Les transferts d’humidité dans les matériaux de construction ont une influenceimportante sur leur durabilité et sur les performances hygriques et thermiques desbâtiments. De nombreux mécanismes d’endommagement chimiques et physiquesde ces matériaux sont en effet dus à l’infiltration d’eau. En conséquence, leur structureporeuse peut évoluer au cours du temps, et des fissures microscopiques commemacroscopiques peuvent s’y développer. La description des matériaux à l’échelle microscopiqueest cependant une source d’erreur importante dans les codes de simulationactuels des transferts d’humidité et de chaleur, notamment en raison du faitque lesmilieux sont considérés comme homogènes, et que les effets du vieillissementdes matériaux sont négligés. Il importe donc de trouver un moyen d’inclure les effetsde l’endommagement dans les simulations de transferts d’humidité et de chaleurà l’échelle du bâtiment. Des méthodes existent pour la prédiction du comportementde milieux soumis à des sollicitations hygriques et mécaniques, mais supposent quel’ensemble des facteurs extérieurs influant sur l’endommagement soient connus toutau long des simulations.Une nouvelleméthodologie est proposée ici pour compléter ces approches prédictives,en combinant des mesures expérimentales d’endommagement avec la simulationde transferts couplés d’humidité et de chaleur. Une étude préliminaire a d’abordété menée, consistant à mesurer la perméabilité vapeur équivalente d’éprouvettes demortier multi-fissurées. Cette démarche a permis d’identifier les besoins expérimentauxet numériques de la suite du travail, visant à modéliser les écoulements dans unréseau discret de fissures sur la base de leur caractérisation. Une méthodologie expérimentalecombinant corrélation d’images numériques et émissions acoustiques aensuite été développée, permettant de disposer de cartographies d’endommagementet de proposer une démarche pour lamesure de réseaux de fissures dans lesmatériauxde construction en place. La méthode optique, associée à une procédure de traitementd’images, a permis de disposer de données précises de la géométrie de réseauxde fissures. De plus, une méthode a été proposée pour permettre l’interprétation desmesures d’émissions acoustiques en termes de quantification, localisation et identificationdes phénomènes d’endommagement.Un code de simulation a ensuite été écrit, permettant d’intégrer ces mesures defissuration dans la modélisation des écoulements couplés d’humidité et de chaleuren milieu poreux. Ce modèle a été validé sur la base de mesures expérimentales : lacorrélation d’images numériques a été appliquée durant la fracturation d’éprouvettesde béton, dans lesquelles l’infiltration d’eau a ensuite été suivie par radiographie auxrayons X. Les résultats numériques obtenus sont en bonne conformité avec lesmesuresexpérimentales en termes de prédiction de la concentration d’eau en deux dimensions.Enfin, laméthodologie a été appliquée à une série de cas test, dans le but demodéliserles performances hygrothermiques de parois multi-couches, incluant des matériauxendommagés, soumises à des conditions climatiques réelles. On a ainsi pu estimer les conséquences potentielles de l’endommagement sur l’accumulation d’eau dans desparois, sur l’amplitude des cycles de sorption et de séchage, ainsi que sur les transfertsthermiques. / An importantmatter in the field of building physics is the questioning of how wellbuildings sustain ageing, and how their overall efficiency evolves over their lifetime.Many causes for degradation are carried by moisture transfer through these porousmaterials. Indeed, infiltratedwatermay transport chemicals, altermechanical properties,and cause freeze thaw damage or mould development. It may also affect thermalproperties and energetic efficiency, as well as the health and comfort of the occupants.The understanding of how moisture transfer properties evolve during the lifespan ofbuildingmaterials is however far fromcomplete. The pore structure of amaterial itselfmay change over time, or be altered by cracks and defects caused bymechanical loadingand aggravated bymoisture-induced degradation. All sizes of fracturesmay have astrong impact on heat and moisture flow in the building envelope, and their influenceis to be accounted for in any long-termperformance assessment, not only of buildingand building components,but of any built structure in general. A considerable amountof work has already been performed in order to allow predicting the hygrothermal behaviourof buildings over longer periods of time. However, an accurate prediction of allranges of damage in a building component, from microscopic to macroscopic cracks,supposes an extensive knowledge of all damage-inducing, time-varying boundary conditionsof the problem during the simulation time. This also implies high computationalcosts, as well as important needs formaterial characterisation.As a complement to these predictive methods, a new approach was undertaken,combining experimental characterisation of crack patterns and numerical simulationsof coupled heat and moisture transfer. First, a preliminary study was conducted, consistingof measurements of the water vapour permeability of diffusely damaged constructionmaterials.This allowed identifying the experimental and numerical requirementsof the remainder of the work, which aimed at providing measurements of fracturenetwork geometries for their explicitmodelling in heat andmoisture transfer simulations.Digital image correlation and acoustic emission monitoring were then performedduring the degradation of cementitiousmaterials, in order to obtain quantitativedata on crack pattern geometries, and to assess the possibilities for damagemonitoringat the building scale. The optical technique, along with an appropriate imageprocessing procedure, was found suitable for providing precisemeasurements of fracturenetworks. Amethodwas also proposed for the interpretation of acoustic emissionrecordings in terms of damage quantification, localisation and identification.Then, a newmodel for coupled heat andmoisturemodelling in cracked porousmediawas developed, that allows including such measurements of fracture patterns intoa finite element mesh, and simulating flow accordingly. This model was validated onthe basis of experimentalmeasurements: digital image correlationwas performed duringthe fracturing of concrete samples, in which moisture uptake was then monitoredusing X-ray radiography. A good accordance was found between experimental and numericalresults in terms of 2-dimensional moisture concentration distributions. The validated code was then used for the simulation of test cases, in order to assess the hygrothermalperformance of damagedmulti-layered building components subjected toreal climatic conditions. The consequences of fractures on themoisture accumulationin walls, on the amplitude of sorption/desorption cycles and on the thermal performance,were observed.

Nous nous intéressons au contrôle non destructif par ultrasons des matériaux industriels. En pratique, les signaux réceptionnés par le transducteur ultrasonore sont analysés pour détecter les discontinuités de la pièce inspectée. L'analyse est néanmoins rendue difficile par l'acquisition numérique, les effets de la propagation ultrasonore et la superposition des échos lorsque les discontinuités sont proches. La déconvolution parcimonieuse est une méthode inverse qui permet d'aborder ce problème afin de localiser précisément les discontinuités. Ce procédé favorise les signaux parcimonieux, c'est à dire ne contenant qu'un faible nombre de discontinuités. Dans la littérature, la déconvolution est généralement abordée sous l'hypothèse d'un modèle invariant en fonction de la distance de propagation, modalité qui n'est pas appropriée ici car l'onde se déforme au cours de son parcours et en fonction des discontinuités rencontrées. Cette thèse développe un modèle et des méthodes associées qui visent à annuler les dégradations dues à l'instrumentation et à la propagation ultrasonore, tout en résolvant des problèmes de superposition d'échos. Le premier axe consiste à modéliser la formation du signal ultrasonore en y intégrant les phénomènes propres aux ultrasons. Cette partie permet de construire un modèle linéaire mais non invariant, prenant en compte l'atténuation et la dispersion. L'étape de modélisation est validée par des acquisitions avec des matériaux atténuants. La deuxième partie de cette thèse concerne le développement de méthodes de déconvolution efficaces pour ce problème, reposant sur la minimisation d'un critère des moindres carrés pénalisé par la pseudo-norme L0. Nous avons développé des algorithmes d'optimisation spécifiques, prenant en compte, d'une part, un modèle de trains d'impulsions sur-échantillonné par rapport aux données, et d'autre part le caractère oscillant des formes d'onde ultrasonores. En utilisant des données synthétiques et expérimentales, ces algorithmes associés à un modèle direct adapté aboutissent à de meilleurs résultats comparés aux approches classiques pour un coût de calcul maîtrisé. Ces algorithmes sont finalement appliqués à des cas concrets de contrôle non destructif où ils démontrent leur efficacité. / This thesis deals with the ultrasonic non destructive testing of industrial parts. During real experiments, the signals received by the acoustic transducer are analyzed to detect the discontinuities of the part under test. This analysis can be a difficult task due to digital acquisition, propagation effects and echo overlapping if discontinuities are close. Sparse deconvolution is an inverse method that aims to estimate the precise positions of the discontinuities. The underlying hypothesis of this method is a sparse distribution of the solution, which means there are a few number of discontinuities. In the literature, deconvolution is addressed by a linear time-invariant model as a function of propagation distance, which in reality does not hold.The purpose of this thesis is therefore to develop a model and associated methods in order to cancel the effects of acquisition, propagation and echo overlapping. The first part is focused on the direct model development. In particular, we build a linear time-variant model that takes into account dispersive attenuation. This model is validated with experimental data acquired from attenuative materials. The second part of this work concerns the development of efficient sparse deconvolution algorithms, addressing the minimization of a least squares criterion penalized by a L0 pseudo-norm. Specific algorithms are developed for up-sampled deconvolution, and more robust exploration strategies are built for data containing oscillating waveforms. By using synthetic and experimental data, we show that the developed methods lead to better results compared to standard approaches for a competitive computation time. The proposed methods are then applied to real non destructive testing problems where they confirm their efficiency.

The diploma thesis is focused on the determination of the mechanical properties and fracture behaviour of the weld joint X5CrNiCuNb16-4 steel prepared by using electron beam technology. The theoretical part is based on summarization of the relevant information about welding, principle of electron beam welding and testing methods of welded joints. The experimental part of the thesis contains results of practical measurements and analyses, realized for evaluation of the mechanical and structural properties of the base material and weld.

This thesis describes the design and implementation of a control system for testing line using ultrasonic testing and magnetic particle testing. The test line is designed for non-destructive testing of railway wheels with detection and localization of surface and subsurface defects. The thesis describes the design and operating principles of the test line. On this basis, the design of a control system that controls various processes throughout the test line is clearly described. The proposed control system was implemented in the industrial application.

Ultrasonic pulse method is a non-destructive method, which is used in the construction industry to evaluate individual parameters of building structures. The aim of the thesis was to create the prerequisites for determining the rate of ultrasonic pulse propagation on refractory silica fittings and quartz glass fittings. Selected factors influencing the speed of ultrasonic pulse propagation in the tested samples were studied, namely the influence of the sounding direction, the influence of the natural frequency of the probes and the influence of the acoustic coupling material on the ultrasonic pulse method.

The diploma thesis deals with non-destructive testing of concrete as well as with the relationship between determined parameters and the compressive strength of concrete. The thesis is mainly focused on the ultrasonic pulse velocity method and the rebound hammer test. The experimental part of the thesis describes non-destructive tests performed on concrete blocks. The compressive strength was tested on the drill cores taken from the concrete blocks. The aim of this thesis is to find regression models of the relationship between the compressive strength and non-destructive parameters, and the subsequent analysis of the results.

This dissertation is focused on the research of the applicability of the thermographic method in the diagnosis of concrete bridges in the Czech Republic. The theoretical part characterizes selected defects of concrete structures and the principle of their detection. The practical part describes the measurements made in the laboratory on the test specimen and the field on the concrete bridge. Most attention is paid to infrared thermography, ground-penetrating radar and ultrasonic pulse-echo method. Based on the results of the dissertation, recommendations for the use of the thermographic test method in practice were developed.

This thesis deals with the rebound hammer method as a tool for approximation of the time limit for handling the concrete. The theoretical part is focused on three fields of knowledge - rebound hammer test, production of precast concrete components and statistical data analysis. The following practical part deals with the design of two single-parameter linear functions for two types of rebound hammer testers - SilverSchmidt L and SchmidtOriginal N. Statistical data processing is completed by the analysis of influential points by using the Cook’s distance. The resulting statistical models are compared with commonly used relationships.

<p>Developing a reliable in-situ non-destructive testing method to determine the strength of in-place concrete is critical because a fast-paced construction schedule exposes concrete pavement and/or structures undergoing substantial loading conditions, even at their early ages. Conventional destructive testing methods, such as compressive and flexural tests, are very time-consuming, which may cause construction delays or cost overruns. Moreover, the curing conditions of the tested cylindrical samples and the in-place concrete pavement/structures are quite different, which may result in different strength values. An NDT method that could directly correlate the mechanical properties of cementitious materials with the sensing results, regardless of the curing conditions, mix design, and size effect is needed for the in-situ application.</p><p>The piezoelectric sensor-based electromechanical impedance (EMI) technique has shown promise in addressing this challenge as it has been used to both monitor properties and detect damages on the concrete structure. Due to the direct and inverse effects of piezoelectric, this material can act as a sensor, actuator, and transducer. This research serves as a comprehensive study to investigate the feasibility and efficiency of using piezoelectric sensor-based EMI to evaluate the strength of newly poured concrete. To understand the fundamentals of this method and enhance the durability of the sensor for in-situ monitoring, this work started with sensor fabrication. It has studied two types of polymer coating on the effect of the durability of the sensor to make it practical to be used in the field.</p><p>The mortar and concrete samples with various mix designs were prepared to ascertain whether the results of the proposed sensing technique were affected by the different mixtures. The EMI measurement and compressive strength testing methods (ASTM C39, ASTM C109) were conducted in the laboratory. The experimental results of mortar samples with different water-to-cement ratios (W/C) and two types of cement (I and III) showed that the correlation coefficient (R²) is higher than 0.93 for all mixes. In the concrete experiments, the correlation coefficient between the EMI sensing index and compressive strength of all mixes is higher than 0.90. The empirical estimation function was established through a concrete slab experiment. Moreover, several trial implementations on highway construction projects (I-70, I-74, and I-465) were conducted to monitor the real-time strength development of concrete. The data processing method and the reliable index of EMI sensing were developed to establish the regression model to correlate the sensing results with the compressive strength of concrete. It has been found that the EMI sensing method and its related statistical index can effectively reflect the compressive strength gain of in-place concrete at different ages.</p><p>To further investigate the in-situ compressive strength of concrete for large-scale structures, we conducted a series of large concrete slabs with the dimension of 8 feet × 12 feet × 8 inches in depth was conducted at outdoor experiments field to simulate real-world conditions. Different types of compressive strength samples, including cast-in-place (CIP) cylinder (4” × 6”) – (ASTM C873), field molded cylinder (4” × 8”) – (ASTM C39), and core drilled sample (4” × 8”) – (ASTM C42) were prepared to compare the compressive strength of concrete. The environmental conditions, such as ambient temperatures and relative humidity, were also recorded. The in-situ EMI monitoring of concrete strength was also conducted. The testing ages in this study were started from 6 hours after the concrete cast was put in place to investigate the early age results and continued up to 365 days (one year) later for long-term monitoring. The results indicate that the strength of the CIP sample is higher than the 4” x 8” molded cylinder , and that core drilled concrete is weaker than the two aforementioned. The EMI results obtained from the slab are close to those obtained from CIP due to similar curing conditions. The EMI results collected from 4 × 8-inch cylinder samples are lower than slab and CIP, which aligns with the mechanical testing results and indicates that EMI could capture the strength gain of concrete over time.</p><p>The consequent database collected from the large slab tests was used to build a prediction model for concrete strength. The Artificial Neuron Network (ANN) was investigated and experimented with to optimize the prediction of performances. Then, a sensitivity analysis was conducted to discuss and understand the critical parameters to predict the mechanical properties of concrete using the ML model. A framework using Generative Adversarial Network (GAN) based on algorithms was then proposed to overcome real data usage restrictions. Two types of GAN algorithms were selected for the data synthesis in the research: Tabular Generative Adversarial Networks (TGAN) and Conditional Tabular Generative Adversarial Networks (CTGAN). The testing results suggested that the CTGAN-NN model shows improved testing performances and higher computational efficiency than the TGAN model. In conclusion, the AI-guided concrete strength sensing and prediction approaches developed in this dissertation will be a steppingstone towards accomplishing the reliable and intelligent assessment of in-situ concrete structures.</p><br>

The masers’s thesis is about the methods of non-destructive testing and about determining the properties of prestressed concrete. The first part pursues an introduction on the prestressed concrete, its essence and material properties. The next section describes the non-destructive diagnostic methods used in the practical part – the ultrasound impulse method, the resonance method and the rebound hardness test method. There are described destructive tests on the specimens for the calculation of the calibration. This is followed by a practical part, which describes the item tested - truss, its manufacturing, storage, and perform the test. Then search value are calculated from the test results and results are compared according to various procedures specified in the standards. The last section is devoted to the calculation of camber truss and loss of preload.