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Dry-mix shotcrete has all the components of concrete but its particular placement technique makes it harder to study than ordinary concrete. Its durability has not been the subject of much analysis and the aim of this paper is to bring new insights in that field. This work focuses especially on the durability of dry-mix shotcrete containing supplementary cementitious materials (SCM) with different aggregate size distributions. The use of SCM in dry-mix shotcrete aims at limiting rebound, reducing the carbon footprint of the binder and enhancing durability. The durability indicators introduced in this work are related to compressive strength, porosity, gas permeability, and chloride migration. Laboratory and on-site tests were carried out. It appears that, despite the high porosity (due to the adopted aggregate-size distribution characterized by very fine particles), shotcrete compressive strength, permeability and chloride penetration resistance are equivalent to or better than those of ordinary concrete. Additionally, this study underlines the limits of a prescriptive approach for achieving a given performance level, as dry-mix shotcrete is defined by its components as well as by its setup (water and final binder contents are very dependent on the nozzelman’s adjustments). In these conditions, the performance-based approach seems more appropriate, even if a large data-base on the properties of dry-mix shotcrete (porosity included) is required. Extending the data-base on dry-mix shotcrete is, therefore, among the expected contribution of this research project.

WOS:000394061300024; International audience; Dry-mix shotcrete has all the components of concrete but its particular placement technique generates losses due to rebound. These losses induce a cost increase and a difference between the initial and in place composition of the concrete. Many parameters influence rebound, but this study focuses on mixture design via supplementary cementitious materials (SCMs). The aim of the paper is to study the relation between fresh properties and rebound of shotcrete, and evaluate how SCMs act on it. This will eventually help to understand what mixture properties are needed to limit rebound and help with the design of mixtures. In this study, 5 mixtures in which cement was partially replaced by metakaolin, ground granulated blast furnace slag or silica fume were shot at different consistencies, in a full scale laboratory facility. Fresh shotcrete was evaluated by penetration tests (static and dynamic). It appeared that the SCM5 were efficient in reducing rebound and their efficiency depended on consistency. Water is one of the main parameters in rebound but it is difficult to control because it is adjusted by the operator. Mixtures with metakaolin and silica fume seem to lower this dependence. Static and dynamic penetration stresses seem to be correlated with rebound and, more precisely, the relation between dynamic measurement and rebound seems independent of the mixture tested. Understanding the levels of static and dynamic penetration stress could make mixture design easier. (C) 2017 Elsevier Ltd. All rights reserved.

WOS:000209197400009; International audience; This paper deals with the valorization of wastepaper sludge ash (WSA) as the main component of Hydraulic Road Binder (HRB). The physical, chemical and mineralogical characteristics of this WSA were studied and this characterization was completed by a study of the reactivity of WSA in presence of lime and gypsum. This study led to the optimization of HRB rich in WSA whose characteristics were tested on mortars and on samples of treated soil. The characterization of WSA and the study of its reactivity showed that WSA had hydraulic properties because of the presence of hydraulic minerals: lime (CaO), mayenite (Ca12Al14O33) and alpha'-Ca2SiO4. The compressive strength of WSA-containing mortars was strongly penalized by the high water demand of the ash but this was not the case for the samples of treated soils. The results obtained on clayey soil treated by a binder optimized by the addition of 20 wt% of gypsum were better than those obtained with conventional commercial binders: their behavior was comparable in the long term but the optimized binder was more efficient in the short term. All the results obtained in this study permit us to conclude that WSA is suitable for use as the main component of HRB. This study is a good example of waste valorization: firstly, the calorific value of sludge produced by the paper recycling industry is recovered at the industrial plant and, secondly, the ash formed during this incineration process is reused as the main component of HRB with interesting added value.

This paper deals with the physical, chemical and mineralogical characterization of WSA in order to evaluate the interest of its potential reuse as a component in hydraulic binders. The results show that WSA contains hydraulic minerals such as lime (CaO), mayenite (Ca12Al14O33) and α′-Ca2SiO4 in addition to gehlenite, the main mineral. WSA can also be considered as a hydraulic mineral admixture, which is very encouraging for the potential reuse of this material in hydraulic binders. However, WSA has some characteristics that could be worrying for its reuse. Firstly, SEM observations show that its particles are very porous, and that could lead to problems of workability of cement-based materials containing WSA. Secondly, the presence of both lime and metallic aluminium could be responsible for swelling when WSA is introduced into cement-based materials. No swelling was observed visually during the hydration of WSA-containing paste in this study but this first qualitative test is not sufficient and further investigations of this specific characteristic will be necessary. Finally, the presence of lime in the WSA could be considered as a problem for its use in binder for construction (risk of expansion) but, from another point of view, it would be very interesting for applications in road works, especially for the stabilization of soil, in which lime is regularly employed because it has useful properties (drying and reinforcement of the mechanical strength of the soils).

Le dragage des sediments est necessaire pour maintenir le transport fluvial mais les sediments extraits sont souvent pollues. La societe Solvay a mis au point un procede pour les traiter et permettre ainsi d’envisager une valorisation : le procede Novosol® . Celui-ci permet de fixer les metaux lourds mais aussi de detruire la matiere organique. Les principales caracteristiques d’un sediment traite et sa valorisation en techniques routieres sont presentees dans cet article. D’un point de vue mecanique, les melanges realises avec les sediments sont conformes aux normes routieres. Les tests environnementaux sur les materiaux incorporant les sediments traites montrent que le relargage est similaire a celui sur materiaux temoins. L’ensemble de ces resultats permet d’envisager l’utilisation des sediments traites Novosol® en techniques routieres.

International audience; The treatment and the valorization of polluted dredged sediments is an important issue. The main benefit is the saving of natural resources and the prevention of landfilling. The valorization of sediments into road base materials require an accurate assessment of their characteristics. This study addresses the mechanical and leaching tests. The Novosol (R) process has been used to treat the dredged sediment and consists in the stabilization of heavy metals using phosphate and the degradation of organics by calcination at 700 degrees C. The characterization (chemical, physical, thermal and environmental) carried out on the treated sediment shows that it is mainly composed with fine particles. The analyses have shown a low bulk density in comparison to that for standard sand. A significant total metal content and the absence of organic matter have been concluded. To evaluate the mechanical behaviour of the road materials, tensile strength and elasticity modulus have been measured. It has been seen that the introduction of treated sediments in materials treated with hydraulic binders improves the tensile strength. An environmental assessment has been made on these hydraulic-binder-treated materials thanks to a percolation test and the EN 12457-2 leaching test. The percolation test allows to evaluate the behaviour under accelerated conditions. The standard leaching test is used in order to assess pollution potential. Both tests show that the release of metallic elements is almost the same for mixtures with or without sediments. The results suggest that the use of treated sediments in road materials is not harmful and brings mechanical benefits.

International audience; This study deals with the reuse of an industrial waste rich in CaCO 3 as a mineral addition and agent 9 of stability in low-strength filling grout for soil reinforcement applications. The physical, chemical 10 and mineralogical characteristics of these Carbonated Residual Brines (CRB) were determined and 11 completed by a study of CRB behaviour in cement-based materials and of the optimization of a 12 composition of low-strength filling grouts rich in CRB filling. The results showed that it was 13 possible to use CRB in low-strength filling grout, in replacement of bentonite and fine sand, with 14 better performance-especially in terms of stability. 15 16 Highlights 17 CRB is essentially composed of calcium carbonates (91%). 18 CRB can replace both bentonite and fine sand in low-strength filling grouts. 19 CRB strongly improves the stability of grouts. 20 21

This paper, which enters in a sustainable development approach, aims to present a method developed by Laboratoire Materiaux et Durabilite des Constructions (LMDC) in Toulouse, for the assessment of the recycling of waste as secondary raw materials in cementbased materials used in civil engineering applications. The approach includes two parts carried out simultaneously: (i) a technological part, the aim of which is the evaluation of the effect of wastes on the chemical, physical and mechanical properties of fresh and hardened concrete; (ii) an environmental part, mainly based on leaching tests, in order to evaluate the environmental impact of wastes used in concrete materials. The method is illustrated with various cases taken from past studies performed in LMDC.

As the incidence of myelodysplastic syndromes (MDS) increases with the ageing of the population, new and promising therapeutic approaches are being developed. “Proper application of such new strategies relies on a thorough diagnosis of these variable and pleiomorphic disorders. Cytology and cytogenetics are included in the stratification of MDS, and are the main classification criteria in two successive systems. However, the progress of multiparametric immunophenotyping and flow cytometry techniques suggest that this approach may soon become an inclusive part of the diagnostic criteria of MDS. In this review of the literature, the features of MDS and the evolution of the classification these disorders is first summarized. An extensive analysis of flow cytometry approaches, especially multiparametric, is then presented, comparing the various strategies and their output. Current information regarding immunophenotyping of MDS indicates that several anomalies in the expression of leukocyte differentiation antigens are invaluable for their diagnosis and prognosis. A more thorough and standardized comparison between normal bone marrow and MDS samples, including pattern evaluation rather than as subset enumeration, should soon further provide an efficient tool for the definition and outcome prediction of these diseases. The diagnosis of myelodysplastic disorders (MDS) currently relies on cytological features and karyotypic anomalies. These methods allow using current classifications to discriminate between the various forms of MDS. A review of the literature demonstrates that the past 5 years have seen increasing information regarding multiparametric immunophenotyping of MDS bone marrow by flow cytometry. These approaches, once standardized, should provide an additional valuable tool for the diagnosis and management of MDS patients.

In order to assess the contribution of FC to the diagnosis of lymph node disorders we retrospectively compared the pathological and the FC diagnosis made in 118 consecutive lymph node biopsies. Pathological diagnosis included non malignant conditions (n = 43), B-cell Non Hodgkin lymphoma (NHL) (n = 30), T-cell NHL (1 case), carcinoma (n = 18), Hodgkin lymphoma (HL) (n = 15), melanoma (n = 2), chronic myelocytic leukemia (n = 12), miscellaneous non-lymphoid tissues (n = 6) and undetermined conditions (n = 2). Among the 116 assessable samples, FC was in agreement with histology in 102 cases (87.9%; 95%CI = 81-93) which included 38 benign conditions (90%; 95% CI = 77-97%), 29 NHL (96.7%; 95% CI = 83-100), 18 carcinomas (100%; 95% CI = 81-100), and 12 HL (80.0%; 95% CI = 52-96). Discrepancies (14 cases) included 3 HL undiagnosed by FC and 2 granulomatous adenitis with an erroneous FC diagnosis of HL. Finally, a malignant condition was suspected only by FC in 5 cases (1 carcinoma, 2 B-cell and 2 T-cell NHL) and subsequently demonstrated by additional diagnostic procedures. In conclusion, this study confirms that FC performed on fresh lymph node samples is a powerful diagnostic tool in patients with malignant lymphoma. A few cases left undiagnosed by classical pathological analysis can be recognized by FC. Carcinoma is readily identified by FC analysis, while some benign conditions and Hodgkin lymphoma can be misdiagnosed with the use of FC, although the potential of FC to properly recognize HL is improving compared to previously reported studies. FC is a useful adjunct to pathological analysis of lymph node specimens.

Myelodysplastic syndromes (MDSs) are heterogeneous diseases of bone marrow (BM) cell precursors for which immunophenotypic characterization is still considered irrelevant despite the accuracy and sensitivity of flow cytometry techniques. The aim of this study was to determine whether immunophenotypic abnormalities could be defined In MDSs and could correlate with the French-American-British classification and cytogenetics. Analysis was performed on 275 BM samples (207 MDS patients, 68 controls) and 25 control blood samples. immunophenotyping was based on a primary gating of blast cells, monocytes, and granulocytes according to CD45 antigen expression and side scatter light diffraction. Immunophenotypic hierarchical clustering was performed to analyze the results, The data obtained show that (1) immunophenotypic clustering partly discriminates patients with refractory anemia with excess blasts/refractory anemia with excess blasts in transformation (RAEB/RAEB-T), chronic myelomonocytic leukemia (CMML), and refractory anemia/refractory anemia with ring sideroblasts (RA/RARS) for CD45(lo) blast cells and patients with RA/CMML, RARS, and RAEB/RAEB-T for CD45(hi)/side scafter(hi) (SShi) granulocytes; (2) the most discriminating markers were CD16, CD34, CD36, CD38, CD71, and HLA-DR for blast cells and CD11b, CD13, CD33, CD36, CD38, CD71, and HLA-DR for CD45(hi)/SShi granulocytes; (3) clusters related to CD34 expression were associated with high levels of blast cells on BM smear; (4) clusters related to high levels of CD36 expression on CD45(lo) blast cells and CID45(hi)/SShi granulocytes were associated with a poor International Prognosis Scoring System score; and (5) high levels of CD71 expression on CD45(hi)/SShi granulocytes were associated with the RARS category. These results show a close relationship between Immunophenotypic abnormalities and BM dysplasia and suggest that flow cytometry could be a future tool for the characterization of MDSs. (C) 2002 by The American Society of Hematology.

WOS:000340304500007; International audience; It is acknowledged in the literature that the performance of supplementary cementing materials such as fly ash or silica fume often depends on the characteristics of the cement used. This work aims to show that this dependence also concerns metakaolin. Compressive strength tests were carried out between 2 days and 2 years using one flash metakaolin and a panel of 11 cements having a wide range of characteristics. At 28 days of age, the difference in terms of strength activity index could reach 0.4 between the most and the least efficient cements. The hydration of MK pastes followed by XRD and thermal analysis showed that the pozzolanic reaction involving MM was postponed with low-C(3)A cements, as characterized by a delay of portlandite consumption and stratlingite formation. Several mechanisms are reviewed and discussed with the aim of explaining the role of cement in the development of the pozzolanic activity of MM. (C) 2014 Elsevier Ltd. All rights reserved.

WOS:000317528900094; International audience; The work reported is a feasibility study to evaluate the pertinence of using metakaolin (MK) in grout intended for soil nailing. MK allows a strong decrease of CO2 emission compared to grouts containing cement only. The experimental program was divided into two steps: a first step to study the formulation parameters of the grouts by means of a mixture design plan, followed by an in situ program of pull-out tests to evaluate the performance of the grouts designed. The results show that metakaolin is compatible with this kind of application, since it improved the environmental balance of grouts by reducing the cement content. Moreover, its pozzolanic effect counteracted some of the cement dilution. The in situ pull-out tests highlighted the minimum performance levels necessary for the grout to fulfill its role of transferring stresses between soil and nail. (C) 2013 Elsevier Ltd. All rights reserved.

WOS:000316304800023; International audience; This paper deals with the utilization of a natural pozzolan as the main component of Hydraulic Road Binder (HRB). A study of its reactivity in presence of lime and gypsum leads to a proposal for an optimized binder composed of 80 wt% pozzolan, 15 wt% lime and 5 wt% gypsum. The characteristics of this binder were tested on mortars and on samples of treated soil and the results lead to the conclusion that it is possible to produce an HRB rich in pozzolan and without cement that can efficiently stabilize clayey soils. (C) 2012 Elsevier Ltd. All rights reserved.

The aim of this work was to carry out a feasibility study to evaluate the pertinence of using metakaolin in grout intended for soil nailing. After a first step of grout optimisation based on technical and environmental constraints, an in-situ study was performed to evaluate the compatibility of metakaolin with this kind of application. This part highlights the minimum performance levels necessary if grout is to fulfil its role of transferring stresses between soil and nail.

This paper presents an original method developed to quantify the reactivity of mineral additions based on the measurement of the lime (CaO) and gypsum (CaSO4, 2H2O) consumed by mineral additions in a paste. Three mineral additions were tested: a Siliceous Filler (SF), a natural pozzolan (Poz) and a Wastepaper Sludge Ash (WSA). The results obtained on SF, considered as a reference, show the efficiency of this method. Its application to Poz and WSA permits the quantity of lime and gypsum consumed by these additions to be evaluated and, thus, the amount of each component to be optimized in Hydraulic Road Binders.

Cet article presente, au travers d'exemples concrets, la strategie d'etude des dechets et sous-produits industriels retenue au LMDC. Cette methodologie, issue de la recherche fondamentale, permet de valoriser autant que possible les sous-produits industriels ou, a defaut, propose une solidification adaptee avant la mise en decharge du dechet.

A cutaneous infiltrate composed of plasmacytoid dendritic cells may occasionally occur in a patient suffering from a myeloid neoplasm. To date, the clinical and pathological features associated with this event remains poorly characterized. Herein, we report a patient with acute myeloid leukemia who developed pruritic papules or erythematous plaques scattered on the skin. Microscopic examination showed a dermal infiltrate rich in plasmacytoid dendritic cells expressing CD4, CD43, CD68, granzyme B, CD123, CD303 [blood dendritic cell antigen 2 (BDCA-2)], CD2-associated protein (CD2AP) and T-cell leukemia/lymphoma oncogene 1 (TCL1). Our observation illustrates further that cutaneous lesions associated with some myeloid neoplasms, especially those featuring a monocytic component, may be composed of plasmacytoid dendritic cells. Because of differences in clinical, pathological and genetic features, this rare condition should be distinguished from blastic plasmacytoid dendritic cell neoplasm. Dargent JL, Delannoy A, Pieron P, Husson B, Debecker C, Petrella T. Cutaneous accumulation of plasmacytoid dendritic cells associated with acute myeloid leukemia: a rare condition distinct from blastic plasmacytoid dendritic cell neoplasm.

With a view of reducing the quantities to be landfilled, the Solvay Company has been working on the development of a treatment for polluted sediments: the Novosol® process. It allows fixing heavy metals and eliminating organic matter. This article reports on the characteristics of a treated sediment and on its use in road building techniques. From mechanical point of view, the performance of the mixtures incorporating sediments is satisfactory since their mechanical strengths are even higher than those of the reference mixtures. The leaching test carried out on the mixtures shows that the release is the same for both materials. Also, on the whole, these results suggest that using treated sediments in road building techniques is conceivable.

The aim of this paper is to study the mineralogical transformations of a MSWI fly ash during an industrial stabilization process. This is divided into three successive steps: washing, phosphation and calcination of the fly ash. Special attention was paid to the characterization of the neoformed calcium phosphates in this study. Microprobe analyses carried out on the treated fly ash showed that the whitlockite and hydroxylapatite formed during the process were rich in silicon and aluminium. One of the major minerals contained in the raw fly ash was gehlenite. In order to study the behaviour of this specific phase during the process, the raw fly ash was washed (first with Na2SO4, then with an acidic solution) to concentrate the gehlenite. The washing was successful and the residue obtained was rich in gehlenite and poor in calcite. Mineralogical characterization of the gehlenite showed that this mineral had the same peaks of diffraction as conventional gehlenite but its composition was relatively different from that of the reference mineral. The behaviour of this mineral with phosphoric acid was studied. The results showed that the gehlenite-like phase reacted with phosphoric acid to form brushite, which transformed into whitlockite during the calcination of the phosphated residue. Both brushite and whitlockite contained significant amounts of silicon and aluminium in their lattice, which confirms the analyses carried out on the calcium phosphates contained in the treated fly ash.

The objective of the work presented in this paper is the quantitative determination of the mineral composition of two complex mineral wastes: a sewage sludge ash (SSA) and a municipal solid waste incineration fly ash (MSWIFA). The mineral compositions were determined by two different methods: the first based on calculation using the qualitative mineralogical composition of the waste combined with physicochemical analyses; the second the Rietveld method, which uses only X-ray diffraction patterns. The results obtained are coherent, showing that it is possible to quantify the mineral compositions of complex mineral waste with such methods. The apparent simplicity of the Rietveld method (due principally to the availability of software packages implementing the method) facilitates its use. However, care should be taken since the crystal structure analysis based on powder diffraction data needs experience and a thorough understanding of crystallography. So the use of another, complementary, method such as the first one used in this study, may sometimes be needed to confirm the results.

In the industrial region of La Louvière (Belgium), healthy persons, presenting at a consultation of preventive medicine, showed differences as a function of smoking and of residence in one of four areas differing in sources of emissions, population density and green zones. Smokers had significantly (P/=0.05) more leukocytes microl(-1), neutrophils microl(-1), CD3+ lymphocytes (lys) microl(-1), CD4+ lys microl(-1), CD25+ lys microl(-1), higher CD4/CD8 ratio's and higher carcino-embryonic antigen serum levels but significantly lower IgG immunoglobulin and serum carotene levels than non-smokers. Compared to persons living in the 'Peripheral area', and after correction for sex, smoking status and age, persons living in the more polluted areas showed significantly more CD3+CD56+ lys microl(-1). Although about the same mean value for the CD4/CD8 ratio was found for the more polluted areas, a higher percentage of their residents showed a ratio that was either1 or/=2.25, significantly so for the Power Station-Landfill area. A non-significant but consistent trend towards higher lymphocyte and CD8 lys counts and higher complement C3c serum levels further suggested an association between residence in a more polluted area and immunologic features. The number of CD3+CD56+ lys microl(-1), reported to be increased in cancer patients, showed a negative correlation with the CD4/CD8 ratio (r(2)=0.132, P0.0001).

BACKGROUND AND PURPOSE: To try to get a better insight on the interaction between dFdC and ionizing radiation at the cellular level, we examined in vitro the effect of dFdC on the cell cycle of two human head and neck squamous cell carcinoma cell lines (SQD9 and SCC61). PATIENTS AND METHODS: Experimental conditions yielding radio-enhancement were used. Confluent cells were incubated with dFdC (5 microM) for different incubation times, washed, pulse-labeled with BrdUrd (10 microM), fixed and then processed for flow cytometry analysis. Alternatively, cells preincubated or not with dFdC were irradiated (5Gy) in drug-free medium, incubated at 37 degrees C for various times and then processed for flow cytometry analysis. RESULTS: In both cell lines, dFdC incubated between 1 and 6 h induced a DNA synthesis inhibition with accumulation of cells in the G1-S boundary followed, when DNA reinitiated, by a synchronous progression of cells throughout the cycle. A slightly different kinetics was observed in the two cell lines. A weak correlation between dFdC radio-enhancement and distribution of cells in the cell cycle was observed. It was also observed that for longer dFdC incubation times, DNA synthesis could reinitiate while cells were still incubated with dFdC. This reinitiation could be correlated with a decrease in the intracellular dFdCTP pool to non-inhibitory levels. Finally in both cell lines, dFdC modified neither the importance nor the kinetics of the radiation-induced G1 delay. CONCLUSIONS: This study provides evidence that gemcitabine used at radio-enhancing concentration induces alteration of cell kinetics and cell redistribution throughout the cell cycle. This effect is cell line-dependent. However, the weak correlation between dFdC radio-enhancement and cell cycle distribution suggests that the cell cycle effect does not constitute the most important mechanism of interaction with ionizing radiation. Our study also indicated that in the two cell lines studied, a modulation of the G1-S checkpoint was not implicated in enhancement of radiation response by dFdC.

Faute de ressources disponibles et de capacite a les gerer, les collectivites territoriales naissantes n’ont ni legitimite, ni credibilite aux yeux de leurs habitants. Pour les accompagner, des pays (ou des regions) ont cree des dispositifs d’appui financier respectueux de leurs responsabilites politiques, techniques et financieres. Accessibles a toutes les collectivites territoriales de leur aire d’intervention, ces dispositifs – Fonds d’appui aux collectivites territoriales – sont des institutions publiques perennes aupres desquelles, apres mobilisation de leur contrepartie, les collectivites territoriales peuvent acceder a des subventions. Des enseignements de demarche plus que de contenu peuvent etre tires de l’experience concrete accumulee depuis quinze ans pour debattre en particulier du statut, de l’organisation et des modalites d’acces a ces Fonds tant avec les responsables politiques et administratifs nationaux qu’avec les elus locaux.

Sprayed concrete is a concrete pneumatically projected onto a surface at high velocity. Dry-mix shotcrete is a process in which dry constituents are introduced into the machine and conveyed through a hose to the nozzle, where the water is added. This process is used in various civil engineering or construction projects; unfortunately, it can lead to high losses of concrete due to rebound (up to 40% of the total mass of material). Such losses induce overconsumption of material, which is damaging for the cost of the work and for the environment. Rebound depends on technicals parameters and mix design. The present work focuses on rebound reduction and also on durability enhancement by modification of the mix design. The influence of aggregate size distribution, water content and supplementary cimentitious material is studied. An analytical approach of rebound phenomenon is also implemented.; Le béton projeté est une méthode de mise en place consistant en la projection pneumatique de béton sur une surface à grande vitesse. Dans le cas de la méthode par voie sèche, le mélange granulats-ciment est introduit sec en machine, l'eau est ajoutée à la fin du transfert. Cette technique, très employée, est néanmoins génératrice de pertes importantes par rebond, pouvant s'élever jusqu'à 40% de la masse projetée. L'enjeu de la réduction des pertes est à la fois économique et environnemental. Les facteurs influents sur le rebond sont liés aux techniques de projection et à la formulation. Ce travail de thèse a pour objectif l'optimisation de la formulation du béton afin de réduire les pertes par rebond, mais également d'améliorer la durabilité. L'étude porte en particulier sur l'influence sur le rebond : du squelette granulaire, de la teneur en eau et de l'emploi d'additifs et/ou d'additions de substitution. Une approche modélisation du phénomène de rebond est également abordée.

Sprayed concrete is a concrete pneumatically projected onto a surface at high velocity. Dry-mix shotcrete is a process in which dry constituents are introduced into the machine and conveyed through a hose to the nozzle, where the water is added. This process is used in various civil engineering or construction projects; unfortunately, it can lead to high losses of concrete due to rebound (up to 40% of the total mass of material). Such losses induce overconsumption of material, which is damaging for the cost of the work and for the environment. Rebound depends on technicals parameters and mix design. The present work focuses on rebound reduction and also on durability enhancement by modification of the mix design. The influence of aggregate size distribution, water content and supplementary cimentitious material is studied. An analytical approach of rebound phenomenon is also implemented.; Le béton projeté est une méthode de mise en place consistant en la projection pneumatique de béton sur une surface à grande vitesse. Dans le cas de la méthode par voie sèche, le mélange granulats-ciment est introduit sec en machine, l'eau est ajoutée à la fin du transfert. Cette technique, très employée, est néanmoins génératrice de pertes importantes par rebond, pouvant s'élever jusqu'à 40% de la masse projetée. L'enjeu de la réduction des pertes est à la fois économique et environnemental. Les facteurs influents sur le rebond sont liés aux techniques de projection et à la formulation. Ce travail de thèse a pour objectif l'optimisation de la formulation du béton afin de réduire les pertes par rebond, mais également d'améliorer la durabilité. L'étude porte en particulier sur l'influence sur le rebond : du squelette granulaire, de la teneur en eau et de l'emploi d'additifs et/ou d'additions de substitution. Une approche modélisation du phénomène de rebond est également abordée.