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The microstructure and performance of calcium sulfoaluminate (CSA) cements are described. CSA cements contain C₄A<sub>3S, 4CaO.3Al₂O₃.SO₃,and are interground with gypsum/anhydrite. They have been used structurally in China for more than 20 years and elsewhere as special cements in non-structural applications. Their long-term behaviour of depends on ettringite, a relatively fragile substance, and a novel matrix former compared with Portland cement. The mineralogy, evolution of hydrate and microstructure of CSA cement pastes and concretes were studied to relate hydration products and microstructure with performances. Samples taken from in-service structures in China, ranging from several to 25 years old, were investigated. Drying methods for cement pastes affect experimental results, especially for ettringite-based materials and are reported. Calorimetry, X-ray diffraction, microprobe and porosimetry are used to investigate early (<24 hours) and late hydration processes in different curing regimes. A "shrinking sphere" model is proposed to explain hydration processes. At early stages, mineralogy differs between inner and outer products: the former contain mainly AFm and C-S-H while the latter contains mainly ettringite and gibbsite. At 25°C, these differences persist but inner products densify the paste. At 55°C, and at 85°C, substantial siliceous hydrogarnet, forms after ~3 d. It is a major inner product. This results in a volume decrease and coarsening of pores. Long-term exposure to higher temperatures ~85°C is harmful. The impact of water:cement ratios on hydration mechanisms is reported. Depths of carbonation of CSA cement concrete are reported: results show similar resistance Portland cement concrete. Pipe immersed in seawater for 16 years shows that CSA cement has excellent resistance to seawater attack. The steel in the pipe is uncorroded even though chloride ions have penetrated the cover. Long-term exposure to high temperatures, 85°C, of CSA cement should be avoided but under normal in-service conditions its long-term behaviour is satisfactory.

Currently in the UK, composite blends of Portland cement (PC) and blastfurnace slag (up to 90%) are commonly used for the encapsulation of low and intermediate level wastes. The high volume replacement of PC is considered necessary in order to to reduce the high heat generation resulting from cement hydration in 500 litre waste packages. While suited to the majority of waste streams, the high pH environment in such systems (usually around 12.5 -13), will cause the corrosion of certain waste metals such as aluminium. Since aluminium is only passive between pH4 - 8.5, the use of an alternative low-pH cement system could serve to reduce/inhibit the corrosion. However, before such cements can be considered, two main research problems must be addressed, as follows: (1) quantitative evaluation of alternative cement systems based on their corrosion performance with aluminium; (2) high heat generation due to the rapid rate of hydration. The research in this thesis was thus divided into two strands, as follows: (1) The design and development of a novel, scientifically robust testing facility for the quantitative monitoring of aluminium corrosion in cement pastes; (2) the development of novel cement composites based on weakly alkaline calcium sulfoaluminate (CSA) cement for the encapsulation of aluminium from nuclear wastes. The output from this research is considered to be of interest to the UK nuclear industry.

One of the benefits of calcium sulfoaluminate (CSA) cements is that these materials gain strength rapidly, where strength development is often measured in hours instead of days. This property makes these materials desirable for use in temporary, non-reinforced repairs of roadways, airfields, and navigable locks. The rapid repair of these infrastructure elements is critical to transporting supplies into regions devastated by disaster. In these austere environments, potable water may not be available in sufficient quantities to make vital repairs, and the use of impure water in the production of CSA cement-based concrete would be advantageous. However, the hydration products formed by CSA cement are substantially different from those formed by portland cement and may react differently to impurities that water sources may contain. This Thesis investigates the impact of various salts and impure water sources on the early-age strength development of commercially-available CSA cement-based concrete.

Embora o uso do cimento Portland com altos teores da fase alita [silicato tricálcico - C3S – (CaO)3.(SiO2)] seja difundido mundialmente, argumentos ambientais indicam a fabricação de cimentos com baixos teores desta fase e altos teores da fase belita [silicato dicálcico - C2S, (CaO)2.(SiO2)] justamente ao contrário do que é produzido atualmente. A alita tendo mais cálcio que a belita, libera mais CO2 para a atmosfera quando ocorre a decomposição do calcário (CaCO3 CaO + CO2 ) durante sua fabricação. Além disso, o C2S é formado a uma temperatura mais baixa (800 a 900ºC) que a temperatura em que o C3S (1350 a 1450ºC) é formado, necessitando desta forma, menos combustível e produzindo um cimento de moagem mais facilitada, tornando-o mais eco-eficiente. Um aspecto negativo dos cimentos belíticos é que os mesmos atingem seu nível máximo de resistência em idades mais avançadas, e este comportamento não é considerado adequado na indústria da construção civil atual, que busca alta produtividade em um curto espaço de tempo. Uma maneira de eliminar este problema seria acelerando as reações iniciais de hidratação e endurecimento. Uma alternativa à esta questão é combinar estes clínqueres belíticos com agentes expansivos de base sulfoaluminato ou em uma produção simultânea no clínquer, tais como os sulfoaluminato de cálcio belítico (CSAB), sendo estes ligantes considerados de baixo impacto ambiental. No entanto, o cimento CSAB requer uma maior quantidade de alumina, que geralmente é provinda da bauxita na sua fabricação. Devido ao elevado custo da bauxita para a produção deste cimento, a utilização de resíduos ricos em alumina é uma opção que pode agregar valor ao resíduo e aumentar a disponibilidade de ligantes de reduzido impacto ambiental. Desta forma, este trabalho apresenta uma alternativa para utilização do resíduo na produção do cimento CSAB. Foi realizada a caracterização físico-química do resíduo estudado, e são apresentados os resultados da produção de clínqueres CSAB formados a partir de três misturas, com variações no teor deste resíduo. As propriedades físico-mecânicas destes clínqueres foram avaliadas e comparadas com um clínquer referência e um cimento Portland comercial, da mesma forma, técnicas de difração de raio X, calorimetria e termogravimetria foram utilizadas para verificar a formação dos produtos de hidratação de pastas. Desta maneira, foi demonstrado que o aproveitamento do resíduo de anodização do alumínio para a produção do cimento CSAB é viável tecnicamente. O produto gerado possui características especiais, apresentando elevado desenvolvimento da resistência mecânica nas primeiras horas de hidratação. / Although currently Portland cement with high alite [(CaO)3.(SiO2)] content is the most used globally, environmental advices call for changes on the production for cements with lower alite and higher belite [(CaO)2.(SiO2)] contents. Alite, having more calcium than belite, releases more CO2 to the atmosphere in the course of cement manufacture, due to limestone decomposition (CaCO3 CaO + CO2 ). Besides, belite is formed at lower temperatures (800- 900ºC) than alite (1350-1450ºC), and for this reason less fuel is necessary for the process. Additionally, clinker is easier to grind, resulting in a less energy demanding and more sustainable process. However, belite cements reach the maximum strength level at later ages, drawing back the fast and active civil construction industry, which aims high productivity in a short time spam. In order to minimize this problem it is possible to accelerate the initial hydration reactions and hardening by combining the belite clinkers with expansive sulfoaluminate base agents, or in a simultaneous clinker production, such as calcium sulfoaluminate belite cements (CSAB). These binders have lower environmental impact. However, CSAB cement requires a higher amount of alumina, which comes from bauxite. As this material is costly, the use of alumina-rich residues comes as an option to aggregate value to the residue and to increase the availability of low environmental impact binders. This work presents an alternative use for alumina-rich residues in CSAB cement production. Physicochemical characterization of the aluminium anodizing sludge is presented together with results of the production of CSAB clinkers from 3 mixtures, with different residue content. Properties of the produced clinkers were evaluated and compared to a control clinker and to an ordinary Portland cement. X-ray diffraction, calorimetry and thermogravimetry analysis track the formation of hydration products in the cement pastes. The use of aluminium anodizing sludge to produce CSAB cement was proved to be technically viable, as the generated product has special characteristics, presenting high mechanical strength development at the first hours of hydration.

Embora o uso do cimento Portland com altos teores da fase alita [silicato tricálcico - C3S – (CaO)3.(SiO2)] seja difundido mundialmente, argumentos ambientais indicam a fabricação de cimentos com baixos teores desta fase e altos teores da fase belita [silicato dicálcico - C2S, (CaO)2.(SiO2)] justamente ao contrário do que é produzido atualmente. A alita tendo mais cálcio que a belita, libera mais CO2 para a atmosfera quando ocorre a decomposição do calcário (CaCO3 CaO + CO2 ) durante sua fabricação. Além disso, o C2S é formado a uma temperatura mais baixa (800 a 900ºC) que a temperatura em que o C3S (1350 a 1450ºC) é formado, necessitando desta forma, menos combustível e produzindo um cimento de moagem mais facilitada, tornando-o mais eco-eficiente. Um aspecto negativo dos cimentos belíticos é que os mesmos atingem seu nível máximo de resistência em idades mais avançadas, e este comportamento não é considerado adequado na indústria da construção civil atual, que busca alta produtividade em um curto espaço de tempo. Uma maneira de eliminar este problema seria acelerando as reações iniciais de hidratação e endurecimento. Uma alternativa à esta questão é combinar estes clínqueres belíticos com agentes expansivos de base sulfoaluminato ou em uma produção simultânea no clínquer, tais como os sulfoaluminato de cálcio belítico (CSAB), sendo estes ligantes considerados de baixo impacto ambiental. No entanto, o cimento CSAB requer uma maior quantidade de alumina, que geralmente é provinda da bauxita na sua fabricação. Devido ao elevado custo da bauxita para a produção deste cimento, a utilização de resíduos ricos em alumina é uma opção que pode agregar valor ao resíduo e aumentar a disponibilidade de ligantes de reduzido impacto ambiental. Desta forma, este trabalho apresenta uma alternativa para utilização do resíduo na produção do cimento CSAB. Foi realizada a caracterização físico-química do resíduo estudado, e são apresentados os resultados da produção de clínqueres CSAB formados a partir de três misturas, com variações no teor deste resíduo. As propriedades físico-mecânicas destes clínqueres foram avaliadas e comparadas com um clínquer referência e um cimento Portland comercial, da mesma forma, técnicas de difração de raio X, calorimetria e termogravimetria foram utilizadas para verificar a formação dos produtos de hidratação de pastas. Desta maneira, foi demonstrado que o aproveitamento do resíduo de anodização do alumínio para a produção do cimento CSAB é viável tecnicamente. O produto gerado possui características especiais, apresentando elevado desenvolvimento da resistência mecânica nas primeiras horas de hidratação. / Although currently Portland cement with high alite [(CaO)3.(SiO2)] content is the most used globally, environmental advices call for changes on the production for cements with lower alite and higher belite [(CaO)2.(SiO2)] contents. Alite, having more calcium than belite, releases more CO2 to the atmosphere in the course of cement manufacture, due to limestone decomposition (CaCO3 CaO + CO2 ). Besides, belite is formed at lower temperatures (800- 900ºC) than alite (1350-1450ºC), and for this reason less fuel is necessary for the process. Additionally, clinker is easier to grind, resulting in a less energy demanding and more sustainable process. However, belite cements reach the maximum strength level at later ages, drawing back the fast and active civil construction industry, which aims high productivity in a short time spam. In order to minimize this problem it is possible to accelerate the initial hydration reactions and hardening by combining the belite clinkers with expansive sulfoaluminate base agents, or in a simultaneous clinker production, such as calcium sulfoaluminate belite cements (CSAB). These binders have lower environmental impact. However, CSAB cement requires a higher amount of alumina, which comes from bauxite. As this material is costly, the use of alumina-rich residues comes as an option to aggregate value to the residue and to increase the availability of low environmental impact binders. This work presents an alternative use for alumina-rich residues in CSAB cement production. Physicochemical characterization of the aluminium anodizing sludge is presented together with results of the production of CSAB clinkers from 3 mixtures, with different residue content. Properties of the produced clinkers were evaluated and compared to a control clinker and to an ordinary Portland cement. X-ray diffraction, calorimetry and thermogravimetry analysis track the formation of hydration products in the cement pastes. The use of aluminium anodizing sludge to produce CSAB cement was proved to be technically viable, as the generated product has special characteristics, presenting high mechanical strength development at the first hours of hydration.

Embora o uso do cimento Portland com altos teores da fase alita [silicato tricálcico - C3S – (CaO)3.(SiO2)] seja difundido mundialmente, argumentos ambientais indicam a fabricação de cimentos com baixos teores desta fase e altos teores da fase belita [silicato dicálcico - C2S, (CaO)2.(SiO2)] justamente ao contrário do que é produzido atualmente. A alita tendo mais cálcio que a belita, libera mais CO2 para a atmosfera quando ocorre a decomposição do calcário (CaCO3 CaO + CO2 ) durante sua fabricação. Além disso, o C2S é formado a uma temperatura mais baixa (800 a 900ºC) que a temperatura em que o C3S (1350 a 1450ºC) é formado, necessitando desta forma, menos combustível e produzindo um cimento de moagem mais facilitada, tornando-o mais eco-eficiente. Um aspecto negativo dos cimentos belíticos é que os mesmos atingem seu nível máximo de resistência em idades mais avançadas, e este comportamento não é considerado adequado na indústria da construção civil atual, que busca alta produtividade em um curto espaço de tempo. Uma maneira de eliminar este problema seria acelerando as reações iniciais de hidratação e endurecimento. Uma alternativa à esta questão é combinar estes clínqueres belíticos com agentes expansivos de base sulfoaluminato ou em uma produção simultânea no clínquer, tais como os sulfoaluminato de cálcio belítico (CSAB), sendo estes ligantes considerados de baixo impacto ambiental. No entanto, o cimento CSAB requer uma maior quantidade de alumina, que geralmente é provinda da bauxita na sua fabricação. Devido ao elevado custo da bauxita para a produção deste cimento, a utilização de resíduos ricos em alumina é uma opção que pode agregar valor ao resíduo e aumentar a disponibilidade de ligantes de reduzido impacto ambiental. Desta forma, este trabalho apresenta uma alternativa para utilização do resíduo na produção do cimento CSAB. Foi realizada a caracterização físico-química do resíduo estudado, e são apresentados os resultados da produção de clínqueres CSAB formados a partir de três misturas, com variações no teor deste resíduo. As propriedades físico-mecânicas destes clínqueres foram avaliadas e comparadas com um clínquer referência e um cimento Portland comercial, da mesma forma, técnicas de difração de raio X, calorimetria e termogravimetria foram utilizadas para verificar a formação dos produtos de hidratação de pastas. Desta maneira, foi demonstrado que o aproveitamento do resíduo de anodização do alumínio para a produção do cimento CSAB é viável tecnicamente. O produto gerado possui características especiais, apresentando elevado desenvolvimento da resistência mecânica nas primeiras horas de hidratação. / Although currently Portland cement with high alite [(CaO)3.(SiO2)] content is the most used globally, environmental advices call for changes on the production for cements with lower alite and higher belite [(CaO)2.(SiO2)] contents. Alite, having more calcium than belite, releases more CO2 to the atmosphere in the course of cement manufacture, due to limestone decomposition (CaCO3 CaO + CO2 ). Besides, belite is formed at lower temperatures (800- 900ºC) than alite (1350-1450ºC), and for this reason less fuel is necessary for the process. Additionally, clinker is easier to grind, resulting in a less energy demanding and more sustainable process. However, belite cements reach the maximum strength level at later ages, drawing back the fast and active civil construction industry, which aims high productivity in a short time spam. In order to minimize this problem it is possible to accelerate the initial hydration reactions and hardening by combining the belite clinkers with expansive sulfoaluminate base agents, or in a simultaneous clinker production, such as calcium sulfoaluminate belite cements (CSAB). These binders have lower environmental impact. However, CSAB cement requires a higher amount of alumina, which comes from bauxite. As this material is costly, the use of alumina-rich residues comes as an option to aggregate value to the residue and to increase the availability of low environmental impact binders. This work presents an alternative use for alumina-rich residues in CSAB cement production. Physicochemical characterization of the aluminium anodizing sludge is presented together with results of the production of CSAB clinkers from 3 mixtures, with different residue content. Properties of the produced clinkers were evaluated and compared to a control clinker and to an ordinary Portland cement. X-ray diffraction, calorimetry and thermogravimetry analysis track the formation of hydration products in the cement pastes. The use of aluminium anodizing sludge to produce CSAB cement was proved to be technically viable, as the generated product has special characteristics, presenting high mechanical strength development at the first hours of hydration.

ROBATEL Industries conçoit et fabrique des emballages pour matières fortement radioactives. Des matériaux de protection neutronique et thermique (PNT) sont utilisés dans ces emballages afin d’assurer la capture des neutrons et de limiter l’augmentation de la température des matières radioactives en cas d’incendie. Ces PNT sont constitués d’une matrice cimentaire ou de plâtre auxquels sont ajoutées des charges minérales ou organiques. Une charge minérale, la colemanite, permet la capture des neutrons grâce à sa teneur élevée en bore, après que l’hydrogène contenu dans les PNT les ait ralentis.Le premier enjeu de cette thèse a été de mettre au point des méthodes d’analyse élémentaire afin de caractériser l’homogénéité chimique des PNT, qui est cruciale, notamment pour le bore. Une technique de mise en solution et deux techniques de dosages ont ainsi été développées. Une autre partie importante de la thèse concerne la caractérisation des propriétés thermiques et mécaniques des PNT. D’un point de vue thermique, des mesures de chaleur de réaction, de capacité calorifique et de conductivité thermique ont été menées pour déterminer la quantité de chaleur (enthalpie) absorbée par le matériau en cas d’incendie. D’un point de vue mécanique, des essais de compression et de flexion ainsi que des essais ultrasonores ont été réalisés afin d’évaluer les valeurs des contraintes à la rupture et les modules d’élasticité des PNT. Au-delà de ces caractérisations, l’amélioration des formulations des PNT existantes et surtout la mise au point de nouvelles formulations sont au coeur de ce travail. Deux plans de mélange ont ainsi été réalisés afin d’enrichir les PNT en bore et en hydrogène tandis qu’un autre a permis l’augmentation de la fluidité d’un PNT grâce à l’ajout d’un superplastifiant. La dernière partie de la thèse a concerné l’étude de nouveaux ciments, les sulfoalumineux, qui présentent des caractéristiques intéressantes étant donné que leurs hydrates sont riches en hydrogène. Pour ces trois nouvelles familles de PNT à base de sulfoalumineux, le retard de prise induit par le bore a été limité. / ROBATEL Industries company designs and products packages for highly radioactive materials. Neutron and thermal protection materials (PNT) are used in those packages to catch neutrons and to limit the increase of temperature due to radioactive materials in case of fire. These PNT are composed of a cement or a gypsum-based matrix with mineral or organic fillers. Once the neutrons have been slowed down by the hydrogen contained in the PNT, a mineral filler named colemanite enables the neutron capture thanks to its high content of boron.The first goal of this thesis is to develop analytical chemistry techniques to check the chemical homogeneity of the PNT, which is crucial, particularly for boron. A dissolution method and two determination techniques have been developed. Another important topic in this thesis is characterization of thermal and mechanical properties. Thermal characterizations include heat of reaction, heat capacity and thermal conductivity measurements to determine the total heat absorbed by the PNT in case of fire. Mechanical characterizations include compression, bending and ultrasonic tests in order to evaluate stress to rupture and elastic moduli of PNT. Beyond the characterizations, the aim of this thesis is to improve pre-existing formulas of PNT and most importantly to propose new formulas. Two mixture designs have been carried out to increase the boron and the hydrogen concentrations of PNT. Another mixture design allowed enhancing the fluidity of a PNT using a superplasticizer. The last part of the thesis deals with the study of new cements called sulfoaluminous that show interesting properties because their hydration products are rich in hydrogen. For these three new PNT families, the increase of the setting time of cement due to boron has been restricted.

Ce travail s’intéresse à la formulation et à la caractérisation de mortiers cimentaires imprimables en 3D. Il a été réalisé dans le cadre du projet MATRICE cofinancé par le fonds Feder et la région Hauts de France. Un cahier des charges pour un matériau cimentaire imprimable est tout d’abord défini sur la base de trois critères : l’extrudabilité, la constructibilité et la conservation des résistances mécaniques sur matériau imprimé. Deux mortiers imprimables sont formulés en utilisant des essais simples à l’échelle du laboratoire. Le premier mortier, à prise lente, est composé d’un liant à base de ciment Portland (OPC). Le second mortier, à prise accélérée, est composé d’un liant mixte (93 % d’OPC et 7 % de ciment sulfoalumineux (CSA)). Des impressions à l’échelle réelle sont ensuite réalisées dans le cadre du projet MATRICE et permettent de valider leur imprimabilité selon l’application de chacun. Le comportement chimique de mélanges de ciment Portland et de ciment sulfoalumineux est ensuite étudié expérimentalement. Les chaleurs d’hydratation mesurées par calorimétrie isotherme augmentent avec le dosage en CSA (de 2 % jusqu’à 10 %) et sont plus élevées que celles des pâtes de ciment contenant 100 % d’OPC et 100 % de CSA. La comparaison des hydrates identifiés dans le mélange à 7 % de CSA à ceux présents dans les deux pâtes de ciment pures montre que la présence de gypse et de chaux provenant du ciment Portland entraîne une hydratation plus rapide de la ye’elimite provenant du CSA et une formation d’ettringite à très court terme. Par contre, la nature des hydrates du ciment Portland n’est pas affectée. Le comportement rhéologique, notamment, la thixotropie, de pâtes constituées de mélanges de ciment Portland et sulfoalumineux (jusqu’à 10 %) est ensuite étudié en fonction de différents paramètres de formulation pendant la première heure. L’augmentation du dosage en CSA (0 % à 10 %) entraîne une augmentation quasi linéaire du coefficient de structuration (Athix) de ces mélanges. Pour les mélanges à 7 % de CSA et 100 % d’OPC, l’influence du rapport E/C et du dosage en superplastifiant sur la thixotropie est ensuite étudiée. L’augmentation du rapport E/C entraîne une diminution quasi linéaire de Athix pour chacune des pâtes de ciment. En revanche, le superplastifiant présente une faible influence comparativement au rapport E/C. / The interest of this study is the formulation and characterization of 3D printing cementitious mortars. This research work has been carried out in the frame of the MATRICE Project, co-funded by the region “Hauts de France” and the European Union with the European Regional Development Fund. Specifications for a cementitious printable material are first set based on three criteria: extrudability, buildability and conserving the compressive strength of the printed material. Two printable mortars are formulated using simple tests on a laboratory scale. The first, with slow setting, is composed of a Portland-based binder (OPC). The second, with accelerated setting, is composed of a mixed binder (93% OPC and 7% sulfoaluminous cement (CSA)). Real scale prints are then realized in the frame of the project MATRICE allowing the validation of the printability of each mortar upon its application. The chemical behavior of Portland cement and sulfoaluminate cement mixes is then studied experimentally. The heats of hydration measured by isothermal calorimetry increase with the CSA dosage (2% to 10%) and are higher than those of cement pastes containing 100% OPC and 100% CSA. The comparison of the hydrates identified in the mix mad of 7% CSA to those present in the two other cement pastes of each cement alone shows that the presence of gypsum and lime from the Portland cement lead to a faster hydration of the ye’elimite from CSA and to an early formation of ettringite. However, the nature of hydrates is not affected. The rheological behavior, in particular the thixotropy, of the cement pastes made of Portland cement and sulfoaluminate cement (up to 10%) is then studied in function of different formulation parameters during the first hour. The increase in CSA dosage (0% to 10%) leads to an almost linear increase of the structuration coefficient (Athix) of theses mixes. For mixes with 7% CSA and 100% OPC, the influence of the W/C ratio and superplasticizer on the thixotropy is then studied. The increase in W/C ratio leads to an almost linear decrease of the Athix for each of cement paste. However, the superplasticizer present a low influence compared to the W/C ratio.

Le béton est le matériau le plus utilisé dans le monde. Son succès vient de son accessibilité et ses performances mécaniques, surtout lorsqu'il est renforcé par de l'acier. Dans le béton, l'acier doux est naturellement protégé par la formation d'une couche d'oxyde protectrice. Ceci est possible avec l'alcalinité du béton résultant de l'hydratation du ciment Portland.Cependant, la fabrication du ciment Portland est responsable de 5 à 7% des émissions anthropiques mondiales de CO2. Le développement du ciment Belite-Ye'elimite-Ferrite (BYF) comme liant alternatif est une solution prometteuse avec une diminution de 20 à 30% des émissions de CO2 par rapport à la production de ciment Portland. Les propriétés sont en cours d'évaluation et la possibilité d'utiliser l’acier doux en renfort sans corroder en fait partie.Cette thèse traite de la corrosion de l'acier incorporé dans des matériaux à base de ciment BYF sous différents angles. Tout d'abord, une étude d'hydratation détaillée a été effectuée pour comprendre l'évolution de l'électrolyte, c'est-à-dire de la solution interstitielle et de l'assemblage de phases. Ensuite, la passivation des barres d'armature d'acier ordinaire intégrées dans des mortiers renforcés a été étudiée. De plus, des analyses ont été effectuées avec des échantillons d'acier immergés dans des extraits aqueux de pâtes de ciment équivalentes pour caractériser la structure et l'épaisseur du film passif. Enfin, l'impact des chlorures initiaux sur la corrosion des mortiers renforcés a été évalué.L'hydratation a été caractérisée par plusieurs techniques, au jeune âge et pendant un an, avec des techniques telles que la calorimétrie isotherme, la spectroscopie d'émission optique par plasma à couplage inductif, la thermogravimétrie, la diffraction des rayons X et la porosimétrie par intrusion au mercure. L'évolution de l'acier dans les mortiers a été évaluée avec des techniques électrochimiques. L'applicabilité des techniques non destructives courantes (potentiel de demi-cellule, résistance à la polarisation linéaire, et l'impédance électrochimique) a été validée par des mesures de polarisation potentiodynamique large et une inspection visuelle. Le film passif formé dans des extraits aqueux des mortiers a été caractérisé par des techniques électrochimiques couplées aux mesures de spectroscopie de photoélectrons aux rayons X. Une fois que la passivation établi, l'impact des chlorures initiaux sur les mortiers renforcés a été évalué.Pour le BYF, le processus d'hydratation et les assemblages de phases hydratées sont différents du ciment Portland, mais la solution interstitielle est finalement très basique après un jour (pH de 13). La principale différence est le pH qui est inférieur (10.6) avant la prise. Les mesures ont montré que l'acier se passive avec le même niveau de protection qu’avec le ciment Portland. La différence est le temps nécessaire pour atteindre le meilleur niveau de protection (28 jours avec le ciment BYF au lieu de 7 jours avec le ciment Portland). Les échantillons d’acier immergés dans des extraits aqueux de ciment Portland et BYF après 28 jours d’hydratation ont présenté une épaisseur et une composition similaires, indiquant que le milieu BYF est aussi protecteur que celui de Portland. L'acier passive dans les mortiers BYF (E/C = 0.5) contenant 0.4% de chlorures par masse de ciment, ce qui ne remet pas en question, pour ce nouveau ciment, la limite imposée par la norme européenne EN-206 aux bétons armés. / Concrete is the most widely used material in the world. The success lies on its affordability and mechanical performance, especially when reinforced with steel. Once embedded in the concrete, mild steel is naturally protected by the formation of a protecting oxide layer. This is possible thanks to the alkalinity of the concrete which results from the hydration of the Portland cement.However, Portland cement manufacturing is responsible of about 5 to 7% of the global anthropogenic CO2 emissions. The development of Belite-Ye’elimite-Ferrite (BYF) cement as alternative binder is a promising solution with a decrease of 20 to 30% in CO2 emissions compared to Portland production. The properties are being evaluated and the possibility of using mild steel reinforcement without corroding is part of it.This thesis approaches the corrosion of steel embedded in BYF cement based materials from various angles. First, a detailed hydration study was performed to understand the evolution of the “electrolyte”, i.e. of the pore solution and of the phase assemblage. Second, the passivation of ordinary steel rebar embedded in reinforced mortars was investigated. In addition, analyzes were carried out with steel samples immersed in aqueous extracts of equivalent cement pastes to characterize the structure and the thickness of the passive film. Finally, the impact of the initial chlorides on corrosion of reinforced mortars was evaluated.The hydration was characterized by several techniques, at early-age and then over one year, with techniques such as isothermal calorimetry, inductively coupled plasma optical emission spectroscopy, thermogravimetry, X-ray diffraction and mercury intrusion porosimetry. The evolution of steel embedded in mortars was evaluated with several electrochemical techniques. The applicability of current non-destructive techniques (half-cell potential readings, linear polarization resistance and electrochemical impedance spectroscopy) has been validated by large potentiodynamic polarizations and visual inspection. The passive film formed in aqueous extracts of the mortars was characterized with electrochemical techniques coupled to X-ray photoelectron spectroscopy measurements. Once the passivation understood, the impact of the initial chlorides on the reinforced mortars was evaluated.For the BYF, the hydration process and the hydrated phase assemblages are different from Portland cement, but the interstitial solution is finally very basic after one day (pH of 13). The main difference is the pH that is lower (10.6) before setting. The measurements showed that steel was effectively passivated in BYF mortars with the same level of protection as with Portland cement. The difference between the BYF and Portland cement is the time required that to reach the greatest level of protection (28 days instead of 7 days), probably because of initial lower pH value. The steel immersed in Portland and BYF aqueous extracts obtained after 28 days of hydration exhibited similar thickness and composition of protective layer, indicating that BYF media was as protective as Portland ones. Steel passivates in BYF mortars (W/C = 0.5) containing 0.4% chlorides by cement mass which is in agreement with the limit imposed by the European Standard EN-206 to reinforced Portland concretes.