References of "Courard, Luc"
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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 detailNanocomposite fiber reinforced mortars
Coppola, Bartolomeo; Di Maio, Luciano; Courard, Luc ULg et al

in Proceedings of the International Conference on Composites/Nano Engineering (2014)

The use of fibers to reinforce a brittle material is an extensively studied application. In the field of cementitious materials a wide range of fibers have been investigated, from natural to synthetic ... [more ▼]

The use of fibers to reinforce a brittle material is an extensively studied application. In the field of cementitious materials a wide range of fibers have been investigated, from natural to synthetic fiber (wood, cellulose, carbon, glass, polypropylene) in order to achieve several purposes. Nowadays there is a continuing effort to take advantage of recent advances in nanotechnology, in the polymer and fiber industry. Nanoclays are some of the most affordable materials that have shown promising results in nanocomposite polymers. They are characterized by a “platelet” structure with average dimension of 1 nm thick and 70 to 150 nm wide. This work is aimed at studying the different behavior of fiber reinforced mortars, containing nanocomposite polymeric fibers. [less ▲]

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See detailParticle size distribution of limestone fillers: granulometry and specific surface area investigations
Courard, Luc ULg; Michel, Frédéric ULg

in Particulate Science and Technology (2014), 32(4),

Mineral fillers can be defined as “inert materials included in a mix design for some useful purpose”. They can be added to compounds in order to complete a large variety of final properties without ... [more ▼]

Mineral fillers can be defined as “inert materials included in a mix design for some useful purpose”. They can be added to compounds in order to complete a large variety of final properties without increasing costs or to improve specific characteristics like hardness, brittleness, impact strength, compressive strength, softening point, fire resistance, surface texture, electrical conductivity, …etc. In Belgium, locally available limestone fillers are specifically very well-adapted for the optimisation of particle packing and flow behaviour of cementitious pastes in concrete mixes. Limestone fillers may be easily characterized in terms of chemical and mineralogical properties. These properties are fundamental for the study of the behaviour of concrete mixes in fresh state and for understanding interactions existing at the level of the Interfacial Transition Zone between aggregates and cement paste. These properties are however insufficiently discriminant and particle size, as well as shape distribution, seem to have a potential influence on physical phenomena which happen during the setting process. The aim of this paper is to compare five major techniques used to quantify the size and the shape of limestone fillers particles: laser diffraction scattering, wet sieving and image analysis for particle size measurement and BET adsorption and Blaine permeability methods for specific surface area. [less ▲]

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

in ACI Materials Journal (2014), 111

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 detailNear-to-Surface properties affecting bond strength in concrete repair
Courard, Luc ULg; Piotrowski, Tomasz; Garbacz, Andrzej

in Cement and Concrete Composites (2014), 46

One of the main processes for repairing concrete structures is patch repair. Efficiency and durability of a repaired system depends on the bond between concrete substrate and repair material. By ... [more ▼]

One of the main processes for repairing concrete structures is patch repair. Efficiency and durability of a repaired system depends on the bond between concrete substrate and repair material. By increasing the surface roughness, the surface treatment of concrete substrate can promote mechanical interlocking that is one of the basic mechanisms of adhesion. Nevertheless, some problems may arise from “co-lateral” effects of the treatment, especially due to the development of microcracks inside the substrate. In the presented paper, the effect of concrete substrate surface preparation has been characterized by roughness measurement, description of microcracking in the near-to-surface layer and a pull-off cohesion test. After repair, pull-off bond strength has been evaluated. It is concluded that selection of a suitable surface treatment technique should be preceded by the analysis of its aggressiveness in relation to the concrete substrate strength. A procedure for bond strength estimation using multiple regression approach, based on parameters describing surface quality really generated from various roughening techniques, is then proposed. [less ▲]

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See detailRecycling and sustainable development
Courard, Luc ULg

Scientific conference (2013, December 17)

Conditions for developing recycling in good conditions (environmental, economical and social)

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See detailDe l’expérimentation à la modélisation des propriétés hygrothermiques de parois isolées en paille
Louis, Arnaud ULg; Evrard, Arnaud; Courard, Luc ULg et al

in Annales du Bâtiment et des Travaux Publics (2013)

Some results of aPROpaille project are presented. The goal of this project is to improve the knowledge about hygrothermal performances of walls in which thermal insulation is mainly provided by straw ... [more ▼]

Some results of aPROpaille project are presented. The goal of this project is to improve the knowledge about hygrothermal performances of walls in which thermal insulation is mainly provided by straw. Besides an overall characterization of straw properties and two types of earth plaster, a series of tests was performed to determine the hygrothermal properties of these materials: porosity, sorption curve, water vapour diffusion, capillary absorption, total water absorption, specific heat and thermal conductivity. The determination of these parameters required sometimes the implementation of unusual protocols or unreleased materials. Numerical simulations based on the properties defined in the test campaign are also presented. Results clearly point out the influence of the type of plaster and the orientation of fibres into straw bale. [less ▲]

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See detailDe l’expérimentation à la modélisation des propriétés hygrothermiques de parois isolées en paille
Louis, Arnaud ULg; Evrard, Arnaud; Biot, Benjamin et al

Conference (2013, May 31)

First results of aPROpaille project are presented. The goal of this project is to improve the knowledge about hygrothermal performances of walls in which thermal insulation is mainly provided by straw ... [more ▼]

First results of aPROpaille project are presented. The goal of this project is to improve the knowledge about hygrothermal performances of walls in which thermal insulation is mainly provided by straw. Besides an overall properties characterization of straw and two types of earth plaster, a series of tests was performed to determine the hygrothermal properties of these materials: porosity, sorption curve, water vapour diffusion, capillary absorption, total water absorption, specific heat and thermal conductivity. The determination of these parameters required sometimes the implementation of unusual protocols or unreleased materials. Numerical simulations based on the properties defined in the test campaign are also presented. Results clearly point out the influence of the type of plaster and the orientation of fibres into straw bale. [less ▲]

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See detailMatériaux et systèmes constructifs: critères de sélection
Courard, Luc ULg

Conference given outside the academic context (2013)

Donner quelques idées sur les raisons qui amènent l'ingénieur à baser son choix des matériaux sur des critères autres que techniques

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See detailDurabilité (s) des matériaux de construction : un challenge pour l’ingénieur
Courard, Luc ULg; Bissonnette, Benoît

Conference (2013, May 10)

Le choix des matériaux utilisés dans la construction repose sur des critères techniques identifiables et quantifiables tels la résistance mécanique, le comportement chimique ou le transfert de chaleur ... [more ▼]

Le choix des matériaux utilisés dans la construction repose sur des critères techniques identifiables et quantifiables tels la résistance mécanique, le comportement chimique ou le transfert de chaleur, paramètres qui permettent non seulement de satisfaire les exigences opérationnelles de l'ouvrage, mais aussi d'en garantir la durabilité et la durée de vie utile attendues. Quoi qu'il en soit, ces critères ne sont aujourd’hui plus suffisants: énergie grise, analyse de cycle de vie, incidence sur l’environnement, qualité environnementale des constructions, etc. sont de nouveaux facteurs qui interviennent dans le caractère « durable » des constructions. L’ingénieur se doit désormais d'intégrer ces considérations dans le dimensionnement et la réalisation des ouvrages, ce qui constitue un réel challenge pour l’avenir. [less ▲]

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See detailDetermination of Moisture Diffusivity During Drying of Mortar Cement: Experimental and Modeling Study
Bennamoun, Lyes ULg; Kahlerras, Loubna ULg; Michel, Frédéric ULg et al

in International Journal of Energy Engineering (2013), 3(1), 1-6

The aim of this study is the experimental characterization of the behaviour of a mortar during convective drying. We focalise on mortar that has a rate water-cement of 0.5. The drying tests are developed ... [more ▼]

The aim of this study is the experimental characterization of the behaviour of a mortar during convective drying. We focalise on mortar that has a rate water-cement of 0.5. The drying tests are developed in a micro-convective dryer that can use samples weighing from 0 to 8g. The advantage of these experiments is to reproduce the natural conditions that can be found during the treatment of the mortar-atmosphere problems. The response of the drying curve or the drying kinetic depends on the applied drying conditions. So, the temperature of the air varies from 60°C to 130°C, the velocity of the air is changed from 2 m.s-1 to 5 m. s-1and the relative humidity is kept less than 1.7%. The comparison between the experimental results and the proposed analytical solutions of the equation of diffusion represented by Fick’s law, applied for a finite shape, allows determination of the values of the diffusion coefficient. It has a value of 1.71×10-10 m2.s-1 at 60°C, 13.69×10-10 m2.s-1 at 90°C and 16.27×10-10 m2.s-1 at 130°C. Calculation of the activation energy and the D0 constant are also possible. [less ▲]

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See detailSurface properties of concrete and criteria for adhesion of repair systems
Courard, Luc ULg; Garbacz, Andrzej; Piotrowski, Tomasz et al

in Van Gemert, Dionys; Kabashi, Naser; Nushi, Violeta (Eds.) et al Proceedings of the 1st Symposium on Polymers in Concrete (2013)

Before any repair operation, an effective assessment of the concrete substrate has to be performed. Usually next to the surface reparation of concrete, evaluation of the cohesion of the superficial ... [more ▼]

Before any repair operation, an effective assessment of the concrete substrate has to be performed. Usually next to the surface reparation of concrete, evaluation of the cohesion of the superficial concrete is requested for adhesion and durability reasons. Many authors describe the influence of the surface preparation technique on the superficial cohesion of concrete or the adhesion. However, the real effects of surface preparation technique only begin to be investigated in terms of superficial microcracking or roughness quantification. This project was performed in regards to the influence of concrete substrate strength and preparation technique efficiency. The effect of the concrete removal/preparation technique is most likely dependent upon the nature and the quality of the concrete substrate. Preparation techniques are compared from the point of view of concrete removing but also potential deterioration. The visual observation of the concrete surfaces indicates that the high pressure water jetting technique induces a particular texture characterized by large waves mostly parallel to the water flow. The concrete slabs have afterwards been covered with a Self-Compacting Repair Mortar and adhesion has been characterized. [less ▲]

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See detailComparison of shear and pull-off tests for testing adhesion of different content limestone fillers mortars used as repair system
Chendes, Remus; Dan, Sorin; Courard, Luc ULg

in STOIAN, Valeriu; DAN, Daniel; BOB, Corneliu (Eds.) et al Construction sustainability: efficient solution for design, execution and rehabilitation of the building (2013)

When a repair operation is performed and a new concrete or mortar is applied on the old concrete substrate, it is very important to have a good bond between the old concrete layer and the repair concrete ... [more ▼]

When a repair operation is performed and a new concrete or mortar is applied on the old concrete substrate, it is very important to have a good bond between the old concrete layer and the repair concrete system. The bond strengths usually determinate using pure tensile tests (pull-off tests) because of the field applicability of this category of tests. However, in most of the applications, shear stress is the main reason of the bond failure. In general, bond strength under tensile is considered smaller than bond strength in shear stress conditions. The objective of this paper is to compare the results obtained from tensile and shear tests and to potentially determine a mathematical relation between shear and tension. The materials used for tests are Ordinary Portland Cement and modified limestone fillers mortars. Specific humidity storage conditions have been selected. [less ▲]

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See detailŚlad węglowy betonu
Załęgowski, Kamil; Jackiewicz-Rek, Wioletta; Garbacz, Andrzezj et al

in Materialy Budowlane (2013), 496

Different approaches of carbon foot print of concrete estimation were investigated. It was shown that value of CO2 emissions varies depending on accepted specificity of calculations. Special attention was ... [more ▼]

Different approaches of carbon foot print of concrete estimation were investigated. It was shown that value of CO2 emissions varies depending on accepted specificity of calculations. Special attention was focused on possibilities of production of concrete with decreased „carbon foot print”. Reduction of cement content by mineral additives replacement in concrete mixture as well as influence of aggregate type used, conditions of concrete transport and built in and CO2 sequestration via carbonation process du ring „pri ma ry and se cond li fe” of con - cre te we re al so ta ken in to con si de ra tion. [less ▲]

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See detailFixation du CO2 dans les blocs de béton à base de granulats recyclés
Parmentier, Véronique; Michel, Frédéric ULg; Courard, Luc ULg

in Gagné, Richard (Ed.) Actes de la 14ème édition des Journées Scientifiques (2013)

A l’heure où l’industrie cimentière est majoritairement responsable de la production de CO2 dans le secteur de la construction, il s’avère utile de compenser cette production par un phénomène inverse: la ... [more ▼]

A l’heure où l’industrie cimentière est majoritairement responsable de la production de CO2 dans le secteur de la construction, il s’avère utile de compenser cette production par un phénomène inverse: la captation du CO2. Ce processus d’absorption de CO2, appelé carbonatation, améliore certaines propriétés du béton lors de la conversion du dioxyde de carbone CO2 en carbonate de calcium CaCO3. Les préoccupations environnementales actuelles motivent l’étude de la carbonatation dans le but de maximiser l'absorption du dioxyde de carbone. Les granulats recyclés, produits à base de déchets de béton concassés mécaniquement, peuvent prendre place dans de nouvelles applications en béton. Ils peuvent remplacer les granulats naturels en tout ou en partie, épargnant ainsi l’extraction des matières premières naturelles. La combinaison des deux approches vise à élaborer un produit dont l’impact environnemental est réduit au minimum. [less ▲]

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See detailRecyclage et valorisation des déchets et sous-produits industriels en construction : conditions et expériences
Courard, Luc ULg

Conference (2013)

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, notre activité ... [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, notre activité humaine n'est pas infiniment développable, car bornée par des limites 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. Une saine politique des déchets s'articule autour de trois axes fondamentaux : • réduire le flux des déchets à la source, par la mise au point de procédés de fabrication nouveaux, appelés technologies propres, qui engendrent moins de flux polluants, et par l'action menée au niveau de la consommation, en favorisant l'utilisation minimale de produits jetables et maximale d'éco-produits ; • accroître la récupération et la valorisation : la récupération consiste à sortir un produit du circuit production-évacuation conduisant à la mise en décharge, et la valorisation procède de plusieurs manières : o le recyclage, qui consiste à refaire le même produit que le produit initial (bouteilles en verre) ; o la réutilisation, qui consiste à fabriquer un autre produit que celui qui a donné naissance au déchet (bouteilles en PVC pour la fabrication de jouets) ; o le réemploi, qui consiste à prolonger la durée de vie d'un produit (bouteilles consignées) ; o la régénération, qui consiste à redonner au déchet les qualités et propriétés du produit initial par un ou plusieurs procédés adaptés (purification des huiles de vidange) ; o la valorisation énergétique, par incinération. • éliminer et traiter proprement les déchets, c'est-à-dire transformer le déchet pour qu'il n'ait plus d'impact négatif sur l'environnement (procédés d'inertification, mise en Centre d’Enfouissement Technique). Cette troisième étape est l'étape ultime et n'intervient que si toutes les autres possibilités ont été envisagées. S'il n'est pas possible de supprimer la production de déchets, sous-produits ou résidus industriels ou urbains, il convient alors de définir les meilleures conditions de valorisation. Presque toutes les activités industrielles portant atteinte aux ressources naturelles et dégradant l'environnement, le recyclage et la valorisation des déchets est un devoir autant qu'une nécessité. En effet, au cours des dernières années, les besoins croissants en matériaux de construction ont amené un épuisement des ressources de matériaux traditionnellement utilisés dans le secteur. La distance de transport entre le lieu de production et le site de construction ne cesse donc d'augmenter. Outre leur demande en matériaux de construction, les mêmes zones se caractérisent aussi par une importante production de déchets industriels et urbains dont l'évacuation est peu compatible avec l'environnement. On doit donc les verser dans des C.E.T., où il faut payer une redevance. A titre d’exemple, pour une démolition et une reconstruction routière, dans le cas où la nouvelle construction suit immédiatement la démolition, si le recyclage est possible sur site, l'économie totale des matériaux peut atteindre 50 % se répartissant comme suit : • 70 % dans la réduction des frais de transport ; • 20 % dans le coût moins élevé des matériaux ; • 10 % en évitant les frais de mise en décharge. On voit donc l'intérêt économique qu'il y a d'aborder les opérations de démolition et de reconstruction de façon coordonnée. Mais c'est le transport même qui peut être le facteur limitatif majeur à la réutilisation des déchets. Son prix est fonction de la quantité transportée et de la distance, indépendamment de la valeur marchande du produit transporté car il en coûte autant de transporter des déchets ou des matériaux de bonne qualité : il n'est donc pas intéressant de transporter des produits de faible valeur marchande sur des grandes distances. Le recyclage sera donc d'autant plus intéressant que: • la zone de décharge est plus éloignée ; • le coût du versage est élevé ; • les matières premières qui pourraient être remplacées par des déchets sont d'un approvisionnement difficile et / ou coûteux. Un autre facteur limitant la réutilisation est, ce que l'on pourrait appeler de façon péjorative, le réglementarisme: pour qu'un matériau puisse être utilisé dans le génie civil ou le bâtiment, il doit rencontrer certaines "spécifications". Cela entraîne, dans le cas envisagé de la réutilisation de déchets, à se retrouver dans la situation où un matériau n'a pas de spécifications car il est nouveau et peu utilisé, et il n'est pas ou peu utilisé car il n'est pas couvert par des spécifications ! Seules la recherche et la volonté de changement permettent de sortir de ce cercle vicieux. Ces considérations ont pour avantage de montrer que, dans tous les cas, il convient d'évaluer l'opportunité de la réutilisation des déchets à plusieurs niveaux : • évaluation technique : o caractérisation des déchets : propriétés physiques, mécaniques et chimiques ; o durabilité et évolution dans le temps ; o constance des performances du déchet ; • évaluation logistique et économique : o endroit de production des déchets et transports ; o conditionnement ; o quantité produite et constance de production ; • évaluation écologique et économique : o diminution des quantités mises en décharge ; o obligation d'élimination d'un déchet. On ne recycle donc pas n'importe quoi, à n'importe quel prix et n'importe comment ! Les besoins du génie civil sont en général de quatre ordres principalement, à savoir les: • matériaux, sur lesquels pèsent de faibles exigences et consommés en grande masse, consommés en grandes masses dans les remblais mais transportables sur de faibles distances en raison des coûts; • granulats, qui doivent répondre à des spécifications diverses selon la place qu’ils occuperont dans les structures et les techniques de traitement utilisées. Les exigences de qualité peuvent à ce niveau devenir élevées, voire sévères pour les couches de surface, pour conduire à des produits finis de qualité identiques à celle des matériaux traditionnels; • liants, qui doivent répondre à des spécifications bien précises et dont les propriétés doivent rester constantes dans le temps. Employés en petite quantité et concurrentiels de produits coûteux (ciments, bitumes), ils peuvent connaître des conditionnements préalables à l’emploi et supporter des coûts de transport plus élevés; • activants, qui seront utilisés en petites quantités, ce qui peut poser des problèmes de collecte, stockage, distribution et régularité. Si l'intérêt technico-économico-écologique apparaît clairement dans le rapport qui existe entre l'offre en sous-produits et les besoins du génie civil, il est aussi clair que l'utilisation de tels produits pose un certain nombre de difficultés : • aptitude technique à entrer dans la composition de matériaux (normes); • aptitude à l'emploi de matériaux utilisant ces déchets; • optimisation économique des emplois possibles; • incidence sociale sur l'emploi dans les entreprises fournissant des produits nobles; • effet sur l'environnement. L’exposé portera sur des exemples de recyclage et de valorisation d’une série de sous-produits industriels et de déchets : • laitiers de haut-fourneau et scories d’aciérie ; • cendres volantes de centrales thermiques au charbon ; • gypses résiduaires ; • caoutchoucs ; • bétons et revêtements bitumineux ; • papiers, cartons et matières plastiques ; [less ▲]

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See detailA surface engineering approach applicable to concrete repair engineering
Garbacz, Andrzej; Courard, Luc ULg; Bissonnette, Benoît

in Bulletin of the Polish Academy of Sciences. Technical Sciences (2013), 61(1), 73-84

The objective of the paper is to analyze the effect of surface roughness and superficial microcracking upon dhesion of repair systems using concrete surface engineering approach. The results presented in ... [more ▼]

The objective of the paper is to analyze the effect of surface roughness and superficial microcracking upon dhesion of repair systems using concrete surface engineering approach. The results presented in this paper have been obtained within the framework of research projetcs performed to develop a better understanding of factors affecting the adhesion of repair materials through a surface engineering approach. Based on the results of investigations, the authors showed that the durability and quality of concrete repairs depend to a large degree on the characteristics of the substrate. Mechanical preparation and profiling of the concrete surface to be repaired has to be balanced with potential co-lateral effects such as superficial cracking, too often induced as a result of inappropriate concrete removal method selection, and the loss of benefits due to better mechanical anchorage. The results obtained confirm also that Concrete Surface Engineering, as a scientific concept, will definitely contribute to shed more light on how to optimize repair bond, taking into account interactions between materials at different observation scales. [less ▲]

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