP and STA, both from French hydroelectric reservoirs, are characterized on physical, chemical and mineralogical aspects. SEP is used as raw material partial replacement for clinker synthesis and the other one is calcined in the range 550-1000 degrees C aiming to obtain a pozzolanic reactive material that could be used as supplementary cementitious material in blended Portland cement. After thermal treatments, the products are characterized and compared to ordinary Portland cement (OPC) and to pozzolanic active materials (fly ash from pulverized- coal power plant). Results showed that each sediment is suitable for the only tested reuse option. For the clinker prepared with SEP sediment, the morphology and the mineralogical composition correspond to those of a typical Portland clinker. Concerning calcined STA pozzolanic activity, the optimum thermal treatment was found to be 900 degrees C using the chemical Frattini test. Similar compressive strength results were obtained with calcined STA and silico-aluminous fly ash.