Étude de la durabilité d'un sédiment, traité au ciment et additifs

CAEN-BU Sciences et STAPS (141182103) / SudocSudocFranceF

Valorisation des sédiments marins contaminés par solidification/ stabilisation à base de liants hydrauliques et de fumée de silice

Des travaux de recherche effectuées sur le traitement des sédiments revalorisés ont été entrepris depuis une dizaine d années et ont fait l objet de plusieurs publications comme relaté dans l'étude bibliographique présentée dans ce rapport. L essentiel a porté sur la caractérisation physique, puis mécanique en fonction des dosages en ciments et additifs. Ainsi, les travaux de recherche entrepris dans cette thèse entre dans le cadre de la poursuite des recherches dans ce domaine. Elle définie les modalités d étude, ayant pour objet la valorisation des sédiments de dragage du Port En Bessin en vue d obtention d un matériau final utilisable en techniques routières. Ainsi la première phase de l étude consiste en une caractérisation des boues aussi bien dans leur composition que dans leur comportement aux contraintes mécaniques. Les caractéristiques mécaniques sont aussi étudiées dans la partie formulation. Une planche expérimentale en techniques routières a permis l étude en conditions réelles d utilisation du matériau. Des analyses sont réalisées pour étudier le relargage de certains polluants (métaux lourds, HAP...) et comparent les résultats avec les prévisions réalisées à partir des essais de lixiviation. D autres paramètres concernant le comportement géotechnique du matériau ont été vérifiés et comparés aux prévisions attendues pour voir si l ensemble des résultats obtenus ne montre pas de dérive par rapport aux prévisions. Le matériau peut être ainsi mis en œuvre dans une troisième phase pour la réalisation finalement d une plate forme routière.The reuse of the dredged sediments in road construction has been studied and published in the previous researches which are presented in this rapport. The main objective is to enhance the physical and mechanical characteristics of the mix by incorporating binders (cement and/or pozzolanic binder). The preliminary study performed on fine dredged sediments revealed the identification of the mechanical characteristics measured on the mixes is compatible with their use as a base course material. The result shows that the treatment by hydraulics binders could satisfy the needed mechanical characteristics. However the proportion of hydraulics binders needed to meet prescribed specification is important so the reuse of the dredged sediments of Port en Bessin in road construction as an alternative material could be achieved. The construction of the experimental road has allowed to evaluate the compatibility of this designed material with the current practice with standard materials. To evaluate the environmental impacts of the used material, leaching tests are performed. The leaching tests were performed to verify the predicted release of pollutants based on total dissolution. And for the final part, the fine dredged sediments were used for the construction of the of the platform road.CAEN-BU Sciences et STAPS (141182103) / SudocSudocFranceF

Investigation of natural dewatering of dredged sediments incorporating evaporation and drainage

Whether driven by the need to dispose of contaminated sediment, a reduction in the size of confined disposal areas, or a lack of land adjacent to dredge sites, dewatering practices have gained prominence over the past few years. It is necessary to dewater these dredged sediments so that they can be used for beneficial purposes, such as industrial or construction backfill material. This study explores the natural dewatering method that reduces the water content of dredged sediment through evaporation and drainage. This research implemented two types of dredged sediments from different origins to determine the effects of sediment type on both evaporations as well as dredging. First, the effects of diameter on the rate of evaporation (ROE) and the potential of evaporation (POE) were investigated. The measured POE was then compared to the predicted POE using Rohwer's and Penman's models. In order to improve the handling of these dredged sediments prior to beginning the valorization process, a correlation between the decrease in water content and the increase in shear strength is discussed. This research will improve the handling of these sediments for transportation and indirect management of dredged sediment valorization

Valorization of a Highly Organic Sediment: From Conventional Binders to a Geopolymer Approach

International audienceThe objective of this research is to investigate the possible reuse of dredged sediments from the port of Cherbourg, France, as an alternative material in road engineering and as a backfill material. These dredged sediments contain high percentages of organic matter (OM), and the presence of OM in the sediment, even in small amounts, can affect the engineering properties of sediments. This research was carried out in two series: the sediment was treated with traditional hydraulic binders (ordinary Portland cement (OPC), calcium sulfo-aluminate (CSA) cement, quarry sand (QS), lime, and a combination of them) in the first series, and with pozzolanic binders in the second series (ground-granulated blast-furnace slag (GGBS) and fly ash (FA)), along with the introduction of an activator. According to French legislation, these two pozzolanic binders (GGBS and FA) have no carbon footprint as they are industrial by-products, and therefore, the second series of this research is considered to be highly eco-friendly and economical. Sediment treated with hydraulic binders yielded a maximum value of unconfined compressive strength (UCS) of 1 MPa at 28 days. Out of eight formulations made using traditional binders, only one formulation barely met the French criteria to be used in the sub-base layer of roads. The development of geopolymer using alkali-activated GGBS and then the incorporation of 30% sediments yielded a UCS value above 2 MPa at 28, 60, 90, and 180 days. Furthermore, the addition of 5% lime and 3% granular calcium carbonate in the same mixture (geopolymer + 30% sediments) increased the UCS by up to 60% and 90%, respectively

Valorisation des sédiments du barrage de Zardezas (Algérie): Caractérisation et aptitude au compactage des sédiments

International audienceEn raison du taux élevé d'envasement des barrages et autres retenues d'eau, zones de sédimentations en rivières (oueds) ou à l'embouchure de celle-ci, la gestion durable des sédiments est devenue une véritable préoccupation nationale en Algérie. Cependant, une gestion durable des sédiments dragués dans ces zones implique une recherche de filières de valorisation à proximité des lieux de prélèvements. Une valorisation en matériau routier, de remblai, voire de remplissage peut constituer une solution potentiellement acceptable mais aussi, qui répond aux besoins d'aménagement du territoire Algérien. Une approche méthodologique de valorisation consiste à caractériser le sédiment et à définir ses propriétés d'aptitude au compactage pour répondre à la mise en place de ces matériaux routiers. Cette approche propose pour des sédiments dragués en-amont du barrage de Zardezas (Skikda, Algérie) pour un réemploi en tant que matériaux de remplacement en techniques routières. La caractérisation minimale de ces sédiments et leurs caractéristiques, sont établies et discutées. L'aptitude au compactage a été effectuée selon deux essais : l'essai Proctor normal et l'essai de compactage miniature à énergie équivalente. Les résultats d'essai de compactage sont analyses en relation avec les caractéristiques du sédiment et les moyens d'essai mis en oeuvre. Les conclusions portent sur la caractérisation minimale et la potentialité de valorisation en matériau routier ou de remblai et sur les avantages de l'essai de compactage miniature utilisé

Optimization of an Eco-Friendly Hydraulic Road Binders Comprising Clayey Dam Sediments and Ground Granulated Blast-Furnace Slag

International audienceThis study investigated the potential use of Zerdezas dam Calcined Sediments (CS) and El-Hadjar Blast Furnace Slag (GGBS) from northern Algeria as a partial replacement of cement (C) in normal hardening hydraulic road binders. Two binder mix designs were optimized using a Response Surface Methodology (RSM). The first mix, 50C35GGBS15CS, consisted of 50% cement, 35% blast furnace slag, and 15% calcined sediment. The second mix, 80C10GGBS10CS, consisted of 80% cement, 10% blast furnace slag, and 10% calcined sediments. The tests of workability, setting time, volume expansion, compressive and flexural strengths, porosity, and SEM were conducted to ensure that both mixes meet the standard requirements for road construction binders. The two proposed mixes were qualified as normal hardening hydraulic road binder. The reuse of the sediments will contribute to a better disposal of dam sediments and steel industry waste and to preserve natural resources that are used for manufacturing cement. It will also contribute to the environmental impact reduction of cement clinker production by reducing greenhouse gas emissions

Recycling of Excavated Soils from Mini-Trenches Made on Road or Sidewalks to Install Public Utilities

International audienceDigging trenches on roads, sidewalks, or banks to accommodate public demands is required for the installation of water pipelines, natural gas lines, electric cables, and optical fibers. The soils extracted from these trenches always have substantial environmental and economic consequences, as these soils are frequently regarded as waste due to their poor engineering properties. As a result, a suitable location and method for disposing these excavated soils must be found, and this procedure is exceedingly costly, time consuming, and environmentally unfriendly. It is far more efficient to reuse these excavated soils for refilling the same trenches. This study is a part of a French national project. The national project aims to dig 5 to 25 cm wide trenches to install public utilities and to refill them using the same excavated material in the form of self-compacting mortar. The goal of this research is to determine the best ecofriendly binder for the soil excavated from various sites by conducting laboratory-scale physio-chemical and mechanical testing. This study examined the unconfined compressive strength (UCS) assessed by both destructive and non-destructive (ultrasonic) testing methods. By utilizing low CO2-emitting ecofriendly binders incorporating industrial byproducts (fly ash and GGBS), this work has broadened the possibility of reusing trench cuttings to refill the same trenches