References of "Courard, Luc"
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See detailLIGHTWEIGHT CEMENTITIOUS MORTAR MADE WITH FOAMED PLASTIC WASTE AGGREGATES
Coppola, Bartolomeo ULg; Di Maio, Luciano; Courard, Luc ULg et al

in Durability and Sustainability of Concrete Structures – Workshop Proceedings, Bologna 1-3 October 2015 (2015)

In recent years the increasing interest for eco-sustainable building materials and the rising issue of plastic waste disposal are leading to the engineering of new composite construction materials ... [more ▼]

In recent years the increasing interest for eco-sustainable building materials and the rising issue of plastic waste disposal are leading to the engineering of new composite construction materials incorporating post consumer recycled plastics, able at the same time to meet new standard requirements, in terms of energy efficiency, and to reduce the consumption of natural resources. In the context of these issues, we have performed investigations on the effects of the addition of foamed artificial aggregates deriving from recycled plastic materials to a cementitious mortar. For this purpose, several mortar samples containing natural sand and different amounts (10, 25 and 50 % by volume) of foamed recycled plastic wastes were produced. The foaming of the recycled plastic waste was performed in laboratory by a foam extrusion process using a blowing agent (2 wt.%). An artificial aggregates particle size distribution similar to standard sand was used. Rheological and physical properties of lightweight mortar were studied. The improved surface roughness of foamed plastic aggregates ensures a more continuous interface and the presence of surface pores provides interlocking effect with cement paste. Replacement of natural sand by artificial aggregates produces a lightweight mortar but reduces mechanical properties. [less ▲]

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See detailOn the Shape Simulation of Aggregate and Cement Particles in a DEM System
He, Huan; Stroeven, Piet; Pirard, Eric ULg et al

in Advances in Materials Science and Engineering (2015)

Aggregate occupies at least three-quarters of the volume of concrete, so its impact on concrete’s properties is significant. Both size and shape of aggregate influence workability, mechanical properties ... [more ▼]

Aggregate occupies at least three-quarters of the volume of concrete, so its impact on concrete’s properties is significant. Both size and shape of aggregate influence workability, mechanical properties, and durability of concrete. On the other hand, the shape of cement particles plays also an important role in the hydration process due to surface dissolution in the hardening process. Additionally, grain dispersion, shape, and size govern the pore percolation process that is of crucial importance for concrete durability. Discrete element modeling (DEM) is commonly employed for simulation of concrete structure. To be able to do so, the assessed grain shape should be implemented. The approaches for aggregate and cement structure simulation by a concurrent algorithm-based DEM system are discussed in this paper. Both aggregate and cement grains were experimentally analyzed by X-ray tomography method recently. The results provide a real experimental database, for example, surface area versus volume distribution, for simulation of particles in concrete technology. Optimum solutions are obtained by different simplified shapes proposed for aggregate and cement, respectively. In this way, more reliable concepts for aggregate structure and fresh cement paste can be simulated by a DEM system. [less ▲]

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See detailFundamental approach for the concept of concrete repair compatibility
Courard, Luc ULg; Bissonnette, Benoît; Garbacz, Andrzej

in Dehn, Frank (Ed.) Concrete Repair, Rehabilitation and Retrofitting IV (2015)

Before being translated in terms of physical, mechanical and chemical of materials, the initial step for evaluating compatibility is interface creation. The thermodynamic properties of the materials as ... [more ▼]

Before being translated in terms of physical, mechanical and chemical of materials, the initial step for evaluating compatibility is interface creation. The thermodynamic properties of the materials as well as transport mechanisms – diffusion, capillary succion – at the interface and roughness of the concrete substrate are acting from the beginning and influencing the durability of the bond strength. A review of the main parameters influencing bond development is presented on the base of the equilibrium of the surface free ener-gies of liquid and solid, applied to the concept of repair mortars, coating and hydrophobic treatments [less ▲]

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See detailA repair quality control with elastic waves based methods vs. substrate quality
Garbacz, Andrzej; Piotrowski, Tomasz; Courard, Luc ULg et al

in Dehn; Beushausen, Hans (Eds.) Concrete Repair, Rehabilitation and Retrofitting IV (2015)

An adhesion in repair system is one of the most important factors that affect the repair efficiency. The elaboration of reliable nondestructive method for an adhesion mapping is one of the most important ... [more ▼]

An adhesion in repair system is one of the most important factors that affect the repair efficiency. The elaboration of reliable nondestructive method for an adhesion mapping is one of the most important tasks. A majority of NDT methods mentioned in EN 1504-10 and ACI Concrete Repair Manual for assessment of concrete structures are based on propagation of stress waves. However, these investigations are rarely focused on evaluation of bond strength. Repair system is difficult to test with NDT methods because of many factors influencing stress wave propagation. In this paper the effect of a quality of concrete substrate on propagation of stress waves in repair system and their influence on possibility of estimation of the bond strength is discussed. [less ▲]

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See detailA quantitative approach to the concept of concrete repair compatibility
Bissonnette, Benoît; Modjabi-Sangnier, François; Courard, Luc ULg et al

in Dehn, Frank; Beushausen, Hans (Eds.) Concrete Repair, Rehabilitation and Retrofitting IV (2015)

The work reported in this paper is part of a wider research program intended to provide the repair industry with improved fundamental knowledge to implement rational design methods and rules for repairs ... [more ▼]

The work reported in this paper is part of a wider research program intended to provide the repair industry with improved fundamental knowledge to implement rational design methods and rules for repairs. In that regard, there is a strong need to study the fundamental relationships and parameters that underlie the repair compatibility concepts, in particular those relating to dimensional compatibility. In the first part of the paper, classical formulas derived for thick cylindrical specimens were used to analyze the tensile stress buildup in annular restrained shrinkage test specimens, taking into account the restraining conditions the investigated ring test method and the individual concrete properties/phenomena determined experimentally (elastic modulus, creep coefficient, drying shrinkage deformation). By comparing the ring test results with the calculated tensile stresses, the validity and accuracy of the theoretical approach could be appraised. A quantitative approach for the evaluation of the performance of concrete repair in terms of dimensional compatibility was then developed. Derived from the basic strain balance approach (ratio between the total deformability in tension and the drying shrinkage deformation), a parameter referred to as dimensional compatibility index (CI) was introduced in order to analyze the evolution of dimensional compatibility as a function of time for a given concrete mixture, taking into account the actual degree of restraint in the element. Compatibility index evolution curves were calculated for various repair concrete mixtures in order to highlight material behavior relating to composition parameters and temperature. As it requires the evaluation of a limited number of individual properties that are for most readily available (i.e. strength, elastic modulus, shrinkage), the compatibility index expressed in terms of deformation carries a lot of potential as a relatively simple and convenient analytical tool for assessing the cracking sensitivity of concrete repair materials. Overall, it can be stated that a good correlation was found between the ring test results and the tensile stress values calculated based on individual concrete properties / phenomena and that the proposed calculation method lays ground for evaluating quantitatively the dimensional compatibility of repair materials and defining suitable performance criteria. [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 (2015), 48(11), 3687-3701

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 (2015), 48(11), 3675-3686

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 detailEvaluation of the durability of hydrophobic treatments on concrete architectural heritage
Lucquiaud, Vincent ULg; Courard, Luc ULg; Gérard, Olivier et al

in Restoration of Buildings and Monuments = Bauinstandsetzen und Baudenkmalpflege (2014), 20(6), 395404

The protection of historical concrete structures is a challenge for the coming years. Hydrophobic treatment may reduce the deterioration process while providing protection against water penetration ... [more ▼]

The protection of historical concrete structures is a challenge for the coming years. Hydrophobic treatment may reduce the deterioration process while providing protection against water penetration. Existing commercial products —mainly silane or siloxane in either water or solvent based formulations– were submitted to different ageing processes including UV radiation, dry-wet cycles, thermal shocks, freeze-thaw cycles, carbonation and their effectiveness has been evaluated on the basis of contact angle, vapour and chloride permeability and, capillarity water absorption. The results obtained clearly show that hydrophobic treatments display a good behaviour under the main ageing conditions. [less ▲]

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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 detailEffect of misalignment on pulloff test results: numerical and experimental assessments
Courard, Luc ULg; Bissonnette, Benoît; Garbacz, Andrzej et al

in ACI Materials Journal (2014), 111(2), 153-162

The successful application of a concrete repair system is often evaluated through pull-off testing. For such in-situ quality control (QC) testing, the inherent risk of misalignment might affect the ... [more ▼]

The successful application of a concrete repair system is often evaluated through pull-off testing. For such in-situ quality control (QC) testing, the inherent risk of misalignment might affect the recorded value and eventually make a difference in the acceptance of the work. So far, the issue of eccentricity in pull-off testing has been ignored in field practice, because it is seen as an academic issue. This paper presents the results of a project intended to quantify the effect of misalignment on pull-off tensile strength evaluation and provide a basis for improving QC specifications if necessary. The test program consisted first in an analytical evaluation of the problem through 2-D FEM simulations and, in a second phase, in laboratory experiments in which the test variables were the misalignment angle (0°, 2° and 4°) and the coring depth (15 mm [1.18 in.], 30 mm [2.36 in.]). It was found that calculations provide a conservative but realistic lower bound limit for evaluation the influence of misalignment upon pull-off test results: a 2° misalignment can be expect to yield a pull-off strength reduction of 7 to 9 % respectively for 15-mm [1.18-in.] and 30-mm [2.36-in.] coring depths, and the corresponding decrease resulting from a 4° misalignment reach between 13 and 16%; From a practical standpoint, the results generated in this study indicate that when specifying a pull-off strength limit in the field, the value should be increased (probable order of magnitude: 15%) to take into account the potential reduction due to testing misalignment. [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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