No description available.

The objective of this research was to quantify the effects of selected parameters on the accuracy of concrete cover measurements on bridge decks. This research involved three full-factorial laboratory experiments each designed to investigate one of three primary variables. These primary variables included distance to a parallel adjacent bar, distance to a reinforcement intersection, and incorrect bar size input for the cover meter. Each experiment also involved four secondary variables known to affect cover readings. These secondary variables included actual cover depth, meter brand, antenna type, and bar size. Statistical analyses were performed to determine the significance of each factor. A margin of error of 0.125 in., corresponding to the increase in diameter between successive U.S. standard rebar sizes, was established as the threshold for practical importance in the data analysis. Three primary findings resulted from the three experiments performed in this research. For the meters and antennas tested, the results of the field-of-view experiment indicated that, if the spacing is greater than approximately 4.0 in., the returned readings are within the threshold for practical importance established for this research. The results of the proximity-to-an-intersection experiment indicated that, regardless of where the measurement is taking place in relation to an intersection, the operator can be confident that the errors will be less than 0.125 in. as long as the bar in question is above the intersecting bar. The results of the wrong-bar-size experiment indicated that, if the operator of the cover meter does not know the actual rebar size in question, the measured cover will be within 0.125 in. of the actual cover depth as long as the meter input is within one bar size of the correct value. Obtaining accurate cover measurements on bridge decks is important for quality assurance, service life prediction, and rehabilitation programming.

Submitted by Silvana Teresinha Dornelles Studzinski (sstudzinski) on 2016-06-13T17:14:24Z No. of bitstreams: 1 Fernanda Pacheco_.pdf: 2975053 bytes, checksum: ee3a33ed030278d4b1f1df978656449b (MD5) / Made available in DSpace on 2016-06-13T17:14:24Z (GMT). No. of bitstreams: 1 Fernanda Pacheco_.pdf: 2975053 bytes, checksum: ee3a33ed030278d4b1f1df978656449b (MD5) Previous issue date: 2016-04-11 / Nenhuma / Cresce o interesse pelo estudo da durabilidade das estruturas de concreto, devido à norma de desempenho e seus critérios de vida útil das edificações, somado à percepção da perda precoce de vida útil das construções. Há definições em normas técnicas e na literatura científica sobre os parâmetros de projeto das estruturas de concreto armado, como a relação água/cimento, consumo de cimento, resistência mecânica à compressão e cobrimento das armaduras. Porém, até o presente momento no Brasil, não estão estabelecidas as relações entre estas características para proporcionar maior flexibilidade ao profissional na especificação dos parâmetros das estruturas visando à durabilidade. Soma-se a esta lacuna a necessidade de consideração das classes de agressividade, definidas em virtude dos agentes deletérios às estruturas. Neste contexto, o objetivo deste trabalho é a definição da relação entre os parâmetros dos concretos e como estes variam em função das classes de agressividade ambiental, focando no cobrimento necessário para garantia da durabilidade das estruturas. Dessa forma, propôs-se o estudo com concretos, em concordância com as especificações de normas, verificando a frente de ataque das estruturas por modelos teóricos de previsão de vida útil, somados à realização dos ensaios acelerados de deterioração de carbonatação acelerada e névoa salina. Foram definidos períodos de realização do ensaio que representam cada uma das classes de agressividade da ABNT NBR 6118:2014, norteados pelos modelos teóricos de deterioração das estruturas. Após, cada um dos quatro traços de concreto foi submetido a diferentes agressividades. Diante disto, determinou-se o impacto no cobrimento das armaduras para cada classe de agressividade, mais amena ou mais severa. Cada um destes traços foi avaliado quanto às características físicas e mecânicas. Verificou-se que o cobrimento necessário às armaduras varia de maneira linear com a resistência à compressão dos traços, denotando a possibilidade de considerar mais de uma classe de resistência de concreto e o cobrimento nas diferentes classes de agressividade, como ocorre em algumas normas técnicas internacionais de dimensionamento de estruturas. Destaca-se que a diferença do cobrimento necessário em relação às classes de agressividade se torna mais acentuada quando utilizados concretos de resistência superior a 30MPa. Ainda, percebeu-se que o ataque por íons cloreto é mais severo que a carbonatação, tendo determinado, na maioria das verificações, a espessura mínima de concreto para garantir a durabilidade almejada. Por fim, a análise estatística apontou influência significativa do traço na frente de carbonatação e apenas entre os traços 1 e 4 em relação à resistência frente a névoa salina. / The amount of studies that focus on concrete structures durability has been increasing because of the new Brazilian Standard regarding to Performance and its life cycle criteria for buildings, added to the perception of early lifespan loss of buildings. There are definitions in technical standards and scientific literature about project parameters of concrete structures, as water/cement, cement consumption, compressive strength and concrete covering. However, up to this date in Brazil, no relations have been established between these characteristics in a way to grant more flexibility for the professionals when specifying parameters of structures focusing on durability. Besides this gap, there is a necessity to consider the aggressiveness classes established by agents which are deleterious to structures. Within this context, this study aims to define the relations between the parameters of different concretes compositions and how they differentiate due to the environmental aggressiveness classes, focusing on the necessary covering to ensure durability. Thus, the study of concretes according to Standard specifications was proposed, besides checking the attack front of structures through theoretical life cycle prediction models, and the conduction of accelerated tests of carbonation and salt spray. The test periods that were defined represent each one of the aggressiveness classes of ABNT NBR 6118, guided by the theoretical models of deterioration of structures. After this, each of the four concrete mixes was submitted to different aggressiveness. Thereby, it was possible to determine the impact in the coating of the reinforcement for each aggressiveness class, whether milder or more severe. Each mix was evaluated for physical and mechanical characteristics. It was found out that the concrete cover necessary for the steel bars varies linearly with the compressive strength resistance of the mixes, indicating the possibility to consider more than one resistance class of concrete and coating within different aggressiveness classes, as occurs in some international technical standards of dimensioning of structures. It is noteworthy that the difference of concrete cover necessary in relation to aggressiveness classes becomes rougher when concretes with compressive strength higher than 30 MPa are used. Another observation is that that the attack for chloride ions is more severe than carbonation, determining, in most verifications, the minimum thickness to ensure the expected durability. Lastly, the statistical analysis pointed out a significant influence of the mix in the carbonation front and between the mixes 1 and 4 for salt spray.

De même degré d'importance que les paramètres de formulation, les conditions de consolidation sont des facteurs déterminants pour la durabilité des bétons conventionnels vibrés. Dans le cas des bétons autoplaçants (BAP), grâce à leur grande fluidité, la mise en place dans les coffrages a lieu par écoulement libre sous l'effet de leur poids propre. Leur consolidation se fait sans vibration grâce à leurs caractéristiques rhéologiques. Il est donc légitime de penser que, les caractéristiques rhéologiques des BAP peuvent avoir une influence importante sur les propriétés qui déterminent la durabilité. Cette thèse étudie les liens possibles entre les caractéristiques rhéologiques des BAP et leur durabilité vis-à-vis du transport des agents agressifs. Dix-sept formulations de BAP couvrant une large gamme de caractéristiques rhéologiques et se différenciant uniquement par leur dosage en adjuvants ont été étudiées à cet effet. Trois modèles rhéologiques classiques ont été mis en oeuvre pour la détermination des paramètres rhéologiques des bétons étudiés.L'essai de sorptivité et dans une moindre mesure l'essai de carbonatation accélérée ont été utilisés comme indicateur de durabilité vis-à-vis du transport des agents agressifs. La durabilité de la couche superficielle au contact respectivement avec le coffrage en bois et en PVC a été étudiée et les résultats ont été comparés à la durabilité du béton à cœur. Cette étude a été faite en tenant compte des échanges hydriques et de l'arrangement granulaire au droit du coffrage. D'autre part, l'étude de la durabilité de la couche superficielle dans des conditions de mise en place proches du chantier a été faite sur 6 poutres partiellement armées longues de 2 m ainsi que sur 3 bétons semi-autoplaçants légèrement vibrés.Les résultats montrent qu'il existe une corrélation forte entre la viscosité plastique du modèle Bingham modifié ou le coefficient de consistance du modèle Herschel-Bulkley et la sorptivité. Très probablement, la viscosité agit sur le volume relatif des pores capillaires de gros diamètres. L'étude spécifique de la couche superficielle a montré que sa sorptivité dépend du type de coffrage utilisé à cause des éventuels échanges hydriques opérés entre le béton et la surface du coffrage. De plus, l'arrangement granulaire au droit du coffrage est également influencé. Ainsi, la sorptivité de la couche superficielle au contact du PVC est proche mais inférieure à celle du béton à cœur. La sorptivité de la couche superficielle au contact du bois est significativement inférieure à celle de la couche superficielle au contact du PVC tout en restant corrélé avec la viscosité plastique du modèle Bingham modifié ou le coefficient de consistance du modèle Herschel-Bulkley. / Consolidation conditions are determining factors for the sustainability of conventional vibrated concrete as like as formulation parameters. In the case of self-consolidating concrete (SCC), due their fluidity, casting is done by free flow under the influence of their own weight. Consolidation in the forms is done without vibration due to their rheological characteristics. It is therefore reasonable to expect that the rheological characteristics of SCC would have a significant influence on the durability's properties. This thesis examines the possible links between the rheological characteristics of SCC and vis-à-vis durability's transport of aggressive agents. In total, Seventeen SCC mixtures covering a wide range of rheological properties were investigated. Three current rheological models were studied to determine the rheological parameters. In other hand, durability of cover concrete close of site conditions was studied on 6 partially reinforced beams and 3 semi-workable concrete vibrated slightly.Sorptivity test was used as indicator of vis-à-vis aggressive transport durability. The durability of the concrete cover layer in contact respectively with the wooden and PVC frame has been studied and the results were compared with the durability of interior bulk concrete. This study was made taking into account the exchange of water and aggregate arrangement against the formwork.Good correlation between initial plastic viscosity determined by the Bingham modified model or consistency coefficient determined by the Herschel-Bulkley model of SCC and the sorptivity measured during the first hours of testing is established. It is likely that the initial plastic viscosity or consistency coefficient has a marked influence on the volume of the largest capillary pores of concrete, which can significantly affect durability. The specific study of the concrete cover showed that its sorptivity depends on the type of formwork used because of water exchanges made between the concrete surface. Aggregate arrangement against the formwork was also modified. Sorptivity of the concrete cover of PVC is near but below that of the interior bulk concrete. Sorptivity of the concrete cover against wooden frame is significantly less than over of against PVC while being correlated with the plastic viscosity of modified Bingham or consistency coefficient of Herschel-Bulkley model.

Résumé : De même degré d’importance que les paramètres de formulation, les conditions de consolidation sont des facteurs déterminants pour la durabilité des bétons conventionnels vibrés. Dans le cas des bétons autoplaçants (BAP), grâce à leur grande fluidité, la mise en place dans les coffrages a lieu par écoulement libre sous l’effet de leur poids propre. Leur consolidation se fait sans vibration grâce à leurs caractéristiques rhéologiques. Il est donc légitime de penser que les caractéristiques rhéologiques des BAP peuvent avoir une influence importante sur les propriétés qui déterminent la durabilité. Cette thèse étudie les liens possibles entre les caractéristiques rhéologiques des BAP et leur durabilité vis-à-vis du transport des agents agressifs. Dix-sept formulations de BAP couvrant une large gamme de caractéristiques rhéologiques et se différenciant uniquement par leur dosage en adjuvants ont été étudiées à cet effet. Trois modèles rhéologiques classiques ont été mis en œuvre pour la détermination des paramètres rhéologiques des bétons étudiés. L’essai de sorptivité et dans une moindre mesure l’essai de carbonatation accélérée ont été utilisés comme indicateur de durabilité vis-à-vis du transport des agressifs. La durabilité de la couche superficielle au contact respectivement avec le coffrage en bois et en PVC a été étudiée et les résultats ont été comparés à la durabilité du béton à cœur. Cette étude a été faite en tenant compte des échanges hydriques et de l’arrangement granulaire au droit du coffrage. D’autre part, l’étude de la durabilité de la couche superficielle dans des conditions de mise en place proches du chantier a été faite sur 6 poutres partiellement armées longues de 2 m ainsi que sur 3 bétons semi-autoplaçants légèrement vibrés. Les résultats montrent qu’il existe une corrélation forte entre la viscosité plastique du modèle Bingham modifié ou le coefficient de consistance du modèle Herschel-Bulkley et la sorptivité. Très probablement, la viscosité agit sur le volume relatif des pores capillaires de gros diamètres. L’étude spécifique de la couche superficielle a montré que sa sorptivité dépend du type de coffrage utilisé à cause des éventuels échanges hydriques opérés entre le béton et la surface du coffrage. De plus, l’arrangement granulaire au droit du coffrage est également influencé. Ainsi, la sorptivité de la couche superficielle au contact du PVC est proche mais inférieure à celle du béton à cœur. La sorptivité de la couche superficielle au contact du bois est significativement inférieure à celle de la couche superficielle au contact du PVC tout en restant corrélé avec la viscosité plastique du modèle Bingham modifié ou le coefficient de consistance du modèle Herschel-Bulkley. / Abstract : Consolidation conditions are determining factors for the sustainability of conventional vibrated concrete as like as formulation parameters. In the case of self-consolidating concrete (SCC), due to their fluidity, casting is done by free flow under the influence of their own weight. Consolidation in the forms is done without vibration due to their rheological characteristics. It is therefore reasonable to expect that the rheological characteristics of SCC would have a significant influence on the durability’s properties. This thesis examines the possible links between the rheological characteristics of SCC and durability’s transport of aggressive agents. In total, seventeen SCC mixtures covering a wide range of rheological properties were investigated. Three current rheological models were studied to determine the rheological parameters. In other hand, durability of cover concrete close to site conditions was studied on 6 partially reinforced beams and 3 semiworkable concrete vibrated slightly. Sorptivity test was used as indicator of aggressive transport durability. The durability of the concrete cover layer in contact respectively with the wooden and PVC frame has been studied and the results were compared with the durability of interior bulk concrete. This study was made taking into account the exchange of water and aggregate arrangement against the formwork. Good correlation between initial plastic viscosity determined by the Bingham modified model or consistency coefficient determined by the Herschel-Bulkley model of SCC and the sorptivity measured during the first hours of testing is established. It is likely that the initial plastic viscosity or consistency coefficient has a marked influence on the volume of the largest capillary pores of concrete, which can significantly affect durability. The specific study of the concrete cover showed that its sorptivity depends on the type of formwork used because of water exchanges made between the concrete surface. Aggregate arrangement against the formwork was also modified. Sorptivity of the concrete cover of PVC is near but below that of the interior bulk concrete. Sorptivity of the concrete cover against wooden frame is significantly less than over of against PVC while being correlated with the plastic viscosity of modified Bingham or consistency coefficient of HerschelBulkley model.

FRP laminates and fabrics, used as an externally bonded reinforcement (EBR) to strengthen or repair concrete members, have proven to be an economical retrofitting method. However, when used to strengthen long-span members or members with limited access, the labor and equipment demands may negate the benefits of using continuous EBR FRP. Recently, CFRP rod panels (CRPs) have been developed and deployed to overcome the aforementioned limitations. Each CRP is made of several small diameter CFRP rods placed at discrete spacing. To fulfill the strengthening length, CRP’s are spliced together and made continuous by means of overlaps (or finger joints). In this doctoral dissertation, the effectiveness of spliced CRPs as flexural strengthening reinforcement for RC members was investigated by experimental, analytical and numerical methods. The experimental research includes laboratory tests on (1) RC beams under four-point bending and (2) double-lap shear concrete specimens. The first set of tests examines the behavior of concrete members strengthened with spliced CRPs. Several beams were fabricated and tested, including: (a) unstrengthened, (b) strengthened with spliced CRPs, (c) strengthened with full-length CRPs, and (d) strengthened with full-length and spliced CFRP laminates. The double-lap shear tests serve to characterize the development length and bond strength of two commonly used CRPs. Several small-scale CRPs, with variable bond lengths, were tested to arrive to an accurate estimation of development length and bond strength. Several other specimens were additionally tested to preliminarily examine the effects of bond width and rod spacing. A 3D nonlinear finite element simulation was utilized to further study the response of CRP strengthened RC beams, by extracting essential data, that couldn’t be measured in the experimental tests. Additionally, analytical tools were added to investigate the behavior of tested bond and beam specimens. The first tool complements the double-lap shear tests, and provides mathematical terms for important characteristics of the CRP/concrete bond interface. The second tool investigates concrete cover separation failure, which was observed in the beam testing, for RC beams strengthened with full-length and spliced CRPs.

In today’s situation new methods are constantly evolving in the construction industry where the sustainability of a construction is of utmost importance. Prefabricated concrete is a type material that is highly durable in terms of long life without producing damaging effects. As a result, the material has been used increasingly in the manufacture of construction. Construction industry is continuously developing, which means new ways to construct buildings. Within construction, usage of prefabricated concrete is a method that has become increasingly successful. With this method, the construction period is shortened considerably and the construction process will be more beneficial for the environment and the various safety aspects. This master thesis was written in cooperation with AB Strängbetong, is one of the largest companies in Sweden that uses prefabricated elements. The company has a concept called TempoDeck and is currently building a parking garage in Ullared, with the life with a life expectancy of 50 years, that is life class L50. The objective of the study was to check whether the construction work fulfilled the requirements of the standards. In addition, the purpose was also to investigate the possibility of a different type of facade design by reducing the height of the joists and beams. The thesis includes a literature review, a case study, an archive analysis as well as calculations with the Norwegian program E – bjelke. A guidance from AB Strängbetong has also been used. The results showed that the existing structure fulfilled the life class L50 according to the requirements. In addition, the results showed that it was aesthetically possible to modify the car park, to make it more appealing. However, it would be more profitable to keep the design as it is to the future constructions. / I dagsläget utvecklas ständigt nya metoder inom byggbranschen där hållbarheten i en konstruktion är av ytterst stor vikt. Betong är ett material som är mycket hållbart då det har en väldigt lång livslängd utan att det ger större skadeverkan. Detta resulterar i att materialet brukas allt mer i tillverkning av byggnationer. Byggnadsteknik är i kontinuerlig utveckling vilket medför nya sätt att uppföra byggnader. Byggverksamhet går mer och mer åt att använda prefabricerade betongelement, en byggmetod som har blivit allt mer framgångsrik. Med denna metod kan byggtiden kortas ner väsentligt, byggprocessen blir även hälsosammare för omgivningen och är bättre ur olika arbetsmiljöaspekter. Detta examensarbete skrevs i samarbete med AB Strängbetong som är ett av de största företagen i Sverige som använder sig av prefabricerade element. Företaget har ett koncept vid namn TempoDeck och har byggt ett parkeringshus med en förväntad livslängd på 50 år, det vill säga livslängdsklassen L50. Uppdraget som gavs var att kontrollera om denna byggnation klarade av kraven enligt normerna. Syftet var även att kunna utveckla en annan typ av fasadutformning genom att minska höjden på bjälklaget och balkar. Avgränsningen inom studien är att den endast gjorts på ett företag, AB Strängbetong, och fokuseras bara på parkeringshus med hänsyn till betongens täckskiktskrav. Examensarbetet fullföljdes genom inläsning av litteratur, fallstudie såsom arkivanalys och beräkningar, med det norska programmet E-bjelke, samt handledning från AB Strängbetong. Resultaten visade att den befintliga konstruktionen klarade av livslängdsklassen L50 med hänsyn till kraven. Det fanns även möjligheter till att estetiskt sätt ändra på parkeringshusets utseende, för att få den mer tilltalande. Det skulle dock vara mer ekonomiskt lönsamt att behålla utformningen som konceptet har till de framtida byggnationerna.

Alcali – silica reaction often causes destruction of a concrete.constructions. In the theoretical part is described creation and causes of the ASR including assessment of individual components of concrete and their testing. The practical part is devoted to the results of some control tests of the concrete cover in the section 18 of the highway D1 (Měřín - Velké Meziříčí) and section D1-20 (Velké Meziříčí - Lhotka), the mechanical properties of the upper and the lower layer of the concrete cover and measuring the resistance of concrete against chemical deicing agents.

This thesis deals with the study of cement – concrete coverings. The aim of the thesis is a summary of current knowledge of these constructions. The experimental part of this paper deals with the design of concrete for the lower layer of cement – concrete cover. Emphasis is placed on the elimination of microcracks and to increase the lifetime of these construction.

Numera sker all industriell torkning av virke i sågverken i virkestorkar, som värms upp och därmed torkar virket till den optimala slutfuktkvot som tillönskas. Virkestorkar byggda i betong har länge varit ett stort problem för sågverksindustrin. Problematiken går tillbaka till 80-talet då man tvingades riva ett flertal torkar på grund av att betongtorkarna höll på att vittra sönder. Detta gällde för alla betongtorkar byggda fram till 70-talet. Det genomfördes i slutet på 90-talet en stor rapportundersökningen som behandlade de flesta typer av skador i betongtorkar. Fram tills idag har en närmare undersökning ej gjorts och det har fortfarande inte hittats standarder för reparation och underhåll som förlänger livslängden på betongtorkar. Sågverksindustrin förlorar varje år 10-tals miljoner kronor på reparationer och underhåll som i de flesta fall inte verkar fungera. Därför finns det en stor efterfrågan av tydliga instruktioner för val av material och hur dessa reparationer skall gå till. Rapporten behandlar den allmänna problematiken av skador som uppstår p.g.a. bland annat väldigt högt temperaturbelastade virkestorkar som är konstruerade i betong. Arbetet är uppdelat i två faser den ena fasen består av en teoridel som bland annat förklarar skadorna och dess uppkomst i betongtorkar. Den andra fasen behandlar en fältundersökning som genomfördes under rapportskrivningen samt de förslag till åtgärder som tagits fram. Denna rapport är en liten del av ett stort pågående projekt, där CBI Betonginstitutet och SP trä är projektutförare och samverkar med deltagande sågverk i Sverige och Norge samt leverantörer. Projektet ska mynna ut i en Guideline till sågverksindustrin, för att kunna utföra rätt reparationer med rätt materialval och därmed förlänga betongtorkarnas livslängd. Detta med utgångspunkt från fältundersökningens provtagningar. / Nowadays, all the process of industrial drying of lumber in sawmills are done in kilns, which the wood is heated and dried for the desired optimal moisture content. Timber drying kilns built in concrete has for a long time been a major issues for the sawmill industry. The problems goes as far back to the 80s when several wood kilns was forced to be demolished due to concrete kilns were about to crumble. This was mainly for all the concrete dries built up until the 70s. In the late 90's a report survey was carried out to investigate the damages that were inflicted in concrete dries. No other survey has been done since then and the report didn’t give tangible standards for repairs and maintenance that extends the service life in wood kilns. The sawmill industry loses each year tens of millions on repairs and maintenance that hasn’t shown any results of working. Therefore, there is a great demand of clear instructions for the selection of materials and how these repairs need to be done. The report deals with the general issues of very high temperature-loaded kilns constructed in concrete. The work is divided into two phases; one phase consists of a theoretical part including explaining of the damages and its emergence in the concrete kilns. The second phase deals with a field survey conducted during the report writing as well as the proposed measures have been developed. This report is one small part of a large ongoing project, where CBI and SP wood are the project implementers and interact with participating sawmills in Sweden and Norway and the suppliers. The project will culminate in a Guideline for the sawmill industry, to be able to perform the correct repair with proper materials and thereby extend the life of concrete kilns. This is based on field survey sampling. The project will culminate in a Guideline for the sawmill industry, to be able to perform the correct repair with proper materials and thereby extend the life of concrete drying. This is based on field survey sampling.