Formulation of mortars based on thermally treated sediments

To successfully transition any economy towards sustainable development requires reducing the consumption of raw materials while maintaining production levels. In the French construction sector, nearly 55% of extracted materials are aggregates. A potential solution to decreasing the carbon footprint of the construction sector and reducing the consumption of raw materials consists in recovering industrial byproducts, in particular reclaiming dredged sediments for use as a mineral component in mortar formulas. However, these sediments require adequate and optimal pretreatment to be implemented effectively. Several processing techniques have thus far been applied to improve specific physicochemical properties. Heat treatment through calcination has proven effective in removing organic matter and activating the pozzolanic properties of the sediments. The present study demonstrates that optimizing the heat treatment of marine sediment additives affects the physicomechanical and environmental properties of mortar. Compared with a standard reference mortar, substituting an optimum portion of cement with sediments that were calcination-treated at 750 °C achieved at least identical and even improved mechanical properties of the cement matrix. Incorporating up to 20% of calcined sediment as a cement substitute did not affect the durability of the mortar. In fact, a cement substitution of 10% improved the accelerated carbonation behavior. The characteristics of these mortar formulas were evaluated from an environmental and life cycle point of view and compared with inert waste reference thresholds (in accordance with the French inert waste storage facilities directive of 2010).