Sediment-based fired bricks strength optimization - A discussion on different approaches

International audienceSustainable sediment management is a global issue due to dredging of rivers and river mouths for both navigability and flood protection needs. Previous studies on sediments beneficial uses have shown that essentially the targeted materials relate to roads and ceramics (bricks, tiles). For sustainable management, these recovery sectors impose the minimization of transport and the restriction of the use of binders with a high carbon footprint and addition materials in mixtures (renewable resources). Ceramics for construction appears to constitute a direct recovery method for dredged sediments. Even if it requires adequate water content for manufacturing, it does not require any addition of material. However, mixtures of sediments can be operated to improve the chemical composition before firing (optimization). Waste as aggregates (foundry and pickling sand, silica fume, crushed brick, ...) can be incorporated in such mixtures (ecofriendly recovery). Different approaches are available to ensure the feasibility (composition and implementation) of producing ceramic materials for construction (bricks, tiles, pottery). In practice, they are mainly based on industrial methodological approaches (diagrams by Winkler, Augustinik, Sembenelli). These diagrams were drawn up from well-identified non-renewable resources (clays, sands) from mines and quarries. For dredged sediments i.e. mixtures of clay, silty particles and fine sands, other approaches should be defined based on these practical approaches. They can be defined considering the nature and mineralogy of clays, or based on specific properties of the sediment or else resulting from statistical methods. These latter are considered as coupled approaches more efficient for a laboratory investigation. This type of coupled approach combined with an appropriate experimental method, provides a guide for any feasibility study of raw or fired sediment based bricks. A complete but simple methodology for recovering sediments as ceramic construction material is outlined