References of "Courard, Luc"
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See detailRessources secondaires et matériaux bio-sourcés: complémentarité pour une construction durable
Courard, Luc ULg

Scientific conference (2014, November 06)

Le recyclage n'est pas un luxe ou une mode mais une nécessité, qui provient d'une constatation fort simple : nous vivons dans un monde limité. Contrairement à ce que nous avons cru fort longtemps, notre ... [more ▼]

Le recyclage n'est pas un luxe ou une mode mais une nécessité, qui provient d'une constatation fort simple : nous vivons dans un monde limité. Contrairement à ce que nous avons cru fort longtemps, notre activité humaine n'est pas infiniment développable, car bornée en termes d'énergie, de ressources naturelles, d'espace ou simplement de capacité d'adaptation de la nature. De cette constatation et de cette prise de conscience doit découler un comportement qui, essentiellement, est basé sur le respect que nous avons de nous-mêmes et donc de la nature (à ménager et non à aménager). Le recyclage, la réutilisation, le réemploi, la régénération ou la valorisation sont des comportements qui visent à minimiser l'énergie utilisée, à tirer un parti maximum des matériaux, à réduire les risques de pollution au moment de la fabrication, de l'utilisation ou de l'élimination de ces matériaux. D'une manière générale, cela signifie que l'on cherche à retarder le plus possible le moment où un objet devient un déchet. Cette démarche nécessite une vision d'ensemble de la vie du matériau ou de l'objet (Analyse du Cycle de Vie), au cours de laquelle un bilan est établi à chaque étape de vie - extraction des matières premières, fabrication, transformation, recyclage, élimination. Complémentairement aux matériaux dits « naturels » ou d’origine végétale, l’industrie de la construction intègre de plus en plus ces matériaux alternatifs, non sans quelques réticences psychologiques, normatives et techniques. Source de pollution importante (CO2, déchets solides, ..), la construction constitue aussi un réservoir majeur pour la valorisation de déchets et de sous-produits industriels : à côté de la filière traditionnelle de production des matériaux de construction et de la résurgence des matériaux bio-sourcés, les matériaux recyclés contribuent également au développement des matériaux du futur. [less ▲]

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See detailWhy and how to repair concrete? Compatibility assessment
Courard, Luc ULg

Scientific conference (2014, October 27)

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See detailEffects of the presence of free lime nodules into concrete: experimentation and modelling
Courard, Luc ULg; Degée, Hervé ULg; Darimont, Anne ULg

in Cement and Concrete Research (2014), 64

When nodules of lime are embedded into concrete, the expansion accompanying the transformation of CaO into Ca(OH)2 induces stresses and strains in both the lime nodule and in the concrete matrix. The ... [more ▼]

When nodules of lime are embedded into concrete, the expansion accompanying the transformation of CaO into Ca(OH)2 induces stresses and strains in both the lime nodule and in the concrete matrix. The concrete cover thickness, the diameter and the shape of the lime nodule as well as the mechanical characteristics of concrete and lime are the key parameters influencing the development of internal pressure and hence controlling the risk of cracking or pop-out. In order to study the effect of lime into cementitious concretes, laboratory investigations and modelling have been performed and show that the minimum cover thickness necessary to avoid the development of the pop-out phenomenon is estimated of the order of half the diameter of the inclusion. This is coming from the observation that expansion happens inside the porosity of the hydrated lime Ca(OH)2: ESEM and DRX analysis confirm the effect of confinement in the development of crystals. [less ▲]

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See detailMatériaux du futur: ressources naturelles ou secondaires?
Courard, Luc ULg

Scientific conference (2014, August 26)

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See detailDurabilité des ciments ternaires à base de laitier vis-à-vis des attaques sulfatiques
Rondeux, Mélanie ULg; Courard, Luc ULg; Michel, Frédéric et al

Scientific conference (2014, July 03)

Depuis plusieurs années, des recherches sont effectuées afin de substituer une partie du clinker, composant principal du ciment Portland, dont la production libère des quantités importantes de CO2, par ... [more ▼]

Depuis plusieurs années, des recherches sont effectuées afin de substituer une partie du clinker, composant principal du ciment Portland, dont la production libère des quantités importantes de CO2, par les laitiers de haut-fourneau, les cendres volantes et/ou les fillers calcaires. Dans le projet CEMCALC I, la possibilité de remplacer une partie de ce clinker par du laitier de haut fourneau et du filler calcaire a été étudiée. Plusieurs compositions de ciment ternaire (clinker, laitier, filler) ont été étudiées, notamment vis-à-vis des attaques sulfatiques à 5°C. Des mesures de module d’élasticité dynamique, de vitesse sonore, ainsi que des analyses DRX et des observations au MEB ont été réalisées. Les ciments montrant la meilleure résistance aux attaques sulfatiques à 5°C sont ceux qui contiennent le plus de laitier. Les phases responsables de la dégradation des éprouvettes sont les croûtes secondaires de gypse, ainsi qu’une solution solide composée d’ettringite et de thaumasite. [less ▲]

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See detailConcrete Surface Engineering for Cultural Heritage
Courard, Luc ULg

Scientific conference (2014, June)

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See detailPathologies des bétons: causes et effets
Courard, Luc ULg

in Evaluation des structures en béton (2014, February 20)

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See detailDétermination des propriétés de couches dans le béton à l'aide d'un géoradar commercial à hautes fréquences: approche pic-à-pic et analyse fréquentielle du coefficient de réflexion
Van der Wielen, Audrey ULg; Nguyen, Frédéric ULg; Courard, Luc ULg

in Annales du Bâtiment et des Travaux Publics (2014)

The Ground Penetrating Radar (GPR) is an efficient tool for the non-destructive inspection of concrete structures. It is widely used for the detection of rebars or humid zones or for evaluating the ... [more ▼]

The Ground Penetrating Radar (GPR) is an efficient tool for the non-destructive inspection of concrete structures. It is widely used for the detection of rebars or humid zones or for evaluating the thickness of elements. But when an element contains a thin layer, the radar waves are submitted to multiple reflections on the interfaces and the layer appears in the radargram as a single reflection, whose detailed analysis can allow determining the thickness and the permittivity of the thin layer. Two approaches were considered in this paper. In the first one, the analysis is based on the peak-to-peak reflection amplitude. The second approach uses a frequency analysis of the reflection coefficient, whose amplitude and phase can then be calculated for several frequencies. With this method, the thickness and permittivity of the layer can in theory be simultaneously determined. Both methods were numerically validated through finite difference simulations and experimentally tested on concrete samples containing an air layer of variable thickness. We showed that the frequency analysis allowed to reach a higher precision in the parameters estimation for a limited additional computing cost. The method efficiency depends on the conditions and is optimal for layers with a high permittivity presenting a large contrast with the matrix. [less ▲]

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See detailLimestone fillers cement-based composites: effects of blast furnace slags on fresh and hardened properties
Courard, Luc ULg; Michel, Frédéric ULg

in Construction and Building Materials (2014), 51

Limestone filler is a raw material that is already used in several applications like paints, bricks, bituminous mixtures…etc. Moreover, and particularly in Belgium, classical additions for concrete like ... [more ▼]

Limestone filler is a raw material that is already used in several applications like paints, bricks, bituminous mixtures…etc. Moreover, and particularly in Belgium, classical additions for concrete like fly ashes and granulated blast furnace slags are becoming rare; there is a need for new additions that could have a positive effect on the properties of the fresh and hardened cementitous composites. Substitution of limestone filler in Portland cement and Granulated blast furnace slag cement has been realized between 15 and 27 % in mass. In addition to the characterization of the powder itself – specific mass, specific surface and laser granulometry – the problem of the water demand has been analysed: it seems that it remains constant with the substitution rate. Electric conductivity has also been performed in order to study the evolution of the “dormant” period. Tests on hardened mortars were performed with regard to mechanical properties and evolution of the porosity. Test results indicate that the porosity seems to be finer in the case of granulated blast furnace slags cements, partially due to a very low diameter of the slags particles. Oxygen permeability doesn’t seem to be influenced by the filler while capillary absorption increases with substitution rate. Finally, carbonation rate, sulphate resistance and chloride penetration show quite interesting behaviours, leading to the conclusion that limestone fillers maybe a good substitution material. [less ▲]

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See detailEffects of limestone fillers on surface free energy and electrical conductivity of the interstitial solution of cement mixes
Courard, Luc ULg; Michel, Frédéric ULg; Perkowicz, Sylwia et al

in Cement and Concrete Composites (2014), 45

Most of concrete formulations actually contain mineral additives that are used as an inert filler or supplementary cementitious material (as type II addition). These materials are generally used in order ... [more ▼]

Most of concrete formulations actually contain mineral additives that are used as an inert filler or supplementary cementitious material (as type II addition). These materials are generally used in order to increase concrete performances both in its fresh and hardened states. The mineral additives usually improve the consistency and workability of fresh concrete and reduce the water demand for a required concrete slump because of an additional volume of fines. The way of action depends on the physical and chemical characteristics of fillers. The study of surface free energies and electric conductivities of interstitial solutions of cement mixes modified by blast furnace slags and limestone fillers contributes to a better knowledge of hardening and interaction process. [less ▲]

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See detailDetermination of Particle Size, Surface Area, and Shape of Supplementary Cementitious Materials by Using Different Techniques
Arvaniti, Eleni; Juenger, Maria; Bernal, Susan et al

in Materials and Structures (2014)

The particle size distribution, surface area and shape are fundamental characteristics of supplementary cementitious materials (SCMs). Accurate measurement of these properties is required in computational ... [more ▼]

The particle size distribution, surface area and shape are fundamental characteristics of supplementary cementitious materials (SCMs). Accurate measurement of these properties is required in computational efforts to model the hydration process, and the characterization of these parameters is also an important practical issue during the production and use of blended cements. Since there are no standard procedures specifically for the determination of physical properties of SCMs, the techniques that are currently used for characterizing Portland cement are applied to SCMs. Based on the fact that most of the techniques have been developed to measure cements, limitations occur when these methods are used for other materials than cement, particularly when these have lower fineness and different particle shape and mineralogical composition. Here, samples of fly ash, granulated blast furnace slag and silica fume were tested. Different results obtained using several methods for the determination of specific surface area are presented. Recommendations for testing SCMs using air permeability, sieving, laser diffraction, BET, image analysis and MIP are provided, which represent an output from the work of the RILEM Technical Committee on Hydration and Microstructure of Concrete with Supplementary Cementitious Materials (TC-238-SCM). [less ▲]

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See detailPhysical Characterization Methods for Supplementary Cementitious Materials.
Arvaniti, Eleni; Juenger, Maria; Bernal, Susan et al

in Materials and Structures (2014)

The main supplementary cementitious materials (SCMs) that are used today are industrial by-products. In most cases the quality of these materials cannot be controlled during their production, resulting in ... [more ▼]

The main supplementary cementitious materials (SCMs) that are used today are industrial by-products. In most cases the quality of these materials cannot be controlled during their production, resulting in materials with varied characteristics. The adequate physical characterization of SCMs is important to better predict their performance and optimize their use in concretes production. There are standardized methods used to determine the particle characteristics for Portland cements that are usually adopted to characterize SCMs; however, these methods may not be as accurate when applied to SCMs. This paper is an overview of the techniques that are currently used for the determination of the density, particle size distribution, surface area and shape of SCMs. The main principles of each method are presented. The limitations that occur for the SCMs measurements are also discussed. This paper is an output from the work of the RILEM Technical Committee on Hydration and Microstructure of Concrete with Supplementary Cementitious Materials (TC-238-SCM). [less ▲]

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See detailConcrete repair bond: evaluation and factors of influence
Bissonnette, Benoît; Courard, Luc ULg; Garbacz, Andrzej et al

in Grantham, Michael; Basheer, Muhammed; Magee, Bryan (Eds.) et al Proceedings of the 5th International Conference on Concrete Repair (2014)

Repair and strengthening of existing concrete structures are among the biggest challenges civil engineers are facing today and will have to face in the years to come. Present concerns of sustainable ... [more ▼]

Repair and strengthening of existing concrete structures are among the biggest challenges civil engineers are facing today and will have to face in the years to come. Present concerns of sustainable development emphasizing repair instead of new construction will only strengthen this trend. Concerted efforts towards improving the durability of concrete repairs are still needed from scientists and engineers. One of the critical aspects of durability of concrete repairs and overlays is lasting and sufficient interfacial bond between repair material and existing concrete substrate. This paper summarizes some of the findings of a collaborative study devoted to the most significant factors influencing bond in repairs (roughness, degree of saturation and carbonation of the substrate) and its field evaluation (type of loading, device misalignment). Based on the test results collected in different test programs, guideline-type recommendations for surface preparation prior to repair were issued. [less ▲]

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See detailEvaluation of the mechanical integrity of a concrete surface by means of combined destructive methods
Courard, Luc ULg; Bissonnette, Benoît; Garbacz, Andrzej et al

in Grantham, Michael; Basheer, Muhammed; Magee, Bryan (Eds.) et al Proceedings of Concrete Solutions (2014)

As a tight bond between the repair and the old concrete is required, the soundness of the prepared surface has to be carefully assessed. This paper presents the results of an investigation intended to ... [more ▼]

As a tight bond between the repair and the old concrete is required, the soundness of the prepared surface has to be carefully assessed. This paper presents the results of an investigation intended to assess and compare quantitatively different test methods, namely the Schmidt rebound hammer, the pull-out test and the pull-off test, to evaluate superficial mechanical integrity of a substrate after concrete removal operations. Although it does not yield a precise evaluation of compressive strength, the Schmidt rebound hammer test is recognized as a useful tool for performing quick surveys to assess concrete uniformity. The pull-off test is very well correlated with the splitting-tensile test, but it is not suited for vertical and overhead surfaces. The Capo pull-out test has limited interest for surface preparation, as it is applicable to flat surfaces only. Conversely, the accelerated pull-out test showed interesting potential as a simple and relatively rapid means for assessing the mechanical integrity of a concrete surface prior to repair for any type of concrete surface. It appears from the results generated in this study that the combination Schmidt hammer / pull-off test could fill the needs for the evaluation of horizontal surfaces after concrete removal, while the combination Schmidt hammer / accelerated pull-out test could be used effectively on vertical and overhead surfaces. [less ▲]

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See detailAdhérence des réparations en béton: évaluation et facteurs d'influence
Bissonnette, Benoït; Courard, Luc ULg; Jolin, Marc et al

in Damidot, Denis (Ed.) Actes de la 15ème édition des journées scientifiques (2014)

La réparation et le renforcement des structures existantes en béton comptent parmi les plus importants défis auxquels les ingénieurs civils sont confrontés aujourd’hui et qu’ils devront relever dans les ... [more ▼]

La réparation et le renforcement des structures existantes en béton comptent parmi les plus importants défis auxquels les ingénieurs civils sont confrontés aujourd’hui et qu’ils devront relever dans les années à venir. Les préoccupations actuelles concernant le développement durable favorisent la réfection au détriment de la construction neuve et ne peuvent que renforcer cette tendance. Des efforts concertés de la part des scientifiques et ingénieurs sont encore nécessaires afin d’améliorer la conception des réparations en béton et d’en assurer la qualité et la fiabilité attendues. L’un des aspects essentiels de la durabilité des réparations en béton et des revêtements ou traitements de surface est la qualité de l’adhérence entre le matériau de réparation et le béton existant. Le présent article résume les principales conclusions de travaux réalisés en collaboration en vue d’identifier les facteurs influençant l’adhérence des réparations (la rugosité, le degré de saturation et la carbonatation du substrat) et l’évaluation de celle-ci en conditions in situ (type de chargement, alignement de l’appareil). Sur la base des résultats recueillis, des recommandations concernant la préparation de la surface avant réparation ont été émises dans un guide du USBR aux États-Unis. [less ▲]

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See detailPatch repair: compatibility issues
Garbacz, Andrzej; Courard, Luc ULg; Bissonnette, Benoît et al

in Grantham, Michael; Basheer, Muhammed; Magee, Bryan (Eds.) et al Proceedings of the 5th International Conference on Concrete Repair (2014)

Repair of any concrete structure results in formation of complex, at least two-component repair systems. Compatibility approach is treated as a basic requirement during selection of repair material ... [more ▼]

Repair of any concrete structure results in formation of complex, at least two-component repair systems. Compatibility approach is treated as a basic requirement during selection of repair material. Recently, the understanding for compatibility requirements in repair systems approach is demonstrated in many papers. The aim of this paper is analyzing the compatibility between repair materials and concrete substrate in the case of patch repair. The compatibility issues were discussed in light of the various requirements which determine the mathematical space of loads, including chemical, mechanical and other physical (mainly thermal) loads. N-dimensional compatibility space is created, taking into account selected patch material control parameters. The requirements for good compatibility between repair material and concrete substrate can be formulated by using mathematical inequalities, where the variables are the material control parameters. The effects of properties of the both repair material and concrete substrate were analyzed using computer system ANCOMP developed at Warsaw University of Technology. Usability of this approach was demonstrated using selected case study as an example. [less ▲]

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See detailEtude de la durabilité des hydrofuges de surface pour la conservation du patrimoine en béton
Lucquiaud, Vincent ULg; Courard, Luc ULg

Poster (2014)

La protection du patrimoine historique en béton est un challenge pour les années futures. Un traitement hydrofuge retarde l’apparition de pathologies du béton et apporte une protection contre la ... [more ▼]

La protection du patrimoine historique en béton est un challenge pour les années futures. Un traitement hydrofuge retarde l’apparition de pathologies du béton et apporte une protection contre la pénétration de l’eau. Les produits existants - essentiellement du silane et siloxane base - ont été soumis à différents processus de vieillissement, tels que la carbonatation accélérée, des rayons UV, des cycles d'humidification, des chocs thermiques, et des cycles de gel-dégel. Leur efficacité a été évaluée suivant la mesure de l’angle de contact, leur perméabilité à la vapeur d’eau et aux chlorures et leur absorption capillaire. Les résultats de l’étude montre un bon comportement de ces produits aux les principaux vieillissements étudiés. [less ▲]

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See detailDurability of hydrophobic treatments on concrete monuments
Courard, Luc ULg; Lucquiaud, Vincent ULg; Gérard, Olivier et al

in Proceedings of 7th International Conference on Water Repellent Treatment and Protective Surface Technology for Building Materials (2014)

The protection of concrete historical structures is a challenge for the coming years. Hydrophobic treatment may induce a delay in degradations progress as well as a protection against water penetration ... [more ▼]

The protection of concrete historical structures is a challenge for the coming years. Hydrophobic treatment may induce a delay in degradations progress as well as a protection against water penetration. Existing products - mainly silane and siloxane based – have been submitted to different ageing processes including UV radiation, moistening cycles, thermal shocks, freeze-thaw cycles, carbonation and efficiency has been evaluated on the base of contact angle, vapour and chloride permeability and, capillarity absorption. Investigation results clearly show a good behaviour of hydrophobic treatments under main ageing conditions. [less ▲]

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See detailArgile, miscanthus et autres matériaux bio-sourcés
Grigoletto, Sophie ULg; Courard, Luc ULg

Scientific conference (2014)

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See detailDetection of near-field, low permittivity layers with Ground Penetrating Radar: analytical estimation of the reflection coefficient
Van der Wielen, Audrey; Courard, Luc ULg; Nguyen, Frédéric ULg

in LAMBOT, Sébastien (Ed.) Proceedings of 15th International Conference on ground Penetrating Radar (2014)

The reflection coefficient of GPR waves encountering embedded thin layers is commonly estimated using a plane wave, far field approximation. But when the thin layer is situated in the near field of the ... [more ▼]

The reflection coefficient of GPR waves encountering embedded thin layers is commonly estimated using a plane wave, far field approximation. But when the thin layer is situated in the near field of the antenna, the spherical nature of the waves and the possible propagation of a lateral wave into the layer may have a strong influence on the measured reflected amplitude. In this work, we studied through 2D FDTD simulations the behavior of a radar wave interacting with thin layers of different thicknesses. The snapshots and radargrams showed a large influence of the layer thickness on the wave propagation. For the very thin layers, the evanescent wave plays a major role and the plane wave approximation gives a good estimation of the reflection coefficient. For thicker layers, the specific inclination of each multiple reflection has to be taken into account, as well as the lateral wave propagation. On the basis of these observations, we determined which analytical method should be used for the analytical prediction of the reflection coefficient, as a function of the layer thickness. [less ▲]

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