Tesi: "Concrete Ageing"

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Mogilnickij, Edgar. "Betoninio ir gelžbetoninio elementų betono įtempių relaksacijos dėl tiesinio valkšnumo skaitinė analizė". Master's thesis, Lithuanian Academic Libraries Network (LABT), 2012. http://vddb.laba.lt/obj/LT-eLABa-0001:E.02~2012~D_20120723_105605-79936.

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Baigiamajame magistro darbe pasiūlytas gelžbetoninio elemento skaitinis modelis itempių – deformacijų būvio analizei tirti veikiant ilgalaikei apkrovai. Betono relaksacijos uždaviniui spresti taikyta Volterra integraline lygtis. Sprendimas grindžiamas apibendrintosios vidurkio teoremos taikymu betono įtempių istorijai rasti. Skaičiavimams taikyta specialiai tuo tikslu parašyta kompiuterinė programa, realizuota pasitelkiant procedūrinio programavimo paradigma bei programavimo klaba C# (MS Visual Studio aplinka). Gauti rezultatai atspindėti kiekybiškai tiriant, betono senėjimo koeficiento kitimą, įtempių kitimą, deformacijų kitimą laiko atžvilgiu. Gautų sprendinių korektiškumas patikrintas su Ghali et.al 2002 knygoje pateiktais sprendiniais betono senėjimo koeficientui. Darbe pasiūlytos apytikslės formulės leidžiančios nustatyti gelžbetoninio elemento senėjimo koeficientą pagal betono senėjimo koeficientą, gautą sprendžiant betono relaksacijos uždavinį. Tai leidžia daug tiksliau nustatyti betono įtempių kaitą nei EC-2 priimama senėjimo koeficiento reikšmė - 0.8. Paklaidų sumažinimimas, įvertinant betono įtempių kaitos istoriją, lemia tikslesnį įlinkių prognozavimą bei armatūrinio plieno taupymą išanksto įtempto gelžbetoninio konstrukcijose. Darbą sudaro skyriai: įvadas, betono elgsena esant trumpalaikei ir ilgalaikei apkrovai, teorinė uždavinio formuluotė, pasiūlytas skaitinis modelis, analitinis modelis, skaitinio modelio realizacija, senėjimo koeficiento skaičiavimas ir... [toliau žr. visą tekstą]
In the thesis, the numerical model for reinforced concrete time dependent stress – strain analysis has been proposed. Volterra‘s integral equation serves the basis to resolve the pure relaxation task of plain concrete element as well as predicting the stress development history in analysis of reinforced concrete uniaxialy loaded column. The calculations were conducted by an original computer code written using C# programming language (MS Visual Studio surrounding) according to the procedural programming technique. The results has been reflected studying the change in the time-dependent stresses of concrete as well as evaluating the coefficient of ageing and strains development with time. The correctness of the results obtained was verified with the results given in Ghali et.al 2002 book in terms of the concrete ageing coefficient resulted from the pure relaxation task. In the thesis, the approximate expressions for description of the reinforced concrete ageing coefficient using the plain concrete coefficient of ageing, obtained from relaxation task, were also proposed. This allows us to determine the concrete stresses in more accurate way than EC-2 approximate approach based on value of 0.8 for the ageing coefficient. These approximations enables the reduction of errors, more proper evaluation in the concrete stress history and deflections as well as can economize the reinforcement quantity in the prestressed concrete structures. The Thesis involves the following chapters:... [to full text]

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2

Honorio, de Faria Tulio. "Modelling Concrete Behaviour At Early-Age : Multiscale Analysis And Simulation Of A Massive Disposal Structure". Thesis, Cachan, Ecole normale supérieure, 2015. http://www.theses.fr/2015DENS0045/document.

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La prédiction précise du comportement à long et court terme des structures en béton dans le domaine nucléaire est essentielle pour assurer des performances optimales (intégrité, capacité de confinement) pendant leur durée de vie. Dans le cas particulier des structures massives en béton, la chaleur produite au jeune âge par les processus d'hydratation ne peut pas s’évacuer rapidement, si bien que des températures élevées peuvent être atteintes et les gradients de température qui en résultent peuvent conduire à la fissuration, en fonction des conditions aux limites et contraintes internes auxquelles ces structures sont soumises. Les objectifs de cette étude sont (1) d'effectuer des simulations numériques afin de décrire et prédire le comportement thermo-chimio-mécanique au jeune âge d'une structure massive en béton dédiée au stockage de déchets en surface, et (2) de développer et appliquer des outils de changement d'échelle pour estimer rigoureusement, à partir de la composition du matériau, les propriétés physiques du béton nécessaires à une analyse au jeune âge. Une étude chimio-thermique visant à déterminer l'influence de la convection, du rayonnement solaire, du re-rayonnement et de la chaleur d'hydratation sur la réponse thermique de la structure est tout d’abord menée. Des recommandations pratiques concernant les températures de bétonnage sont fournies afin de limiter la température maximale atteinte au sein de la structure. Ensuite, au moyen d'une analyse mécanique, des stratégies de modélisation simplifiées et plus complexes (prenant en compte l’endommagement couplé au fluage) sont mises en œuvre pour évaluer des scénarios intégrant différentes conditions aux limites issues de l'analyse chimio-thermique précédente. Dans un second temps, une étude prenant en compte le caractère multi-échelle du béton est réalisée. Un modèle simplifié de cinétique d'hydratation du ciment est proposé. Les évolutions des fractions volumiques des différentes phases au niveau de la pâte de ciment peuvent être alors estimées. Par la suite des outils d’homogénéisation analytiques et numériques développés dans un cadre vieillissant sont présentés et appliqués pour estimer les propriétés mécaniques et thermiques des matériaux cimentaires. Les données d’entrée utilisées dans l'analyse structurelle sont finalement comparées avec les estimations obtenues dans l'analyse multiéchelle. Pour conclure, la stratégie proposée dans cette thèse vise à prédire le comportement des structures massives en béton à partir de la composition du béton au moyen d'une approche séquentielle: le comportement du béton est estimé via les outils de changement d’échelle, fournissant ainsi les données d'entrée pour l'analyse phénoménologique à l’échelle de la structure
The accurate prediction of the long and short-term behaviour of concrete structures in the nuclear domain is essential to ensure optimal performances (integrity, containment roperties) during their service life. In the particular case of massive concrete structures, at early age the heat produced by hydration reactions cannot be evacuated fast enough so that high temperatures may be reached and the resulting gradients of temperature might lead to cracking according to the external and internal restraints to which the structures are subjected. The goals of this study are (1) to perform numerical simulations in order to describe and predict the thermo-chemo-mechanical behaviour at early-age of a massive concrete structure devoted to nuclear waste disposal on surface, and (2) to develop and apply upscaling tools to estimate rigorously the key properties of concrete needed in an early-age analysis from the composition of the material. Firstly, a chemo-thermal analysis aims at determining the influence of convection, solar radiation, reradiation and hydration heat on the thermal response of the structure. Practical recommendations regarding concreting temperatures are provided in order to limit the maximum temperature reached within the structure. Then, by means of a mechanical analysis, simplified and more complex (i.e. accounting for coupled creep and damage) modelling strategies are used to assess scenarios involving different boundary conditions defined from the previous chemo-thermal analysis. Secondly, a study accounting for the multiscale character of concrete is performed. A simplified model of cement hydration kinetics is proposed. The evolution of the different phases at the cement paste level can be estimated. Then, analytical and numerical tools to upscale the ageing properties are presented and applied to estimate the mechanical and thermal properties of cementbased materials. Finally, the input data used in the structural analysis are compared with the estimations obtained in the multiscale analysis. To conclude, the entire strategy proposed in this thesis aims at predicting the behaviour of massive concrete structures from the composition of the concrete by means of a sequenced approach: concrete behaviour is estimated using the upscaling tools, providing then the input data to the phenomenological analysis at the structure level

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Edwards, Ylva. "Influence of waxes on bitumen and asphalt concrete mixture performance". Doctoral thesis, KTH, Väg- och banteknik, 2005. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-553.

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This doctoral thesis consists of a literature review, presented in two papers, and another six papers describing experimental studies of the influence of different kinds of wax and polyphosporic acid on bitumen and asphalt concrete mixture properties. The literature review should give an extensive description of the field of knowledge concerning wax in bitumen. Effects of wax in crude oil, bitumen and asphalt concrete as well as test methods for studying these effects are described. Theories behind possible mechanisms are also discussed, and commercial wax as additive to bitumen for different purposes included. The experimental parts comprise laboratory studies involving totally five 160/220 penetration base bitumens from different sources, two isolated bitumen waxes, five commercial waxes and one polyphosphoric acid. Asphalt concrete slabs, containing base or modified bitumen were prepared and tested. Binder properties were evaluated using different types of laboratory equipment, such as dynamic shear rheometer (DSR), bending beam rheometer (BBR), differential scanning calorimeter (DSC), force ductilometer, as well as equipment for determining conventional parameters like penetration, softening point, viscosity, and Fraass breaking point. Fourier Transform Infrared (FTIR) spectroscopy and Thin Layer Chromatography (TLC-FID) were used for chemical characterization. The binders were aged by means of the rolling thin film oven test (RTFOT) and pressure ageing vessel (PAV) in combination. Asphalt concrete properties were evaluated at low temperatures using the tensile strain restrained specimen test (TSRST) and creep test at -25°C. Dynamic creep testing was performed at 40°C, as well as complex modulus tests between 0 and 20°C. Binder test results indicated that the magnitude and type of effect on bitumen rheology depend on the bitumen itself, type of crystallizing fraction in the bitumen and/or type and amount of additive used. Bitumen composition was found to be of decisive importance. Adding polyethylene wax or polyphosphoric acid, especially to a non-waxy 160/220 penetration grade bitumen, showed no or positive effects on the rheological behaviour at low temperatures (decrease in stiffness) as well as medium and high temperatures (increase in complex modulus and decrease in phase angle). However, the corresponding positive effects could not be shown in dynamic creep testing (at 40°C) of asphalt concrete mixtures containing these modified binders. Adding FT-paraffin decreased the physical hardening index for all bitumens. Also polyethylene wax and montan wax showed this effect for some bitumens. Slack wax showed a large increasing effect on physical hardening, and polyphosphoric acid none or a minor negative effect. No correlation between physical hardening index (PHI) and wax content by DSC was found in this study, involving both natural bitumen wax and commercial wax. Addition of the commercial waxes used showed no or marginally positive influence on bitumen ageing properties for the bitumens and test conditions used. Comparing asphalt mixture test results to the corresponding binder test results, the effects on asphalt mixtures from adding commercial wax or polyphosphoric acid were less evident. Significant binder physical hardening by BBR could not be confirmed by TSRST.
QC 20101006

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Horák, Marek. "Analýza stárnutí vybraných materiálů stokových sítí". Doctoral thesis, Vysoké učení technické v Brně. Fakulta stavební, 2014. http://www.nusl.cz/ntk/nusl-233817.

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The doctoral thesis deals with analysis of the ageing of concrete and reinforced concrete pipes in sewage systems. The ageing of the sewage system is caused by several reasons, for example material abrasion, chemical and biological corrosion and subsequent static overload sewer construction. One of the common causes of degradation of sewage systems made from materials bonded with cement sealant is biogenic sulphate corrosion. Due to the corrosion the degradation of the pipe walls accelerates, particularly in upper part of the pipe and reduces planned lifetime of the sewage system. There is proposed new ageing analysis monitoring method for observation and evaluation of the loss of thickness of concrete and reinforced concrete pipes, which is caused by biogenic sulphate corrosion. Residual lifetime is calculated from the expected corrosion rate, it`s the loss of wall thickness on the monitored section of the sewer system. There is designed the monitoring system of the loss of wall thickness on the sewage system for practical application of the measurement procedure, which is administrated in cooperation with the BVK, a. s. The thesis uses existing knowledge regarding this subject. We use this information for better understanding of the process of the loss of wall thickness in sewage systems in real time and the posibility to correct and in-time implementation of appropriate operational measures. This should cause the limitation of the degradation process of piping material while extended service life and safe operation in sewage systems within the required time period. Based on the methodology is proposed to determine the residual life of the sewage system and maintenance and rehabilitation can be done more effectively. There is needed to be noted that only long-term monitoring period can bring a better overview of the technical condition of sewage systems in time and thus better and more effective maintenance and rehabilitation, which is related to the effective u

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Staškus, Ignas. "Įtempių ir deformacijų būvis kintamai apkrovai laiko atžvilgiu". Master's thesis, Lithuanian Academic Libraries Network (LABT), 2014. http://vddb.library.lt/obj/LT-eLABa-0001:E.02~2014~D_20140619_161144-46488.

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Monolitinio pastato įrąžoms skaičiuoti, projektuotojas kurdamas pastato skaičiuotinį modelį, jį traktuoja kaip ,,akimirksniu“ pastatytą. Pastato statybos metu nuolatinė apkrova nuo perdangų savojo svorio, auga palaipsniui, betonuojant aukštą po aukšto, kol galiausiai, užbetonuojamas paskutinis aukštas. Darbe pasiūlytas ir skaitiškai realizuotas modelis, įvertinantis betono ir armatūros įtempių bei deformacijų kitimo istoriją dėl laike palaipsniui augančios apkrovos nuo perdangų savojo svorio. Darbe taikomas superpozicijos principas betono valkšnumo deformacijoms, atsižvelgiant į Volterra lygtį. Pasiūlyta matematinė formuluotė pagrįsta matriciniu skaičiavimu ir apibendrintąja funkcijos vidurkio teorema taikant betono valkšnumui. Skaitiniu būdu gauti rezultatai patikrinti analitiškai. Modelis pritaikytas daugiaaukščio pastato papildomų šlyties jėgų perdangose, atsirandančių dėl gretimų kolonų skirtingų poslinkių vystymosi per laiką radimui. Gauti rezultatai patikrinti su apytikslio skaičiavimo rezultatais, taikant normų EC-2 reikalavimus betono valkšnumo deformacijoms. Perdangų praspaudimą kolona, kai pastarosios yra greta pastato standumo branduolių, kurių deformatyvumas yra ženkliai mažesnis, reiktų tikrinti atsižvelgiant į papildomas šlyties jėgas, atsirandančias dėl betono susitraukimo ir valkšnumo įtakos. Darbo apimtis – 99 p. teksto, 54 iliustr., 12 lent. ir 9 literatūros šaltiniai. Atskirai pridedami priedai.
The designer calculates a building as an instantly built. However, during construction the permanent load is increasing gradually because the floors are built step by step. This paper introduces a numerically implemented mathematical model for the column analysis accounting for the stress and strain change in reinforcement and concrete with time due to the increasing in time permanent loads induced by the self-weight of each slab during construction. The mathematical formulation is based on the superposition principle for the creep strain described by Volterra's integro-differential equation and involves a matrix solution of linear equations derived via application of the generalized mean theorem for integration. The results obtained are also verified analytically. Finally, the proposed model is applied to calculate extra shear forces caused by the deflections appearing to the adjacent columns of different cross-sections. The results obtained are also compared with the approximate calculation treating the building as an instantly built. The results indicate that additional shear forces due to different displacements of the adjacent columns are quite mild. However, the additional shear forces can be sufficiently high, if the column is located near the high stiffness walls in a non-sway building. In this case, the extra shear forces should be determined via time-dependent analysis accounting on the creep and shrinkage strains relying on the gradually increasing load during... [to full text]

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Tchetgnia, Ngassam Inès Leana. "Durabilité des réparations des ouvrages d'art en béton". Phd thesis, Université Paris-Est, 2013. http://tel.archives-ouvertes.fr/tel-00981689.

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Près de la moitié des réparations réalisées sur les ouvrages en béton se concluent par un échec prématuré. Cela se traduit principalement par le décollement de la couche réparatrice, dû à un manque d'adhérence de cette couche sur le support dégradé, et par la corrosion des armatures métalliques de la structure. C'est ainsi que l'Europe consacre la moitié du budget alloué à la construction à la réhabilitation des ouvrages. Deux types de produits de réparation sont principalement proposés sur le marché, les mortiers hydrauliques et les mortiers modifiés par des polymères. Les propriétés intrinsèques de ces produits sont connues mais peu d'études portent sur l'évolution de ces propriétés à long terme, notamment lorsque les matériaux sont appliqués sur un support en béton dégradé. L'objectif de cette thèse est de mieux comprendre l'influence de la présence de polymère dans les mortiers sur la durabilité des réparations des ouvrages d'art en béton. Pour mener à bien cette étude, des mortiers modifiés de formulation connue et contrôlée ont été préparés en laboratoire à partir de l'analyse de la composition de plusieurs produits de réparation commerciaux. Les propriétés intrinsèques à l'état frais et durci de ces deux types de matériaux ont été analysées, en s'intéressant notamment à l'influence de la nature et de la teneur en polymères et à l'influence de la cure appliquée sur ces matériaux. L'augmentation de la quantité de polymère entraîne l'accroissement des propriétés mécaniques des mortiers. Cet effet est surtout visible en flexion car les polymères viennent renforcer l'interface granulat-liant. La cure des mortiers à 40°C permet d'améliorer leurs performances mécaniques et de diminuer leur porosité car dans ces conditions, la formation de films de polymère entremêlés aux hydrates de ciment est favorisée. Un essai a également été développé pour mesurer l'adhérence des mortiers sur un support représentant le béton à réparer. L'influence de la présence de polymère et de l'état de surface du support sur l'adhérence a été analysée, ainsi que l'évolution de l'adhérence pendant la conservation des éprouvettes dans des environnements différents. Ces essais ont permis de montrer que l'addition de polymère permettait d'augmenter l'adhérence des mortiers contenant des polymères par rapport aux mortiers non-modifiés. Après trois mois de durcissement, l'adhérence maximale est obtenue à partir de 10% de polymère. L'augmentation de la rugosité et la saturation en eau du support n'ont pas entraîné d'augmentation de l'adhérence par rapport aux surfaces sèches et planes. Comme pour les propriétés intrinsèques des mortiers modifiés, une cure à 40°C permet d'améliorer l'adhérence alors qu'une immersion dans l'eau est défavorable. Enfin, le risque de corrosion des armatures enrobées de mortiers modifiés a été étudié en caractérisant les propriétés électrochimiques des aciers ainsi que les propriétés de transfert d'espèces agressives dans les mortiers. L'addition de polymères dans les mortiers renforce la protection des armatures métalliques grâce à leurs propriétés d'isolant électrique. Dans la plupart des cas, ils limitent également la diffusion du CO2 et des ions chlorure dans le matériau

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Bichet, Lionel. "Mécanismes de transports dans la fissuration des matériaux hétérogènes : application à la durée de vie d’exploitation des centrales nucléaires". Thesis, Montpellier, 2017. http://www.theses.fr/2017MONTS001/document.

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Les propriétés du béton constituant les enceintes de confinement des centrales électronucléaires évoluent sous les effets de mécanismes de vieillissement résultant notamment de transferts couplés de chaleur et de masse au sein du matériau. Ces phénomènes peuvent être modélisés par des équations de transports moyennées : lois de Fick pour le transport d’espèces en solution et lois de Fourier pour la description de la diffusion thermique. Dans cette étude, les développements concernent la diffusion de la thermique dans un milieu hétérogène fissuré représentant un matériau cimentaire dégradé chimiquement. Le problème thermo-mécanique est traité à l'aide d'une approche multi-corps reliés par des lois d’interactions enrichies (zones cohésives). La diffusion thermique est écrite dans le formalisme cohésif-volumique en prenant en compte le couplage entre un état d'endommagement local de la zone cohésive et une conductivité homogénéisée. Afin d'optimiser les coûts de calculs, une étude est menée sur la dimension d'un volume élémentaire représentatif (VER). Pour cela, la méthode d'eigenerosion est étendue à la fissuration de milieux hétérogènes puis appliquée aux milieux cimentaires. La propagation de fissures sous chargement thermique est ensuite analysée dans des VERs de béton dégradés représentatifs des enceintes de confinement des centrales nucléaires après plusieurs années. Le vieillissement est modélisé par un taux de pré-dégradation initial entre le mortier et les granulats. Le développement de multi-fissures est relié au taux de pré-dégradation et la formation "d'écrans" à la diffusion de la thermique est mise en avant
During their confinement in a nuclear power plant, the mechanical properties of the constitutive materials of concrete change as a result of ageing. This is due to the transportation of chemical species at the microscopic level of the media. Firstly, this can be modelled with average equations. The Fick laws represent the evolution of chemical diffusion and the Fourier laws, the transportation of heat at a mesoscopic level. In this research, we will consider thermal evolution on a fractured media.This thermomechanical problem is solved with a staggered method. The mechanical contribution used an approach based on multi-bodies system linked with cohesive zone models. The thermal problem is based on the approximation of the heat transfer equation at the cohesive interface. This approach has been implemented and validated. The description of the heat trough the interface is composed with the definition of an homogenised conductivity and the local damage parameter. In order to optimize the computational cost with a good agreement of the crack propagation, a criterion is proposed for sizing a representative elementary volume (REV). The eigenerosion method is used, validated and extended to heterogeneous media. Two studies are carried out on the morphological properties on a cementious media. As a result of those studies, a minimal size for a REV is defined.Crack spread under thermal loads are investigated on a media representing the concrete of the containment of a nuclear power station. The ageing effect are taken into account as an initial damage between the mortar and the aggregates. These parameters are expressed in terms of rate of initial damage. A study is proposed for different values of this rate. As assumed, the development of multi-cracks is linked with the rate of initial damage and the creation of thermal border is proposed

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Bouhjiti, David El Mahdi. "Analyse probabiliste de la fissuration et du confinement des grands ouvrages en béton armé et précontraint". Thesis, Université Grenoble Alpes (ComUE), 2018. http://www.theses.fr/2018GREAI058/document.

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Abstract (sommario):

Cette thèse porte sur le vieillissement des grands ouvrages en béton armé et précontraint dotés d’une fonction de confinement comme les bâtiments réacteurs des centrales nucléaires. Elle vise en particulier l'analyse probabiliste de l’évolution de leurs états de fissuration et de perméabilité dans le temps sous chargements Thermo-Hydro-Mécaniques (THM) simultanés et variables. L’étanchéité de telles structures est due à la faible perméabilité du béton mais reste conditionnée surtout par la maîtrise de la fissuration. Or, l'évolution de la perméabilité, l'apparition des fissures et leur propagation dépendent fortement de plusieurs aléas (les conditions de mise en œuvre, la variabilité spatio-temporelle des propriétés du béton et des chargements THM subis par la structure, etc.). Ainsi, la prise en compte de ces aléas dans les modèles numériques de vieillissement est une nécessité afin de permettre une meilleure évaluation de la performance de la structure dans son état présent et, surtout, permettre une prévision plus précise et plus fiable de son état futur. Pour y parvenir, cette thèse propose une stratégie globale de modélisation stochastique Thermo-Hydro-Mécanique avec post-traitement de la Fuite (THM-F), à l’échelle de Volumes Structurels Représentatifs, adaptée à la complexité du problème traité, au nombre important de paramètres THM-F intervenant dans les calculs et à son coût numérique. En particulier, les points suivants sont traités :(a) Modélisation du vieillissement tenant compte des effets de jeune âge : La modélisation des phénomènes de vieillissement est basée sur un modèle THM-F chaîné. En particulier, la modélisation proposée de la fissuration repose sur le couplage des lois d’échelle énergétique et des champs aléatoires autocorrélés selon une formulation locale, régularisée et vieillissante de l’endommagement. Cela permet une meilleure évaluation du risque de fissuration tant d’un point de vue qualitatif que quantitatif. Par conséquent, la prévision de l’étanchéité est aussi améliorée.(b) Identification des paramètres THM-F les plus influents : En appliquant une méthode d’analyse de sensibilité de type OFAT (One-Factor-At-a-Time) au modèle THM-F retenu, l’effet de la variabilité des différents paramètres en entrée sur la réponse numérique est quantifié. Cela permet de hiérarchiser les effets et de classifier les paramètres selon leur importance vis-à-vis du vieillissement (particulièrement en termes de fissuration et d’étanchéité).(c) Analyse de la propagation d’incertitudes THM-F : Des méthodes basées sur les surfaces de réponse (plans d’expérience adaptatifs, chaos polynomiaux) sont proposées pour construire des méta-modèles THM-F et analyser la propagation d’incertitudes moyennant un coût et une précision raisonnables. Étant donné la nature explicite des méta-modèles, la méthode de Monte Carlo est directement appliquée pour accéder à des fonctions de répartition, des indicateurs de sensibilité globaux et des analyses de fiabilité.L’applicabilité du modèle stochastique THM-F proposé aux grands ouvrages de confinement en béton armé et précontraint est évaluée en se basant sur la maquette VeRCoRs (enceinte de confinement à l’échelle 1 :3) selon des critères de représentativité physique du comportement et des mesures d’incertitudes simulés et de coût numérique
Concrete is a heterogeneous, multiphasic and ageing material. Consequently, its properties show intrinsically spatiotemporal variations. For large reinforced and prestressed concrete structures such as Nuclear Containment Buildings (NCB), these variations directly affect the kinetic of their ageing process in terms of cracking, drying, creep and tightness. They also lead, within the structure's volume, to a non-negligible spatial heterogeneity of the concrete's behavior to the applied Thermo-Hydro-Mechanical (THM) loads during the operational lifespan. Consequently, the introduction of such variations in numerical models is a mandatory step to enhance the assessment of these structures’ present behavior and the accuracy of predictive analyses of their future one. With that aim in view, the thesis suggests a global coupling strategy of THM-L models (Thermo-Hydro-Mechanical with Leakage estimation) and non-intrusive stochastic approaches adapted for the strongly non-linear and time consuming simulations of ageing phenomena and the large number of inputs they require. Applied to the VeRCoRs mock-up (1:3 scaled containment building) at the scale of Representative Structural Volumes (RSV), this thesis addresses the following issues:(a) RSV-based modeling of concrete ageing from the early age phase: The modeling of concrete’s ageing is based on a staggered Thermo-Hydro-Mechanical with Leakage evaluation (THM-L) strategy. In particular, concrete cracking is modeled according to a Stochastic Size Effect Law (SSEL) and a regularized, local, ageing and damage-based constitutive model. The spatial heterogeneity of the concrete's properties (mainly the Young's modulus) is described using Random Fields (RF). This leads to a better description of concrete cracking both qualitatively and quantitatively. Accordingly, the modeling of the structural tightness is also improved.(b) Most influential THM-L parameters: Using a 1st order sensitivity analysis strategy (One-Factor-At-a-Time OFAT perturbation method), the relative effect of the THM-F parameters on the computed behavior is quantified. The obtained results show a hierarchized list of the most influential parameters and their associated physical phenomena. A selection is then achieved to keep relevant parameters only for uncertainty propagation step and higher-order sensitivity analyses throughout the THM-L coupling path.(c) Uncertainties propagation through THM-L calculation steps: Surface Response Methods (SRM) are used to define the associated RSV-based THM-L meta-models. For the stochastic modeling of concrete’s cracking an original Adaptive-SRM-based algorithm is suggested. Whereas for continuous THM-L quantities, a Polynomial Chaos based strategy is retained. Finally, as the meta-models are explicit within a defined and bounded domain, crude Monte Carlo Method is applied, at low cost, aiming at the CDFs and the reliability analysis of the considered variables of interest.Eventually, the suggested SFEM shall lead operators to a better quantification of uncertainties related to the behavior of their strategic civil engineering structures. This remains a crucial step towards the enhancement of durability assessment and repair/maintenance operations planning

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9

Pedro, Rudimar. "Produção de blocos de concreto celular usando espumígeno de ácidos graxos de coco e resíduos de pedras roladas de ágata". reponame:Biblioteca Digital de Teses e Dissertações da UFRGS, 2017. http://hdl.handle.net/10183/163466.

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Abstract (sommario):

O estado do Rio Grande do Sul é o terceiro maior produtor de pedras preciosas do Brasil, atrás apenas de Minas Gerais e da Bahia, destacando-se a produção de ágatas na região de Salto do Jacuí. Na lavra e beneficiamento são produzidos grandes quantidades de resíduos que estão a espera de destino e utilização ambientalmente correta. De modo específico, este trabalho avaliou a possibilidade de utilização do resíduo de ágata rolada na fabricação de blocos de concreto celular espumígeno (BCCE), utilizados como blocos de vedação na construção civil. Adicionalmente, desenvolveu-se uma mistura de dois agentes espumígenos provenientes de ácidos graxos de coco, como agente incorporador de ar, pela adição de espuma pré-formada. A metodologia de produção foi baseada no modelo de produção dos blocos de uma pequena indústria na Região de Passo Fundo/RS, que produz e comercializa BCCE. Em um estudo prévio de bancada, foram estudadas a composição da espuma, a granulometria do resíduo, o teor de água e o tempo de mistura. Os materiais componentes do BCCE são resíduo de sílica de pedras roladas de ágatas (SiO2 - 92,5%), espuma preparada com ácidos graxos de coco, água de qualidade potável e cimento como agente aglomerante. Nos testes de bancada, foram confeccionados 36 corpos de prova, em forma cilíndrica, de tamanho 50 mm de diâmetro por 100 mm de altura, com diferentes volumes de ar incorporado, divididos em três grupos. As amostras foram deixadas durante 28 dias à temperatura ambiente, em processo de cura, e após foram analisados quanto à resistência à compressão, densidade e distribuição das bolhas de ar. Os resultados foram avaliados pela Análise de Variância e demonstraram que o Grupo II apresentou densidade de 430 Kg/m3, e resistência de 0,92 MPa. Este resultado está próximo do atendimento aos requisitos da norma para classe de resistência de < 400 Kg/cm3 (NBR 13438, 2013).
The state of Rio Grande do Sul is the third largest producer of gemstones in Brazil, only losing to the states of Minas Gerais and Bahia, and agate production stands out in the region of Salto do Jacuí. Great amounts of waste, which are waiting for environmentally correct destination and use, are produced in mining and processing. Particularly, this study assessed the potential use of rolling waste of agates in civil construction, and the manufacturing of foam concrete blocks as a full substitute for sand. Additionally, a mixture was made of two foaming agents derived from coconut fatty acids as air-developer agent, and as hydraulic binder the Portland CP V ARI-RS cement. The production methodology was based on the production model of the blocks in a small industry, which produces and sells foam concrete blocks in the region of Passo Fundo, RS, Brazil. In a previous bench study the parameters foam composition, residue granulometry, water content, and mix time were adequate and later replicated industrially. The materials composing foam concrete blocks are rolled agate stones silica (SiO2 – 92.5%), foam from coconut fatty acids, fresh water, and cement as binder. In bench tests, 36 cylindrical specimens were produced, with 50 mm of diameter and 100 mm of height, with different volumes of incorporated air, divided into three groups. The samples were kept at room temperature for 28 days with healing process, and after that, the resistance to compression, density, and air bubbles distribution were analyzed. Results were assessed by Analysis of Variance, and showed that Group II presented density of 430 Kg/m3 and resistance of 0.92 MPa. This result is close to meeting the requirements of the norm for resistance class of < 400 Kg/cm3 (NBR 13438, 2013).

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Alachek, Ibrahim. "Comportement au cours du temps des éléments de structure multi-matériaux collés : application aux structures hybrides béton – GFRP". Thesis, Lyon, 2018. http://www.theses.fr/2018LYSE1111/document.

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Ce travail porte sur l'étude des comportements en flexion à court et long termes des poutres hybrides collées constituées d'un profilé pultrudé GFRP et d'une dalle en béton, assemblés par un joint de colle époxy. L'utilisation du collage dans des structures réelles se heurte encore à la réticence des concepteurs en raison du manque de garanties sur la durabilité à long terme et de l'absence d'outils de modélisation donnant la durée de vie en service des assemblages collés. La présente étude constitue donc un jalon dans cette démarche de compréhension du comportement à long terme de ces structures collées. Elle s'appuie sur analyse multi-échelles qui permet d'aborder le problème à l'échelle locale de l'interface (essai pushout) et à l'échelle globale de l'élément de structure (essai de flexion sur des poutres). Des essais de vieillissement accéléré ont tout d'abord été conduits pour étudier les effets de l'humidité et de la température sur l'adhésif seul et sur l'assemblage structural et il en ressort que l'eau, et notamment une immersion prolongée, s'avère particulièrement néfaste à la résistance au cisaillement des éprouvettes et modifie leur mode de ruine. La réponse instantanée de l'assemblage pultrudé-béton a ensuite été plus amplement étudiée. Grâce à une étude paramétrique expérimentale, une géométrie et une méthode de fabrication des éprouvettes ont été définies pour assurer la reproductibilité des résultats et limiter leur dispersion. De plus, un modèle numérique 3D a été développé dans le code d'éléments finis Cast3m et montre une distribution de contraintes, notamment de cisaillement, non uniforme le long de la surface de collage avec une concentration aux extrémités du joint. Une analyse paramétrique numérique a permis d'identifier les dimensions des dallettes et du joint de colle comme des paramètres influents sur la résistance des éprouvettes. Enfin, le comportement en fluage d'une poutre hybride est étudié. Sous l'effet d'un vieillissement naturel, seul, le joint d'adhésif ne s'avère pas impacté. Des essais de fluage en flexion 3-points ont été effectués pour étudier les réponses à long terme du profilé seul et de la poutre hybride. Ils montrent une augmentation considérable du déplacement des poutres en raison du fluage et du retrait du béton et du fluage du profilé. Des modèles 3D en variables locales, dans le cadre de la viscoélasticité linéaire, sont développés dans Cast3m et permettent de fidèlement restituer l'évolution des déplacements et des états de déformation au cours du temps pour les différentes poutres testée
This dissertation focuses on the short- and long-term responses of bonded hybrid beams consisting of a GFRP-pultruded profile bonded by an epoxy adhesive joint to a reinforced concrete-slab. The problems related to the durability and the long-term response of these structures still represent an open issue. The present study is meant to increase the knowledge and understanding of these hybrid structures in this context. Firstly, different accelerated ageing tests were carried out to evaluate the effects of some environmental agents such as water, moisture and freeze thaw cycles in the behaviour of GFRP/concrete bonded assemblies. Mechanical characterizations were carried out on control and exposed of both materials and push-out specimens to quantify the degradation and damage of the mechanical resistance of each material and of the adhesive bond properties. The water effect on the adhesion of the joints was found to be significant, especially at longer immersion times. The second part was directed at characterizing the push-out test. An experimental parametric study was performed to elaborate a methodology of fabrication of the push-out specimens that can reduce the dispersion of results and give an accurate prediction of the shear strength on a limited set of specimens. Also, a 3D finite-element model was developed using the finite-element code Cast3m. This model showed that the stress components, especially peel and shear stresses, are not constants across the bonding area and peaking near the free edges (stress concentrations). A numerical parametric study allowed to conclude that the most effective geometrical parameters influencing bond between GFRP and concrete were the bonded length and the dimensions of the concrete substrate. Last part deals with experimental and numerical investigations carried out to study the short- and long-term flexural behaviour of full-scale hybrid beams. All experiments showed considerable increase in beam deflection over time due to concrete creep and shrinkage and GFRP creep. Finally, 3D-finite-element models, realized with Cast3m, are developed based on the incremental formulation of the linear-viscoelasticity theory. The proposed models allow evaluation of the long-term deflection of the pultruded and hybrid beams. Using the proposed model, evolution with time of stresses, strains and displacements in different location of the hybrid beam are obtained

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11

Agouzal, Eki. "Réduction de modèles en mécanique non-linéaire quasi-statique pour l'estimation de l'état par recalage en assimilation de données : application aux enceintes de confinement". Electronic Thesis or Diss., Bordeaux, 2024. http://www.theses.fr/2024BORD0075.

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Dans le domaine de la gestion du parc nucléaire, Electricité de France (EDF) s’efforce d’assurer une compréhension exhaustive de l’état mécanique des enceintes de confinement de ses centrales. Une attention particulière est portée à l’évaluation des taux de fuite à travers les enceintes de confinement à double paroi. Pour atteindre cet objectif, d’importants travaux de recherche ont été entrepris, visant à développer des modèles thermo-hydro-mécaniques (THM) de haute robustesse, spécialement conçus pour la modélisation du vieillissement de ces imposantes structures en béton précontraint. Une étape cruciale consiste à coupler ces modèles à des méthodologies d’optimisation avancées, notamment l’assimilation de données. L’objectif des ingénieurs est d’incorporer les données existantes du parc nucléaire dans ces modèles numériques afin d’obtenir les paramètres physiques optimaux. Cette approche permet de générer des simulations numériques qui reflètent au mieux la réalité observée. Cependant, de tels algorithmes peuvent nécessiter des calculs répétés qui peuvent rendre son coût prohibitif. Dans cette optique, cette thèse vise à développer des méthodes de réduction de modèles pour les problèmes de mécanique non linéaire avec variables internes, ainsi qu’à concevoir des algorithmes permettant de coupler ces méthodologies d’assimilation de données aux modèles réduits, en vue d’accélérer le temps de résolution tout en préservant une qualité d’approximation adéquate. En se basant sur les équations caractéristiques de ces problèmes et sur le contexte industriel, spécifiquement le traitement des problèmes de mécanique non-linéaire quasi-statique avec variables internes dans le code de qualité industrielle code_aster, nous détaillons la mise en place d’un modèle réduit par projection utilisant la Proper Orthogonal Decomposition (POD). Cette construction d’une approximation linéaire est ensuite combinée à un processus d’hyper-réduction à travers la méthode ECSW. Dans un second temps, nous avons étendu cette méthodologie à un cas industriel spécifique, à savoir une section courante de l’enceinte de confinement d’une centrale nucléaire. Ce cas implique un matériau nécessitant une modélisation multiple (non linéaire tridimensionnelle pour le béton et linéaire unidimensionnel pour l’acier) avec un comportement mécanique thermo-hydro activé. De plus, nous avons élaboré des algorithmes basés sur les régions de confiance pour aborder des problèmes d’assimilation de données variationnelle en utilisant des modèles réduits. Nous proposons une validation sur des cas en élasticité et des premiers pas sur des cas en mécanique non-linéaire avec code_aster. Enfin, nous proposons des méthodes visant à accélérer les processus itératifs mettant en jeu les modèles réduits que nous avons conçu. Cela inclut le développement d’un processus d’hyper-réduction incrémental ou encore une approche bi-fidélité pour le sampling de l’espace paramétrique
In the field of nuclear power plant management, Electricité de France (EDF) strives to ensure acomprehensive understanding of the mechanical state of the nuclear containment buildings (NCBs). Specialemphasis is placed on evaluating leakage rates through double-walled NCBs. To achieve this objective,major research work has been undertaken to develop highly robust thermo-hydro-mechanical (THM) models,specially designed to model the ageing of these large pre-stressed concrete structures. A pivotal phase involvesthe integration of these models with advanced optimization methodologies, particularly data assimilation.The engineers aim to incorporate existing data from the nuclear fleet into these numerical models to obtainoptimal physical parameters. This approach enables the generation of numerical simulations that reflectobserved reality as closely as possible. However, such algorithms can require repeated calculations, which canmake them prohibitively expensive. With this in mind, this thesis aims to develop model reduction methodsfor nonlinear mechanics problems with internal variables, as well as to design algorithms for coupling thesedata assimilation methodologies to reduced models, with a view to accelerating solution time while preservingadequate approximation quality. Drawing upon the characteristic equations governing these issues andconsidering the industrial framework, specifically the treatment of quasi-static non-linear mechanics problemswith internal variables using the industrial-grade code code_aster, we elaborate on the implementation of aprojection-based reduced model employing Proper Orthogonal Decomposition (POD). This construction of alinear approximation is then combined with a hyper-reduction process using the ECSW method. In a secondstep, we have extended this methodology to a specific industrial case, namely a standard section of a NCB. Thiscase involves a multi-modeling material (three-dimensional nonlinear for concrete and one-dimensional linearfor steel) featuring thermo-hydro-activated mechanical behavior. Moreover, algorithms based on trust-regionshave been devised to address variational data assimilation problems relying on reduced order models. Wepropose validation on elasticity cases and first steps on nonlinear mechanics cases with code_aster. Finally,we introduce methods to expedite iterative processes involving the designed reduced models. These methodsencompass the development of an incremental hyper-reduction process and a bi-fidelity approach for samplingthe parametric space

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12

Jafferji, Hajar. "Incorporating cinnamaldehyde into concrete for corrosion mitigation". Digital WPI, 2017. https://digitalcommons.wpi.edu/etd-dissertations/59.

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Concrete structures can prematurely deteriorate due to the corrosion of reinforcing steel. Corrosion can occur through chloride ingress due to exposure to aggressive media such as seawater and deicing salts. Corrosion causes over $100 billion in damage annually. There are many corrosion mitigation techniques on the market today; these techniques have limited effectiveness as demonstrated by the fact that billions of dollars are still being expended each year due to corrosion-related damage. Therefore, there is a need for innovative approaches to corrosion prevention. This research program used cinnamaldehyde (CA), a bioactive agent derived from cinnamon bark, as a method for corrosion mitigation. Although CA can prevent the corrosion of metals, its hydrophobicity has a negative effect on hydration when incorporated in cementitious systems. In order to avoid these negative consequences while harnessing the anti-corrosive properties, CA was incorporated in a cementitious mixture through the use of lightweight aggregate (LWA). Several tests were carried out to investigate the potential chemical and mechanical effects due to the addition of LWA pre-wet with CA. Promising results were observed, in which the time to corrosion was prolonged by 91 %.

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13

Selander, Anders. "Hydrophobic Impregnation of Concrete Structures : Effects on Concrete Properties". Doctoral thesis, KTH, Brobyggnad inkl stålbyggnad, 2010. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-12179.

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Hydrophobic impregnations often referred to as water repellent agents, today mainly consisting of alkylalkoxysilanes, are often used on concrete to prolong the service life of the structure. This is accomplished by protecting the reinforcement bars from chlorides or by changing the moisture content inside. When the concrete is treated with a water repellent agent the properties of the surface layer becomes hydrophobic and thereby water droplets are stopped from entering, still allowing water vapour to pass through. This change can reduce chloride ingress and stop heavy rain from penetrating through the surface layer. This thesis presents results concerning how the properties of concrete are affected by a hydrophobic impregnation. Moisture transport and fixation in the surface layer of the concrete are studied as well as the secondary effects of more practical use such as the effect on chloride ingress, water absorption and humidity level. It also presents results on how the penetration depth and concentration of the water repellent agent (i) depend on a number of parameters, and (ii) affect the outcome of the treatment. Water repellent treatments on a number of different concrete structures in Stockholm, ranging from tunnel to high-rice building, are evaluated as well. The three most important factors for the penetration of any water repellent agent into concrete are time, porosity and degree of saturation. A semi-empirical equation is derived that gives an idea on how much these factors affect the efficient penetration depth of the water repellent agent. The depth and concentration have a major effect on the performance of the treatment. The moisture diffusion coefficient for a water repellent treated concrete is close to constant and not nearly as dependent on the relative humidity (RH) as for untreated concrete. Unlike untreated concrete, where capillary suction plays an important role for the moisture transport at high RH, the vapour transport is the dominant transport mechanism even at high RH for water repellent treated concrete. The moisture fixation is affected by a water repellent treatment and the effect is clearest at high moisture levels. The main reason for this is that the capillary porosity is affected by the treatment to a relatively high degree while the gel porosity to a large extent remains unaffected. A hypothesis is presented which suggests that the RH inside the concrete at the time of the treatment affects not only the depth and concentration but also in which range of pore radii the water repellent agent is present and active. The durability of hydrophobic impregnations can be divided into surface effects and in depth effects. The first is sensitive to the environmental and mechanical loadings and normally disappears within a year while the later can be long lasting if a sufficient depth is reached. Hydrophobic impregnations are not the answer to all problems in concrete related to moisture, but if correctly used it can prolong the service life of the structure which will lead to savings of natural resources and thus both economical and environmental savings for the community.
Vattenavvisande impregneringsmedel, som i dagsläget till största del består av alkylalkoxysilaner, används ofta på betong för att förlänga livslängden på konstruktionen. Detta syfte uppnås genom att armeringen skyddas mot klorider eller att fukthalten inuti betongen sänks. När betongen impregneras ändras ytskiktets fuktmekaniska egenskaper från hydrofila till hydrofoba vilket gör att vattendroppar kan stoppas medan vattenånga tillåts passera. Dessa förändrade egenskaper kan medföra att kloridinträngningen minskar och att kraftiga regn inte tränger genom det impregnerade skiktet. Denna avhandling presenterar resultat om hur betongen påverkas av en vattenavvisande impregnering. Fukttransport och fuktfixering i betongens ytskikt har undersökts men även sekundära effekter som kloridinträngning, vattenabsorption och förändring i fuktinnehåll vilka alla är av större praktisk nytta. Avhandlingen presenterar också resultat om vilka faktorer som påverkar impregneringens inträngningsdjup och koncentration samt vilken betydelse dessa har för funktionen. För att utvärdera impregneringars effekt i olika miljöer har ett stort antal objekt i Stockholm undersökts, innefattande olika konstruktioner från en tunnel till höghus. Impregneringens inträngningsdjup och koncentration har en avgörande betydelse för dess funktion. De tre viktigaste faktorerna för alla impregneringsmedels inträngning i betong är tid, porositet och fuktnivå. En semiempirisk ekvation har tagits fram där det framgår hur dessa tre faktorer påverkar det slutliga inträngningsdjupet för impregneringen. Till skillnad från obehandlad betong är transportkoefficienten för en impregnerad betong nästan oberoende av den relativa fuktigheten (RF) i omgivningen. Vid höga RF, där största delen av fukttransporten i obehandlad betong sker på grund av kapillärkrafter, är ångtransporten fortfarande den dominerande transportmekanismen i impregnerad betong. Fuktfixeringen i betong påverkas av en impregnering och effekten är störst vid höga RF. Det är dock tydligt att en viss mängd fukt finns inuti den impregnerade betongen. Detta kan förklaras med att största delen av kapillärporerna påverkas av impregneringen medan gelporerna förblir obehandlade. Resultaten indikerar också att fuktnivån vid impregneringstillfället avgör vilken del av porsystemet som kan behandlas och inte bara koncentrationen och inträngningsdjupet. Långtidsegenskaperna hos impregneringen kan delas upp i yt- och djupeffekt. Effekten på ytan avtar normalt sett inom ett år på grund av damm och partiklar, UV-ljus, slitage mm. Djupeffekten påverkas däremot inte av dessa faktorer och kan finnas kvar i decennier. Vattenavvisande impregneringar är inte lösningen på alla fuktrelaterade problem i betong, men om de används på rätt sätt så kan det förlänga livslängden på många konstruktioner. Detta leder till ett bättre hushållande med naturresurser och därmed både ekonomiska och miljömässiga besparingar för samhället.
QC20100715

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14

Donjuan, Jose. "Evaluation of bonding agent application on concrete patch performance". Thesis, Kansas State University, 2014. http://hdl.handle.net/2097/18669.

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Master of Science
Department of Civil Engineering
Kyle Riding
The durability of partial depth concrete repair is directly related to the bond strength between the repair material and existing concrete. The wait time effects of cementitous grouts, epoxy, acrylic latex, and polyvinyl acetate bonding agents were observed on bond strength. Three rapid repair materials were as a comparison to bond strength, as well as concrete samples with no bonding agents having dry conditions and saturated surface dry moisture condition. The bonding agents and rapid repair materials were tested in a controlled laboratory environment. Bond strength loss with wait times of 0, 2, 5, 10, and 30 minutes were observed when bonding agents were applied. The laboratory samples were loaded using a direct shear test. Field tests were performed using the same repair materials and bonding agents. When the agents were applied in the field the wait times used were 0, 15, 30, and 45 minutes. 7 day and 5 month pull off tensile tests were performed during the field experiment. The data from both experiments show that when using cement grout bonding agents the high bond strength can be obtained when the repair material is applied within 15 minutes of application of the cement grout, and after 15 minutes bond loss can be expected. Wait time didn't have a significant effect on epoxy and acrylic latex bonding agents as long as they were placed before setting. The polyvinyl acetate agent and repair materials can develop high bond strength in laboratory settings, but when used in the field the bond strengths experience loss. When not using bonding agents in a repair, adequate bond strength can be obtained when using saturated surface dry condition.

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Assali, Mirella Pennacchi. "Emprego de agentes retardadores em substituição aos desmoldantes convencionais na moldagem de concreto para recebimento do revestimento de argamassas". Universidade de São Paulo, 2012. http://www.teses.usp.br/teses/disponiveis/3/3146/tde-18072013-154420/.

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As estruturas de concreto são moldadas em formas tratadas com desmoldantes e sua presença dificulta a adesão da argamassa fresca, com posterior descolamento no estado endurecido. Este estudo tem por objetivo explorar o potencial de uso de agentes retardadores em substituição aos desmoldantes convencionais na moldagem de concreto para obtenção de superfícies com maior capacidade de ancoragem das argamassas. A viabilidade do uso de agentes retardadores foi verificada determinando-se de modo comparativo a resistência de aderência à tração da argamassa e do chapisco aplicados sobre corpos de prova de concreto moldados em formas de madeira plastificada tratadas com agente retardador e com desmoldante convencional. O ensaio de aderência mostrou que a utilização de agentes retardadores possibilita maior facilidade para a remoção da camada superficial do concreto, resultando em aumento de rugosidade e absorção superficial, permitindo maior resistência de aderência da argamassa e chapisco. Posteriormente, foram coletados agentes retardadores do mercado e avaliados: desempenho na aplicação sobre as formas, impacto dos produtos na saúde do trabalhador e no meio ambiente, e o efeito retardador na hidratação do cimento. Também foram avaliados quanto: a aplicabilidade dos produtos e sua influência no preparo da superfície para o recebimento da argamassa quando tratadas com produtos retardadores e convencionais em três tipos de formas. O estudo mostrou que o uso de agente retardador pode ser uma técnica viável para reduzir os problemas de descolamento do revestimento aplicado sobre superfícies de concreto. Através dos ensaios específicos desenvolvidos e adaptados para esta pesquisa, foi possível identificar que existem diferenças de comportamentos entre os produtos, sendo eles convencionais ou retardadores, e que os tipos de forma influenciam nestes comportamentos. Foi verificado também que as formas mais simples e com custos menores podem ser mais apropriadas para utilização destes produtos.
The concrete structures are cast in molds treated with a release agent (demolding product), and its presence hinders the mortars initial adhesion in the plastic state, as well as the bond strength after hardening. The study aims is to explore the potential use of retarding agents to replace conventional release agents in the concrete formwork. The technical viability of using a retarding agent was verified by comparing the tensile bond strength of rendering mortars applied on concrete surfaces cast with a conventional release agent and on concrete surfaces cast with a retarding release agent. The results showed that, through the use of retarding products, the removal of the concrete surface layer was possible by increasing the surface roughness, the surface water absorption and the tensile bond strength of the mortar to this concrete. Performance tests were also done with retarding products commercially available in the Brazilian market to verify the behavior of such products during application on molds, their impact on workers health and on the environment, and the retarding effect in cement hydration. It was also evaluated the applicability of these products and their influence on surface preparation to receive mortar when treated with retarding and conventional products, in three types of molds. Retarding products showed to be a viable technique for reducing the detachment problems of rendering mortars applied on concrete surfaces. Through the specific tests developed and adapted for this study, it was observed that there are differences in behavior between the conventional or retarding products, and also observed how these types of molds can influence the performance of the products. It was also observed that the simplest molds with lower cost can be more suitable in this application.

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16

Houhou, Noureddine. "Durabilité des interfaces collées béton/renforts composites : développement d'une méthodologie d'étude basée sur un dispositif de fluage innovant conçu pour être couplé à un vieillissement hygrothermique". Phd thesis, Université Paris-Est, 2012. http://tel.archives-ouvertes.fr/tel-00765147.

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Le programme de recherche développé dans le cadre de cette thèse a pour principal objectif de concevoir, réaliser et valider une méthodologie d'étude des effets du vieillissement des interfaces collées, basée sur l'utilisation d'un dispositif de fluage innovant pouvant être couplé à un vieillissement hygrothermique. Celui-ci reprend la configuration classique de joint à double recouvrement mais permet de solliciter sous charge constante l'assemblage collé béton/composite. Il présente de plus certaines spécificités (zones de joint non sollicitées, compatibilité avec une machine d'essai à simple recouvrement existante,...) qui permettent de recueillir un grand nombre de résultat expérimentaux complémentaires. En premier lieux, nos travaux présentent une synthèse bibliographique retraçant le contexte du renforcement par composites collés et précisant les principaux mécanismes physico-chimiques susceptibles d'affecter la durabilité des adhésifs. Le manuscrit décrit ensuite les travaux expérimentaux menés pour étudier le comportement mécanique et physico-chimique des deux adhésifs sélectionnés pour la réalisation des joints collés béton/composites. Finalement, une approche prédictive basée sur i) des tests de fluage thermo-stimulés, ii) sur l'application du Principe de Superposition Temps-Température et iii) sur l'utilisation du modèle rhéologique de Burger, a permis de proposer un modèle de fluage non linéaire pour chacun des deux systèmes de colle. La seconde partie des travaux expérimentaux concerne la conception et la validation d'un dispositif innovant destiné à la caractérisation du comportement en fluage des interfaces collées béton/composite. Un élément important du cahier des charges de ce dispositif était d'en limiter l'encombrement, de sorte qu'il soit possible de tester plusieurs corps d'épreuve dans une chambre climatique au volume réduit, en vue d'étudier les effets synergiques du fluage et du vieillissement environnemental sur la durabilité des joints collés. Dans ce contexte, un prototype capable de solliciter en fluage trois corps d'épreuves à double recouvrement réalisés avec le procédé de renforcement Sika®Carbodur®S et connectés sur un unique circuit hydraulique, a été conçu et réalisé. Les résultats issus du prototype ont permis de le valider, en vérifiant notamment le maintient dans le temps de la charge appliquée, et le comportement symétrique des corps d'épreuve à double recouvrement. Le comportement mécanique des interfaces collées s'est révélé répétable, symétrique et conforme aux diverses modélisations réalisées, soit en calculant la réponse instantanée de l'interface au moyen d'un logiciel aux Eléments Finis (E.F.) ou à partir du modèle analytique de Volkersen, soit en calculant la réponse différée de l'interface en intégrant le modèle de fluage non linéaire de l'adhésif identifié précédemment dans le calcul aux E.F.. La dernière partie des travaux présentés dans le manuscrit concerne la réalisation d'un banc complet de fluage impliquant 14 corps d'épreuves à double recouvrement. Ces corps d'épreuve sont réalisés pour moitié avec le système de renforcement Sika®Carbodur®S et pour l'autre moitié avec le système Compodex. Le banc de fluage est installé dans la salle de vieillissement hygrothermique du Département Laboratoire d'Autun (40°C ; 95% H.R.). Tous les corps d'épreuves sont sollicités en fluage par un système de chargement alimenté par un circuit hydraulique similaire à celui utilisé pour le prototype, mais complété par une centrale hydraulique régulant la pression à partir de la mesure d'un capteur de pression. Pour compléter ces caractérisations sur interfaces collées, des essais de vieillissement sont également menés sur des éprouvettes d'adhésifs massiques stockées dans la salle climatique, certaines d'entre elles étant simultanément soumises à des sollicitations de fluage

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17

TAYLOR, AARON THOMAS. "VERIFICATION OF THE USE OF A CARBON BLOCKING AGENT FOR FLY ASH IN CONCRETE". University of Cincinnati / OhioLINK, 2007. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1196052971.

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18

Themeli, Andrea. "Etude du potentiel d'emploi des bitumes naturels dans la production des liants bitumineux durs et des enrobés à module élevé". Thesis, Strasbourg, 2015. http://www.theses.fr/2015STRAD020.

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Le but de ce travail est d’étudier le potentiel d’un bitume naturel (BN) extrait en Albanie pour la production des bitumes durs (BD) et des enrobés à module élevé (EME). Pour la production des BD, différentes techniques de raffinage du pétrole existent. Néanmoins, avec certains bruts pétroliers il est impossible de les fabriquer. De plus, les BD de raffinerie comportent souvent des défauts qui limitent leurs applications. Ces raisons, couplées à des questions d’approvisionnement, conduisent à chercher des méthodes de substitution. Dans ce contexte, il est intéressant d’utiliser des BN. Cette étude a montré que le BN d’Albanie donne des BD et des EME en conformité avec la Normalisation Européenne, résistants au vieillissement et performants aux basses températures. Un dosage adéquat permet de formuler des matériaux d’une dureté désirée en réponse des exigences techniques des applications routières visées tout en facilitant la gestion des stocks de bitumes dans les centrales d’enrobages
The aim of this thesis is to study the potential of a natural bitumen (NB) mined in Albania in the production of hard bitumens (HB) and that of high modulus asphalt concrete (HMAC). Various petroleum refining techniques are available for the production of HB. Nevertheless, this is impossible with some crude oils. In addition, HB from refineries often present shortcomings which limit their applications. These reasons, coupled with practical issues related to HB supply, motivate the research of alternative methods. In this industrial context it is interesting to use NB. This study has shown that the Albanian NB provides HB and HMAC in accordance with European Standards, resistant to aging and relatively performant at low temperatures. The proper dosage of this NB allows the formulation of materials of desired properties, in response to the technical requirements of the considered road applications, facilitating in this way the use of bitumen stocks in asphalt concrete production plants

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19

Novosad, Petr. "Architektonické betony". Doctoral thesis, Vysoké učení technické v Brně. Fakulta stavební, 2016. http://www.nusl.cz/ntk/nusl-355643.

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In the development of concrete structures and its finishes we are constantly looking for new ways to highlight the aesthetic value of the concrete. With all the possibilities of shapes, textures and colours, an architectural concrete in the hands of an architect and designer becomes a material, which can be used to express different individual and specific ideas. It is necessary to recognize and cope with these possibilities, but also the limits, which determine the properties of concrete as the proper design and implementation creates excellent finishes that are otherwise inaccessible to other materials and technologies. The theoretical part includes an extensive summary carries out a research on issues of architectural concrete and its production. From this research comes a new definition of architectural concrete and the newly redesigned and determined classes of architectural concrete with respect to the continuous development of technologies and production possibilities, rendering and surfacing. The aim of the thesis is to verify the possibilities of producing quality architectural concrete and additional treatment of the surface with respect to the desired aesthetic quality.

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20

Nardinocchi, Alessandro. "ADVANCED CEMENT-BASED COMPOSITES: STUDY OF THE SINERGIC EFFECT BETWEEN FIBER-REINFORCEMENT AND EXPANSIVE AGENT". Doctoral thesis, Università Politecnica delle Marche, 2016. http://hdl.handle.net/11566/243126.

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calcestruzzi fibrorinforzati a matrice cementizia ( FRCC) sono materiali da costruzione relativamente recenti, che stanno desta ndo molto interesse per via delle loro grandi potenzialità applicative in ambito di ingegneria civile e non solo. Il principale vantaggio di tale t ecnologia rispetto al tradizionale calcestruzzo armato è la maggiore durabilit à del materiale, grazie alla possibilità di ridurre l ’ insorgenza di fessurazioni (e soprattutto di limitarne l ’ ampiezza), di ridurre i fenomeni di ritiro, di ridurr e la vulnerabilità ai fenomeni di corrosione. In termini di prestazioni meccaniche, l ’ aggiunta di fibre generalmente non comporta un aumento della resistenza di picco a flessione ma semplicemente un miglioramento del comportamento post-fessur ativo (con benefici in termini di duttilità, tenacità, resistenza all ’ impatto e alla fatica). Tuttavia se si riuscisse ad aumentare il valore della resi stenza massima a flessione (così come della resistenza residua), si raggiun gerebbe un prezios o traguardo per i FRCC, che permetterebbe di ridurre l a quantità di armature longitudinali (o anche di eliminarle completame nte in alcuni casi), con un risparmio in termini di manodopera, o di ri durre le sezioni degli elementi strutturali con un miglioramento in termi ni di leggerezza (con notevoli vantaggi in zona sismica) ed efficienza energetica. In particolare, lo scopo di questo studio è stato quello di valutare l ’ influenza di differenti dosaggi di un ’ agente espansivo a base di ossido di calcio sulle pr oprietà di calcestruzzi fibrorinforzati a matrice cemen tizia (FRCC) realizzati con differenti tipi di fibre: meta lliche, polimeriche e vetro. Si è posta attenzione al ritiro da essiccamento ed alla resistenza a flessione dei FRCC, poiché alcuni autori hanno evidenziato un a possibile sinergia tra agente espansivo e fibre metalliche in termini di a umento di resistenza di picco a flessione/trazione del FRCC. Obiettivo finale dello studio è stato il proporzioname nto di miscele cementizie fibrorinforzate capaci di raggiungere alt e prestazioni a flessione, sia in termini di resistenza di picco che in f ase post-fessurativa, simili a quelle ottenibili con i più costosi UHPC. In q ueste nuove miscele messe a punto non sono stati impiegati ingredienti costosi come il fumo di silice o la microsilice, e il dosaggio di cemento è stato contenuto permettendo così di migliorare l ’ impatto ambientale di questo materiale rispetto agli UHPC.
FRCC is a relatively new technology receiving a grea t deal of attention because of huge potential of application in the fiel d of civil engineering, but not limited to. The main advantage of such technol ogy with respect to the traditional concrete reinforced with steel bars ( RC) is related to increased durability, due to reduced cracking (especi ally crack width), reduced shrinkage, reduced vulnerability to corrosio n phenomena. However, in terms of mechanical performance the addition of fibers generally is not able to enhance flexural peak streng th but only to improve the post-cracking behaviour (with benefits in terms of ductility, toughness, impact resistance as well as fatigue strength). Neverthel ess, the enhancement of the flexural peak strength (as well as of residual stresses) would be a precious achievement for FRCC, allowing either to reduce longitudinal steel bar reinforcement (or even completely eliminate it in certain cases), with savings in terms of reduced manpower or to reduce se ction of structural elements (with improved lightening and energy efficiency). In particular, the purpose of this study was to evalua te the influence of different dosages of CaO-based expansive agent on the pr operties of FRCCs prepared with different types of fibers: metalli c, polymeric and glass fibers. The attention was focussed on FRCC drying shrinkage and flexural strength, since some authors detected a synergic effect between expansive agent and steel fibers in terms of increased peak flexura l/tensile strength. The final goal of this study is to proportion FRCC mix tures able to achieve very high performance in bending, both in ter ms of peak strength and post-cracking behavior, close to that obtained by the expensive UHPCs. In these FRCC mixtures, typical ingredients of UHPC such silica fume or micro silica were not used at all, and the cemen t dosage is quite low by improving the ir environmental im pact with respect to UHPCs.

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21

Rouis, Fahima. "Effet des caractéristiques physico-chimiques des ajouts minéraux sur les propriétés rhéologiques des mortiers de bétons fluides équivalents". Thèse, Université de Sherbrooke, 2017. http://hdl.handle.net/11143/10545.

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La vitesse à laquelle le monde actuel fonctionne a des répercutions directes sur tout ce qui nous entoure et, en premier plan, sur le marché de la construction dont les cirières sont de plus en plus exigeants tels que les courts délais de construction, la complexité des formes, etc. L’utilisation des bétons fluides dont les propriétés rhéologiques sont bien maîtrisées est une clé pour satisfaire à ces critères, d’autant plus qu’on se trouve au seuil d’une nouvelle ère dans le monde de la construction incluant l’impression 3D des bétons. Cependant, une sélection adéquate des ajouts minéraux (AM) et des adjuvants chimiques (superplastifiants, SP et agents de viscosité, AV) qui entrent dans la conception des bétons fluides s’avère un problème crucial. Un programme expérimental très étendu est mené pour mettre la lumière sur l’effet de huit différents AM dans des systèmes binaires et ternaires ainsi que l’effet de leurs interactions avec les adjuvants chimiques (SP et AV) sur les propriétés des mortiers de bétons équivalents (MBE). Deux classes de bétons fluides sont visées dans cette étude comprenant les bétons autoplaçants (BAP) pour la construction des bâtiments et les bétons semi-fluides (BSF) pour les infrastructures de transport. Une attention particulière est portée sur les propriétés rhéologiques, sans pour autant négliger la chaleur d’hydratation ainsi que les propriétés mécaniques. Les résultats ont montré qu’il est difficile de faire une généralisation sur l’influence des AM sur les propriétés des MBE. Les propriétés physiques des AM telles que la finesse, la forme ou encore la granulométrie des particules sont des facteurs qui jouent un rôle important dans la rhéologie des bétons fluides. Cependant, l’influence de ces facteurs peut être masquée par l’interaction physique et chimique qui peut avoir lieu entre les poudres et les adjuvants chimiques utilisés (type de SP en présence de ou sans AV compatibles). La morphologie des particules des AM a un effet direct sur la viscosité plastique des MBE. Une forme angulaire et irrégulière (facteur de Ferret autour de 0,4), contribue à augmenter la viscosité plastique des MBE et une forme sphérique (facteur de Ferret proche de 1) contribue à diminuer leur viscosité plastique. Par ailleurs, les résultats de l’analyse statistique ont montré que l’influence des AM en combinaison ternaire (une poudre à faible réactivité avec une poudre à réactivité élevée), en présence d’un rapport eau/poudres (E/P) relativement élevé (0,45), sur la majorité des réponses n’est que la somme des effets individuels de ces poudres. Par contre, un effet d’interaction entre les poudres pour certaines réponses a commencé légèrement à prendre place lorsque le rapport E/P est diminué à 0,41. Cependant, dans le développement des résistances à la compression à 28 et 91 jours, les poudres à réactivité élevée comme la fumée de silice ou le métakaolin avaient généralement une contribution positive plus importante que celle des poudres à faible réactivité. Les résultats de l’hydratation des MBE ternaires, suivie par la calorimétrie isotherme, n’ont pas montré l’effet synergétique escompté de la combinaison d’une poudre à faible réactivité avec une autre à réactivité élevée dû à l’augmentation de la demande en SP en présence de cette dernière. Une optimisation multiparamétrique a permis de sélectionner des ciments ternaires servis au développement des bétons écologiques présentant les meilleures performances. Finalement, l’utilité de la méthode des MBE dans la prédiction de l’effet des AM sur les bétons a été discutée.
Abstract : The speed with which the world operates today has direct repercussions on everything around us and, in the foreground, on the construction market, where the criteria are more and more demanding such as short construction times, complexity of forms, etc. The use of fluid concretes where rheological properties are well controlled is a key to satisfy these criteria, especially since we are on the threshold of a new era in the construction world including the 3D concrete printing. However, an adequate selection of mineral additives (MA) and chemical admixtures (superplasticizers, SP and viscosity agents, VA) that are used in the design of fluid concretes is a crucial problem. A very extensive experimental program is conducted to shed light on the effect of eight different MA in binary and ternary systems as well as the effect of their interactions with the chemical admixtures (SP and VA) on the properties of concrete equivalent mortars (CEM). Two classes of fluid concretes are investigated in this study, including self-consolidating concrete (SCC) for building constructions and semi-flowable concrete (SFC) for transportation infrastructures. Particular attention is paid to the rheological properties, without neglecting the heat of hydration as well as the mechanical properties. The results showed that it is difficult to generalize on the influence of MA on the properties of CEM. The physical properties of MAs such as fineness, shape or particle size distribution are factors that play an important role in the rheology of fluid concretes. However, the influence of these factors can be masked by the physical and chemical interaction that may occur between the powders and the chemical admixtures used (type of SP in the presence or not of a compatible VA). The particle morphology of MA has a direct effect on the plastic viscosity of CEM. An angular and irregular shape (Ferret factor around 0.4) contributes to increase the plastic viscosity of CEM and a spherical shape (Ferret factor close to 1) contributes to decrease their plastic viscosity. Moreover, the results of the statistical analysis showed that the influence of MA in ternary combination (low-reactivity powder with high-reactivity powder), in the presence of a relatively high water-to-powder ratio (W/P) of 0.45, on the majority of responses is only the sum of the individual effects of these powders. On the other hand, an interaction effect between the powders for some responses began slightly when the W/P was decreased to 0.41. However, in developing 28- and 91-day compressive strengths, high-reactivity powders such as silica fume or metakaolin generally had positive contribution higher than low-reactivity powders. Results of ternary CEM hydration followed by isothermal calorimetry did not show the expected synergistic effect of combining a low-reactivity powder with another with high reactivity due to increased demand in SP in the presence of the latter. A multiparametric optimization allowed selection of ternary cements used to develop ecological concretes with the best performance. Finally, the use of the CEM method in prediction of the effect of AM on concrete was discussed.

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Prokkola, H. (Hanna). "Biodegradation studies of recycled vegetable oils, surface-active agents, and condensing wastewaters". Doctoral thesis, Oulun yliopisto, 2015. http://urn.fi/urn:isbn:9789526209869.

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Abstract Biodegradation is an aerobic or anaerobic degradation reaction where bacteria use organic materials as an energy source. In the aerobic biodegradation reaction, bacteria need oxygen as an electron acceptor, whereas an anaerobic reaction takes place in the absence of oxygen. Compounds degrade totally or partially, and produce simple inorganic species, such as CO2, CH4, NH3, NO3−, and H2O, as well as by-products that may be non-biodegradable and/or toxic. In this thesis, the biodegradability of recycled vegetable oils, surface-active agents, and condensing waters from the process of wood drying were studied using the manometric respirometric BOD OxiTop method. The biodegradation of organic compounds was measured under the standard conditions (OECD 301F), and also in other matrices, such as different waters and soils. These are very different environments with respect to the biodegradation reaction in nature. The main differences in waters and soils are their organic and inorganic nutrient contents, bacteria strains, and temperatures. The BOD OxiTop method is based on automatic pressure detection in a closed reactor vessel. Oxygen is consumed and carbon dioxide is formed in the aerobic reaction. The pressure decrease is detected after the carbon dioxide is adsorbed into a NaOH pellet or solution. The pressure change is dependent on oxygen consumption. The degree of biodegradation is calculated from the BOD value of the sample. The studied recycled vegetable oils were found to be 60–83% biodegradable, and the added surface-active agent did not affect their biodegradation. Biodegradation of tall oil soaps was also examined in sand, topsoil, groundwater, and surface water, as well as under OECD 301F standard conditions. Tall oil soaps were proven to be 50–85% biodegradable. Concrete solvent agent (CSA) was also proven to be 78–83% biodegradable under standard conditions. Another detergent, cetyltrimethylammonium bromide (CTAB), was found to be toxic, whereas Triton X-100 biodegraded by only 6% in solution. Biodegradation of the soil matrix was found to be enhanced with added surface-active agents. This can be explained by better wetting of small pores with surface-active agents, as compared to the behavior of pure water. The biodegradation of the matrix occurred even with toxic surface-active agents. Organic pollutants of wastewaters from the process of wood drying were 25–61% biodegradable during a 28-day period, and were proven to be quite pure when considering the carbon content of the samples. Based on these results, the disposal into drainage of condensing waters from wood drying may be regarded as safe, which from an economical viewpoint is a very important conclusion
Tiivistelmä Biohajoavuus on luonnollinen aerobinen tai anaerobinen hajoamisprosessi, jossa bakteerit käyttävät orgaanista materiaalia energian lähteenä. Aerobisessa reaktiossa bakteerit tarvitsevat happea elektronien vastaanottajaksi, kun taas anaerobinen reaktio tapahtuu hapettomissa olosuhteissa. Yhdisteet hajoavat joko täysin tai osittain sekä tuottavat yksinkertaisia epäorgaanisia yhdisteitä, kuten CO2, CH4, NH3, NO3− tai H2O. Reaktiossa voi myös muodostua sivutuotteita, jotka voivat olla biohajoamattomia ja/tai toksisia. Tässä työssä on tutkittu kierrätettyjen kasviöljyjen, pinta-aktiivisten aineiden sekä jätevesien sisältämien orgaanisen aineksien biohajoavuuksia käyttäen manometristä respirometristä BOD OxiTop-menetelmää. Biohajoavuutta mitattiin standardiolosuhteiden (OECD 301F) lisäksi muissakin olosuhteissa, kuten erilaisissa maissa ja vesissä. Nämä ovat kaikki hyvin erilaisia ympäristöjä luonnossa tapahtuville biohajoavuusreaktioille. Pääasialliset erot ovat sekä orgaanisten että epäorgaanisten ravinteiden määrässä, bakteerikannoissa ja lämpötilassa. BOD OxiTop-menetelmä perustuu automaattiseen paineen muutoksen havainnointiin suljetussa astiassa. Aerobisessa reaktiossa kuluu happea ja muodostuu hiilidioksidia, joka imeytetään NaOH-pelletteihin tai -liuokseen ja tästä muodostuu alipaine. Paineen muutokset muunnetaan hapenkulutuksen arvoiksi, joista lasketaan biohajoavuusaste. Tutkittujen kierrätettyjen kasviöljyjen biohajoavuusasteet vaihtelivat välillä 60–83 %, eikä lisätty pinta-aktiivinen aine vaikuttanut kyseisten ekoöljyjen biohajoavuuteen. Mäntysaippuoiden biohajoavuus tutkittiin standardiolosuhteiden lisäksi hiekassa, mullassa, pohjavedessä sekä pintavedessä. Niiden biohajoavuusasteet vaihtelivat välillä 50–85 %. Betoninpesuaineen biohajoavuusaste standardiolosuhteissa oli 78–83 %. Kahdesta tutkituista pinta-aktiivisista aineista setrimoniumbromidi (CTAB) oli myrkyllinen liuosolosuhteissa eikä täten biohajonnut ja Triton X-100 biohajosi vain 6 %. Pinta-aktiivisen aineen lisääminen maahan aiheutti matriisina käytetyn maan biohajoamisen. Tämä voitiin selittää siten, että pintajännityksen laskemisen jälkeen neste voi paremmin tunkeutua maan pieniin huokosiin ja näin tuoda hajoamatonta orgaanista ainesta ja uusia bakteereita biohajoavuuskäyttöön. Tämä ilmiö havaittiin myös myrkyllisen pinta-aktiivisen aineen lisäyksen jälkeen. Jätevesien sisältämät orgaaniset ainekset hajosivat 25–61 % 28 päivän aikana ja niiden havaittiin olevan hiilen määrän huomioon ottaen hyvin puhtaita. Tässä tutkimuksessa saatujen tulosten perusteella tutkitut puunkuivauksen kondenssivedet voidaan laskea viemäriin, mikä on erittäin tärkeä tulos ekologiselta ja taloudelliselta kannalta katsottuna

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23

Bednárek, Jan. "Tepelně izolační lité žárobetony". Master's thesis, Vysoké učení technické v Brně. Fakulta chemická, 2014. http://www.nusl.cz/ntk/nusl-217091.

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The thesis deals with the possibility of specific weight lowering of kaolin suspensions using air-entraining agents. These agents are usually used as concrete admixtures. The goal of the thesis is to verify an alternative possibility of creating porous structure in kaolin suspensions in order to prepare heat insulating moulded refractory concretes without using lightweight fillers. The effect of several air-entraining agents was compared, after that the dosage of agent and mixing conditions were optimized. The stabilization of prepared foams and practical application of selected agents were also part of the thesis.

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24

Delporte, Corinne. "L'anhydrite naturelle de faulquemont et sa valorisation sous forme de béton sulfate : Mécanisme d'hydratation et mise au point d'accélérateurs de prise hydraulique". Nancy 1, 1988. http://www.theses.fr/1988NAN10113.

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Investigation expérimentale de l'hydratation de ce matériau anhydre (CaSO::(4)), pouvant se transformer en agregats de gypse (CaSO::(4), 2H::(2)O), pour donner un béton à résistance mécanique élevée ; mise au point d'un accélérateur de prise original, mettant en jeu simultanément les ions nitrates et sulfates

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25

Brito, Suerde Miranda de Oliveira. "O concreto e o simb?lico no cotidiano da educa??o em sa?de: pr?ticas, representa??es e processo identit?rio dos agentes comunit?rios de sa?de de Jo?o Pessoa PB". Universidade Federal do Rio Grande do Norte, 2004. http://repositorio.ufrn.br:8080/jspui/handle/123456789/14133.

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Made available in DSpace on 2014-12-17T14:35:50Z (GMT). No. of bitstreams: 1 SuerdeMOB.pdf: 874734 bytes, checksum: b379e6f1b20ef308d4bc0a1f81a1e28b (MD5) Previous issue date: 2004-08-13
Coordena??o de Aperfei?oamento de Pessoal de N?vel Superior
The present study is about an etnographic research based on the Theory of Social Representation and its complementary approach, the Theory of Central Core based on the bourdiesianos concepts of field and habitus , concerning that these concepts, articulated to the constructed social representation, may contribute to the study of social identities. Its aim is to acknowledge which identity references community health agents (CHA), agents from Community Health Agent Program (CHAP) and Family Health Program (FHP) from Jo?o Pessoa PB and which social representation is constructed by them towards health education. The study had the participation of 119 CHAs, from which 90,3 % were female and 9,7% were male. Since the identity is also built by the representation of others towards the group, 63 professionals of the FHP group (16 nurses, 16 nursing assistents, 12 doctors, 9 dentists, 6 dentistry office assistents, 4 coordinators, 1 psicologist and 1 receptionist) and 1 nurse from CHAP took part of the study, oficial documents from the Health Ministry were analyzed, verbal information from its representatives were also taken into consideration, as well as reports from the many benefitiaries of the CHA, CHAP and FHP. For data collecting, we used the combination of (a) Direct Observation and Participant Observation of the functioning micro-areas of the CHA at the Family Health Units, and the Union of the Agents; (b) Free-Association of words and expressions to stimulate the CHA , Health Education and Health ; (c) Questionnaire; (d) Interviews. The interviews were submitted to a thematic analysis of its topic. The free-association was analyzed taking in consideration the v?rgesiana proposal (a combination of the frequency and average order of evocation) which treatment enabled the identification of the central and peripheral systems of social representation towards health education and the community health agent. A test of central refutation, associated to the analysis of the indicated evocations as the most important, provided empirical evidence of social representation towards health education as orientation , prevention and hygiene , as well as the identity of CHA as supervisor , friend , help , important , and the link between the community and the Family Health Staff. Other professionals from CHAP, FHP and the Health Ministry share all of these representational contents, especially the concepts of friend and link , also shared by the community. A habitus towards the community health agents was identified, as a representation based on trust and friendship, which gives the professional a great importance towards the daily inconsistencies faced by the community
O presente estudo trata-se de uma pesquisa de cunho etnogr?fico, fundamentada na Teoria das Representa??es Sociais e na sua abordagem complementar, a Teoria do N?cleo Central, embasado nos conceitos bourdiesianos de campo e de habitus, tomando como princ?pio que tais conceitos, articulados ao construto representa??o social, podem contribuir com o estudo das identidades coletivas. Objetiva apreender quais as refer?ncias identit?rias de agentes comunit?rios de sa?de (ACSs) do Programa de Agentes Comunit?rios de Sa?de (PACS) e do Programa Sa?de da Fam?lia (PSF) do munic?pio de Jo?o Pessoa PB e qual representa??o social ? por eles constru?da acerca da educa??o em sa?de. Participaram do estudo 119 ACSs, dos quais 90.3% mulheres e 9,7% homens. Uma vez que a identidade tamb?m ? constru?da pela representa??o dos outros sobre o grupo, 63 profissionais da equipe do PSF (16 enfermeiras, 16 auxiliares de enfermagem, 12 m?dicos, nove odont?logos, seis auxiliares de consult?rio odontol?gico, quatro coordenadores, um psic?logo e uma recepcionista) e uma enfermeira do PACS foram part?cipes do estudo, al?m de serem analisados documentos oficiais do Minist?rio da Sa?de e terem sido consideradas informa??es verbais de seus representantes, assim como depoimentos de usu?rios do PACS e do PSF sobre o ACS. Para a coleta de dados, utilizamos a seguinte combina??o de instrumentos: (a) Observa??o Direta e Observa??o Participante nas micro-?reas de atua??o dos ACSs, nas Unidades de Sa?de da Fam?lia; e na associa??o e no sindicato da categoria; (b) Associa??es Livres de palavras e express?es para os est?mulos agente comunit?rio de sa?de , educa??o em sa?de e sa?de ; (c) Question?rios e (d) Entrevistas em Profundidade. As entrevistas foram submetidas ? an?lise tem?tica de conte?do. As associa??es-livres foram analisadas segundo a proposta verg?siana (combina??o da freq??ncia e da ordem m?dia de evoca??o), tratamento que permitiu identificar os sistemas central e perif?rico da representa??o social de educa??o em sa?de e de agente comunit?rio de sa?de. Um teste de refuta??o da centralidade, associado ? an?lise das evoca??es indicadas como mais importantes, forneceu evid?ncia emp?rica da representa??o social da educa??o em sa?de como orienta??o , preven??o e higiene , bem como da identidade do ACS como orientador , amigo , ajuda , importante e elo de liga??o entre a comunidade e a Equipe Sa?de da Fam?lia . Todos estes conte?dos representacionais s?o compartilhados pelos outros profissionais do PACS e do PSF e pelo Minist?rio da Sa?de, havendo destaque para o ser amigo e ser elo de liga??o , igualmente compartilhados pela comunidade. Foi constatado um habitus de agente comunit?rio de sa?de, calcado na afetividade, o qual ancora o ser-fazer deste trabalhador, ante as inconsist?ncias cotidianas de alimenta??o, vestu?rio, emprego e medica??o presentes na comunidade

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26

Helnan-Moussa, Benjamin. "Influence de la température sur la thixotropie des bétons autoplaçants". Thesis, Artois, 2009. http://www.theses.fr/2009ARTO0203/document.

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L’objectif de cette thèse est d’étudier l’influence de la température sur la thixotropie des bétons autoplaçants (BAP). L’intérêt de ce travail s’inscrit dans la perspective d’optimiser les formulations des BAP dans une large gamme de température. Un plan factoriel composite centré a été adopté dans le but de minimiser le nombre d’essais tout en étudiant les effets des facteurs (température et dosage en agent de viscosité (AV)) et leurs interactions sur les propriétés rhéologiques des BAP.La première phase de l’étude consistait à quantifier la thixotropie du béton juste après le malaxage et durant la période dormante en fonction du dosage en AV à des températures comprises entre 11.3 et 30.7°C selon le protocole proposé par Wallevik sur le rhéomètre BML4. Les résultats ont montré que l’indice de thixotropie présente un minimum respectivement pour un dosage en AV de 0.28 % (par rapport à la masse d’eau) et une température de 24°C. Cependant, ce protocole ne permet pas d’étudier la déstructuration des BAP, facteur recherché par exemple dans les coulages multicouches. Nous avons donc été amenés à retenir un protocole utilisé dans les gels et appelé protocole Dolz. L’application de ce dernier aux pâtes de ciment et aux BAP a permis de mettre en évidence une nouvelle grandeur, le potentiel de déstructuration K. Les valeurs du potentiel K montrent qu’au delà d’un certain dosage en AV et d’une certaine température, apparaissent des phénomènes d’encombrement qui réduisent le potentiel K. Ainsi, le potentiel K apporte des informations complémentaires pour l’aide à la sélection de dosages adéquats du couple superplastifiant – agent de viscosité en fonction de la température de coulage
The aim of this thesis was to study the influence of the temperature on the thixotropy of self-consolidating concrete (SCC). The research significance comes within the perspective to optimize the design of SCC in a wide range temperature. A factorial composite experimental plan was carried out in order to minimize the total number of tests while studying the effects of factors (temperature and dosage of viscosity modifying admixture (VMA)) and their interactions on the rheological properties of SCC. The first phase of the study was to quantify the thixotropy of concrete proportioned with various dosage of VMA at different temperatures ranging from 11.3 to 30.7°C just after mixing and at different time during the dormant period using the protocol proposed by Wallevik in BML4 rheometer. The results indicated that the values of thixotropy index present a minimum respectively with a VMA dosage of 0.28 % (by mass of water) and a temperature of 24°C.On the other hand, this protocol does not allow studying the destructuration of SCC, useful factor needed for example in the multi-layer casting. We therefore had to retain a protocol used in gels and called Dolz protocol. The application of this last to cement pastes and SCC has revealed a new grandeur, the potential of destructuration K. The values of K show that beyond a certain dosage in VMA and a certain temperature, the congestion phenomena appear that reduce the potential K. In this case, the potential of destructuration provides complementary information to assist in the selection of appropriate dosages of couple superlasticizer-VMA whatever the casting temperature may be

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27

Cortier, Olivier. "Quantification des bénéfices des revêtements perméables. Modélisation à l'échelle de la structure et du bassin versant". Thesis, Normandie, 2018. http://www.theses.fr/2018NORMC247/document.

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Les revêtements perméables se développent en France et à l’étranger comme une technique d’avenir en réponse aux enjeux de la protection des sols et de l’amélioration du cycle de l’eau en milieu urbain. Le développement de pavés drainants au sein du laboratoire de l’ESITC Caen a mis en évidence le besoin de quantifier les apports des revêtements perméables pour répondre aux attentes des acteurs locaux et favoriser l’utilisation de ces techniques par les aménageurs. Dans ce but, ce travail de thèse porte sur la description des processus hydrologiques au sein des revêtements perméables et la quantification de leurs bénéfices sur le ruissellement urbain. Deux modèles ont été développés pour répondre à ces objectifs.Le premier permet de modéliser les processus hydrologiques au sein des structures perméables avec une approche physique basée sur la résolution de l’équation de RICHARDS par la méthode des éléments finis. Cette modélisation apporte des éléments de compréhension sur l’influence des propriétés de la structure et de son environnement sur ses performances. Elle a abouti à la proposition d’une représentation conceptuelle du comportement hydrologique des structures perméables. Le second modèle permet de modéliser le comportement hydrologique d’un bassin versant avec une approche par systèmes multi-agents. Différents scénarios d’implantation de revêtements perméables ont été simulés sur un site d’étude réel situé à Ouistreham en Normandie. L’exploration de ce modèle apporte des éléments de quantification des bénéfices de l’implantation des revêtements perméables sur le ruissellement de surface. Les résultats obtenus mettent en évidence le lien entre le ratio de surface perméable sur la surface imperméable et la réduction du ruissellement. Ils soulignent l’importance de la dispersion des zones de revêtements perméables pour optimiser leurs bénéfices
Permeable pavements are developing in France and abroad as a promising response to the growing issues of ground protection and the improvement of the water cycle in urban areas. The development of pervious concrete within the laboratory of ESITC Caen had highlighted the need to quantify the contributions of the permeable pavement, and thus meeting the expectations of local authorities and encouraging the use of these techniques by urban planners. In this purpose, this Phd aims at describing the hydrological mechanisms of the permeable pavements and quantifying their benefits on surface runoff. Two models were developed to respond to these objectives. The first one allows modeling the hydrological processes inside permeable pavement structures with a physically-based approach, which solves RICHARD’s law with a finite element method. This modeling enables the understanding of the influence of the properties of the structure and its environment on its performances. Results have led to the proposal of a conceptual representation of permeable structures. The second model allows modeling the hydrological behavior of an urban catchment with an agent-based approach. Various scenarios of permeable pavement implemantations were simulated on a real study site located at Ouistreham in Normandy. The analysis of this model enables the quantifying of the benefits of the implementation of permeable pavements on surface runoff. Results highlight the link between the permeable surface on the impermeable surface ratio and the reduction of runoff. They emphasize the importance of dispersing permeable pavement areas to maximize their benefits

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28

Popelková, Adéla. "Ultralehké betony s vysokými užitnými vlastnostmi". Master's thesis, Vysoké učení technické v Brně. Fakulta stavební, 2018. http://www.nusl.cz/ntk/nusl-372211.

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This diploma thesis deals with the technology of production of ultralight concretes using direct lighten cementing compound and at the same time indirect lighten using lightweight aggregate. Further work deals with the choice of suitable raw materials for these concretes. The practical part consists of a proposal of several different recipes, experimental verification and by comparing their properties in a fresh or hardened state.

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29

Alvarado, patino Nelson Andrey. "Évaluation des performances thermomécaniques des enrobés bitumineux à fort taux de recyclage : Apport du procédé de régénération Fenixfalt". Thesis, Rennes, INSA, 2018. http://www.theses.fr/2018ISAR0021/document.

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Une étude expérimentale a été effectuée sur diverses formules de trois familles d’enrobés bitumineux avec des taux de recyclage variables et la présence ou non de régénérant. La composition des mélanges et le procédé de fabrication ont été élaborés afin d’effectuer une étude comparative. L’enrobage produit des variations des paramètres physico-chimiques des liants telles que la consistance, la température de transition vitreuse, les fractions cristallisables, les taux d’aromatiques et d’asphaltènes ; ces variations sont limitées en présence de régénérant. Lorsque le taux d’AE augmente, la compactibilité et l’orniérage des mélanges diminuent et leur rigidité viscoélastique augmente, mais le régénérant limite ces variations. Globalement, les AE produisent une augmentation de la résistance à la fatigue des formules et un aplatissement des droites de Wöhler. Le régénérant améliore le paramètre de fatigue ɛ6 ; les performances en fatigue augmentent avec la TBA et l’indice colloïdal du liant ainsi qu’avec la diminution de la viscosité de l’enrobé. L’impact favorable d’un taux élevé d’AE et du régénérant sur le trafic admissible a été déterminé suite au dimensionnement d’une structure souple tri-couche. À basse température, la détérioration par les AE de la ductilité en traction et de la température de rupture par retrait empêché se trouvent limitées par le régénérant ; un compromis est cependant à trouver avec la résistance à la fatigue. Les formules régénérées mises en œuvre sur la couche de roulement d’une route départementale ont subi une moindre évolution après six ans de service que les mélanges non régénérés
An experimental programme has been performed on three types of bituminous mixes with variable recycling rates and the possible addition of rejuvenator. The mix composition and the production process have been defined in order to perform a comparative analysis. The coating process modifies the physico-chemical parameters of the binders, like consistency, glassy transition temperature, cristallizable moiety, aromatics and asphaltenes rates; the above variations are limited by using the rejuvenator. As the RAP content increases, the compactibility and the rutting of the mixes decrease and the viscoelastic stiffness increases, but the rejuvenation reduces these variations. Globally, RAP increases the fatigue resistance of the mixes and flattens the Wöhler curve. Rejuvenation enhances ɛ6 fatigue parameter; fatigue performances increase with R&B temperature and colloidal index of the binder and as the viscous component of the mixes decreases. The positive impact of a high rate of RAP and of the rejuvenation on the allowable traffic has been evaluated from the structural design of a threelayered pavement. At low temperature, the deterioration of the tension ductility and of the stress restrained failure temperature produced by the RAP, is limited by the rejuvenation; a compromise with the fatigue resistance has to be found. The rejuvenated mixes laid as surface layers on a provincial road have experienced a smaller evolution that non rejuvenated mixes

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Li, Chien-Hao, e 李健豪. "The Feasibility Research of Hydrophobic Concrete Waterproofing Agent". Thesis, 2017. http://ndltd.ncl.edu.tw/handle/stnnkz.

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碩士
國立臺北科技大學
土木工程系土木與防災碩士班
105
Taiwan is located in subtropical area where is wet and rainy, and most buildings in Taiwan are made of reinforce concrete, Moisture will make concrete leak and cause efflorescence. Leaking has taken over 14% of estate transaction disputes, so that researches and applications of different waterproof materials is an important issue. There are many studies on waterproof engineering, while most of those are about physical blocking or injecting waterproof materials into concrete’s damaged area to stop the water’s infiltration.However, some impacts like irradiating UV or earthquake would decrease the function of waterproofing, so these ways couldn’t improve concrete leaking and infiltration problems thoroughly. This study collected related literature about often used waterproof materials in Taiwan,and listed the ways of applications,advantages and disadvantages to understand the overview of waterproof engineering in Taiwan.Then, by experiencing the waterproof agent from America, we will know if it conforms the standards of Chinese National Standards 3763. The results showed the composite grouts’ initial setting time fell between 3~3.5 hours, the final setting time fell between 5~5.5 hours; the composite grouts didn’t shrink, warpage, or occur expansion cracking after the stability test. The experimental group and control groups’ 350kgf/cm2 and 280kgf/cm2 concrete’s average compression ratio have reached 0.99 and 1.00; the mortor’s average compression ratio has reached 0.97;the experimental groups and control groups’ water absorption ratio were lower than 0.5 after been reviewed; the water permeability of the concrete and mortor’s permeability average ratio are both lower than 0.5. Those results showed the waterproof agent conforms the standards of Chinese National Standards 3763, and it is feasible to apply on concrete and mortor.

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Xiao-day, Fu, e 符曉天. "Evaluation of Recycled Asphalt Concrete by Adding Recycling Agent". Thesis, 2010. http://ndltd.ncl.edu.tw/handle/49584510156402435829.

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碩士
高苑科技大學
土木工程研究所
98
Using the reclaimed asphalt pavement to be the hot recycled asphalt concrete mix has become the current major trend. How to improve the quality of use has been the subject of study since the use of recycled asphalt concrete. Scholars found that adding renewable agent can effectively enhance the performance of recycled asphalt concrete pavement. Recycling agent is not common used on the pavement due to its high cost. In this study, the target material viscosity of 2000 poise and 5000 poise of the test sample will be deployed by fresh asphalt, reclaimed asphalt pavement and recycling agent. Firstly, the optimal asphalt content of recycled asphalt concrete is calculated by Marshell test. Then many further experiments such as indirect tension, MR test, static creep and dynamic creep, water stripping indirect tension strength test and wheel track rutting are executed to evaluate the physical and mechanical properties. The results show that the test sample added with recycling agent is indeed significant softening of the hard material and restores elasticity. The difference is small among basic physical properties such as viscosity, ductility and specific gravity in the same target viscosity samples. The values of Marshall stability also has very similar. The performance of test sample added with recycling agent is better in indirect tension, after stripping the residual strength and the dynamic and static creep deformation. The test sample of target viscosity of 5000 poise of the mechanical properties is higher than that of target viscosity of 2000 poise in the values of Marshall stability value, the tensile capacity and stripping ability.

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32

cheng, po-hao, e 城珀皓. "The Evaluation of Recycling Agent for Recycled Asphalt Concrete". Thesis, 2008. http://ndltd.ncl.edu.tw/handle/42299669720534786190.

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碩士
高苑科技大學
土木工程研究所
96
The recycled asphalt concrete were been used in Taiwan for decades. The recycling agents (rejuvenator) can improve the quality and performance of pavement maintained or built by recycled asphalt concrete. However, the contractor intend to use softer asphalt instead of recycling agents in recycled asphalt concrete production because the price is higher. The self-made recycled agent was produced by mixing rubber process Oil (Aromatic based) with AC-5 asphalt. The performance of self-made recycled agent and one recycled agent collect from the market were compared. Both agents were classified as ASTM D4552 RA-5 recycled agent. Viscosity, penetration, and rheology of mixed binders and the marshall stability, resilient modulus, moisture induced damage of asphalt mixture were measured to evaluate the performance of both recycled agents. The test result show that both agents had significant influence on the properties of aged asphalt abstracted from recycled asphalt pavement (RAP) as well as the performance of recycled asphalt concrete mixture. There are slightly difference between agents, however, the properties of self-made agent can be adjust by change the proportion of rubber process oil and AC-5 asphalt. In the end, the researcher suggest the customized recycled agent based on the properties of aged asphalt in RAP were recommended in the production of asphalt concrete.

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CIOU, CIN-WEI, e 邱欽偉. "The Recycle Agent on promotion the Recycling Asphalt Concrete quality". Thesis, 2009. http://ndltd.ncl.edu.tw/handle/d3654u.

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碩士
國立中央大學
土木工程研究所
97
When the recycled asphalt concrete carries on the Marshall mixture design , usually use graph hand painted decides Viscosity with AI MS-2 . This research the error which possibly causes the hand painted decision ,the use formula computation, the use value judges ,and discusses recycled asphalt concrete increase recycle agent, mixes actually in the factory carries on the laboratory result .Test result increase the recycle agent under same condition ,the stable value and the indirect tension test not too big difference, has to the recycled asphalt concrete increases recycle agent to be good to TSR ,but has still not surpassed general HMA .Regarding attains and the cost consideration about recycle agent ,suggested that uses Chinese Petroleum Corporation the AC-5 asphalt . In the last few years , the road Pavement quality to the recycled asphalt concrete has the bad phenomenon one after another, Discusses the recycled asphalt concrete by way of this research result on the Practical question, contains the depth of pavement, asphalt content, to deposit the place, work quantity, to flow to aspects and so on control to carry on the analysis.

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Shiu, Jen-Shiuan, e 徐振軒. "A Study of Asphalt Concrete Material Added with Recycle Agent". Thesis, 2006. http://ndltd.ncl.edu.tw/handle/54254494488221826277.

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碩士
國立中興大學
土木工程學系所
94
Because the lack of sandstone and used again of resources, the use of regenerated asphalt concrete is a tendency in the future. The government sets into action, provide the use of recycle materials can’t over 40% in the design. But in asphalt mixed factory, over used of recycle materials is common. Because the recycle materials should be used carefully for pavement recycle materials with high viscosity. When the capacity of recycle materials is too much, it often caused the damage in pavement. Thus the use carefully of recycle materials is the most important topic in the future. This research use the RAP with viscosity of 42800 poises come from the road in the nan-gang industry zone. According to the suitable design to add recycle agent of RA-25, RA-75 and RA-250 into RAP for allot RAB with percent of 10%, 20%, 30%, 40%. Test its physical property, toughness value, indirect tension strength, stable value and flow value, probe into the application of difference recycle agent. The result of research find when add over 10% recycle agent into the recycle asphalt, the expanded character of RAP will increase clearly, show the RA can increase the cohesion of RAP, promote the engineering character; In the toughness test, the RAP with RA, the tension . strength and toughness value are higher than the RAP with AC-20. then the result of RAP with RA-75 is better than other. The indirect tension test of the mixed materials with RA-75 show RA-75 can decrease the viscosity of maturing asphalt better. After several Marshall tests, we can know the RAB with RA-75, its stable value is higher than RAB with other two RA, the quality of asphalt is better than the other. Thus suggest mixed factory can use RA-75 first when in the selection of RA.

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Chen, Chien-Rung, e 陳建榮. "Determining the feasible proportion of Recycling Agent in mixing Asphalt Concrete using RAP". Thesis, 2015. http://ndltd.ncl.edu.tw/handle/49884325846926646812.

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碩士
國立屏東科技大學
土木工程系所
103
Recycling agent is capable of improving the properties after aging brittle asphalt additives, all have good mobility, can quickly and eliminating material mixing reaction, reducing the viscosity of the asphalt after aging reply so close to the original character. Therefore, add the right amount of regenerated catalyst recycled asphalt concrete quality and contribute to the work of improvement. This study RA-5 recycling agent directly eliminating material mixing, the regenerative agent interaction to achieve the goal of eliminating the material viscosity of 2000 ± 400 poises, and then with the new aggregates and new asphalt cement mix made with AC-20 asphalt Mixture. Test process is expected to add four different eliminating proportion (0%, 20%, 40%, 60%) were produced test specimen, carried Marshall stability and flow value value test, retention strength test, wheel track rutting tests to understand addition on the engineering properties of recycled asphalt concrete regenerated catalyst. With consideration of the cost of the project, carried out the unit price of recycled asphalt recycling agent added. Finally, a comprehensive overall assessment in order to explore an appropriate addition ratio of regenerating agent. The result shows that regenerated catalyst can really regulate aging asphalt Viscosity. But a recycling agent adding recycled asphalt concrete is not a panacea agent, according to Marshall stability tests excessive dosage shows that there is a downward trend when excessive dosage. Whether or not due to excessive addition of regenerated catalyst, recycled asphalt concrete caused structural damage, weakening occurs, there are further explored space.

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Chih-Hsien, Lin, e 林志賢. "A Study, which Engineering Property of Celluar Concrete Affecting by Foamed Agent Property and Mixture Proportioning Design". Thesis, 2001. http://ndltd.ncl.edu.tw/handle/26786236281179735953.

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Abstract (sommario):

碩士
國立海洋大學
河海工程學系碩士在職專班
89
This study focus to discuss how foamed agent property and mixture proportioning design affect engineer property of celluar concrete. At this study, the celluar concrete adopts absolute volume mixture design. The test variables include water to cement ratio, air content, foamed agent, replacement of cement by fly ash, sand and cement ratio and polypropylene fiber and cement ratio, etc. Also, to match with many tests, such as the celluar concrete air content, slump flow spreading, compressive and tensile splitting strength, oven-dry weight, water absorption, permeability and microstructure. The result shows that the strength of celluar concrete is the strongest, water absorption and permeability is the lowest if using SDS foamed agent. However, the volume stability is the best if using SDBS foamed agent and the workability of celluar concrete is better if adopting PEG foamed agent. Cement of Water to cement ratio is between 0.45~0.60, which has the best air void stability. When water to cement ratio is lower than 0.45 or higher than 0.60, the average size of structure obviously will increase. The compressive strength of celluar concrete will reduce as the air content increase. The more replacement of cement by fly ash are, the lower slump flow spread, oven-dry weight and strength are. It''s an obvious case of the replacement over 20% decreasing. When sand and cement ratio is one time of concrete weight, it has the best slump flow spread. With the ratio increase, the oven-dry weight will improve but the strength will decrease. To add polypropylene fiber and celluar concrete, the compressive and tensile splitting strength respectively go up to 30% and 80%.

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37

Wen, Lo Zang, e 羅贈文. "Effects of Glass Fiber,Air Entraining Agent and Lightweight Aggregate on Thermal Conductivity of High Performance Concrete". Thesis, 1998. http://ndltd.ncl.edu.tw/handle/25989261492395608001.

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碩士
國立臺灣科技大學
營建工程技術學系
86
High Performance Concrete (HPC) is a new construction material with high strength and high slump flow. However owing to its higher density, it also possesses higher thermal conductivity and is even easier to spall in fire temperature than ordinary concrete. In order to promote its engineering application, these negative fire -resistance characters need to be improved. This research tries to mix respectively the lightweight aggregate, fiber glass and air entraining agent in HPC and studies the effect of improvement of these mixtures on the fire-resistance behavior of HPC. The research project is divided into two parts : the first part studies the effect of the mixtures on the spalling and thermal expansion behavior of HPC； while the second part deals with the effect of the mixtures on the thermal conductivity and volumetric heat capacity of HPC. This report presents the research outcome of the second part. The parameters considered in this study are the strength of concrete , the amount of the lightweight aggregate, fiber glass and air entraining agent. A number of 30cm×30cm×10cm HPC specimens have been made and tested under an one-dimensional heat load. The temperature rate was set to be 5℃/min in the tests and the maximum temperature was 1000℃. Using the temperature data measured from the thermal couples installed in the testing specimens to gather with the derived difference equation for heat conduction, the thermal conductivity and the volumetric heat capacity of HPC are than determined . It is indicated from this study that concrete with higher fc'' has also higher thermal conductivity. Reducing the amount of the above-mentioned mixtures in HPC will reduce its thermal conductivity and increase its volumetric heat capacity as well. This research also conducts a nonlinear heat conduction finite element analysis using the obtained thermal conductivity and the volumetric heat capacity as input material properties. The temperature distributions resulted from the analysis agrees very well with the measured ones. This indicates that the method developed to measure the thermal conductivity and volumetric heat capacity in this study is quite reliable .

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38

Mao-Li, Jiang, e 江茂利. "Effects of Fiber Glass,Air Entraining Agent and Lightweight Aggregate on the Thermal Expansion Property of High Performance Concrete". Thesis, 1998. http://ndltd.ncl.edu.tw/handle/45377223169879619520.

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Abstract (sommario):

碩士
國立臺灣科技大學
營建工程技術研究所
86
High Performance Concrete (HPC) is a new construction material with high strength and high slump flow. However owing to its higher density, it also possesses higher thermal conductivity and is even easier to spall in fire temperature than ordinary concrete. In order to promote its engineering application, these negative fire-resistance characters need to be improved. This research tries to mix respectively the lightweight aggregate, fiber glass and air entraining agent in HPC and studies the effect of improvement of these mixtures on the fire-resistance behavior of HPC. The research project is divided into two parts : the first part studies the effect of the mixtures on the spalling and thermal expansion behavior of HPC；while the second part deals with the effect of the mixtures on the thermal conductivity and volumetric heat capacity of HPC. This report presents the research outcome of the first part. The parameters considered in this study are the strength of concrete , the amount of the lightweight aggregate, fiber glass and air entraining agent. A number of 10cm×10cm×30cm HPC specimens have been made and tested under a 3-dimensional heat load. The temperature rate was set to be 5℃/min in the tests and the maximum temperature was 800℃. The variations of the length of specimens were continuously investigated during the thermal load tests. After the tests，the residual thermal strains and the crack widths were measured. The test results indicate that adding fiber glass and air entraining agent in the HPC have the observable efficacy on avoiding spalling of HPC. However adding lightweight aggregate have no such efficacy . The HPC with increasing amount of fiber glass have smaller thermal strain and crack widths，while the ones with increasing amount of air entraining agent have also smaller crack widths but larger thermal strain. It is also found that the ranges in the variation of the thermal strain and the residual thermal strain of HPC at peck temperature are more pronounced than that of the normal strength concrete（NSC）. And the thermal expansion coefficient of the 8000psi HPC is close with that of the NSC，while the coefficient of the 10000psi HPC is smaller than that of the NSC.

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39

Jiang, Mao-Li, e 江茂利. "Effects of Fiber Glass,Air Entraining Agent and Lightweight Aggregate on the Thermal Expansion Property of High Performance Concrete". Thesis, 1998. http://ndltd.ncl.edu.tw/handle/97971109439160975971.

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40

FALLIANO, DEVID. "Calcestruzzi schiumati estrudibili: le proprietà e le potenzialità di un materiale da costruzione innovativo". Doctoral thesis, 2018. http://hdl.handle.net/11570/3131445.

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L’attività di ricerca presentata in questa tesi ha come campo di indagine quello dei calcestruzzi cellulari, in particolare schiumati, che appartengono all'ampia categoria dei calcestruzzi leggeri. I manufatti realizzati con queste miscele cementizie alleggerite con schiuma posseggono diverse importanti qualità, tra cui leggerezza, isolamento termico, resistenza al fuoco, economicità; tuttavia la scarsa tenuta dimensionale di tale materiale allo stato fresco non permette di poterne sfruttare appieno ed in maniera economicamente vantaggiosa le evidenti potenzialità. Le indagini sperimentali qui presentate, partendo dallo studio delle schiume liquide e passando attraverso la comprensione del loro comportamento all'interno della pasta cementizia e delle proprietà del materiale alleggerito che ne risulta conducono all'innovativo calcestruzzo schiumato estrudibile ed alla scoperta delle sue proprietà fisiche, meccaniche (con la presentazione di alcune strategie adottate per incrementarle), morfologiche e reologiche, mettendone in luce gli aspetti peculiari. Viene inoltre mostrato come proprio questi ultimi non solo permettano che il calcestruzzo schiumato estrudibile possa essere industrializzato in modo più semplice, efficiente ed economicamente conveniente rispetto alle tecniche attualmente impiegate nell'industria dei calcestruzzi leggeri, ma ne suggeriscano anche un suo impiego “ingegnerizzato” attraverso delle soluzioni che, sfruttando la tecnica della coestrusione, permettono di ottenere in un unico elemento proprietà in antitesi come l’ottimo isolamento termico e le buone resistenze meccaniche.
This thesis is related to the field of foamed concrete that belongs to the wider category of lightweight concrete and typically includes cement, water, preformed foam and fine sand. The foam component gives rise to the development of air voids within the cementitious matrix which results in a series of advantageous properties including: low self-weight, thermal insulating and sound absorption properties, fire resistance and cost-effectiveness. However, the fresh state poor dimensional stability of this lightweight cementitious paste doesn’t allow to exploit its potential in an economically advantageous way. The research activity of this thesis starting from the study of liquid foams and the comprehension of its behavior inside the cementitious matrix, and passing from an experimental campaign focused on classical foamed concrete leads to the innovative extrudable foamed concrete. The characteristics of this new kind of cellular concrete in terms of mechanical strengths (with the illustration of some strategies adopted to increase them) and physical, morphological and rheological properties are deducted through extensive experimental campaigns and presented here. The extrudable foamed concrete peculiarities make sure that it can be industrialized in a simpler, more efficient and cost-effective way than the processes currently used in the lightweight concrete industry. Moreover, its use in a multilayer engineered element, in which the number of layers, their density and thickness can be designed according to the needs, is presented.

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Tesi sul tema "Concrete Ageing"

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