Sediment-based fired brick strength optimization : A discussion on different approaches

Sustainable sediment management is a global issue due to dredging of rivers and river mouths for navigability and flood protection. 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. Although 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 Winckler, Agustinik, 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 the specific properties of the sediment or else resulting from statistical methods. In the case study of manufacturing fired bricks from river sediments, various approaches have been implemented to verify the feasibility of brick production. They are presented, discussed and evaluated through a mechanical parameter (compressive strength). The relationship between each approach and the necessary characterization of the sediments is given. A methodology for recovering sediments as ceramic construction material is outlined