Fresh properties of mortars are important factors in altering the performance of self compacting concrete (SCC). Measurement of the rheological properties of the fine mortar part of concrete is generally used in the mix design of SCC. It can be stated that SCC rheology can be optimized if the fine mortar part of concrete is designed properly. However, measurement of the rheological properties is often impractical due to the need for complex equipment. Therefore, more practical methods of assessing mortar workability are often preferred. In this study, four mineral admixtures, three superplasticizers (SP) and two viscosity modifying admixtures (VMA) were used to prepare self compacting mortar (SCM). The mineral admixtures included fly-ash, brick powder, limestone powder, and kaolinite. Two of the SPs were polycarboxylate based and another one was melamine formaldehyde based. One of the viscosity modifying admixtures was based on an aqueous dispersion of microscopic silica and the other one was based on high molecular weight hydroxylated polymer. Within the scope of the experimental program, 43 mixes of SCM were prepared from different materials with keeping the amount of mixing water constant. Workability of the fresh mortar were determined using V - funnel and slump flow tests. The setting time of the mortars, were also determined. The hardened properties that were determined included the ultrasonic pulse velocity (UPV) and the strength which was determined at 7, 28, and 56 days. It was concluded that among the mineral admixtures used, only fly-ash and limestone powder increased the workability of the mixes. The two polycarboxylate based SPs yield approximately the same workability and the melamine formaldehyde based SP was not as effective as the other two.

In CANDU reactors, under normal operating conditions, the inlet headers collect and distribute single-phase liquid flow (heavy water) to the fuel cooling channels via the feeders. However, under some postulated loss of coolant accidents, the inlet headers may receive two-phase fluid (steam/water) and the fluid forms a stratified region inside the header. To predict the thermalhydraulic behaviour of headers for the reactor safety analysis, the two-phase flow distribution within the headers and through the feeders must be modelled. In order to analyse the two-phase flow behaviour of a scaled CANDU inlet header / a transparent and instrumented version of a header with 5 feeders was previously built in the Mechanical Engineering Department of Middle East Technical University (METU-Two Phase Flow Test Facility / METU-TPFTF). The aim of this study is to investigate two-phase flow distribution through multiple outlets from such a horizontal drum both numerically and experimentally. For this purpose, three-dimensional incompressible finite difference equations in cylindrical coordinates were derived by using two-fluid model to simulate adiabatic two-phase flow (air/water) in the header numerically. The discretized equations were then programmed into a computer code which was developed specifically for modelling the header type geometry. A method based on the principles of Implicit Multi Field (IMF) technique has been utilised to solve those equations. The solution algorithm was tested by using some numerical benchmark problems. A number of experimental tests covering single and two-phase flow distribution through outlet pairs from the header were performed. Void fractions and flow rates obtained from these tests are in good agreement with the code results. The code also predicts the void fraction and pressure distribution in the header satisfactorily.

$aL’objectif de cette thèse est de comprendre le phénomène de suffusion (érosion interne) dans ses processus et ses conséquences sur le comportement mécanique des sols à faible cohésion par l’établissement d’une relation directe ou indirecte entre la stabilité interne de ces matériaux et leur critère de rupture. L’érosion interne vue essentiellement sous l’angle de la suffusion a été analysée par des modélisations numériques et des essais expérimentaux. Les principaux essais utilisés sont : - Ecoulements d’eau à travers un matériau granulaire dans une colonne. - Essais de cisaillement triaxial non drainés. Pour la modélisation numérique, PFC3D a été utilisé pour les simulations d’essais triaxiaux et la prise en charge du couplage fluide solide a été possible grâce à une option de type CFD (Coupling Fluid Dynamique). Ce code DEM a permis le développement d’une nouvelle méthode de génération d’échantillon granulaire à partir de sa courbe granulométrique et de sa porosité cibles. L’évolution des porosités, celle des courbes granulométriques et de l’état de stabilité interne avant et après écoulement ont été identifiées comme indicateur du niveau de suffusion. Les critères de stabilité de Kenney & Lau et de Kezdi ont permis d’apprécier la stabilité interne des échantillons. Les conséquences de la suffusion se sont manifestées par : Une diminution de l’angle de frottement interne dans le cas d’une suffusion interne; une augmentation de l’angle de frottement dans le cas d’une suffusion externe. Les comparaisons des résultats expérimentaux et numériques tant pour les écoulements que pour les essais triaxiaux ont présenté de bonnes concordances. Enfin, une proposition d’un nouveau critère de stabilité interne est établie, elle est déduite de l’analyse des relations entre le comportement mécanique et la stabilité interne, notamment la contractance du matériau. / The objective of this thesis is to understand the phenomenon of suffusion (internal erosion) in its process and its effects on the mechanical behavior of loose soil by establishing a direct or indirect relationship between the internal stability of these materials and failure criterion. Numerical modeling and experimental tests analyzed the internal erosion in terms of the suffusion. The main tests used are : - Water flows through a granular material in a column. - Undrained shear triaxial tests. For numerical modeling, PFC3D was used for simulations of triaxial tests and the treatment of solid fluid coupling was possible through a CFD type of option (Coupling Fluid Dynamics). This DEM code has allowed the development of a new method of generating granular sample from its grading curve and its target porosity. The evolutions of porosity, grading curves and the state of internal stability before and after discharge were identified as indicator of suffusion. Kenney & Lau and Kezdi stability criteria were used to assess the internal stability of samples. The consequences of suffusion were expressed by: A reduction of the internal friction angle in the case of an internal suffusion; an increase of the friction angle in the case of an external suffusion. Comparisons of experimental and numerical results for both flows and triaxial tests have shown good agreements. Finally, a proposal of a new criterion of internal stability is established, it is deducted from the analysis of the relationship between the mechanical behavior and internal stability, including the material contractance.

Att gjuta med betong under vatten är utmanande, och det ställs höga krav på både betongen och utförandet för att resultatet ska bli bra. Peab Anläggning har uppmärksammat en del problem med denna typ av gjutningar och ville därför tydliggöra problematiken för att öka chansen för bra resultat vid framtida undervattensgjutningar. Problemen bestod dels av gjutskador på den färdiga betongkonstruktionen, och dels av problem med betongen under gjutningens gång i form av skum och separation. Examensarbetet sammanställer svårigheterna med undervattensgjutning med självkompakterande betong (SKB) och undersöker vilka faktorer som påverkar det färdiga gjutresultatet. Detta har gjorts genom en litteraturstudie, intervjuer med kunniga personer inom ämnet samt besök på arbetsplatser där undervattensgjutningar utförts. De svårigheter som identifierats delas in under fyra huvudrubriker; planering inför gjutning, betong, form samt utförande. Planeringen inför gjutningen är mycket viktig men svår då många faktorer måste tas hänsyn till, såsom väder och trafik. För att minimera risken för oönskade gjutuppehåll krävs det även en förberedande plan med lösningar på problem som kan uppstå under gjutdagen. Svårigheten med färsk betong är att det är ett levande och därmed oförutsägbart material. Det är nödvändigt att betongen har god sammanhållning så att betongens cementpasta inte vaskas ut i vattnet. Det är även viktigt att betongen har rätt konsistens för att kunna omsluta all armering och fylla ut hela formen. Betongen testas när den kommer till arbetsplatsen. Bland annat kontrolleras betongens lufthalt samt homogenitet och flytbarhet, det senare med hjälp av flytsättmått. Det är viktigt att ta hänsyn till dessa kontroller och att ta beslutet att inte gjuta med dålig betong. Det ställs även höga krav på formen vid undervattensgjutningar. Den måste vara helt tät och byggas på rätt sätt så att skum och bottenslam kan rinna ut ur formen. En svårighet är att dykarna behöver utföra en del av formbyggandet under vattenytan. Utförandet är en stor utmaning, då arbetsmomentet är komplicerat och man gjuter i blindo. Metoden går ut på att betong pumpas ner under vattenytan genom ett betongrör med en undervattensventil. Under gjutningens gång är det viktigt att rörets mynning hela tiden är under betongytan och att gjutröret hålls vertikalt. Slutligen är det värt att nämna att litteraturen som finns idag om undervattensgjutningar är bristfällig, något som gör det svårt att lära sig om ämnet. De förslag på lösningar som grundas på slutsatsen är att all betong som kommer till arbetsplatsen bör testas, trots att det inte alltid är ett krav. Detta så att ett beslut kan tas kring varje enskilt betonglass om betongen är godkänd att gjuta med. För att öka chansen att betongen har önskade egenskaper är det viktigt att betongbilen som levererar betongen till arbetsplatsen är ren och inte innehåller rester av annan betong. Det krävs under hela arbetet en god kommunikation mellan både pumpmaskinist, dykare och arbetsledning för att de gemensamt ska kunna lösa eventuella problem som uppstår. Slutligen rekommenderas att ta hjälp av varandra och dra nytta av den kompetens och erfarenhet som finns inom företaget. / Casting with concrete under water is challenging, and requires high standards on both the concrete and the work practice to achieve good results. Peab noticed problems with this type of casting, and wanted to clarify the difficulties to increase the chance of good results with future underwater castings. The problems were injuries on the finished concrete structure and troubles with the concrete during casting such as foam and separation in the concrete. This paper compiles the difficulties with underwater casting with self-consolidating concrete (SCC) and investigates the factors that affect the final result. This has been done through interviews with experienced people, a literature review and visits to construction site that performed underwater casting. This paper identifies four main issues; pre-casting planning, concrete quality, form and work procedure. The planning is very important but difficult, as many factors need to be considered, such as weather, land traffic and boat traffic. In order to minimize the risk of unwanted breaks during casting, it is good to have a preparatory plan with solutions to problems that may occur. The difficulty with concrete is that it's a living, and thus unpredictable, material. It is very important that the concrete has good cohesion so that the concrete's cement paste is not washed out in the water. It is also necessary that the concrete has good consistency to ensure it will enclose all reinforcement and fill in the entire form. The concrete is tested when it arrives to the construction site. Among other things, the air content as well as homogeneity and flowability are controlled, the latter controlled by a slump flow test. It is important to take these controls into consideration, and to make the decision not to cast with bad concrete. The requirements on the form used during underwater casting are high. It must be completely dense and properly constructed so that foam and sludge can flow out of the form. One difficulty is that the divers sometimes need to build parts of the form under the water. The work practice is challenging as it's complicated and done blindly. The used method is to pump concrete under the water surface through a concrete pipe with an underwater valve. During the casting process, the mouth of the pipe must always be below the concrete surface and the casting tube should be kept vertically. Finally, it is worth mentioning that the literature available today about underwater casting is inadequate, which makes it difficult to learn about the subject. The suggested solutions presented in the report are that all concrete coming to the construction site should be tested, even though it is not always a requirement. Thus, the decision of whether the concrete had a high enough quality for casting would be made for each delivery. In order to increase the chances of the concrete having desired properties, it is important that the truck delivering concrete to the construction site is clean and does not contain residues of a different concrete. Throughout the work, a good communication between pump operator, diver and management is needed to jointly solve problems. At last, it is recommended to help each other and take advantage of the expertise and experience within the company.

Die COVID-19-Pandemie machte deutlich, wie wichtig die Verfügbarkeit eines Schnelltests für ein funktionierendes Gesundheitssystem ist. Mit dieser einfachen Technologie kann die Unsicherheit in den unterschiedlichen und teils kontroversen statistischen Kennzahlen signifikant verringert werden. Immunoassays wie LFIA, FPIA und ELISA (Lateral Flow Immunoassay, Fluoreszenzpolarisationsimmunoassay und Enzymimmunoassay) werden in der Diagnostik und der Umweltanalyse eingesetzt. Die Verwendung von LFIA für ein Screening vor Ort bietet eine Alternative zu instrumentellen Methoden sowie komplizierteren Immunoassay-Formaten und liefert innerhalb von 10 bis 15 Minuten Ergebnisse. Verfahren mit Membranen als feste Träger erlauben parallele Assays in derselben Probe. In dieser Arbeit wurden Latex-Mikropartikel-basierte und Gold-Nanopartikel-basierte LFIAs zum Nachweis von Bisphenol A (BPA) entwickelt. Ein Ziel der Arbeit war die Entwicklung von Nitrocellulose-Membranen, Konjugatpads, Membranbehandlungen sowie einer geeigneten LFIA-Vorbehandlung zwecks Optimierung. Die Ergebnisse eines LFIA-Tests können sowohl mit bloßem Auge als auch instrumentell interpretiert werden. Die visuelle Nachweisgrenze (vLOD) wurde bei 10 μg/L gefunden, die berechnete instrumentelle Nachweisgrenze (cLOD) war 0,14 μg/L. Die Synthese der Haptenproteinkonjugate und deren weitere Bewertung in einem ELISA-Aufbau führte zu einem hochempfindlichen Assay mit einer Nachweisgrenze von 0,05 μg/L. Zusätzlich wurde ein Mix-and-Read-FPIA zur Bestimmung von BPA entwickelt. Dafür wurden neue Tracer-Moleküle, welche Fluorophore mit Derivaten des Analyten verbinden, einschließlich eines C6-Spacers (Ahx) synthetisiert. Der Einfluss der Ahx-Tracer-Brückenlänge auf die Assay-Empfindlichkeit wurde abgeschätzt, die Nachweisgrenze lag bei 1,0 μg/L mit einem Arbeitsbereich von 2 bis 155 μg/L. Die Methoden wurden für reale Proben gegen LC-MS/MS als Referenzmethode mit guter Übereinstimmung mit LFIA, FPIA und ELISA validiert. / The COVID-19 pandemic made it obvious how important the availability of a rapid test is for an efficient healthcare system. This simple technology can significantly reduce the uncertainty in the various and sometimes highly controversial statistical figures of a pandemic. Immunoassays, like LFIA, FPIA and ELISA (lateral flow immunoassay, fluorescence polarization immunoassay, enzyme immunoassay) are used in diagnostics and environmental analysis. The use of LFIA for on-site screening is an alternative to instrumental methods and to more sophisticated immunoassay formats. Results from LFIA are obtained within 10 to 15 min. Methods that use membranes as solid supports allow parallel assays to be performed in the same sample. In this work, latex microparticles-based and gold nanoparticles-based LFIAs for a rapid detection of bisphenol A (BPA) were developed. The work focused on the search for suitable nitrocellulose membranes, conjugate pads, membrane treatments, as well as for a proper LFIA pretreatment to optimize the performance. The results of an LFIA test can be interpreted both by naked eye and instrumentally. The visual limit of detection (vLOD) was found to be 10 μg/L, the calculated instrumental limit of detection (cLOD) was 0.14 μg/L. The synthesis of the required hapten-protein conjugates and further evaluation in an ELISA setup resulted in a highly sensitive assay with a limit of detection of 0.05 μg/L. Additionally, a mix-and-read FPIA for determination of BPA was developed. Here, new tracer molecules that link fluorophores to derivatives of the analyte were synthesized, including a C6 spacer (Ahx). The influence of the Ahx tracer bridge length on the assay sensitivity was estimated. The limit of detection was 1.0 μg/L with a working range from 2 to 155 μg/L. The methods were validated for real samples against LC-MS/MS as reference method with good agreement with LFIA, FPIA, and ELISA.

When subjected to a combination of moment and shear force, a reinforced concrete (RC) beam with either little or no transverse reinforcement can fail in shear before reaching its full flexural strength. This type of failure is sudden in nature and usually disastrous because it does not give sufficient warning prior to collapse. To prevent this type of shear failure, reinforced concrete beams are traditionally reinforced with stirrups. However, the use of stirrups is not always cost effective since it increases labor costs, and can make casting concrete difficult in situations where closely-spaced stirrups are required. The use of steel fiber reinforced concrete (SFRC) could be considered as a potential alternative to the use of traditional shear reinforcement. Concrete is very weak and brittle in tension, SFRC transforms this behaviour and improves the diagonal tension capacity of concrete and thus can result in significant enhancements in shear capacity. However, one of the drawbacks associated with SFRC is that the addition of fibers to a regular concrete mix can cause problems in workability. The use of self-consolidating concrete (SCC) is an innovative solution to this problem and can result in improved workability when fibers are added to the mix. The thesis presents the experimental results from tests on twelve slender self-consolidating fiber reinforced concrete (SCFRC) beams tested under four-point loading. The results demonstrate the combined use of SCC and steel fibers can improve the shear resistance of reinforced concrete beams, enhance crack control and can promote flexural ductility. Despite extensive research, there is a lack of accurate and reliable design guidelines for the use of SFRC in beams. This study presents a rational model which can accurately predict the shear resistance of steel fiber reinforced concrete beams. The thesis also proposes a safe and reliable equation which can be used for the shear design of SFRC beams.

When subjected to a combination of moment and shear force, a reinforced concrete (RC) beam with either little or no transverse reinforcement can fail in shear before reaching its full flexural strength. This type of failure is sudden in nature and usually disastrous because it does not give sufficient warning prior to collapse. To prevent this type of shear failure, reinforced concrete beams are traditionally reinforced with stirrups. However, the use of stirrups is not always cost effective since it increases labor costs, and can make casting concrete difficult in situations where closely-spaced stirrups are required. The use of steel fiber reinforced concrete (SFRC) could be considered as a potential alternative to the use of traditional shear reinforcement. Concrete is very weak and brittle in tension, SFRC transforms this behaviour and improves the diagonal tension capacity of concrete and thus can result in significant enhancements in shear capacity. However, one of the drawbacks associated with SFRC is that the addition of fibers to a regular concrete mix can cause problems in workability. The use of self-consolidating concrete (SCC) is an innovative solution to this problem and can result in improved workability when fibers are added to the mix. The thesis presents the experimental results from tests on twelve slender self-consolidating fiber reinforced concrete (SCFRC) beams tested under four-point loading. The results demonstrate the combined use of SCC and steel fibers can improve the shear resistance of reinforced concrete beams, enhance crack control and can promote flexural ductility. Despite extensive research, there is a lack of accurate and reliable design guidelines for the use of SFRC in beams. This study presents a rational model which can accurately predict the shear resistance of steel fiber reinforced concrete beams. The thesis also proposes a safe and reliable equation which can be used for the shear design of SFRC beams.

When subjected to a combination of moment and shear force, a reinforced concrete (RC) beam with either little or no transverse reinforcement can fail in shear before reaching its full flexural strength. This type of failure is sudden in nature and usually disastrous because it does not give sufficient warning prior to collapse. To prevent this type of shear failure, reinforced concrete beams are traditionally reinforced with stirrups. However, the use of stirrups is not always cost effective since it increases labor costs, and can make casting concrete difficult in situations where closely-spaced stirrups are required. The use of steel fiber reinforced concrete (SFRC) could be considered as a potential alternative to the use of traditional shear reinforcement. Concrete is very weak and brittle in tension, SFRC transforms this behaviour and improves the diagonal tension capacity of concrete and thus can result in significant enhancements in shear capacity. However, one of the drawbacks associated with SFRC is that the addition of fibers to a regular concrete mix can cause problems in workability. The use of self-consolidating concrete (SCC) is an innovative solution to this problem and can result in improved workability when fibers are added to the mix. The thesis presents the experimental results from tests on twelve slender self-consolidating fiber reinforced concrete (SCFRC) beams tested under four-point loading. The results demonstrate the combined use of SCC and steel fibers can improve the shear resistance of reinforced concrete beams, enhance crack control and can promote flexural ductility. Despite extensive research, there is a lack of accurate and reliable design guidelines for the use of SFRC in beams. This study presents a rational model which can accurately predict the shear resistance of steel fiber reinforced concrete beams. The thesis also proposes a safe and reliable equation which can be used for the shear design of SFRC beams.

Asphalt joints are potentially weakest parts of every pavement. Despite of their importance, reliable tools for measuring their mechanical properties for design and performance assessments are still scarce. This is particularly true for cold joints when attaching a new hot pavement to a cold existing one as in case of large patches for pavement repair. In this study, three static fracture testing methods, i.e. indirect tensile test (IDT), direct tension test (DTT) and 4 point bending (4PB), were adapted and used for evaluating different laboratory made joints. The results suggested that joints with inclined interfaces and also the ones with combined interface treatments (preheated and sealed) seemed to show more promising behaviors than the vertical and untreated joints. It was also confirmed that compacting from the hot side towards the joint improved the joint properties due to imposing a different flow pattern as compared to the frequent compaction methods. The latter finding highlighted the importance of asphalt particle rearrangements and flow during the compaction phase as a very little known subject in asphalt industry. Studies on compaction are of special practical importance since they may also contribute to reducing the possibility of over-compaction and aggregate crushing. Therefore, in this study, a new test method, i.e. Flow Test (FT), was developed to simulate the material flow during compaction. Initially, asphalt materials were substituted by geometrically simple model materials to lower the level of complexity for checking the feasibility of the test method as well as modeling purposes. X-ray radiography images were also used for capturing the flow patterns during the test. Results of the FT on model materials showed the capability of the test method to clearly distinguish between specimens with different characteristics. In addition, a simple discrete element model was applied for a better understanding of the test results as a basis for further improvements when studying real mixtures. Then, real mixtures were prepared and tested under the same FT configuration and the results were found to support the findings from the feasibility tests. The test method also showed its potential for capturing flow pattern differences among different mixtures even without using the X-ray. Therefore, the FT was improved as an attempt towards developing a systematic workability test method focusing on the flow of particles at early stages of compaction and was called the Compaction Flow Test (CFT). The CFT was used for testing mixtures with different characteristics to identify the parameters with highest impact on the asphalt particle movements under compaction forces. X-ray investigations during the CFT underlined the reliability of the CFT results. In addition, simple discrete element models were successfully generated to justify some of the CFT results. / <p>QC 20151104</p>

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