Design of new blended cement based on marine dredged sediment

This paper investigates a new beneficial alternative use of marine dredged sediments as a new material for cement production. The sediment from the northern coast of Brittany (France) is considered. Firstly, the raw sediment is characterized using several techniques. The physical properties such as water content, particle size distribution and density are measured. Its mineralogy is studied using Xray diffraction and thermal analysis. The chemical analyses are done in order to quantify the composition in oxides, heavy metals, PCBs, and PAHs. The results show that the sediments have high water content, important fine particles, and the main minerals observed are calcite, quartz, kaolinite, illite, and muscovite. Secondly, the sediment is treated at high temperature (650 degrees C and 850 degrees C) in order to eliminate all organic compounds and activate the clay minerals. Six blended cements are formulated by mixing Portland cement (CEM I) and the treated sediment with different mass content (8%, 16% and 33%). Pastes and standardized mortars based on the new blended cements are then prepared and characterized. The microstructure is studied using thermal analysis. Open porosity, apparent density, gas permeability, elastic modulus and compression strength are measured on mortars. The results show that thermal treatment at 650 degrees C is more interesting than the one at 850 degrees C in terms of both energy saving and mechanical performance. The sediment treated at 650 degrees C presents interesting properties; particularly it developed a better compressive strength than calcareous filler and can be used successfully in the design of blended cement. (C) 2012 Elsevier Ltd. All rights reserved.