CNRS Engineering Laboratory for Mechanical and Electrical Applications Laboratory

Pau, France

CNRS Engineering Laboratory for Mechanical and Electrical Applications Laboratory

Pau, France
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Mindeguia J.-C.,University Bordeaux 5295 F 33400 Talence France | Carre H.,CNRS Engineering Laboratory for Mechanical and Electrical Applications Laboratory | Pimienta P.,University Paris Est Creteil | La Borderie C.,CNRS Engineering Laboratory for Mechanical and Electrical Applications Laboratory
Fire and Materials | Year: 2014

The behaviour of six concretes at high temperature (600°C) and in particular the risk of fire spalling is studied. Tests are performed with two sizes of samples: small samples (300×300×120mm3) and small slabs (700×600×150mm3). Different storage conditions (pre-drying at 80°C, air and water storing) are used to highlight the effect of the initial water content. Thanks to different scenarios of heating, the influence of the heating curve is studied.Results enabled to identify parameters that highly influence the risk of fire spalling: initial water content and concrete permeability during heating. The permeability of concrete can increase during heating due to the melting of the polypropylene fibres or by thermal damage. This thermal damage is important when heating is violent (ISO 834 or increased hydrocarbon fire), or when concrete is made with silico-calcareous aggregates (flint).Fire spalling cannot be explained by either the only thermo-mechanical behaviour of concrete, or only by the appearance of high pore gas pressure. Based on the recent hypothesis of the critical zone, the formation of a saturated layer of liquid water is consistent with the results obtained. © 2014 John Wiley & Sons, Ltd.


Mindeguia J.-C.,University of Bordeaux 1 | Hager I.,Cracow University of Technology | Pimienta P.,University Paris Est Creteil | Carre H.,CNRS Engineering Laboratory for Mechanical and Electrical Applications Laboratory | La Borderie C.,CNRS Engineering Laboratory for Mechanical and Electrical Applications Laboratory
Cement and Concrete Research | Year: 2013

This paper presents the results of an experimental study carried out on several concretes at temperature up to 600 C. It deals with a high temperature phenomenon of concrete, the transient thermal strain (TTS). From reviews of some experimental and numerical works on TTS, we focused our study on the influence of several parameters: load level, compressive strength, heating scenarios, and nature of the aggregates. We also present results of concrete transient mass loss and strains in the radial direction. The study is completed by an assessment of TTS in uniaxial tension and of pure cement paste in compression. The results of the study allow us to better understand the physical origins of TTS. In particular, the results are consistent with the following explanation: TTS is mainly due to the drying and dehydration of the material up to 400 C and, at higher temperatures, the increase of TTS can be explained by the thermomechanical damage of concrete. © 2013 Elsevier Ltd.


Mindeguia J.-C.,University of Bordeaux 1 | Carre H.,CNRS Engineering Laboratory for Mechanical and Electrical Applications Laboratory | Pimienta P.,University Paris Est Creteil | La Borderie C.,CNRS Engineering Laboratory for Mechanical and Electrical Applications Laboratory
Fire and Materials | Year: 2015

The behaviour of six concretes at high temperature (600 °C) and in particular the risk of fire spalling is studied. Tests are performed with two sizes of samples: small samples (300 × 300 × 120 mm3) and small slabs (700 × 600 × 150 mm3). Different storage conditions (pre-drying at 80 °C, air and water storing) are used to highlight the effect of the initial water content. Thanks to different scenarios of heating, the influence of the heating curve is studied. Results enabled to identify parameters that highly influence the risk of fire spalling: initial water content and concrete permeability during heating. The permeability of concrete can increase during heating due to the melting of the polypropylene fibres or by thermal damage. This thermal damage is important when heating is violent (ISO 834 or increased hydrocarbon fire), or when concrete is made with silico-calcareous aggregates (flint). Fire spalling cannot be explained by either the only thermo-mechanical behaviour of concrete, or only by the appearance of high pore gas pressure. Based on the recent hypothesis of the critical zone, the formation of a saturated layer of liquid water is consistent with the results obtained. Copyright © 2014 John Wiley & Sons, Ltd.


Abadie S.M.,CNRS Engineering Laboratory for Mechanical and Electrical Applications Laboratory | Harris J.C.,University of Rhode Island | Grilli S.T.,University of Rhode Island | Fabre R.,French National Center for Scientific Research
Journal of Geophysical Research: Oceans | Year: 2012

In this work, we study waves generated by the potential collapse of the west flank of the Cumbre Vieja Volcano (CVV; La Palma, Canary Island, Spain) through numerical simulations performed in two stages: (i) the initial slide motion and resulting free surface elevation are first calculated using a 3D Navier-Stokes model; (ii) generated waves are then input into a 2D (horizontal) Boussinesq model to further simulate propagation to the nearby islands. Unlike in earlier work on CVV, besides a similar extreme slide volume scenario of 450km3, in our simulations: (i) we consider several slide scenarios featuring different volumes (i.e., 20, 40, 80km3), which partly result from a geotechnical slope stability analysis; (ii) we use a more accurate bathymetry; and (iii) an incompressible version of a multiple-fluid/material Navier-Stokes model. We find wave trains for each scenario share common features in terms of wave directivity, frequency, and time evolution, but maximum elevations near CVV significantly differ, ranging from 600 to 1200m (for increasing slide volume). Additionally, our computations show that significant energy transfer from slide to waves only lasts for a short duration (order 200s), which justifies concentrating our best modeling efforts on the early slide motion phase. The anticipated consequences of such wave trains on La Palma and other Canary Islands are assessed in detail in the paper. Copyright 2012 by the American Geophysical Union.


Perlot C.,CNRS Engineering Laboratory for Mechanical and Electrical Applications Laboratory | Rougeau P.,Center Detudes Et Of Recherches Of Lindustrie Du Beton | Dehaudt S.,Center Detudes Et Of Recherches Of Lindustrie Du Beton
Cement and Concrete Composites | Year: 2013

Metakaolin improves the engineering properties of concrete because of its double effect on cementitious matrix (filler effect and pozzolanic properties). Moreover, metakaolin can reduce the environmental impact of concretes due to its lower carbon dioxide emission than clinker. The development of a slurry form of metakaolin opens new fields of investigations, such as its incorporation into self-compacting concretes (SCC). This study compares several SCC formulations that differ in their content of metakaolin and the form of metakaolin (powder or slurry). Limestone filler is included to study the benefit of employing ternary blended binder. As a main conclusion, the use of metakaolin, especially in slurry form, combined with limestone filler incorporation appears particularly suitable for SCC manufacture with high mechanical properties and durability, and very for the precast process optimization: it allows the mixing sequence to be shortened, while maintaining high workability, and more importantly the enhancement of strength at early age due to the particles deflocculating. The incorporation of metakaolin in slurry form appears particularly suitable to elaborate SCC and advantageous for precast product manufacturing as part of a sustainable development approach. © 2013 Elsevier Ltd. All rights reserved.


Medina M.M.,CNRS Engineering Laboratory for Mechanical and Electrical Applications Laboratory | Abadie S.,CNRS Engineering Laboratory for Mechanical and Electrical Applications Laboratory | Mokrani C.,Federico Santa María Technical University | Morichon D.,CNRS Engineering Laboratory for Mechanical and Electrical Applications Laboratory
Proceedings of the International Offshore and Polar Engineering Conference | Year: 2016

In this work, the impulsive stage of a wave impact on a vertical breakwater is modelled based on the analogy with a water wedge impact. Coupling between pressure along the wall and caisson displacement is neglected. The aim of the present paper is to briefly present the method and verify the uncoupling hypothesis using Navier-Stokes numerical simulations. The water wedge analogy allows us first to analyse the influence of the wedge interface inclination (45°, 60° and 80°) on the sliding. Considering an ideal case without friction and uplift force, caisson sliding motion is found to decrease with wedge angle. Conversely, the velocity acquired by the caisson increases with the wedge inclination. In the 45. case, we show that the sliding simulated with a Navier-Stokes model taking into account the flow/structure coupling is finally close to the one estimated with the analytical method developed in this study, therefore validating the decoupling hypothesis. © Copyright 2016 by the International Society of Offshore and Polar Engineers (ISOPE).


Ehtash M.,CNRS Laboratory of Chemical Process Safety | Ehtash M.,High Institute for Engineering Profession | Fournier-Salaun M.-C.,CNRS Laboratory of Chemical Process Safety | Dimitrov K.,University of Lille Nord de France | And 2 more authors.
Chemical Engineering Journal | Year: 2014

The removal of phenol from aqueous media such as wastewater, using pertraction in rotating discs contactor is investigated. Preliminary equilibrium extraction study with several organic solvents show that vegetable oils (rapeseed and sunflower oils) can substitute classically volatile organic solvents used as phenol extracting agents. Rapeseed oil allows very efficient removal of phenol from acid aqueous solutions (feed phase) to basic aqueous solution (receiving phase) during batch pertraction studies. In order to optimize operating conditions, the influence of parameters, such as rotating discs speed and initial phenol concentration in the feed phase, on phenol mass transfer is studied. The transport rate of phenol increases with increasing the rotating discs speed. The increase of feed phase phenol concentration has not influence on its transport rate. Semi-continuous pertraction process allows the concentration of phenol. © 2014 Elsevier B.V.


Gangnant A.,Institut Universitaire de France | Saliba J.,Institut Universitaire de France | La Borderie C.,CNRS Engineering Laboratory for Mechanical and Electrical Applications Laboratory | Morel S.,Institut Universitaire de France
Cement and Concrete Research | Year: 2016

The computational power allows nowadays the development of mesoscopic models of concrete, based on finite element or lattices approaches, which represent the contribution of inclusions to the behavior of concrete. However, the smallest heterogeneities are often removed to these simulations for decreasing the computation time. In this paper, the effect of aggregate classes on the fracture behavior of a plain concrete is studied. Different simulations are performed from a mesoscopic model based on a diffuse meshing technique and Fichant's damage model, in which the smallest aggregates are successively removed from the granular skeleton to the benefit of a homogenized continuous mortar. The effects of these simplifications are then evaluated by comparing the fracture behaviors obtained to the one of the reference concrete. The results show the relevance of modeling all classes of aggregates in order to obtain an accurate description of the failure behavior of concrete. © 2016 Elsevier Ltd


Abadie S.,CNRS Engineering Laboratory for Mechanical and Electrical Applications Laboratory | Mokrani C.,CNRS Engineering Laboratory for Mechanical and Electrical Applications Laboratory
Proceedings of the Coastal Engineering Conference | Year: 2012

In this paper, we study the wave impact process with a multi-fluid Navier-Stokes model (THETIS). Preliminary simulations have been conducted, first on a plunging wave generated by unstable Stokes initial condition, and second, involving a dam breaking bore impact. In both cases, a convergence study shows pressure peak results instability when using different meshes. This is due to the incapacity of the model to ensure, after a certain time of computation, the exact same surface profile at impact when simulating a specific case with different meshes. This instable numerical behavior is somehow similar to peak pressure instabilities observed in experiments. This similarity shows the critical role played by local free surface shape at impact on impulsive loads. When initializing the model with a specific interface right at impact, convergence is observed and the pressure peaks are correctly assessed by the code for moderate intensity impact. However, further improvements are still needed especially regarding the interface tracking technique to simulate the most violent impacts involving the weaker dead rise angles. The paper also encourages us to use numerical simulations preferably to study impact flow at local scale.


Perlot C.,CNRS Engineering Laboratory for Mechanical and Electrical Applications Laboratory | Carcasses M.,CNRS Materials and Construction Durability Laboratory | Verdier J.,CNRS Materials and Construction Durability Laboratory
Materials and Structures/Materiaux et Constructions | Year: 2013

Since the decalcification of cement paste has been largely reviewed, we focus our studies on the influence of aggregate nature on this phenomenon in relation to the type of cement used, Ordinary Portland Cement or blended cement with fly ash and slag. Some characteristics of similar mortar mixtures where only aggregate nature differs (lime and siliceous sand) are therefore compared for the two types of cement before and after chemical decalcification induced by ammonium nitrate attack: mechanical strength, microstructure (porosity observed by mercury intrusion and profiles of oxide content trough degraded and sound zones determined by electronic microprobe analysis), transport properties (chloride ions diffusivity, gas and water permeabilities). The characterization of sound mortars underlines that siliceous aggregates promote less porous cementitious matrix. The duplication of ammonium nitrate attacks on same material allows testing the experimental parameters governing the degradation. The flows of calcium leached, the microstructure and the evolution of transport properties with decalcification suggest that limestone aggregates are not inert material. Consequently, for the mortars incorporating siliceous sand, the cementitious matrix is more decalcified and this leads to an amplification of ionic transports, especially through blended cement paste. © 2012 RILEM.

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