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See detailSaturation level of the superficial zone of concrete and adhesion of repair systems
Courard, Luc ULg; Lenaers, Jean-François; Michel, Frédéric ULg et al

in Construction & Building Materials (2011), 25((5)), 2488-2494

Appropriate surface saturation level is essential for the durability of the repaired structure. The repair material is often blamed for ‘‘not sticking’’, although the general source of the trouble lies ... [more ▼]

Appropriate surface saturation level is essential for the durability of the repaired structure. The repair material is often blamed for ‘‘not sticking’’, although the general source of the trouble lies with the substrate surface conditioning. An extensive research project has been undertaken to develop specifications and performance criteria for surface preparation of concrete substrates. A field test was developed to evaluate the optimum moisture conditioning of the substrate concrete prior to application of repair material; this has been calibrated and compared with destructive and non-destructive on three types of concrete and two types of surface preparation. In order to evaluate different saturation levels, concrete samples have been stored in more than 12 modes of conservation. Finally, repair mortars have been applied on concrete substrates and adhesion was measured for different concrete surface saturation levels. Initial Surface Absorption Test (ISAT) can be used as an attractive quantitative test to evaluate saturation level of concrete substrate. Moreover, it is clearly shown that saturation levels higher than 50% and lower than 90% are requested for promoting adhesion of PCC mortars. [less ▲]

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See detailBonded cement-based material overlays for the repair, the lining or the strengthening of slabs and pavements
Bissonnette, Benoît; Courard, Luc ULg; Fowler, David et al

Book published by Springer (2011)

1.0 INTRODUCTION 2.0 OVERLAY DESIGN PROCESS 3.0 CONDITION EVALUATION OF THE EXISTING STRUCTURE PRIOR TO OVERLAY 4.0 BOND 5.0 STRUCTURAL BEHAVIOUR 6.0 DEBONDING 7.0 DESIGN 8.0 PRACTICE AND QUALITY ... [more ▼]

1.0 INTRODUCTION 2.0 OVERLAY DESIGN PROCESS 3.0 CONDITION EVALUATION OF THE EXISTING STRUCTURE PRIOR TO OVERLAY 4.0 BOND 5.0 STRUCTURAL BEHAVIOUR 6.0 DEBONDING 7.0 DESIGN 8.0 PRACTICE AND QUALITY ASSURANCE 9.0 MAINTENANCE AND REPAIR OF OVERLAYS 10.0 CONCLUSION [less ▲]

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See detailBond (chapter 4)
Silfwerbrand, Johan; Beushausen, Hans; Courard, Luc ULg

in Bissonnette, Benoît; Courard, Luc; Fowler, David (Eds.) et al Bonded cement-based material overlays for the repair, the lining or the strengthening of slabs and pavements (2011)

Good bond is a key factor for providing monolithic action in bonded concrete overlays. This chapter starts with three theoretical sections classifying bond in three groups (complete, uncertain, and poor ... [more ▼]

Good bond is a key factor for providing monolithic action in bonded concrete overlays. This chapter starts with three theoretical sections classifying bond in three groups (complete, uncertain, and poor), defining bond strength, and describing the fundamental bond mechanisms. The main part of this chapter covers a thorough description in chronological order of how the 13 most important factors affect bond. All events from removal of deteriorated concrete to concrete placing and curing and long-term exposure are investigated. There exist a number of different methods to determine bond strength and the most frequent ones are briefly described in a separate section. It is shown that there is an evident relationship between the two most frequently used families of test methods, i.e., between methods determining bond strength in tension and bond strength in shear. Furthermore, it is shown that it is possible to provide durable bond in concrete overlays if all operations for concrete removal, surface cleaning, concrete placing, and curing are conducted meticulously. The chapter is ended by two sections devoted to design strength values in various international codes and performance requirements that can be used for quality control. [less ▲]

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See detailCondition evaluation of the existing structure prior to overlay (chapter 3)
Courard, Luc ULg; Trevino, Manuel; Bissonnette, Benoît

in Bissonnette, Benoît; Courard, Luc; Fowler, David (Eds.) et al Bonded cement-based material overlays for the repair, the lining or the strengthening of slabs and pavements (2011)

The knowledge and analysis of the causes of degradations is the first step in repairing existing concrete structures. The assessment is performed by using destructive and non destructive methods. These ... [more ▼]

The knowledge and analysis of the causes of degradations is the first step in repairing existing concrete structures. The assessment is performed by using destructive and non destructive methods. These allow detecting modification of physical, chemical and/or mechanical properties of concrete: cracking, deformation, spalling, carbonation, etc., are various causes of distress, with potential irreversible consequences on concrete structure behaviour. A description of specific methods for pavements and structural slabs is proposed; it is usually recommended to combine complementary methods for efficient diagnosis. This chapter wants to offer an overview of techniques and references that could help the user in selecting the most appropriate investigation program. [less ▲]

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See detailInfluence of clay in limestone fillers for self compacting cement based composites
Courard, Luc ULg; Michel, Frédéric ULg; Piérard, Julie

in Construction & Building Materials (2011), 25

High workability together with a good resistance to segregation is needed for cement based composites, specifically fresh Self-Compacting Mortars (SCM); in this prospect, the amount of coarse materials ... [more ▼]

High workability together with a good resistance to segregation is needed for cement based composites, specifically fresh Self-Compacting Mortars (SCM); in this prospect, the amount of coarse materials has to be reduced and replaced by fine material. Several limestone fillers are here compared and analysed. These by-products are issued from different industrial sectors, such as the aggregate and lime production industry (quarrying operations) and the ornamental stones industry (sawing operations). Particular attention has been paid to clay content, as consistency of fresh mortars was varying, while other physical characteristics like granulometry remained the same. Relationship between the physico-chemical properties of the fillers and the properties of fresh and hardened mortars are brought forward. Even if it may affect fresh properties of mortars, results clearly show that clay type and content has minor influence than limestone filler itself. [less ▲]

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See detailThe evaluation of the surface free energy of liquids and solids in concrete technology
Courard, Luc ULg; Michel, Frédéric ULg; Martin, Marie

in Construction & Building Materials (2011), 25

This paper presents initial results from an extensive study on the calculation of the surface free energy of mineral materials. The usefulness of such evaluation is demonstrated through the technological ... [more ▼]

This paper presents initial results from an extensive study on the calculation of the surface free energy of mineral materials. The usefulness of such evaluation is demonstrated through the technological operation of casting and moulding concrete. Surface interactions will firstly act on the dispersion of particles inside the concrete mix and the viscosity of the fresh material; the specific effect of superplasticizers and Modifying Viscosity Agent is presented through the determination of surface free energy properties. The second analysis is dealing with the interactions between mineral and vegetal oils applied on the wooden or steel formwork and fresh concrete. The evaluation of contact angle and interfacial forces help to efficiently select the most appropriate material. [less ▲]

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See detailEclatement du béton dû à granulats contaminés à la chaux vive
Courard, Luc ULg; Darimont, Anne ULg; Degée, Hervé ULg

Article for general public (2011)

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See detailConcrete Repair Science: new trends - 10 Years cooperation between the University of Liège and the Politechnika Warsawska
Courard, Luc ULg; Garbacz, Andrzej

Book published by Université de Liège (2010)

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See detailSurfology: new investigations techniques and approaches
Courard, Luc ULg; Garbacz, Andrzej

Scientific conference (2010, November 29)

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See detailRecherche dans le domaine du béton à l'Université de Liège (2009-2010)
Dotreppe, Jean-Claude ULg; Franssen, Jean-Marc ULg; Somja, H. et al

Scientific conference (2010, October 21)

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See detailParticle packing of concrete containing blended cement
He, Huan ULg; Courard, Luc ULg; Pirard, Eric ULg

Conference (2010, September 20)

Physical particle packing is becoming a hot topic in concrete technology as more and more types of granular materials are used in concrete either for ecological or for engineering purposes. Aggregate is ... [more ▼]

Physical particle packing is becoming a hot topic in concrete technology as more and more types of granular materials are used in concrete either for ecological or for engineering purposes. Aggregate is used as concrete’s skeleton, whereby the particles are stabilized by the cementitious matrix. Packing efficiency governs the spatial characteristics of this structure and thereby influences concrete’s properties. Fine-grained sand can be used to further improve density of the aggregate structure. The particulate cement is also frequently blended by fine mineral admixtures to influence performance of the paste and the properties of the matured concrete. The so-called filler effects increase packing density of the blended cement and possibly reduce water demand. High performance characteristics require suitable blending materials of proper properties (fineness, shape, chemical components, etc.). A number of theoretical packing models have been proposed for prediction of packing characteristics and the resulting concrete properties. A minimum voids ratio has been mathematically derived for certain particle size distributions. This allowed establishment of some optimum graded mixtures for concrete production. On the other hand, the computer simulation approach provides a powerful tool for simulating particle packing. Computational concrete (compucrete) has been developed for a wide range of research purposes. Application of computer simulation to particle packing offers a promising perspective in concrete technology; it provides a proper representation of the heterogeneous concrete material, and renders the possibility of studying the effects of a wide range of technological parameters. In this study, an advanced DEM will be utilized for investigate the packing properties of admixtures blended cement. This new-developed system is capable of packing simulations of arbitrary-shaped particles. Experimental shape analysis of each identical group of particles provides fundamental references of shape simulation strategy. Finally, computer simulation structures of blended cement paste both in fresh and hardened states will be compared with the experimental approach. Correlation of particle packing characteristics and properties of blended cement paste will be analyzed and discussed. Optimization of blending efficiency and improvement of concrete properties are pursued using packing modeling. [less ▲]

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See detailUtilisation du GPR pour la détection des discontinuités dans les tabliers de ponts
Van der Wielen, Audrey ULg; Nguyen, Frédéric ULg; Courard, Luc ULg

Scientific conference (2010, August 27)

Le Ground Penetrating Radar (GPR) est une technique non destructive utilisée depuis des décennies dans l’auscultation des sols. Depuis quelques années, l’apparition sur le marché d’antennes à hautes ... [more ▼]

Le Ground Penetrating Radar (GPR) est une technique non destructive utilisée depuis des décennies dans l’auscultation des sols. Depuis quelques années, l’apparition sur le marché d’antennes à hautes fréquences a permis d’appliquer cette méthode à des structures de moindre épaisseur, et notamment aux tabliers de ponts en béton. A l’Université de Liège, des travaux sont menés afin d’améliorer la détection des discontinuités dans les tabliers de ponts en béton. Dans une première étude expérimentale, 12 échantillons en béton contenant des défauts simulant des délaminations ont été réalisés et scannés par radar. Nous avons ainsi pu représenter les défauts en 3D et constater que leur visibilité était dépendante de leur épaisseur. Actuellement, une seconde étude théorique et expérimentale porte sur la détermination exacte de la limite de détection des couches minces. [less ▲]

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See detailTransport properties of mortars and concretes modified with medium hydraulic activity ground granulated blast furnace slags.
Hadj Sadok, Ahmed; Kenaï, Saïd; Courard, Luc ULg et al

in Sustainable Construction Materials and Technologies (2010, June)

Mechanical characteristics and durability of ground granulated blast furnace slag cement composites depends on the hydraulic activity of the slag. Algerian Blast furnace slag is characterized by a quite ... [more ▼]

Mechanical characteristics and durability of ground granulated blast furnace slag cement composites depends on the hydraulic activity of the slag. Algerian Blast furnace slag is characterized by a quite slow reactivity. Porosity and transport properties of mixes containing up to 50% OPC replacement are compared and analyzed. Mechanical strength, pore size distribution and capillary water absorption are studied after 28 and 90 days of wet curing. The durability of blast furnace slag cement concrete is evaluated through nitrogen permeability and water penetration depth under pressure. First observations seem to indicate finer porosity and lower water absorption than with 100% CEM I 52.5 mortars. Moreover, lower permeabilities to nitrogen and water are also observed for 50% blast furnace slag substitution. [less ▲]

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See detailFrom defects to causes: pathology of concrete and investigation methods.
Courard, Luc ULg; Van der Wielen, Audrey ULg; Darimont, Anne ULg

in Startegjia Izvedbe Sanacij Objektov (2010, May 19)

The proper planning of investigations before carrying out repair works is important if optimum use is to be made of the test data. A major step needs to be taken from knowing, for example, that chloride ... [more ▼]

The proper planning of investigations before carrying out repair works is important if optimum use is to be made of the test data. A major step needs to be taken from knowing, for example, that chloride is present in the concrete, to select the best methods for repair. Engineers require guidance on both the techniques available for the condition assessment of structures and the methods for data interpretation. Two major stages are usually recommended for such an operation: the first stage is based on a rapid-scan visual assessment, often including limited sampling in areas obviously damaged, from which areas can be selected for more detailed investigations. The second stage contains a detailed diagnostic survey that relies on destructive and non destructive testing techniques. Non destructive techniques are more and more utilized not only for the evaluation of the concrete strength but also for the detection of cracks and delaminations. Moreover, the interest for techniques able to evaluate concrete permeability is rising, due to the importance of this factor for durability evaluation. The paper will discuss the assessment of concrete structures and describe the main destructive and non destructive techniques with regard to specific pathologies. [less ▲]

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See detailRelation between bond quality and impact-echo frequency spectrum
Piotrowski, Tomasz; Garbacz, Andrzej; Van der Wielen, Audrey ULg et al

in Restoration of Buildings and Monuments = Bauinstandsetzen und Baudenkmalpflege (2010), 16(4/5), 303-314

According to EN 1504-10 and ACI Concrete Repair Manual, bond strength and interface quality are the main features of repair system necessary to be assessed. Pull-off test is most commonly used for bond ... [more ▼]

According to EN 1504-10 and ACI Concrete Repair Manual, bond strength and interface quality are the main features of repair system necessary to be assessed. Pull-off test is most commonly used for bond strength evaluation but growing interest in nondestructive techniques (NDT) is recently noted. Impact-echo (IE) is treated as the most promising one for this purpose. The aim of this paper is to analyze an effect of bond quality on stress wave propagation in repair systems. A group of samples has been prepared in order to obtain repair systems of different bond quality. Prior to repair, quality of concrete substrates has been characterized according different techniques: compressive strength, superficial cohesion, surface roughness index and cracking quantification. Than a polymer-modified repair mortar has been applied. After hardening, IE signals have been recorded and pull-off bond strength determined. The relationships between parameters characterizing surface quality, bond strength, IE frequency spectrum and results of wavelet analysis of IE signal have been analyzed. [less ▲]

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See detailOn the relation between bond quality and impact-echo frequency spectrum
Piotrowski, Tomasz; Garbacz, Andrzej; Van der Wielen, Audrey ULg et al

in Proceedings of the 13th International Congress on Polymers in Concrete ICPIC 2010 (2010)

According to EN 1504-10 and ACI Concrete Repair Manual, bond strength and interface quality are the main features of repair system necessary to be assessed. Pull-off test is most commonly used for bond ... [more ▼]

According to EN 1504-10 and ACI Concrete Repair Manual, bond strength and interface quality are the main features of repair system necessary to be assessed. Pull-off test is most commonly used for bond strength evaluation but growing interest in nondestructive techniques (NDT) is recently noted. Impact-echo (IE) is treated as the most promising one for this purpose. The aim of this paper is to analyze an effect of bond quality on stress wave propagation in repair systems. A group of samples has been prepared in order to obtain repair systems of different bond quality. Prior to repair, quality of concrete substrates has been characterized according different techniques: compressive strength, superficial cohesion, surface roughness index and cracking quantification. Than a polymer-modified repair mortar has been applied. Af-ter hardening, IE signals have been recorded and pull-off bond strength determined. The rela-tionships between parameters characterizing surface quality, bond strength, IE frequency spec-trum and results of wavelet analysis of IE signal have been analyzed. [less ▲]

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See detailWykorzystanie impact-echo i radaru do wykrywania defektow ukladu naprawczego nie zawierajacych warstwy powietrza
Garbacz, Andrzej; Harassek, Piotr; Van der Wielen, Audrey ULg et al

in 39th Polish Conference on Non destructive Testing Methods, Szczyrk 26-28 October, Zeszyty Problemowe. Badania nieniszczące (2010)

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See detailSurfology: what does it mean for polymer concrete composites?
Courard, Luc ULg; Garbacz, Andrzej

in Restoration of Buildings and Monuments = Bauinstandsetzen und Baudenkmalpflege (2010), 16(4/5), 1-12

Surfology is a scientific concept including all surface properties of materials and its influence on adhesion. The study of adhesion of polymer concrete composites is on the border - interface - between ... [more ▼]

Surfology is a scientific concept including all surface properties of materials and its influence on adhesion. The study of adhesion of polymer concrete composites is on the border - interface - between materials science and engineering. Interface quality is clearly influenced by surface properties of materials. Quality is uneasy to define but, at the level of interface, it could integrate all what favours the contact between concrete and polymers, like shrinkage, rigidity, surface roughness, wettability, viscosity…etc. Surfology contributes to understand what will make the contact effective or not, and allow interactions of variable intensities between the materials. Different scales of observation – micro to macro - are needed to exactly represent what happens when materials are put into contact. The objective of the paper is to analyse the effect of surface parameters (surfology) on polymer concrete composites. Influence of water content, roughness and type of material will be taken into account as factor influencing wettability and thermodynamic properties of surface. Viscosity and shear level of resinous materials will be considered in the same way. Engineering point of view will be taken into account through adhesion evaluation and correlated to surface material properties. [less ▲]

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See detailNondestructive Detection of Delaminations in Concrete Bridge Decks: A First Experimental Study
Van der Wielen, Audrey ULg; Courard, Luc ULg; Nguyen, Frédéric ULg

in Proceedings of the XIII International Conference on Ground Penetrating Radar (2010)

To detect delaminations in concrete bridge decks, nondestructive techniques (NDT) permit a frequent and large inspection of the slabs without damaging structures. This research was devoted to detect ... [more ▼]

To detect delaminations in concrete bridge decks, nondestructive techniques (NDT) permit a frequent and large inspection of the slabs without damaging structures. This research was devoted to detect simulated defects in twelve repaired concrete slabs. These were scanned with high frequency ground penetrating radar (GPR) with the common offset (CO) and common midpoint (CMP) methods. The electromagnetic waves speed was determined from CMPs. A 3D visualization program was also created to display the CO measurements. The visibility of the inserted defects revealed to be dependent on their lateral extension, their thickness and their constitutive material. [less ▲]

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See detailEvaluation of the effect of load eccentricity in a tensile pull-off test on bond strength
Courard, Luc ULg; Garbacz, Andrezj

Report (2010)

The report presents the results of a research project and the impact of incorrect design on tensile strength values. According to results of laboratory experiments and modelling, it can be observed that ... [more ▼]

The report presents the results of a research project and the impact of incorrect design on tensile strength values. According to results of laboratory experiments and modelling, it can be observed that, if there is an influence of 2° and 4° angle of inclination on pull-off bond strength, it is however not statistically significant: the decrease of pull-off strength is usually no larger than 14% for 4°. [less ▲]

Detailed reference viewed: 53 (0 ULg)