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Formulation d’un matériau cimentaire fibré ultrafluide : application au stockage des déchets radioactifs

Abstract : The aim of the thesis is to design a self-compacting concrete with polypropylene fibers resistant to fire for a use in storage containers of medium activity long-lived waste. The challenge of the work is presented by the use of polypropylene fibers that enhance fire resistance but drastically diminish workability of concrete even when added at small volume fractions. Tests on laboratory scale are conducted with a purpose of evaluating rheological behavior and high temperature behavior of cementitious materials containing polypropylene fibers.In the first part, a study of rheological behavior of cement-based materials containing polypropylene fibers was done. The aim of this study is to investigate the influence of polypropylene fibers on the yield stress of cement pastes and mortars. A model is proposed to be able to evaluate the quantity of paste necessary to compensate the addition of polypropylene fibres according the fluidity of fresh concrete.Then an experimental and numerical investigation of behavior of cementitious materials with polypropylene fibers at high temperature was done so as to optimize the choice of polypropylene fibers for cementitious material to improve its thermal stability. Three different cementitious materials with three different granular skeleton containing various polypropylene fiber geometries and dosages were tested (residual radial permeability test and fire test) in order to select an optimal fiber geometry and dosage. Then thermomechanical computations was developped at maco and meso scale. Then, a choice of diameter, length and dosage of fibres is proposed according to the maximum size of gravels.Finally, a method of concrete formulation with polypropylene fibers optimized from perspectives of rheology and resistance to fire is presented. In this method, fresh and hardened state properties are verified to ensure an accordance with performance criteria specified by the project. At the end, designed mixes were tested in fire tests conducted on uniaxially compressed prisms and, based on outcomes, final mixes are selected for further fire tests on higher scale concrete.
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Submitted on : Sunday, December 5, 2021 - 1:02:18 AM
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  • HAL Id : tel-03466298, version 1

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Fariza Sultangaliyeva. Formulation d’un matériau cimentaire fibré ultrafluide : application au stockage des déchets radioactifs. Génie mécanique [physics.class-ph]. Université de Pau et des Pays de l'Adour, 2020. Français. ⟨NNT : 2020PAUU3041⟩. ⟨tel-03466298⟩

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