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Etude du comportement à la corrosion des armatures tendues dans le béton contaminé par des ions chlorure : Effet anticorrosif d’un inhibiteur à base de phosphates

Abstract : Corrosion in prestressed concrete is considered among the most dangerous pathologies in the civil engineering sector. Indeed, this phenomenon is characterized by the seriousness of its economic and security consequences. The objective of this work is to evaluate the efficiency of a phosphate based inhibitor Na3PO4.12H2O against the corrosion of prestressing steels. The study was first conducted on wires tensioned at 80% Rm and immersed in simulating concrete pore solution. Then it concerned, on one hand, prestressed mortar specimens designed on a laboratory scale and, on the other hand, the long term efficiency of the inhibitor using diffusion cell technique. The results obtained from the study carried out in the concrete simulating medium revealed that the presence of the phosphates causes the increase in the critical threshold of localized corrosion initiation R = [Cl -] / [OH-] up to the value of 5 instead of 0.4. This seems to be due to two phosphate inhibiting actions, namely: the stabilization of the iron oxide protective layer and the formation of very insoluble phosphate compounds which block the active anodic sites, increasing prestressing steel resistance to localized corrosion. The use of Na3PO4.12H2O as an additive slightly reduces the compressive strength of the mortar. However, phosphate compounds resulting from the reaction of the inhibitor with the cement hydrates clog the pores of the mortar and slow down the diffusion of the chlorides. This improves the corrosion behavior of prestressed mortar reinforcement. Finally, when sodium triphosphate is used as a migratory inhibitor or as a means of steel reinforcement pretreatment, the diffusion cell technique has shown its long-term efficiency, thanks to the increase of the period preceding the initiation of a localized corrosion, where the reinforcement is in a passive state.
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https://tel.archives-ouvertes.fr/tel-02091162
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Submitted on : Saturday, April 6, 2019 - 3:00:49 AM
Last modification on : Wednesday, October 14, 2020 - 3:57:42 AM

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  • HAL Id : tel-02091162, version 2

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Hela Ben Mansour. Etude du comportement à la corrosion des armatures tendues dans le béton contaminé par des ions chlorure : Effet anticorrosif d’un inhibiteur à base de phosphates. Matériaux. Université de Lyon; Université de Tunis El-Manar. Faculté des Sciences de Tunis (Tunisie), 2018. Français. ⟨NNT : 2018LYSEI085⟩. ⟨tel-02091162v2⟩

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