## 5 Conclusions  
This investigation was performed with the aim of recovering river sediments from dredging and flax waste in sediment-based bricks for agricultural habitats. The main results obtained or observed according to the defined objectives are as follows:  
* In line with the practice of manufacturing unfired bricks, the sediment was characterized, based mainly on a granulometric analysis and the determination of plasticity limits (Aterberg limits). This characterization showed that this fluvial sediment, depending on the samples collected, met the main criteria, while sometimes being at the limit of certain charts. A lack of clay or even plasticity was noted. * In order to densify the sediment-based brick, a water content needs to be defined for the water-sediment-fiber mixes. This water content was deduced from the normal miniature Proctor test and corresponds to the optimum water content. It was possible to observe a certain variation in the optimum values on the so-called Proctor curves. This can be explained by the intrinsic variability of sediments in general and the small volume of sediments compacted. However, this miniature Proctor test requires a small mass of sediment, and therefore small volumes of sediment to be sampled, and the test is rapid. The value adopted was 22% for this sediment. Sediment-based bricks without fibers were manufactured with water contents of 19%, 22% and 25% for a preliminary study of air drying. The drying time was approximately 13 to 14 days for a moisture content of 22%. * The sediment-based bricks were compacted using equipment adapted to the \(4\text{ cm}\times 4\text{ cm}\times 16\text{ cm}\) models used for mortars, at an energy equivalent to that of the normal Proctor test (600 kN\(\cdot\)m/m\({}^{3}\)). All the sediment-based bricks, whether fiber-reinforced or not, had approximately the same dry density of 1.27 g/cm\({}^{3}\), corresponding roughly to the maximum density of the Proctor test minus 10%. * The addition of waste flax fiber reduces the drying time for dosages ranging from 0.1 wt% to 0.5 wt%. This reduction lasts 2 to 3 days and varies according to fiber length, but it stabilizes at around 0.4 wt%. * Shrinkage was observed in brick specimens. It remained low, at around 0.25% for a sediment-based brick without fibers, but tended to increase with fiber length reaching up to 1.25% for 4 cm fibers. No damage was observed. Figure 21: Evolution of densities of sediment-based bricks with estimated water content. The effect of the fiber content does not influence the final dry density of the sediment-based bricks, but there is a slight influence of the fiber length on the dry density. * The effect of the initial water content for all bricks produced does not affect the final dry density. This is important when defining the initial water content of sediment-water-fiber mixes. The recommended water content can be defined from the optimum water content obtained from the Proctor test, but a deviation of \(\pm 3\) to 4% is allowable. Water content below the optimum value may be recommended to save water. The addition of waste flax fibers improved the mechanical behavior of sediment-based bricks. This improvement was proposed before correcting the granulometric nature of the sediment (addition of clay) or considering stabilization using industrial by-products (fly ash, slag, biomass ash). This mechanical aspect is the subject of part II of a forthcoming article. Conceptualization, D.L. and A.S.; methodology, D.L. and A.S.; validation, D.L. and A.S.; formal analysis, D.L. ; investigation, D.L., A.S., D.N., H.Z. and T.S. ; resources, D.L. ; data curation, D.L. and A.S.; writing--original draft preparation, D.L. and A.S.; writing--review and editing, D.L. ; supervision, D.L., N.L. and H.Z. ; project administration, N.L. and H.Z. ; funding acquisition, N.L. All authors have read and agreed to the published version of the manuscript.