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Avaliacao do comportamento frente a corrosao pelo ataque de cloreto de argamassa armada apos varios tratamentos protetoresCRIVELARO, MARCOS 09 October 2014 (has links)
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Vers une utilisation rationnelle des métakaolins flash : application aux bétons / A rational use of the flash metakaolin : concrete applicationsBucher, Raphaël 10 June 2015 (has links)
L'objectif de ce travail est de contribuer à la valorisation du métakaolin en substitution du ciment dans les matrices cimentaires en levant certains verrous scientifiques. En effet l'utilisation d'additions minérales modifie les propriétés des bétons, que cela soit à l'état frais, à l'état durcissant ou à l'état durci. A l'état frais, la rhéologie a été étudiée avec l'adaptation et l'application d'une méthode de formulation pour béton auto-plaçant. Cette application a été développée jusqu'à l'échelle industrielle. A l'état durcissant, la phase d'hydratation a été étudiée en s'attardant particulièrement sur l'effet de la nature du ciment substitué sur la réactivité du métakaolin. Enfin à l'état durci deux caractéristiques de durabilité ont été explorées, à savoir l'effet du métakaolin sur la carbonatation dans une première partie, puis sur la diffusion des chlorures dans une deuxième partie. / The objective of the present thesis was to promote the use of metakaolin as substitute for cement in cementitious matrix by unlocking several scientific challenges. The use of mineral additions modifies the properties of concrete in the fresh state, the hardening state and the durability state. In the fresh state, rheology was studied by adapting a formulation method for self-compacting concretes. This application was then further developed to be used at an industrial scale. In the hardening state, the hydration phases were analysed with a focus on the effect of the cement nature on the metakaolin reactivity. Finally in the durability state, two particular features were studied:1) the metakaolin effect on the carbonation kinetic and 2) the effect of the metakaolin on the chloride diffusion.
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Evaluation fiabiliste de l'impact des facteurs climatiques sur la corrosion des poutres en béton armé : application au cas libanais / Reliable assessment of the impact of climatic factors on the corrosion of reinforced concrete beams : application to the Lebanese caseEl Hassan, Jinane 05 November 2010 (has links)
Les structures en béton armé exposées à des environnements agressifs subissent des dégradations qui affectent leur intégrité. La corrosion des armatures est l’un des mécanismes de dégradation les plus répandus et les coûteux en terme de maintenance et de réparation. Ce processus est dû à la pénétration des agents agressifs dans le béton, notamment les ions chlorures et le gaz carbonique. Les chlorures induisent une corrosion localisée ou par piqûre, alors que le gaz carbonique engendre une corrosion généralisée ou uniforme. Le déclenchement et la propagation de la corrosion dépendent de plusieurs facteurs liés aux matériaux, aux chargements, à la géométrie et à l’environnement. Ces facteurs présentent de grandes incertitudes qui doivent être prise en comptes à travers une approche probabiliste. Dans ce travail de recherche, nous nous intéressons au mécanisme de corrosion en général. Un intérêt particulier est porté à la prise en compte de l’impact des facteurs climatiques sur ce processus, notamment dans le contexte libanais. Ainsi, nous proposons une modélisation physique de la corrosion des aciers dans les poutres en béton armé qui se déroule en deux phases : - une phase d’initiation durant laquelle les agents agressifs (chlorures et gaz carbonique) pénètrent dans le béton et atteignent des concentrations critiques provoquant la dépassivation de l’acier ; - une phase de propagation durant laquelle il y a corrosion active des aciers et diminution de la résistance de la poutre jusqu’à la défaillance. Les facteurs présentant des incertitudes sont traités comme des variables aléatoires. Pour les modéliser, nous avons étudié, pour les différentes variables aléatoires, de nombreux modèles probabilistes proposés dans la littérature. Nous avons vérifié leur compatibilité vis-à-vis de notre problématique et la possibilité d’assurer les données nécessaires à leur bonne utilisation (notamment la cohérence entre les hypothèses). Ensuite, nous avons retenu les modèles probabilistes les plus adaptés à notre cas. Par ailleurs, l’application des principes fiabilistes nous permet d’évaluer la fiabilité des poutres sujettes à la corrosion vis-à-vis des deux états-limites (ELU et ELS). En effet, la perte de la section d’acier due à la corrosion induit d’une part, une diminution de la capacité portante de la poutre, et d’autre part une augmentation de la contrainte au niveau du béton tendu (provoquant un accroissement des ouvertures des fissures). Ainsi, pour l’état limite de service, la marge de sûreté s’annule lorsque l’ouverture des fissures dépasse la valeur limite préconisée par l’Eurocode 2. Quant à l’état limite ultime, la fonction d’état limite est la résistance en flexion : la défaillance a lieu lorsque le moment résistant équivaut au moment sollicitant. Le calcul fiabiliste est effectué au moyen de simulations de Monte-Carlo. Finalement, nous avons réalisé plusieurs applications aux modèles de corrosions proposées dans ce travail. La première application porte sur l’analyse des sensibilités des modèles de corrosion aux différents paramètres. L’effet des moyennes des paramètres aléatoires ainsi que leurs variabilités sur la réponse du modèle est examiné. Une attention particulière est accordée à l’impact des facteurs climatiques. Ainsi une application du modèle de corrosion induite par les chlorures avec des données réelles de température et d’humidité relatives à trois villes côtières ayant des caractéristiques climatiques différentes est présentée. Ensuite une étude comparative de l’effet du choix des diamètres des armatures et des épaisseurs des enrobages sur la fiabilité à l’état limite ultime et à l’état limite de service est effectuée. Les résultats obtenus ont permis de mettre en évidence l’aspect agressif des facteurs climatiques : un climat chaud et humide est très agressif vis-à-vis de la corrosion induite par les chlorures alors qu’un climat à humidité relative variable favorise la corrosion par carbonatation. (...) / When exposed to aggressive environment, reinforced concrete structures are subject to a degradation mechanism that affects their integrity. Among various environmental attacks, the corrosion of RC structures is considered the most dangerous. The process is launched by the penetration of aggressive agents, precisely the chlorides and carbon dioxide into the concrete. The chlorides induce a localized corrosion, also called pitting corrosion, while on the other hand the carbon dioxide leads to a general corrosion called uniform corrosion. This corrosion phenomenon depends on several factors such as the materials characteristics,loadings, geometry and the environment. All these components include different levels of uncertainties that are taken into account throughout a probabilistic approach. In this work, we propose two models for the corrosion mechanisms induced separately by the chlorides and the carbon dioxide. These models take into account the effect of the climatic condition that is mainly described by the temperature and the relative humidity. In addition to that, as a study case we have treated in details the Lebanese climatic context. We have proposed a physical model of steel corrosion in reinforced concrete beams that occurs in two phases : - An initiation phase where aggressive agents like the chlorides and carbon dioxide penetrate into the concrete and reach a critical concentration values causing the depassivation of the steel ; - A propagation phase in which the active corrosion of steel decreases the strength of the beam leading to its failure. All the factors that have uncertainties are treated as random variables. Several probabilistic models are listed and discussed in the literature while only the models that match with our context are selected. The reliability analysis allowed us to assess the reliability of beams subjected to corrosion in ULS and SLS. The loss of steel section due to the corrosion mechanism induces a decrease of the bearing beam capacity, and an increase in the tension stress in the concrete.This causes an increase of the width of cracks openings. Thus, taking into account the serviceability limit state, the safety margin goes to zero when the width of crack opening exceeds the acceptable width as recommended by the Eurocode 2. The limit state function in ULS is the bending strength. The failure occurs when the applied moment equals or surpasses the resisting moment. The reliability calculations are carried out using Monte-Carlo simulations. Finally, several applications to the corrosion model are proposed via this work. The first application concerns the sensitivity analysis of the corrosion models for the different parameters. The effects of the mean values and the variability of the random variables on the model response are also examined. The impact of climatic factors on the corrosion phenomenon took the biggest part of this work. We have applied the chloride’s corrosion model with the real temperatures and relative humidity of three coastal cities having different climatic characteristics. Then a comparative study showing the effect of the ba rdiameters and the cover thickness on the reliability of the RC beam subjected to aggressive environment is carried out. (...)
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RETRAÇÃO TOTAL E PENETRAÇÃO DE CLORETOS DE CONCRETOS COMPOSTOS COM CINZA DE CCA DE DIFERENTES TEORES DE CARBONO GRAFÍTICO / TOTAL SHRINKAGE AND CHLORIDE PENETRATION OF CONCRETES MADE WITH RICE HUSK ASH WITH DIFFERENT CONTENTS OF GRAPHITIC CARBONSilva, Monique Pafiadache da 27 February 2012 (has links)
Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / The use of agro-industrial by-products with pozzolanic properties has become
an alternative in the cement industry because of the increasing consumption of
cement, aiming at the rational use and sustainability of the mines that produce raw
materials for the production of clinker and longer life of concrete structures. This
research investigates the influence of the curing period and of the use of rice husk
ash with different contents of graphitic carbon on the compressive strength, total
shrinkage and chloride penetration of concretes with high early age strength cement.
The levels of replacement of Portland cement adopted were 0%, 5%, 10%, 20% and
30%, the water/binder ratios of 0.35, 0.50 e 0.65 and the wet curing periods of 3 and
7 days. A mixture containing 10% of silica fume to replace Portland cement was used
as benchmark. Compressive strength was obtained by a compressive test using
cylindrical specimens (Ø 100 mm x 200 mm) according to NBR 5738 and 5739
standards for the ages of 28 and 91 days. The determination of shrinkage was made
according to the recommendations of ASTM C-157 (ASTM, 2006) and ASTM C-490
(ASTM, 2004) in test specimens with 100 mm x 100 mm x 285 mm evaluated at the
ages of 7, 14, 21, 28, 35, 56, 91 and 182 days. Before being immersed in saline, the
test specimens were dried for 91 days. Based on the findings, it has been found, for
all mixtures investigated, that the increase in the wet cure period led to higher
compressive strength values, lower shrinkage values and reduced chloride
penetration for the investigated mixtures. The opposite behavior was observed with
the increase of w/b ratio. The mixtures containing rice husk ash of lower contents of
graphitic carbon (light-colored) showed the highest values of compressive strength.
However, analysis at equal content of replacement shows that this behavior varies
according to the a/agl ratio, age at test and curing period, not indicating a general
tendency. This behavior is also valid for analysis of mixtures with rice husk ash and
silica fume. In the test of shrinkage and chloride penetration following shrinkage, the
mixtures of rice husk ash of lower contents of graphitic carbon have shown, in
general, better performance, with lower shrinkage values and reduced chloride
penetration. / A utilização de subprodutos agroindustriais com características pozolânicas
tem sido uma das alternativas encontradas diante do crescente consumo de
cimento, visando à racionalidade e à sustentabilidade das jazidas fornecedoras de
matérias-primas para produção do clínquer e à maior vida útil das estruturas de
concreto. Nesta pesquisa, investiga-se a influência do período de cura e da
utilização de cinza de casca de arroz com diferentes teores de carbono grafítico na
resistência à compressão axial, retração total e penetração de íons cloreto de
concretos com cimento Portland de alta resistência inicial. Os teores de substituição
ao cimento Portland adotados foram de 0%, 5%, 10%, 20% e 30%, as relações
água/aglomerante de 0.35, 0.50 e 0.65 e os períodos de cura úmida de 3 e 7 dias.
Uma mistura com 10% de sílica ativa em substituição ao cimento Portland foi
empregada como parâmetro de comparação. A resistência à compressão axial foi
avaliada em corpos de prova cilíndricos (Ø 100 mm x 200 mm) segundo as normas
NBR 5738 e 5739, para as idades de 28 e 91 dias. A determinação da retração foi
feita conforme recomendações da ASTM C-157 (ASTM, 2006) e ASTM C-490
(ASTM, 2004) em corpos de prova de dimensões 100 mm x 100 mm x 285 mm
avaliados nas idades de 7, 14, 21, 28, 35, 56, 91 e 182 dias. A avaliação de
penetração de íons cloreto (imersão em solução salina) foi realizada nas idades de
7, 14, 28, 56 e 91 dias. Antes de serem imersos em solução salina, os corpos de
prova foram submetidos a um período de secagem de 91 dias. Dos resultados
obtidos, constatou-se, para todas as misturas investigadas, que o aumento do
período de cura úmida resultou em maiores valores de resistência à compressão,
menores valores de retração e menor penetração de íons cloreto para as misturas
investigadas. Comportamento contrário foi observado com o aumento da relação
a/ag. As misturas compostas com CCA de menor teor de carbono grafítico (clara)
apresentaram os maiores valores de resistência à compressão, contudo, quando se
analisa em igualdade de teor de substituição, esse comportamento varia em função
da relação a/agl, idade de ensaio e prazo de cura, não apresentando uma tendência
geral. Esse comportamento também é válido quando se analisa as misturas com
CCA e SA. No ensaio de retração e de penetração de cloretos após retração, as
misturas compostas com CCA de menor teor de carbono grafítico apresentaram, no
geral, melhor desempenho com menores valores de retração e de penetração de
cloretos.
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Avaliacao do comportamento frente a corrosao pelo ataque de cloreto de argamassa armada apos varios tratamentos protetoresCRIVELARO, MARCOS 09 October 2014 (has links)
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Transporte de cloretos em concretos com adições minerais e o desempenho em relação à corrosão das armaduras / Transport of chlorides in concretes with mineral additions and corrosion performance of reinforcementMartins, Alex Mizael 16 December 2016 (has links)
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Previous issue date: 2016-12-16 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior - CAPES / The introduction of wind energy into the brazilian energy matrix is of paramount importance for
national energy policy. In this context, the viability of wind towers is a fundamental issue. In
Brazil, these towers are built mainly in reinforced concrete, in regions of high aggressiveness
(coastal regions, because of their greater wind potential) and, therefore, it is necessary to develop
high performance concretes that are able to withstand environmental actions to which they are
subjected, mainly the action of the chlorides, so that these structures reach the previously defined
project life, thus guaranteeing the viability of the towers. In this sense, the present work evaluates
the mechanical properties, the mechanisms of transport of chlorides and the performance in
relation to the corrosion of the reinforcement, in concretes that contain high performance pozolanic
mineral additions, in order to evaluate the influence of the presence of these additions in these
properties. Three different study mixes were developed containing respectively, 9% of silica fume
in composition with 1% of nanosilica, 5% of a high fineness metakaolin in composition with 5% of
a slightly less fine metakaolin, both with high pozzolanic activity and a mix containing only 10%
of the finest metakaolin, in addition to a reference mix. Analyzes related to the chloride transport
are presented: penetrability and diffusion; analyzes related to the corrosion of reinforcement:
induction of corrosion by aggressive solution wetting cycles and air drying, surface electrical
resistivity of concrete and corrosion potential, besides the mechanical characterization. The
concretes with incorporation of pozzolanic addition showed, in general, improvements in the
mechanical properties. In the chloride transport properties and corrosion performance of the
reinforcements, the improvements from the mineral additions were significant. Thus, it was
concluded that the incorporation of the different mineral additions studied in the present work
significantly altered the properties of the concrete, with a positive highlight for the properties
associated with durability, in which the benefits of using mineral addition are more pronounced. / A introdução da energia eólica na matriz energética brasileira é de suma importância para a política
energética nacional. Nesse contexto, a viabilidade das torres eólicas é questão fundamental. No
Brasil essas torres são construídas, principalmente, em concreto armado em regiões de alta
agressividade (regiões litorâneas, por terem maior potencial eólico) e, portanto, faz-se necessário o
desenvolvimento de concretos de alto desempenho que sejam capazes de resistir às ações
ambientais às quais são submetidos, principalmente à ação dos cloretos, de maneira que essasestruturas atinjam a vida útil de projeto previamente definida, garantindo assim a viabilidade das
torres. Nesse sentido, o presente trabalho avalia as propriedades mecânicas, os mecanismos de
transporte de cloretos e o desempenho em relação à corrosão das armaduras, de concretos que
contêm adições minerais pozolânicas de alto desempenho, a fim de avaliar a influência dessas
adições nessas propriedades. Foram elaborados três diferentes proporcionamentos de estudo
contendo respectivamente, 9% de sílica ativa em composição com 1% de nanossílica, 5% de um
metacaulim de elevada finura em composição com 5% de um metacaulim um pouco menos fino,
ambos de elevada pozolanicidade e um proporcionamento contendo exclusivamente 10% do
metacaulim de maior finura, além de um proporcionamento de referência. São apresentadas
análises relacionadas ao transporte de cloretos: penetrabilidade e difusão; análises relacionadas à
corrosão das armaduras: indução da corrosão por meio de ciclos de molhagem em solução
agressiva contendo cloretos, medidas de resistividade elétrica superficial do concreto e potencial de
corrosão, além da caracterização mecânica. Os concretos com incorporação de adição pozolânica
apresentaram, em geral, melhorias em suas propriedades mecânicas. Já nas propriedades de
transporte de cloretos, as melhorias advindas das adições minerais foram mais significativas, assim
como no desempenho em relação à corrosão das armaduras. Desse modo, concluiu-se que a
incorporação das diferentes adições minerais estudadas no presente trabalho alterou
significativamente as propriedades do concreto, com destaque positivo para as propriedades
associadas à durabilidade, nas quais os benefícios do uso da adição mineral são mais pronunciados.
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Způsoby využití by-passových cementářských odprašků v technologii stavebních hmot / Methods of using cement kiln by-pass dust in building materials technologySikorová, Věra January 2019 (has links)
This diploma thesis is focused on methods of using cement kiln by-pass dust in building materials technology. By-pass dust was treated to remove chlorides and could then be used as other constituent to various types of cements in the amount of 0–5 wt. % according to ČSN EN 197-1. The properties of dusts before and after chloride removal were examined and after incorporating modified by-pass dust into the cement, the properties of fresh and hardened cement pastes and mortars were studied. It was found that modified by-pass dust after incorporation into cement fulfill requirements of ČSN EN 197-1.
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Alanine, aspartic acid and lactose-capped CuS, ZnS and FeS nanoparticles: synthesis, characterization and propertiesMofokeng, Thapelo Prince January 2017 (has links)
M. Tech. (Department of Chemistry, Faculty of Applied and Computer Sciences), Vaal University of Technology / Water soluble metal sulfide nanoparticles were successfully synthesized using an aqueous, simple and environmentally friendly synthetic method in the presence of ʟ-alanine, ʟ-aspartic acid and lactose, acting as both stabilizers and crystal growth modifiers. The structural and optical properties of the synthesized metal sulfide nanoparticles were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), Fourier transform infrared (FTIR), Ultraviolet-visible (UV-Vis) and photoluminescence spectroscopy.
Colloidal method was employed in the synthesis of CuS, ZnS and FeS nanoparticles from metal chlorides as precursors and thioacetamide (TAA) as a sulphur source. The effect of temperature on the growth and solubility of nanoparticles was investigated. The absorption spectra of all samples prepared were blue shifted as compared to their bulk materials indicating small particles size. The morphologies and sizes of the nanoparticles were influenced by the variation of temperature and capping agent. TEM images revealed interesting changes in the morphology of CuS nanoparticles formed from various capping agents. By varying the temperature, ʟ-aspartic acid-capped CuS nanoparticles changed from rod-shaped particles to particles dominated with hexagonal shape. However, the morphologies of both ZnS and FeS nanoparticles were close to spherical shape and were unaffected by either change of temperature or capping agent. Water-solubility of bio-functionalized CuS, ZnS and FeS nanoparticles was investigated. Amongst the three capping agents used, ʟ-alanine (Ala) was found to be the most effective capping agent to render solubility of the nanoparticles. As the temperature was increased, the solubility of the particles also increased. Cytotoxicity and antimicrobial activity of ʟ-alanine-capped CuS and ZnS nanoparticles were investigated. The particles were less toxic at low to moderate concentrations and only induced toxicity at higher concentrations. Particles synthesized at 95 °C were less toxic compared to other nanoparticles (35 and 65 °C) for both two set of experiments, as informed by the CC50 values. Antimicrobial properties were tested using different strains of both positive and negative bacteria and fungi. It was found that Ala-capped CuS nanoparticles were more effective against the bacteria than Ala-capped ZnS nanoparticles.
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Livslängdsdimensionering av korrosionsutsatta betongkonstruktioner / Lifetime Dimensioning of Corrosion-Exposed Concrete CtructuresAzad Ali, Bawan, Ahmadiyan, Sara January 2019 (has links)
Through history, iron has mainly been used as reinforcement in concrete. Contemporary building technology would not have been possible without reinforced concrete, however, from a global perspective, many concrete buildings have begun to encounter reinforcement corrosion, mainly due to chlorides and carbonation. When the chlorides come into contact with the reinforcing bars, a chemical reaction begins, which causes the iron to oxidize and begin to corrode. In a humid environment when the reinforcement corrodes, the iron expands and bursts the concrete from inside, which in turn results in cracks occurring in the concrete structure. In an environment with lack of oxygen, it often occurs that non expanding rust products form that are not defected on the concrete surface occurs through discoloring or spalling. This type of damage is not detected ocularly and therefore forms a more serious type of injury. This type of rust is a silent type of damage that can cause deteriorated bearing capacity in the construction, since the cross-sectional area of the reinforcement in the concrete decreases. Sweco has been involved in a couple of projects where there have been huge problems due to corrosion of reinforcement. The damages that emerged leading to the repairs of these type of damage costing large sums. This report is based on previous projects, articles, literature studies, reports and interviews. Interviews have been conducted with competent people who have shared their valuable opinions, knowledge and experiences. In order to stop ongoing corrosion of reinforcement and also repair the damage, several alternative solution and repair measures have been devolped. Some of the most relevant suggestions in this report is to remove the damaged concrete and then re-cast or alternatively cast in cathodic protection or a combination of these. / Genom historien har man främst använt sig av järn som armering i betong. Samtidens byggteknik hade inte varit möjlig utan armerad betong, dock behöver man vara uppmärksam på armeringskorrosion framför allt på grund av klorider och karbonatisering. När kloriderna kommer i kontakt med armeringsjärnen påbörjas en kemisk reaktion som leder till att järnen oxiderar och börjar korrodera. I fuktig miljö när armeringen korroderar, expanderar järnen och spränger betongen inifrån vilket i sin tur resulterar i att sprickor uppstår i betongkonstruktionen. I syrefattiga miljöer uppstår det oftast svartrost som är den typ av skada som uppstår inuti en betongkonstruktion. Denna typ av skada upptäcks inte okulärt och blir därför en allvarligare typ av skada. Svartrost är även den typ av skada som kan förorsaka försämrad bärighet i konstruktionen eftersom tvärsnittsarean hos armeringen i betongen minskar. Sweco har varit inblandade i ett par projekt där det har förekommit enorma problem på grund av armeringskorrosion. Skadorna som har uppstått på grund av armeringskorrosion har lett till att reparationerna av dessa skador har varit kostsamma. Denna rapport är baserad på tidigare projekt, artiklar, litteraturstudier, rapporter samt intervjuer. Intervjuer har genomförts med kompetenta personer som har delat med sig av sina värdefulla åsikter, kunskaper och erfarenheter för att få en bättre uppfattning av konsekvenserna som uppstår på grund av armeringskorrosion. För att stoppa pågående armeringskorrosion och även reparera skadorna, har reparationsåtgärder i denna rapport tagits fram. Några utav de mest relevanta förslag på åtgärder i denna rapport är att ta bort den skadade betongen för att sedan gjuta på nytt, alternativt gjuta in katodiskt skydd eller en kombination av dessa.
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Outils de caractérisation et analyse du comportement des matériaux cimentaires soumis à des cycles de gel-dégel en présence de sels / Tools of characterization and analysis of the behavior of ciment based matérials subjected to freeze-thaw cycles in the presence of saltsBouteille, Sébastien 18 April 2013 (has links)
Un béton exposé à des cycles de gel-dégel peut subir des dégradations généralement identifiées sous deux formes. Le gel interne, d’une part, qui affecte le coeur du matériau et peut aboutir à une microfissuration généralisée de la pâte cimentaire. La sensibilité d’un béton courant à ce mode de détérioration peut être diminuée par la présence d’un réseau de bulles d’air au sein de la pâte cimentaire. L’écaillage, d’autre part, qui est une détérioration de surface. Cette dernière est le plus souvent quantifiée par la perte de masse sur la surface exposée. Cette forme de dégradation est fortement influencée par la présence d’une solution aqueuse proche de la surface de béton exposée et de sa concentration en sels fondants (généralement du chlorure de sodium). Lorsque la formulation d’un béton courant n’est pas adaptée pour résister à ce type d’environnement, les dégradations liées au gel interne et à l’écaillage peuvent pénaliser l’exploitation de l’ouvrage concerné dans des conditions de services attendues. Des essais laboratoire, exposant des corps d’épreuve en béton à des cycles de gel-dégel accélérés, permettent d’évaluer la résistance d’un béton face à ces deux formes de détériorations. La communauté scientifique s’accorde sur les essais permettant de caractériser la détérioration par le gel interne et l’aspect protecteur d’un réseau de bulles d’air. Par contre, l’écaillage est encore abordé par diverses procédures expérimentales qui ne font pas consensus et ont peu évolué depuis le milieu des années 1990 (...) / A concrete submitted to freeze-thaw cycles may undergo damages generally identified under two forms. On one hand, the internal frost affects the whole volume of the concrete. It can resul in generalized microcracks into the ciment paste. The sensibility of a common concrete to this deterioration can be decreased by the presence of a network of air bubbles within the ciment paste. On the other hand, the scaling, is a surface deterioration generaly quantified by the loss of mass from the exposed surface. The scaling is strongly influenced by the presence of a solution and its concentration in salts (generally some sodium chloride), over the exposed concrete surface. When a common concrete is not correctly formulated to resist this environment, its degradation can penalize the exploitation of the concerned structure in expected conditions of services. Laboratory tests exposing bodies of concrete to accelerated freeze-thaws cycles, allow to estimate the concrete resistance when exposed to these two kinds of deteriorations. The scientific community agrees on the internal frost laboratory test and on the protective aspect of a network of air bubbles. But the scaling is still approached by experimental procedures which do not make consensus and have little evolved since the middle of the 1990s (...)
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