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Modèle micromécanique pour l'étude de l'anisotropie de la réaction alcali-silice

Abstract : The alkali-silica reaction is an endogenous chemical reaction affecting concrete. Therefore, it is important to model the effects of the reaction so as to estimate the life span of the attacked structures. The reaction leads to a microscopic cracking, due to the pressure of the reaction products which swell by absorption of water, inducing swelling of the concrete. If the concrete is mechanically loaded, the orientation of the microscopic cracking is affected by the local stress state, which induces anisotropy of the mechanical properties and deformations of the concrete. Our work aims at simulating, starting from simple assumptions about the reaction mechanisms, and for a class of fast-reacting aggregates, the development of cracking at the microscopic scale, so as to estimate the deformations and mechanical properties of the attacked concrete. In this purpose, we use a micromechanical description of the concrete, thanks to which we can compute the mechanical properties and deformations from the state of cracking of the concrete. In addition to that, we use an energy fracture criterion to determine the evolution of cracking as the attack progresses. We tested our model on numerous cases. These tests show that this description is well adapted to studying alkali-silica reaction. The identification of the parameters using laboratory experiments yielded good results as far as compression stresses are below 10 MPa. However, the fracture energies identified are greater than accepted values for concretes. We think that our model overestimates the anisotropy of the reaction, which is balanced by higher fracture energies in the identification
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Submitted on : Tuesday, October 15, 2013 - 6:32:09 PM
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Laurent Charpin. Modèle micromécanique pour l'étude de l'anisotropie de la réaction alcali-silice. Autre. Université Paris-Est, 2013. Français. ⟨NNT : 2013PEST1103⟩. ⟨pastel-00873539⟩

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