Développement durable dans les infrastructures de transport

Depuis la crise climatique des années 1970 et le protocole de Kyoto en 1997, et avec la prise de conscience croissante du changement climatique, les spécialistes des infrastructures de transport ont cherché à innover afin d’économiser les ressources naturelles et de réduire la consommation d’énergie et les émissions pour la construction des chaussées

Caractérisation expérimentale du comportement à la rupture en mode I d’interfaces de chaussées

National audienceCe travail de thèse (2015-18) est inclus dans le projet ANR SolDuGri visant à étudier des solutions durables de renforcement de chaussées par l'utilisation de grilles de verre. La durabilité des chaussées ainsi renforcées dépend en partie d'un bon collage entre les différentes couches de matériaux qui les constituent. Afin d'en caractériser le collage, l'essai de fendage par coin (WST) de Tschegg (1986) et Brühwiler and Wittmann (1990) est utilisé. Il est modifié pour tester les interfaces d'éprouvettes extraites de planches d'essais in-situ. Interfaces béton/enrobé (BCMC) (0.7mm/min, T ≈ 20°C

Morphologic and genic effects of waste pollution on the reproductive physiology of Paracentrotus lividus lmk: a mesocosm experiment

: A considerable amount of coastal contamination is caused by wastes deriving from household and the degradation and the metabolism of plants and animals, even if our attention is commonly focused on industrial pollutants and contaminants. Waste pollutants are mainly represented by highly diluted soluble compounds and particles deriving from dead organisms. This complex combination, consisting of suspended particles and dissolved nutrients, has a significant impact on coastal planktonic and benthic organisms, also playing an active role in the global cycles of carbon. In addition, production practices are nowadays shifting towards recirculated aquaculture systems (RAS) and the genic responses of target organisms to the pollution deriving from animal metabolism are still scarcely addressed by scientific investigations. The reservoir of organic matter dissolved in the seawater is by far the least understood if compared to that on land, cause only a few compounds have been identified and their impacts on animals and plants are poorly understood. The tendency of these compounds to concentrate at interfaces facilitates the absorption of dissolved organic compound (DOC) onto suspended particles. Some DOC components are chemically combined with dissolved metals and form complexes, affecting the chemical properties of the seawater and the life of the coastal biota. In this research, we compared the reproductive performances of the common sea urchin Paracentrotus lividus cultured in open-cycle tanks to those cultured in a recirculating aquaculture system (RAS), where pollution progressively increased during the experiment due to animal escretions. Sea urchins were cultured for 7 months under these two conditions and their gametes were collected. Embryos resulting by in vitro fertilization were analyzed by Real Time qPCR to identify possible effects of pollution-induced stress. The fertility of sea urchins was evaluated, as well as the gonadosomatic indices and the histological features of gonads. Our results indicate that pollution due to excess of nutrients, event at sub-lethal concentrations, may hardly impact the reproductive potential of this key species and that chronic effects of stress are revealed by the analyses of survival rates and gene expression

Mode I interlaminar fracture characterization of pavements

Le remplacement des couches supérieures des chaussées bitumineuses par des couches à module plus élevé est une technique courante pour augmenter leur durée de vie et intéressante pour les adapter à de nouveaux usages. Parmi les solutions de matériaux existantes, le béton de ciment (cas ponctuel de l’urbain) ou plus communément les enrobés bitumineux renforcés par grilles sont utilisés. Savoir dimensionner ces structures multicouches complexes et s’assurer d’un bon collage de leurs couches entre elles restent actuellement deux défis majeurs. L’objectif de cette thèse est de caractériser le collage des interfaces enrobés / grille en fibre de verre à partir d’échantillons prélevés sur site réel. Un essai de rupture en mode I, dit essai de fendage par coin (WST) est choisi. La géométrie des éprouvettes est adaptée pour tester la rupture d’interfaces de tels matériaux assemblés sur une surface suffisamment importante pour comporter au moins 3x3 mailles. La technique de corrélation d’images numériques est utilisée pour suivre le décollement et sa propagation. Les essais sont réalisés en statique à vitesse constante de déplacement à l’air ambiant ou sous eau à température contrôlée. L’étude du décollement d’interfaces très résistantes à l’initiation montre la cohérence, simplicité et validité des résultats d’essais WST par rapport à ceux obtenus précédemment en laboratoire (statique, fatigue) et accéléré in situ. Les nombreux tests et différentes analyses des essais WST appliqués aux matériaux du projet ANR SolDuGri permettent de différentier de façon prometteuse la caractérisation du collage des grilles testées. Ils montrent l’intérêt de disposer d’un tel essai de laboratoire.Replacing the damaged bituminous pavement top-layers by ones with higher modulus is a common technique to extend their service life and an interesting solution to adapt roads to new uses. Among the various existing alternatives, the cement concrete (punctual case of the urban) or the most commonly one which is the reinforcement of bituminous pavement with glass fiber grid are used. Designing those complex multilayer structures and ensuring a good bonding between their layers are currently two major challenges. The objective of this thesis is to characterize the bond at the interface between asphalt layers and glass fiber grid using specimens extracted from actual field pavement. The fracture mode I test, named the Wedge Splitting Test (WST), is chosen. The geometry of the specimens is adapted in order to study the interfacial fracture behaviour of such materials assembled in a surface large enough to obtain a minimum of 3x3 meshes of the tested grids. Digital Image Correlation technique is used to monitor the debonding and its propagation. Tests are conducted under static condition with a constant imposed displacement rate at ambient air or underwater and controlled temperatures. The study of the debonding of interfaces with high resistance for the initiation shows the coherence, the simplicity and the validity of the WST results compared to those obtained previously in laboratory (static, fatigue) andin situ accelerated test. Applied to several materials of the ANR SolDuGri project, the numerous tests and various analyses of the WST allow differentiating with a promising way the bond characterization of the tested grids. They show the benefit of such a laboratory test

Caractérisation du collage des interfaces de chaussées par essais de rupture en mode I

Replacing the damaged bituminous pavement top-layers by ones with higher modulus is a common technique to extend their service life and an interesting solution to adapt roads to new uses. Among the various existing alternatives, the cement concrete (punctual case of the urban) or the most commonly one which is the reinforcement of bituminous pavement with glass fiber grid are used. Designing those complex multilayer structures and ensuring a good bonding between their layers are currently two major challenges. The objective of this thesis is to characterize the bond at the interface between asphalt layers and glass fiber grid using specimens extracted from actual field pavement. The fracture mode I test, named the Wedge Splitting Test (WST), is chosen. The geometry of the specimens is adapted in order to study the interfacial fracture behaviour of such materials assembled in a surface large enough to obtain a minimum of 3x3 meshes of the tested grids. Digital Image Correlation technique is used to monitor the debonding and its propagation. Tests are conducted under static condition with a constant imposed displacement rate at ambient air or underwater and controlled temperatures. The study of the debonding of interfaces with high resistance for the initiation shows the coherence, the simplicity and the validity of the WST results compared to those obtained previously in laboratory (static, fatigue) andin situ accelerated test. Applied to several materials of the ANR SolDuGri project, the numerous tests and various analyses of the WST allow differentiating with a promising way the bond characterization of the tested grids. They show the benefit of such a laboratory test.Le remplacement des couches supérieures des chaussées bitumineuses par des couches à module plus élevé est une technique courante pour augmenter leur durée de vie et intéressante pour les adapter à de nouveaux usages. Parmi les solutions de matériaux existantes, le béton de ciment (cas ponctuel de l’urbain) ou plus communément les enrobés bitumineux renforcés par grilles sont utilisés. Savoir dimensionner ces structures multicouches complexes et s’assurer d’un bon collage de leurs couches entre elles restent actuellement deux défis majeurs. L’objectif de cette thèse est de caractériser le collage des interfaces enrobés / grille en fibre de verre à partir d’échantillons prélevés sur site réel. Un essai de rupture en mode I, dit essai de fendage par coin (WST) est choisi. La géométrie des éprouvettes est adaptée pour tester la rupture d’interfaces de tels matériaux assemblés sur une surface suffisamment importante pour comporter au moins 3x3 mailles. La technique de corrélation d’images numériques est utilisée pour suivre le décollement et sa propagation. Les essais sont réalisés en statique à vitesse constante de déplacement à l’air ambiant ou sous eau à température contrôlée. L’étude du décollement d’interfaces très résistantes à l’initiation montre la cohérence, simplicité et validité des résultats d’essais WST par rapport à ceux obtenus précédemment en laboratoire (statique, fatigue) et accéléré in situ. Les nombreux tests et différentes analyses des essais WST appliqués aux matériaux du projet ANR SolDuGri permettent de différentier de façon prometteuse la caractérisation du collage des grilles testées. Ils montrent l’intérêt de disposer d’un tel essai de laboratoire

Experimental evaluation of the interface fracture energy for composite pavements

EATA 2017, 7th International EATA Conference, ZURICH, SUISSE, 12-/06/2017 - 14/06/2017In pavement structures, the weakest part is often the interface between the different material layers. In the present study and following many previous works, the Wedge Splitting Test (WST) is chosen as a quite convenient test method to get the fracture energy of such an interface. An adaptation of the WST equipment is proposed in this paper. The specimen is prepared with a cylindrical groove instead of a rectangular groove with the aim of testing specimens from construction sites. A slim wedge of 14° is used to assure principally the studying of the interface debonding phenomenon in a quasi-pure opening Mode I. A finite element study is conducted to analyse the effect of the variation of boundary conditions on the specimen. The main objective of this study is to compare the static testing results (under controlled displacement rate of 0.7 mm/min at ambient temperature close to 20°C) with those coming from the literature for Ultra-Thin White-topping type of bi-layer specimens

Scale-Up of an Aquaculture Plant for Reproduction and Conservation of the Sea Urchin <i>Paracentrotus lividus</i>: Development of Post-Larval Feeds

Paracentrotus lividus gonads, often referred to as “roe” or “uni” for gastronomical purposes, are among the most appreciated seafood delicacies in the Mediterranean area and worldwide. However, the increasing demand for human consumption has caused a growing pressure on its wild stocks, prompting the need to develop efficient aquaculture systems for its production. The set-up of effective feeds for various life stages and optimal procedures for breeding post-larvae and adult sea urchins still need to be improved. Here, for the first time, we aim at developing artificial feeds for the post-larvae of P. lividus because a critical step to improve our productive skills is post-larval growth. We tested various natural and prepared components to speed up the growth and enhance the survival rates of post-larvae, while taking into account the abiotic and biotic factors influencing the culture conditions in three replicate sets of tanks, characterized by different volumes. We tested formulated feeds and compared them with the effect of fresh foods in the frame of canonical culture practices. Our results indicated the efficiency of a feed composed of spirulina and Ulva rigida. Statistical analyses demonstrated the positive impact of this diet on the growth of post-larvae, behavior and survival rates. In addition, we demonstrated the efficacy of prepared feeds in the sea urchin aquaculture system, because they facilitated manipulation and control of the culture procedures for the satisfactory growth of P. lividus post-larvae

Gene Expression Detects the Factors Influencing the Reproductive Success and the Survival Rates of <i>Paracentrotus lividus</i> Offspring

The increase in the demand for Paracentrotus lividus roe, a food delicacy, causes increased pressure on its wild stocks. In this scenario, aquaculture facilities will mitigate the effects of anthropogenic pressures on the wild stocks of P. lividus. Consequently, experimental studies should be conducted to enhance techniques to improve efficient aquaculture practices for these animals. Here, we for the first time performed molecular investigations on cultured sea urchins. We aimed at understanding if maternal influences may significantly impact the life of future offspring, and how the culture conditions may impact the development and growth of cultured specimens. Our findings demonstrate that the outcomes of in vitro fertilization of P. lividus are influenced by maternal influences, but these effects are largely determined by culture conditions. In fact, twenty-three genes involved in the response to stress and skeletogenesis, whose expressions were measured by Real Time qPCR, were differently expressed in sea urchins cultured in two experimental conditions, and the results were largely modified in offspring deriving from two groups of females. The findings herein reported will be critical to develop protocols for the larval culture of the most common sea urchin, both for research and industrial production purposes for mass production

For Sustainable Reinforcements of Infrastructures with Coated Glass Fiber Grids

International audienceThe road maintenance is a shared subject of concern worldwide and needs a substantial investment. The use of glass fiber grids, for the reinforcement of bituminous pavements and the fight against the rise of cracks, is a solution used successfully and in full development for which more and more examples show very good performance after monitoring roads for many years. The SolDuGri ANR project brings together French companies, Colas, 6D Solutions and Epsilon and public researchers ICUBE/INSA, ICS, the French state laboratory IFSTTAR in order to contribute to the optimization of the choice and the use of these grids for a better efficiency. This article presents the outline of the project and the first results obtained which consist in the study and the modelling of:-The in situ damage of the grids. The mechanical properties (monotonic, elastic modulus, fatigue) of the grids, from a full scale test section, have been studied.-The effect of their presence on the bonding with the asphalt layers. Different tests characterizing the bonding and crack propagation at the interface have been developed.-The IFSTTAR fatigue test track. A full scale test with 6 different sections of grid-reinforced pavement and its modelling have been performed and modelled. Beside these tests, 4 points bending fatigue tests are launched to compare their results with the fatigue test track ones.-The recycling possibilities and the environmental influences of such products. Life cycle assessment analyses have been performed and compared to asphalt concrete based solution. All these results will help these partners to propose recommendations for a better use of glass fiber grids and a design criterion of geogrid-reinforced pavement

Spirit biel/bienne. Développement durable

Wie ein Team mit unterschiedlichen Talenten kann die BFH ihre interdisziplinäre Stärke nutzen und die Veränderung in der Gesellschaft beschleunigenComme une équipe composée de divers talents, la BFH peut user de sa force interdisciplinaire et accélérer la transformation de la société