Self-compacting Backfills using Fly Ash and Dredged Marine Sediments for Public Work Applications

Sediment accumulation at the bottom of ports disrupts maritime activities and disturbs the physicochemical balance of water bodies. In France, the maintenance of the 6500-kilometer long coastline would require the extraction of about 50 million m3 of marine sediments every year. For several years, these sediments were considered waste. However, they are increasingly being acknowledged as a resource in need of management. Several research studies were conducted to find valorization ways that satisfy technical and regulatory requirements. These sediments present interesting heterogeneous physicochemical, mineralogical, and geotechnical characteristics. However, they may contain contamination, which could limit their uses. This paper deals with the possibility of producing self-compacting backfills using dredged marine sediments, fly-ash, and hydraulic binders for public work applications. The impact of dredged sediments on the composition of self-compacting backfills was studied. Moreover, the impact of fly ash and binder type and percentage on the backfill behavior and mechanical properties was discussed

Marine Dredging Sediments Valorization in Self-Compacting Concretes

Rock and eroded soil are transported by wind, tide, and human action (development works), and deposited as sediment in ports, estuaries, and rivers. The sediment accumulation at the bottom of ports disrupts maritime activities and disturbs the physicochemical balance of water bodies. As a result, dredging is necessary to reduce sediment deposits and restore the natural environment for proper port functioning. At the national level, the maintenance of the 6,500-kilometer French coastline would require the extraction of about fifty million cubic meters of marine sediment every year. These dredged sediments have been used in civil engineering applications for about ten years, in order to reduce their economic and environmental impact. The proposed study addresses the potential use of sediments to produce accropode blocks for maritime public works applications. It consists in developing concrete mixtures using dredged marine sediment treated to protect against erosion. A study of material characterization, optimization of the composition of the concrete formulation, as well as a determination of the mechanical, physical and durability properties of the concrete were necessary to validate the technical feasibility of this new solution. Around 700 small accropode blocks were then prepared to better analyze the structure stability against swell effects. The obtained results show that the sediments could not produce Self Compacting Concrete (SCC). However, sediment treatment with 6% by weight of cement has enabled the production of SCC. It is worth noting that the use of superplasticizer was essential to ensure concrete workability. Increasing the cement percentage has also improved the composite workability. Finally, a concrete compressive strength greater than 40 MPa has been achieved when using 300 kg/m3 of treated sediments

Omenn Syndrome : Two Case Reports

Omenn syndrome is a variant of combined severe immunodeficiencydue to mutations in RAG genes. It is characterized by polymorph symptoms andlethal outcome. We report on two cases of Omenn syndrome. Infants were aged 50and 46 days. The clinical and biological signs were typical and complete in the firstcase. In the second case, only the cutaneous signs were present. Diagnosis was confirmedby genetic study. The Rag1 T631 mutation was found in these two patients.Hematopoietic stem cell transplantation could not be done and the evolution wasfatal in both cases because of severe infectious episodes. Prenatal diagnosis wasperformed in the two families and each family has currently a healthy child. In conclusion,early diagnosis of Omenn syndrome may avoid infectious complicationsresponsible for delay in therapeutic management. Genetic study confirms the diagnosis.The treatment usually consists of hematopoietic stem cell transplantationin association with immunosuppressive drugs. Prenatal diagnosis is very importantto allow parents to have healthy children.</p

Primary resistance to clarithromycin, metronidazole and amoxicillin of Helicobacter pylori isolated from Tunisian patients with peptic ulcers and gastritis: a prospective multicentre study

<p>Abstract</p> <p>Background</p> <p>The frequency of primary resistance to antibiotics in H. pylori isolates is increasing worldwide. In Tunisia, there are limited data regarding the pattern of H. pylori antibiotic primary resistance.</p> <p>Aim</p> <p>To evaluate the primary resistance of H. pylori to clarithromycin, metronidazole and amoxicillin and to detect the mutations involved in clarithromycin resistance.</p> <p>Materials and methods</p> <p>273 strains isolated from adults and children were enrolled. The primary resistance to clarithromycin, metronidazole and amoxicillin was evaluated by means of E-test minimal inhibitory concentration (MIC). The real-time PCR using Scorpion primers was performed in all cases to assess clarithromycin primary resistance and point mutations involved.</p> <p>Results</p> <p>No resistance to amoxicillin was detected. For adults, resistance to clarithromycin and metronidazole was found respectively in 14.6% and 56.8%, and respectively in 18.8% and 25% in children. Overall, the rates of global primary resistance to clarithromycin and metronidazole in Tunisia were respectively determined in 15.4% and 51.3%.</p> <p>By the use of Scorpion PCR, the A2143G was the most frequent point mutation observed (88.1%), followed by the A2142G (11.9%); the A2142C was not found and 18 of 42 patients (42.8%) were infected by both the resistant and the susceptible genotype.</p> <p>The association of clarithromycin resistance with gender was not statistically significant, but metronidazole resistant strains were isolated more frequently in females (67.8%) than in males (32.2%) and the difference was significant. As for gastroduodenal diseases, the difference between strains isolated from patients with peptic ulceration and those with non peptic ulceration was not statistically significant. When about the distribution of resistant strains to clarithromycin and metronidazole between the three Tunisian cities (Tunis, Menzel Bourguiba and Mahdia), the difference was not statistically significant.</p> <p>Conclusion</p> <p>Local data regarding the primary resistance of H. pylori to clarithromycin, metronidazole and amoxicillin and the main genetic mutation involved in clarithromycin resistance in vivo (A2143G) are necessary to prove a clear need for a periodic evaluation of antibiotic consumption and new therapeutic strategies in Tunisia in order to avoid the emergence of resistant strains.</p

High Therapeutic Efficacy of a New Survivin LSP-Cancer Vaccine Containing CD4+ and CD8+ T-Cell Epitopes

The efficacy of an antitumoral vaccine relies both on the choice of the antigen targeted and on its design. The tumor antigen survivin is an attractive target to develop therapeutic cancer vaccines because of its restricted over-expression and vital functions in most human tumors. Accordingly, several clinical trials targeting survivin in various cancer indications have been conducted. Most of them relied on short peptide-based vaccines and showed promising, but limited clinical results. In this study, we investigated the immunogenicity and therapeutic efficacy of a new long synthetic peptide (LSP)-based cancer vaccine targeting the tumor antigen survivin (SVX). This SVX vaccine is composed of three long synthetic peptides containing several CD4+ and CD8+ T-cell epitopes, which bind to various HLA class II and class I molecules. Studies in healthy individuals showed CD4+ and CD8+ T-cell immunogenicity of SVX peptides in human, irrespective of the individual's HLA types. Importantly, high frequencies of spontaneous T-cell precursors specific to SVX peptides were also detected in the blood of various cancer patients, demonstrating the absence of tolerance against these peptides. We then demonstrated SVX vaccine's high therapeutic efficacy against four different established murine tumor models, associated with its capacity to generate both specific cytotoxic CD8+ and multifunctional Th1 CD4+ T-cell responses. When tumors were eradicated, generated memory T-cell responses protected against rechallenge allowing long-term protection against relapses. Treatment with SVX vaccine was also found to reshape the tumor microenvironment by increasing the tumor infiltration of both CD4+ and CD8+ T cells but not Treg cells therefore tipping the balance toward a highly efficient immune response. These results highlight that this LSP-based SVX vaccine appears as a promising cancer vaccine and warrants its further clinical development

Mineral waste valorization in road subgrade construction: Algerian case study based on technical and environmental features

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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

Compressed Earth Blocks Using Sediments and Alkali-Activated Byproducts

International audienceSediment dredging is necessary and vital to preserve maritime activities and prevent floods. The management of these sediments represent an environmental challenge for many countries all over the world. This study focuses on evaluating the feasibility of using dredged sediments for the manufacturing of compressed earth blocks (CEB). The alternative construction material has the potential of reducing the need for dredged sediment onshore storage or ocean dumping. Several experimental tests have been conducted on two geopolymer types, which were obtained by mixing sediments from the northern region of France, fly ash (FA), and grounded blast furnace slag (GBFS). The geopolymers, which were activated using an eight-molar concentrated sodium hydroxide solution (NH), were cured at a temperature of 50 °C. The results have shown that a geopolymer content of 36% of FA and 10% of GBFS along with (NH) alkaline solution has significantly improved the mechanical properties of CEBs, which have outperformed those of Portland Cement-stabilized traditional blocks. The use of NH has resulted in the formation of crystalline calcium silicate hydrate (C-S-H) amorphous gel. Adding GBFS to the mix has enhanced the geopolymer paste compressive strength and microstructure because of the formation of additional C-S-H. The valorization of dredged sediments in CEB based on geopolymer stabilization can contribute to the reduction of the CO2 footprint of the construction industry

Valorization of Dredged Sediments and Recycled Concrete Aggregates in Road Subgrade Construction

Large quantities of dredged sediments and recycled concrete materials are generated every year all over the world. The disposal of these large quantities in landfills represents serious environmental problems. Furthermore, high-quality raw materials for construction are depleting, and their use cannot be sustained. The valorization of dredged sediments and recycled concrete materials as alternative construction materials has the potential to reduce the impact of these two issues. In this context, this study aims at investigating the feasibility of using dredged sediments and recycled concrete aggregates as alternative raw material for road subgrade construction. Various mix designs were prepared using dredged sediments and recycled concrete aggregates. The mixes were then treated with quicklime and road binder as specified in the French soil treatment guide. Their physical, mechanical, and geotechnical properties confirmed the feasibility of using recycled concrete aggregates and dredged sediments up to a certain percentage in road subgrade construction. Moreover, they showed that the mixes containing 20% of dredged sediments met road subgrade minimum physical and mechanical properties, such as immediate bearing capacity, unconfined compression strength, indirect tensile strength greater, and UCSI/UCS60 ratio. Finally, leaching tests were conducted to ensure the environmental safety of the various mixes. The results showed that the mixes met the thresholds for their use in road subgrade construction. The feasibility of using dredged sediments and recycled concrete aggregates in foundations and base layers will be studied in future projects

Development of Flash-Calcined Sediment and Blast Furnace Slag Ternary Binders

International audiencePartial cement replacement by low-carbon-impact additions has the potential to reduce CO2 emissions. The aim of this study is the development of a ternary binder that includes ordinary Portland cement (OPC), ground granulated blast furnace slag (GGBS), and flash-calcined sediment (FCS). To upgrade dredged mineral material into FCS, a new heat treatment, i.e., flash calcination, was used. The used materials were physically, chemically, and mineralogically characterized. The mixture design method was used to optimize the design of the ternary blended binders. A model was developed and validated for the prediction of the 90-day compressive strength for mortars composed of OPC (C), GGBS (S), and FCS (F). Five mixes, reference RM (100% OPC), binary mix (50% OPC and 50% GGBS), and three ternary mixes with FCS rates of 10%, 15%, and 20% were characterized in fresh and hardened states. The results show that the incorporation of FCS reduced the workability of the mixes and increased their densities. Moreover, the initial setting time of the mix was delayed, and the heat of the hydration peak was decreased. The 90-day compressive strengths of the mix containing 10% FCS were higher than those of RM. In conclusion, the use of 10% FCS and 40% GGBS was an efficient substitute for 50% OPC