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11 results on '"L'Hostis, V."'

1. Corrosion behavior of iron in cementitious solution at 80°C in anoxic condition

Author

Pally, D., Grenut, B., Miserque, F., Chomat, L., L'Hostis, V., Le Bescop, P., CEA-Direction des Energies (ex-Direction de l'Energie Nucléaire) (CEA-DES (ex-DEN)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA), Laboratoire d'Etude du Comportement des Bétons et des Argiles (LECBA), Service d'Etudes du Comportement des Radionucléides (SECR), Département de Physico-Chimie (DPC), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay-CEA-Direction des Energies (ex-Direction de l'Energie Nucléaire) (CEA-DES (ex-DEN)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay-Département de Physico-Chimie (DPC), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay, and Service de la Corrosion et du Comportement des Matériaux dans leur Environnement (SCCME)

Subjects
cement, corrosion, [PHYS.NUCL]Physics [physics]/Nuclear Theory [nucl-th], Iron, interface, [PHYS.NEXP]Physics [physics]/Nuclear Experiment [nucl-ex]
Abstract

International audience; The Belgian reference concept for high-level radioactive waste packaging proposed by ONDRAF/NIRAS is called Supercontainer. The design of the Supercontainer includes a stainless-steel liner, a concrete buffer and a carbon steel overpack containing one or several waste canisters. An objective of the concrete buffer is to maintain high alkaline conditions on the surface of the overpack during underground disposal of these wastes. In these conditions (alkaline and anoxic conditions), a passive film forms on the surface of the steel, resulting in very low and almost negligible uniform corrosion rates (passive dissolution). This film is generally composed of a double layer an inner layer, accounting for passivity, and a more or less porous outer layer. The latter is in contact with the environment and is formed by precipitation of elements in solution. The presence of silicon and cations from the cementitious environment could lead to neo-formed phases such as ferrous-silicates or phyllosilicates possessing corrosion inhibiting properties. The aim of this work is to study the impact of the cementitious materials during the corrosion at 80DC in anoxic media by characterizing the layer formed during the corrosion process. To ensure these measurements, iron plates were corroded in solution representative of a cementitious environment (at 80DC and under anoxic conditions). Evolution of the nature and growth of the corrosion layer is studied on samples after several duration tests. Corrosion products are characterized by means of several analytical techniques such as scanning electron microscopy, Raman micro-spectroscopy, X-ray diffraction, X-ray photoelectron spectrometry and transmission electronic microscopy. Results have revealed evolution of composition as a function of time. Layers are mainly composed of magnetite and others phases containing iron, calcium and silicon.

Published
2018

2. Corrosion and Green Chemistry

Author

Feron, D., L'Hostis, V., Sarrade, S., CADARACHE, Bibliothèque, CEA-Direction des Energies (ex-Direction de l'Energie Nucléaire) (CEA-DES (ex-DEN)), and Commissariat à l'énergie atomique et aux énergies alternatives (CEA)

Subjects
[PHYS.NUCL] Physics [physics]/Nuclear Theory [nucl-th], [PHYS.NUCL]Physics [physics]/Nuclear Theory [nucl-th], [PHYS.NEXP] Physics [physics]/Nuclear Experiment [nucl-ex], [PHYS.NEXP]Physics [physics]/Nuclear Experiment [nucl-ex], ComputingMilieux_MISCELLANEOUS
Abstract

International audience

Published
2018

3. Reinforced Concrete structures degradation issues impact of Chlorides and of Thermal loadings on Corrosion development

Author

L'Hostis, V., Le Bescop, P., Bary, B., François, Raoul, Laboratoire d'Etude du Comportement des Bétons et des Argiles (LECBA), Service d'Etudes du Comportement des Radionucléides (SECR), Département de Physico-Chimie (DPC), CEA-Direction des Energies (ex-Direction de l'Energie Nucléaire) (CEA-DES (ex-DEN)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay-CEA-Direction des Energies (ex-Direction de l'Energie Nucléaire) (CEA-DES (ex-DEN)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay-Département de Physico-Chimie (DPC), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay, Service de la Corrosion et du Comportement des Matériaux dans leur Environnement (SCCME), Commissariat à l'énergie atomique et aux énergies alternatives (CEA), Laboratoire Matériaux et Durabilité des constructions (LMDC), Institut National des Sciences Appliquées - Toulouse (INSA Toulouse), Institut National des Sciences Appliquées (INSA)-Université de Toulouse (UT)-Institut National des Sciences Appliquées (INSA)-Université de Toulouse (UT)-Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT), Université Toulouse III - Paul Sabatier (UT3), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Institut National des Sciences Appliquées - Toulouse (INSA Toulouse), and Institut National des Sciences Appliquées (INSA)-Institut National des Sciences Appliquées (INSA)

Subjects
[PHYS.NUCL]Physics [physics]/Nuclear Theory [nucl-th], [PHYS.NEXP]Physics [physics]/Nuclear Experiment [nucl-ex]
Abstract

International audience; Reinforced concrete structures of Fukushima Daiichi Nuclear Power Station have been submitted temporarily to specific environmental conditions such as thermal loading (up to 200DC) and chloride ingress (from seawater) [1]. These conditions are susceptible to lead to corrosion of reinforced concrete components of the NPP. This paper aims at studying environmental conditions encountered by concrete structures, and to propose pertinent parameters for reinforcement corrosion monitoring. The first step of the scenario consists in considering that concrete has been in contact with seawater during several days (we estimate a duration of 15 days in this paper) then pure water replace seawater for cooling fuel. A coupled chemistry-transport software (Hytec) has been used to simulate a CEM V type concrete submitted to such scenario (at ambient T DC). Results show that chloride penetrate into concrete until several millimeters during the 15 days in contact with seawater. As soon as pure water replace seawater, chloride species are leached out from the material. After 2 years, calculations estimate that almost all chloride species disappeared from concrete cover. This result show that reinforcement bars located few centimeters inside concrete have not seen chloride species and should not developed chloride-induced-corrosion. Concrete structures have been submitted to thermal loadings as temperatures were above 200 DC just after the accident, and they stayed above 100 DC for about a half year [1]. Then seawater has been injected inside concrete structures to cool fuel. Previous studies [2] determinate that in such conditions, cold part of the structure is damaged and cracked. Thus we can propose that in a first step, external part of concrete structures have been cracked, then internal parts at high temperature put in contact with seawater at ambient temperature would also cracked. In this context, chlorides from seawater can penetrate through cracks and the degradation issue is linked to corrosion of rebars in cracked concrete. In such conditions, field and laboratory experiments [3, 4] show that quality of steel/concrete interface is the main parameter that has to be considered, more than chloride threshold and crack width as it is commonly specified in codes.

Published
2017

4. Identification de la corrosion des armatures dans un beton fissure et carbonate

Author

Ghantous, Rm., Poyet, Stéphane, L'Hostis, V., Tran, Nc., François, Raoul, CEA-Direction des Energies (ex-Direction de l'Energie Nucléaire) (CEA-DES (ex-DEN)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA), Laboratoire d'Etude du Comportement des Bétons et des Argiles (LECBA), Service d'Etudes du Comportement des Radionucléides (SECR), Département de Physico-Chimie (DPC), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay-CEA-Direction des Energies (ex-Direction de l'Energie Nucléaire) (CEA-DES (ex-DEN)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay-Département de Physico-Chimie (DPC), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay, Matériaux et Mécanique des Composants (EDF R&D MMC), EDF R&D (EDF R&D), EDF (EDF)-EDF (EDF), Laboratoire Matériaux et Durabilité des constructions (LMDC), Université Toulouse III - Paul Sabatier (UT3), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Institut National des Sciences Appliquées - Toulouse (INSA Toulouse), Institut National des Sciences Appliquées (INSA)-Institut National des Sciences Appliquées (INSA), Institut National des Sciences Appliquées - Toulouse (INSA Toulouse), Institut National des Sciences Appliquées (INSA)-Université de Toulouse (UT)-Institut National des Sciences Appliquées (INSA)-Université de Toulouse (UT)-Université Toulouse III - Paul Sabatier (UT3), and Université de Toulouse (UT)

Subjects
Corrosion, [PHYS.NUCL]Physics [physics]/Nuclear Theory [nucl-th], Carbonatation, [PHYS.NEXP]Physics [physics]/Nuclear Experiment [nucl-ex], ComputingMilieux_MISCELLANEOUS, Beton arme, Fissuration
Abstract

National audience

Published
2017

5. Que deviendraient nos réalisations architecturales, industrielles ou artistiques si l'humanité disparaissait ?

Author

L'Hostis, V., Musset, A., amplexor, amplexor, CEA-Direction des Energies (ex-Direction de l'Energie Nucléaire) (CEA-DES (ex-DEN)), and Commissariat à l'énergie atomique et aux énergies alternatives (CEA)

Subjects
[PHYS.NUCL] Physics [physics]/Nuclear Theory [nucl-th], [PHYS.NUCL]Physics [physics]/Nuclear Theory [nucl-th], [PHYS.NEXP] Physics [physics]/Nuclear Experiment [nucl-ex], vieillissement, [PHYS.NEXP]Physics [physics]/Nuclear Experiment [nucl-ex], béton, rouille
Abstract

National audience; Dans cette expérience de pensée, nous imaginons comment le monde industriel, architectural et artistique évoluerait si les humains disparaissaient. L'exposé sera structuré selon des allers retours entre les représentations d'ouvrages de science fiction et ce que nous dit la science sur ces sujets (dégradation des ouvrages en béton et développement de la corrosion).

Published
2017

6. Carbonation induced corrosion of steel in concrete based on low pH binders

Author

Serdar, M., L'Hostis, V., Poyet, Stéphane, CEA-Direction des Energies (ex-Direction de l'Energie Nucléaire) (CEA-DES (ex-DEN)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA), Laboratoire d'Etude du Comportement des Bétons et des Argiles (LECBA), Service d'Etudes du Comportement des Radionucléides (SECR), Département de Physico-Chimie (DPC), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay-CEA-Direction des Energies (ex-Direction de l'Energie Nucléaire) (CEA-DES (ex-DEN)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay-Département de Physico-Chimie (DPC), and Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay

Subjects
metakaolin, fly ash, EIS, [PHYS.NUCL]Physics [physics]/Nuclear Theory [nucl-th], low pH binders, nanosilica, lime, [PHYS.NEXP]Physics [physics]/Nuclear Experiment [nucl-ex]
Abstract

International audience; Nowadays, with an increase of awareness of society and industry on the environmental footprints, there is an increasing need in innovative concrete binders, usually secondary resources and by-products, utilised as partial or full substitution of ordinary Portland cement. Most of these materials have beneficial particle size distribution and/or chemical composition, leading to concrete with lower permeability and higher electrical resistivity. At the same time, their different chemistry leads to changes in pH values of pore solution and in concrete microstructure, which could consequently lead to changes in corrosion properties of steel embedded in these types of concrete. These changes in corrosion properties are especially highlighted when concrete is exposed to long-term carbonation process.The aim of this paper is to research the difference in corrosion behaviour of steel in carbonated concrete based on different types of low pH binders. In the paper results on four concrete mixes are presented, all having different type of binder reference mix with ordinary Portland cement, mix with high volume of fly ash and silica fume, mix with blast furnace slag cement with the addition of nanosilica and mix with high volume of metakaolin and lime. After curing reinforced concrete samples were carbonated at 3% CO2 to ensure representativeness with natural carbonation. During early ages and after carbonation changes of corrosion potential, corrosion rate and electrical impedance parameters are monitored and discussed in the paper. Corrosion behaviour was connected to the changes in microstructure of these different types of concrete during carbonation.

Published
2016

7. Identification of rebar corrosion induced by carbonation in cracked concrete subjected to different environmental conditions

Author

Ghantous, Rm., POYET, Stéphane, L'Hostis, V., Tran, NC., François, Raoul, CEA-Direction des Energies (ex-Direction de l'Energie Nucléaire) (CEA-DES (ex-DEN)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA), Laboratoire d'Etude du Comportement des Bétons et des Argiles (LECBA), Service d'Etudes du Comportement des Radionucléides (SECR), Département de Physico-Chimie (DPC), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay-CEA-Direction des Energies (ex-Direction de l'Energie Nucléaire) (CEA-DES (ex-DEN)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay-Département de Physico-Chimie (DPC), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay, European RandD Specific Action SESSA, affiliation inconnue, Laboratoire Matériaux et Durabilité des constructions (LMDC), Institut National des Sciences Appliquées - Toulouse (INSA Toulouse), Institut National des Sciences Appliquées (INSA)-Université de Toulouse (UT)-Institut National des Sciences Appliquées (INSA)-Université de Toulouse (UT)-Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT), Institut National des Sciences Appliquées (INSA)-Institut National des Sciences Appliquées (INSA)-Université Toulouse III - Paul Sabatier (UT3), and Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées

Subjects
carbonation, corrosion, [PHYS.NUCL]Physics [physics]/Nuclear Theory [nucl-th], cracks, [PHYS.NEXP]Physics [physics]/Nuclear Experiment [nucl-ex], reinforced concrete, environmental conditions
Abstract

International audience; Reinforced concrete is a material mainly used in the construction of buildings, historical monuments as well as nuclear power plants (NPP). For different reasons, many concrete structures are subjected to unavoidable cracks that facilitate the diffusion of atmospheric carbon dioxide to the steel/concrete interface. Carbonation at the interface could induce the steel corrosion which could cause the development of new cracks in the structure and thus it is a determining factor for its durability [1][4]. Several environmental parameters may also influence the corrosion development.The objective of this work is therefore to study the effect of the existing cracks on the corrosion development in different environmental conditions (rainfall duration, relative humidity). The environmental conditions tested are representative of those surrounding the cooling towers of electricity of France (EDF) NPP. The results indicate that the corrosion development is influenced by the cracks opening. However, it was found that the corrosion is not dependent on the crack orientation (horizontal/vertical) with respect to rain. Moreover, it was deduced that the most important parameter in the corrosion development is the number of humidification/drying cycles not the rainfall duration.The result obtained will be implemented in an operational model allowing the evaluation of corrosion kinetics of the reinforcement steel in the cooling towers of EDF NPP. This model will serve to optimize the maintenance program, implemented by EDF, which aims to ensure for the cooling towers a service life over 60 years.

Published
2016

8. Reproducing the cooling towers cracks on laboratory specimens for corrosion induced by carbonation studies

Author

Ghantous, R.M., L'Hostis, V., POYET, Stéphane, François, Raoul, Tran, N.C., CEA-Direction de l'Energie Nucléaire (CEA-DEN), Commissariat à l'énergie atomique et aux énergies alternatives (CEA), Laboratoire d'Etude du Comportement des Bétons et des Argiles (LECBA), Service d'Etudes du Comportement des Radionucléides (SECR), Département de Physico-Chimie (DPC), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay-CEA-Direction de l'Energie Nucléaire (CEA-DEN), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay-Département de Physico-Chimie (DPC), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay, Laboratoire Matériaux et Durabilité des constructions (LMDC), Institut National des Sciences Appliquées - Toulouse (INSA Toulouse), Institut National des Sciences Appliquées (INSA)-Institut National des Sciences Appliquées (INSA)-Université Toulouse III - Paul Sabatier (UT3), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées, EDF (EDF), This research was supported by grants from the EDF and CEA, CEA-Direction des Energies (ex-Direction de l'Energie Nucléaire) (CEA-DES (ex-DEN)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay-CEA-Direction des Energies (ex-Direction de l'Energie Nucléaire) (CEA-DES (ex-DEN)), Institut National des Sciences Appliquées (INSA)-Université de Toulouse (UT)-Institut National des Sciences Appliquées (INSA)-Université de Toulouse (UT)-Université Toulouse III - Paul Sabatier (UT3), and Université de Toulouse (UT)

Subjects
[PHYS.NUCL]Physics [physics]/Nuclear Theory [nucl-th], [PHYS.NEXP]Physics [physics]/Nuclear Experiment [nucl-ex], ComputingMilieux_MISCELLANEOUS
Abstract

International audience

Published
2015

9. Corrosion initiation and propagation of RC beams cracked by loading under chloride environment

Author

Yu, Linwen, François, Raoul, Dang, Vu Hiep, L'Hostis, V., Gagné, R., Laboratoire Matériaux et Durabilité des constructions (LMDC), Université Toulouse III - Paul Sabatier (UT3), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Institut National des Sciences Appliquées - Toulouse (INSA Toulouse), Institut National des Sciences Appliquées (INSA)-Institut National des Sciences Appliquées (INSA), Hanoi Architectural University, Laboratoire d'Etude du Comportement des Bétons et des Argiles (LECBA), Service d'Etudes du Comportement des Radionucléides (SECR), Département de Physico-Chimie (DPC), CEA-Direction des Energies (ex-Direction de l'Energie Nucléaire) (CEA-DES (ex-DEN)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay-CEA-Direction des Energies (ex-Direction de l'Energie Nucléaire) (CEA-DES (ex-DEN)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay-Département de Physico-Chimie (DPC), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay, Université de Sherbrooke (UdeS), Institut National des Sciences Appliquées - Toulouse (INSA Toulouse), Institut National des Sciences Appliquées (INSA)-Université de Toulouse (UT)-Institut National des Sciences Appliquées (INSA)-Université de Toulouse (UT)-Université Toulouse III - Paul Sabatier (UT3), and Université de Toulouse (UT)

Subjects
reinforcement, corrosion, rebar, [PHYS.NUCL]Physics [physics]/Nuclear Theory [nucl-th], concrete, [PHYS.NEXP]Physics [physics]/Nuclear Experiment [nucl-ex]
Abstract

National audience; This paper deals with corrosion initiation and propagation in pre-cracked reinforced concrete beams exposed to a chloride environment under sustained loading. The cracking maps, corrosion maps, chloride profiles, cross-section loss and corrosion rate of one group of two beams cast in 2010 were examined. Experimental results show that, after rapid initiation of corrosion at the crack tip, the corrosion process almost stops and the time elapsing before corrosion re-start depends on the exposure conditions and also on the cover depth. The case of horizontal tensioned (and cracked) surface exposed to chloride appears to be very detrimental condition leading to fast propagation stage of corrosion and high corrosion rate.

Published
2015

10. Kinetics of corrosion propagation in reinforced concrete contaminated with chlorides

Author

Bouteiller, V., L'Hostis, V., Marie-Victoire, E., Schneider, J., Boinski, F., Cremona, C., Département Structures et Ouvrages d'Art (IFSTTAR/SOA), Institut Français des Sciences et Technologies des Transports, de l'Aménagement et des Réseaux (IFSTTAR)-PRES Université Paris-Est, Laboratoire d'Etude du Comportement des Bétons et des Argiles (LECBA), Service d'Etudes du Comportement des Radionucléides (SECR), Département de Physico-Chimie (DPC), CEA-Direction des Energies (ex-Direction de l'Energie Nucléaire) (CEA-DES (ex-DEN)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay-CEA-Direction des Energies (ex-Direction de l'Energie Nucléaire) (CEA-DES (ex-DEN)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay-Département de Physico-Chimie (DPC), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay, Laboratoire de recherche des monuments historiques (LRMH), Centre de Recherche sur la Conservation (CRC ), Muséum national d'Histoire naturelle (MNHN)-Ministère de la Culture et de la Communication (MCC)-Centre National de la Recherche Scientifique (CNRS)-Muséum national d'Histoire naturelle (MNHN)-Ministère de la Culture et de la Communication (MCC)-Centre National de la Recherche Scientifique (CNRS), Centre d'Etudes et d'Expertise sur les Risques, l'Environnement, la Mobilité et l'Aménagement (Cerema), and ANR-06-RGCU-0001,APPLET,Durée de vie des ouvragresen béton : Approche Prédictive PerformantieILE et probabilisTE(2006)

Subjects
corrosion, rebar, [PHYS.NUCL]Physics [physics]/Nuclear Theory [nucl-th], concrete, [PHYS.NEXP]Physics [physics]/Nuclear Experiment [nucl-ex]
Abstract

International audience; Rebar corrosion of reinforced concrete is the main cause of deterioration of structures such as bridges, piers, monuments, etc. Considering the amount of structures built using reinforced concrete all along the 20th century, monitoring and control of reinforcement bear a significant practical importance in durability assessment. The aim of this paper is (i) to study the corrosion kinetics of reinforced concrete structures in the propagation phase in order to ascertain the corrosion process versus time and (ii) to propose a prediction for reinforced concrete structure durability based on steel thickness loss. In the aim of improving corrosion comprehension and prediction, within the French national project APPLET, reinforced concrete slabs, polluted by chlorides (mix or wetting/drying cycles) were exposed to outdoor environmental conditions as well as to controlled temperature and relative humidity conditions during a three years period. Corrosion of reinforcement was monitored four times per year by the means of three measurements (half-cell potential, electrochemical impedance spectroscopy and linear polarization resistance) and then, corrosion current density was calculated. Destructive analyses of the steel/concrete interface were also conducted in order to determine the steel loss by gravimetry and the nature of the oxide species by Raman microspectroscopy. Results show that in order to accurately predict the durability of reinforced concretes, measurements need to be performed regularly because the corrosion rate is an instantaneous value that fluctuates with time. Concerning the kinetics of the corrosion propagation phase for chlorinated concretes, the data analysis evidenced that steel thickness loss versus time follows a power law rather than a linear law. Moreover, the occurrence of cracks was related to the steel loss versus time. Finally, the steel loss obtained on samples exposed to outdoor conditions was relatively close to the one observed on samples exposed to controlled conditions.

Published
2014

11. Corrosion behaviour of Mg alloys cladding from nuclear reactors fuel in alkaline solutions

Author

Agullo, J., Muzeau, B., Bataillon, Christian, L'Hostis, V., CEA-Direction des Energies (ex-Direction de l'Energie Nucléaire) (CEA-DES (ex-DEN)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA), and CADARACHE, Bibliothèque

Subjects
[PHYS.NUCL] Physics [physics]/Nuclear Theory [nucl-th], [PHYS.NUCL]Physics [physics]/Nuclear Theory [nucl-th], [PHYS.NEXP] Physics [physics]/Nuclear Experiment [nucl-ex], Mg alloys cladding, nuclear reactors fuel, alkaline solutions, Corrosion behaviour, [PHYS.NEXP]Physics [physics]/Nuclear Experiment [nucl-ex]
Abstract

International audience; The reprocessing of spent fuel from the French UNGG (Graphite Gas Natural Uranium) nuclear power plants generates cladding wastes such are Mg-Mn alloys. A storage strategy is to encapsulate these wastes into cement matrix. The main issue is hydrogen evolution as the main consequence of the corrosion of Mg alloys, regardless of concrete radiolysis. In fact Mg acts as an anode in most of galvanic corrosion systems and the hydrogen can be produced either by water reduction or by Anodic Hydrogen Evolution (AHE). In the last case, an increase in the rate of hydrogen production with increasing applied potential is observed. This phenomenon called "Neg-ative Different Effect" (NDE) is in contradiction with the conventional Tafel equation. The corrosion of magnesium may produce Mg$^+$ cations which react quickly with water to produce hydrogen and stable Mg$^{2+}$ cations. The interstitial solution in concrete pores is characterized by a very high pH. To reproduce the pH solution around 13, 0.1M NaOH solutions were prepared and used as electrolytes from electrochemical experiments. Stainless steel, platinum and graphite were used as cathode to investigate basic galvanic coupling as it can be encountered in the real wastes. The purpose of this work was to investigate the galvanic corrosion of Mg alloys in the high pH solutions. The study of Mg corrosion behaviour was carried out using elec-trochemical measurement: ZRA mode. The analysis of the surface and the corrosion products were performed by Raman spectroscopy. The first results showed a galvan-ic corrosion rate more important with stainless steel rather than with graphite.

Published
2014

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