Study of the Deterioration of Concrete Incorporating Sulfide-Bearing Aggregates

In the Trois-Rivières area (Québec, Canada), several hundred foundations of private houses, apartment and public buildings were built using concrete incorporating an anorthositic gabbro coarse aggregate containing sulfide minerals. A large number of those concrete structures developed serious deterioration within 3 to 5 years after their construction, which triggered, in many cases, their demolition/replacement. To help understanding the deterioration mechanisms and the conditions most prone to the development of premature damage, as well as quantifying the rate of deterioration, concrete blocks, 1 m x 1 m x 0.225 mm in size, were extracted from housing foundations just prior to their demolition. The blocks were disposed on an outdoor exposure site where they were monitored for the development of cracking and expansion over a five-year period. More than three hundred cores were extracted at different depths in eight housing foundations. A variety of tests including in-situ relative humidity measurements, petrographic, physical, mechanical and chemical tests on those cores were conducted for a full condition assessment of the concrete. A good correlation was observed between the monitoring of crack and the development of expansion in concrete foundation walls of different initial damage degree. Deterioration was also found to be largely influenced by the exposure conditions and RH conditions within the concrete. The determination of the total sulfur content of the concrete is a way to estimate the amount of sulfide minerals in the aggregate but significant variability was observed on values measured on different core samples from the same foundation

Attachement et fonctionnement conjugal chez les hommes consultant un service d'aide psychologique

Cette thèse de doctorat, constituée de deux articles, porte sur des facteurs liés à la détresse conjugale. Le premier article repose sur une recension des écrits et vise à enrichir la compréhension des liens qui unissent la satisfaction conjugale, l'attachement adulte, le patron de communication demande-retrait et la violence conjugale. Ces liens sont conceptualisés selon le modele vulnérabilités - stresseurs - adaptation (VSA). L'insécurité d'attachement est conçue comme une vulnérabilité personnelle qui influence l'adaptation des conjoints dans leur relation. Le patron demande-retrait et la violence conjugale formeraient des processus d'adaptation peu fonctionnels lors des conflits. Ils seraient en interaction réciproque avec la satisfaction conjugale. Le deuxième article présente les résultats d'une étude corrélationnelle effectués auprès de 55 hommes en difficultés conjugates. Les résultats montrent que l'anxiété d'abandon est liée positivement à la violence psychologique et que ce lien subit une médiation par le patron de communication demande-retrait et la satisfaction conjugale. L'anxiété est aussi liée positivement à la violence physique, où le patron demande-retrait joue également un rôle médiateur. L'évitement de l'intimité est relié directement à la violence psychologique. Les résultats montrent aussi un rôle médiateur de la satisfaction conjugale dans le lien unissant l'évitement de l'intimité à la violence psychologique, mais celui-ci disparaît lorsque la désirabilité sociale est contrôlée. La violence des hommes anxieux est interprétée comme une façon d'attirer l'attention de leur partenaire sur leurs besoins, alors que la violence psychologique serait une manière de préserver une distance chez les hommes qui présentent de l'évitement de l'intimité

The impact of active galactic nuclei and cooling mechanisms on the intra-cluster properties in the L-Galaxies semi-analytical model

The intra-cluster medium (ICM) plays a key role in galaxy formation. The cooling of hot gas and its recycling due to feedback are key parameters in understanding the regulation of star formation. Semi-analytical models (SAMs) are quick simulations that allow us to test our understanding of galaxy formation processes. Most of them produce results agreeing fairly well with various galaxy observations, however they fail in reproducing the ICM properties. In this work we focus on the active galactic nuclei (AGN) feedback and cooling mechanisms affecting the ICM, by developing new physically motivated methods that give a more accurate ICM description in the L-Galaxies SAM. We start by correcting the baryon content of each halos in the simulation. Due to halo mass fluctuations, halos ended up with an over density of baryons. This problem was resolved by introducing an extra phase for the baryons to keep track of the gas that would be considered leaving the halo (during contractions) or inflating (halo growth). Although this solution solved the baryon problems, it did not answer the question of the excess of hot gas stored inside the virial radius. We investigated different feedback mechanisms, from SNR to black holes and found that ejecting the gas with powerful AGN jets is compulsory to reduce the hot gas content of the halos. In order to reduce the gas content, a new model of AGN feedback was implemented and tuned to reproduce the observational gas fractions available in the literature. The AGN can not only now reheat cold and cooling gas, but also eject it via powerful jets. In addition to this feedback, four new black hole accretion models were compared, based on different gas reservoir. The most accurate agreement with observations for most AGN and galaxy properties came from a model where the AGN was fed by accretion of cold clouds from the ISM of the host galaxy. Finally we investigate the effect of our improved feedback on the ICM itself. In addition to the new AGN feedback, we developed a more physical cooling mechanism based on Bremsstrahlung radiation and a Beta profile of the gas. This change enabled us to give X-ray predictions for our model to compare with observational data, including the most recent XMM results. We found that the change in cooling only slightly affects the results (gas fractions, metallicities), as expected. However the X-ray luminosities of our groups and clusters of galaxies are now in agreement with observations, mainly due to the gas content reduction done by the new feedback mechanism. This new version of L-Galaxies manages to reproduce both galaxies and ICM properties in fairly good agreement with observational data

Variabilité inter-et intraspécifique de la composition chimique de la phase minérale des ciments utilisés dans la construction du tube de plusieurs polychètes bioconstructeurs

International audienceSeveral species of marine polychaetes reside in individual protective tubes. These tubes may be agglomerated in patches of varied sizes with very high densities, or form massive reef-like mounds which can be stretch over several kilometers. These polychaetes can thus be considered as the most important building organisms after corals in coastal environments. We especially focused on several species belonging to the families of Sabellariidae, Terrebeliidae and Pectinariidae. Tubes grains are glued together with biomineralized cement secreted from a building organ connected to specialized glands. Different methods of micro-analysis were used to analyze the biomineral components of these cements for four varyingly gregarious tube-building polychaetes: Lanice conchilega, Pectinaria koreni, Sabellaria alveolata and Phragmatopoma caudata. The aim of this study is to describe and compare the inter- and the intraspecific variability in the main biomineral components of cement at local, regional and continental scales. Scanning Electron Microscopy confirms an identical structure of the cement within species of Sabellariidae in Europe and America. Electron Probe Micro-Analysis (EPMA) confirms the presence of calcium, phosphorus, and magnesium plus traces of manganese in all cements, with varying concentrations of these elements at different locations for the same species or for different species at the same location. Finally, our dataset is compared with previous studies from literature

Analyse bibliométrique des publications scientifiques mondiales sur les fruits et légumes (F&L) au cours de la période 2000-2009

L'analyse du corpus des publications mondiales du Web of Science (WoS) traitant des fruits et légumes au cours de la période 2000-2009 (90 751 publications) permet de dégager les grandes tendances de la recherche mondiale sur les Fruits et Légumes (F&L). Cependant, il faut noter que l'implication des sciences économiques et sociales reste sous-estimée car ces disciplines sont mal représentées dans le WoS. La répartition globale des publications entre les légumes, les fruits ou les F&L représente respectivement 53,3 %, 43,4 % et 3,3 % du corpus. Sur la période considérée, les trois premiers pays publiant sont les Etats-Unis, l'Espagne et le Japon. L'UE 27 en tant que telle occupe toutefois la première position en nombre de publications. La Chine et le Brésil se caractérisent par une augmentation importante de leur nombre de publications au cours des dix dernières années, ce qui les positionne maintenant devant la France. La France conserve toutefois sa position au 8ème rang mondial en nombre de publications annuel entre 2000 et 2009. La comparaison du taux de croissance annuel moyen (TCAM) de la recherche sur F&L et de celui de l'ensemble du WoS a permis de constater que la recherche F&L mondiale se caractérise par un dynamisme très important. En France, le même type d'analyse montre que la recherche F&L suit la même progression que l'ensemble de la recherche française. Une part importante (39 %) des publications F&L du corpus mondial se fait dans des revues de notoriété " exceptionnelle " ou " excellente ". La recherche française, qui n'est pas spécialisée dans le domaine des F&L, publie cependant une majorité de ses travaux (55,5 %) dans ce même type de revues. En France, l'Inra occupe une place importante dans les publications nationales sur F&L puisqu'il est impliqué dans 54,2 % d'entre elles. Les publications Inra consacrées aux légumes représentent 51,1 % du corpus F&L Inra et celles sur les fruits 47 %, les 1,9 % restant sont consacrés à la fois aux fruits et aux légumes. L'Inra se caractérise aussi par le fort pourcentage de ses collaborations internationales (37,8 %). Trois centres de recherche Inra (PACA, Montpellier et Bordeaux-Aquitaine) ont publié chacun plus de 10 % du corpus. Les deux principaux départements de recherche impliqués sont Santé des Plantes et Environnement (SPE) et Génétique et Amélioration des Plantes (GAP) ; dans 27,5 % des cas, les publications relèvent de collaborations entre plusieurs départements de recherche, ce qui illustre les approches intégrées des questions scientifiques actuelles. Une analyse précise des thématiques des publications Inra a permis de dresser des profils thématiques pour les départements et pour les centres de recherche. Outre leurs thématiques propres, les départements de recherche sont impliqués dans la valorisation de travaux interdisciplinaires. Selon les centres, une ou plusieurs thématiques prédominent : par exemple, les centres d'Angers Nantes, Bordeaux Aquitaine et Rennes consacrent une part importante de leurs publications à la " Maîtrise des bio-agresseurs " alors que le centre PACA est impliqué de manière quasi équivalente dans quatre thématiques. La création d'une base de données thématique regroupant les publications F&L mondiales permet de disposer d'un outil puissant et utilisable pour de nombreuses analyses. La fiabilité de cette base a été rendue possible grâce à de nombreuses étapes de tris, d'analyse et de synthèse des résultats, ce qui a nécessité près d'un an de travail. Par ailleurs, les études bibliométriques portant sur un pas de temps d'une durée de 10 ans permettent de repérer les changements intervenus au cours de cette période : pays ou institutions émergents, thématiques ou espèces étudiées... Enfin, en disposant des données mondiales, il est aussi possible d'analyser des sous-parties du corpus de diverses importances : un continent, un pays, un consortium (ex. Agreenium) ou même une institution. Ce corpus mondial permet aussi d'apprécier finement les évolutions éventuelles des thématiques et des partenariats ainsi que les interactions entre les différents sujets étudiés. La diffusion des résultats obtenus sera réalisée via l'Internet Inra (pages consacrées au groupe Filière Fruits et Légumes) ; elle se fera aussi au travers d'une publication dans une revue scientifique à comité de lecture et d'une communication dans une revue de vulgarisation spécialisée sur les fruits et légumes. Les résultats obtenus serviront également à la rédaction de notes synthétiques, par exemple pour le futur GIS Fruits ou le GIS PIClég. En conclusion, cette étude bibliométrique constitue à notre connaissance un premier exemple d'une analyse sur 10 ans du potentiel de recherche consacré aux fruits et légumes dans le monde. Elle a permis de d'utiliser de nouveaux outils méthodologiques très performants et d'acquérir une véritable vision des évolutions des recherches dans le domaine des fruits et légumes au cours de la dernière décennie

Field and Laboratory Investigations on the Use of Fly Ash and LI-Based Admixtures to Prevent ASR in Concrete

Since the early 1990’s, CANMET (Department of Natural Resources Canada) is carrying out a comparative field and laboratory research program to investigate the efficacy of laboratory test procedures for properly predicting the long-term efficacy of supplementary cementitious materials (SCM) in controlling expansion due to alkali-silica reaction (ASR). Binary and ternary concrete systems, i.e. fly ash (Class F), lithium-based admixtures, fly ash / Li-based admixtures, were selected with a variety of alkali-silica reactive aggregates. The expansive behaviour of the various combinations listed above was investigated in the laboratory using concrete prisms stored under accelerated test conditions (38oC and 100% RH). Exposure blocks cast from the above mixtures were placed outdoors at the CANMET facilities located in Ottawa (Canada). This paper compares the results of expansion testing in the laboratory against that of exposure blocks after 15 years outdoors. The results are also analysed in view of providing recommendations for the use of such materials / combinations for the manufacture of concrete that will be at a minimum risk of developing deleterious expansion and cracking due to ASR

Tools for analyzing and mapping scholarly publications not indexed by the Web of Science: the case of fruit and vegetable publications by the French National Institute for Agricultural Research (INRA)

Publication Inra prise en compte dans l'analyse bibliométrique des publications scientifiques mondiales sur les Fruits, les Légumes et la Pomme de terre. Période 2000-2012. http://prodinra.inra.fr/record/256699Introduction. The fruit and vegetable sector group of the French National Institute for Agricultural Research (INRA) carried out a bibliometric analysis of INRA publications on fruits and vegetables produced between 2002 and 2006. While a previous study focused on scientific publications indexed by the Web of Science, this study took into account the remaining INRA publications, i.e., gray literature, technical papers and scientific papers not indexed by the Web of Science. Materials and methods. Different steps were taken to constitute and process a corpus of INRA researchers' publication data. The citation corpus gathering bibliographic data was mainly constituted using the INRA institutional repository (ProdINRA). To ensure exhaustivity, a survey was carried out to collect INRA researchers' publications. Due to the different types of publications involved, we had to develop an original method to constitute a complete database which could allow bibliometric analysis. The Sphinx Plus(2) Survey program was used to analyze publications and Pajek software was used to visualize networks. Results. A total of 2,224 publications were authored by INRA between 2002 and 2006. We analyzed the typology of fruits and vegetables studied at INRA, the INRA research centers and research divisions involved, the main research topics, and the national and international partners of INRA authors. Graphic visualizations allowed an attractive presentation of relationships between authors within and outside INRA. Conclusion. This study led to the mapping of INRA fruit and vegetable research publications. It confirmed that INRA plays an active role in the field of fruit and vegetable research. French research is carried out in the main INRA research centers located in horticultural and/or fruit regions, particularly in South-Eastern France. Despite the fact that the nature of these publications provides less opportunity for co-publication, this study highlights the relationships between INRA and French partners or foreign countries

Behavior of epoxy bonded bars in concrete affected by alkali-silica reaction

Installation of drilled-in epoxy-bonded reinforcing bars is generally an effective strengthening method to increase the flexural and shear capacities of deficient concrete structures. However, most of the available studies characterizing the bond behavior of epoxy bonded bars in concrete have been carried out on sound concrete elements—that is, without any pathological material damage. This raises the question of bond capacities in existing damaged elements. This study investigates the influence of alkali-silica reaction (ASR) on the capacity of post-installed reinforcing bars. ASR is a deleterious mechanism that causes expansion and cracking in the affected concrete elements. Pullout tests on post-installed reinforcing bars having embedded lengths of 2db, 4db, and 5db with 15M reinforcing bars (db = 15.9 mm [0.626 in.]) have demonstrated a drop-in bond strength when concrete is affected by ASR. In addition, the study revealed that the progression of concrete expansion due to ASR may lead to some confinement of the post-installed reinforcing bar and possibly increases the bond strength

Spatiotemporal and cross-scale interactions in hydroclimate variability:a case-study in France

International audienceUnderstanding how water resources vary in response to climate at different temporal and spatial scales is crucial to inform long-term management. Climate change impacts and induced trends may indeed be substantially modulated by low-frequency (multi-year) variations, whose strength varies in time and space, with large consequences for risk forecasting systems. In this study, we present a spatial classification of precipitation, temperature, and discharge variability in France, based on a fuzzy clustering and wavelet spectra of 152 near-natural watersheds between 1958 and 2008. We also explore phase–phase and phase–amplitude causal interactions between timescales of each homogeneous region. A total of three significant timescales of variability are found in precipitation, temperature, and discharge, i.e., 1, 2–4, and 5–8 years. The magnitude of these timescales of variability is, however, not constant over the different regions. For instance, southern regions are markedly different from other regions, with much lower (5–8 years) variability and much larger (2–4 years) variability. Several temporal changes in precipitation, temperature, and discharge variability are identified during the 1980s and 1990s. Notably, in the southern regions of France, we note a decrease in annual temperature variability in the mid 1990s. Investigating cross-scale interactions, our study reveals causal and bi-directional relationships between higher- and lower-frequency variability, which may feature interactions within the coupled land–ocean–atmosphere systems. Interestingly, however, even though time frequency patterns (occurrence and timing of timescales of variability) were similar between regions, cross-scale interactions are far much complex, differ between regions, and are not systematically transferred from climate (precipitation and temperature) to hydrological variability (discharge). Phase–amplitude interactions are indeed absent in discharge variability, although significant phase–amplitude interactions are found in precipitation and temperature. This suggests that watershed characteristics cancel the negative feedback systems found in precipitation and temperature. This study allows for a multi-timescale representation of hydroclimate variability in France and provides unique insight into the complex nonlinear dynamics of this variability and its predictability