The thesis deals with the analysis of a reinforced concrete digestate tank. The tank is built as a semi-underground construction. The roof is designed as a reinforced concrete dome, which is prestressed in a circular beam with prestressing cables - monostrands. The calculation of internal forces were performed by the software SCIA Engineer. The structure was assessed for the ultimate limit state and the ultimate serviceability state, in terms of watertightness for the width of cracks.

A two-parameter fracture criterion (TPFC) is used to correlate and predict failure loads on cracked configurations made of ductile materials. The current study was conducted to validate the use of the fracture criterion on more brittle materials, using elastic-plastic finite-element analyses with the critical crack-tip-opening angle (CTOA) failure criterion. Forman generated fracture data on middle-crack tension, M(T), specimens made of thin-sheet 7075-T6 aluminum alloy, which is a quasi-brittle material. The fracture data included a wide range of specimen widths (2w) ranging from 3 to 24 inches. A two-dimensional (2D) finite-element analysis code (ZIP2D) with a ''plane-strain core" option was used to model the fracture process. Fracture simulations were conducted on M(T), single-edge-crack tension, SE(T), and single-edge-crack bend, SE(B), specimens. The results supported the TPFC equation for net-section stresses less than the material proportional limit. However, some discrepancies were observed among the numerical results of the three specimen types. Thus, more research is needed to improve the transferability of the TPFC from the M(T) specimen to both the SE(T) and SE(B) specimens.

Betong är ett av de mest använda byggnadsmaterialen i dagens samhälle. Några av anledningarna till detta är att den har lång livslängd, är naturligt material som är 100 % återvinningsbart samt ej lättantändligt material. Även om betong har många fördelar så är den inte helt idealisk eftersom den har en låg draghållfasthet. En betongkonstruktion kan spricka på grund av förhindrade rörelser som skapar dragspänningar. Förhindrade rörelser kallas för tvång och kan beskrivas i form av en tvångsfaktor. I detta examensarbete definieras tvångsfaktor som en spänningskvot mellan påtvingade spänningar och påtvingade spänningar vid fullständigt tvång. Fastlåsningsgrad, rörelsemöjlighet och styvhetsrelation mellan det nygjutna elementet och motgjutningen är avgörande parametrar vid beräkning av tvång och ett typiskt fall kan exempelvis vara en vägg gjuten mot grund. En helt förhindrad konstruktion kan ha en tvångsfaktor som är lika med 1 medan en konstruktion som kan röra sig fritt kan ha en tvångsfaktor som är lika med 0. En relativ lägre tvångsfaktor fås däremot om krypningseffekten beaktas eftersom den har gynnsam inverkan på tvånget. Betongen kan spricka på grund av tvånget och om sprickan inte är förväntad eller är större än den förväntade för den dimensionerade lasten då betraktas den som skada. Att förhindra vattengenomträngning eller läckage innebär dessutom att genomgående sprickor i vattentäta betongkonstruktioner bör undvikas. Det är således viktigt att beakta tvånget vid sprickriskanalyser av vattentäta betongkonstruktioner. Syftet med det här examensarbetet var att undersöka tvånget utifrån flera aspekter vilket gjorde att arbetet uppdelades i 3 analyser. Analys 1 syftade på att bekräfta de typiska fallen som anges i eurokoden SS-EN 1992–3 samt att utvärdera angivna tvångsfaktorer vid beräkning av tvångsdeformationer. Följaktligen användes finita elementprogram för modellering av de fallen från eurokoden och samtidigt gjordes handberäkningar för att komplettera analysen. I analys 2 studerades hur tvånget påverkas mellan konstruktionsdelar med ändring av bärverksdimensioner. Bärverket som studerades var vägg gjuten mot bottenplatta. Föränderliga parametrar var plattans bredd och tjocklek samt väggens höjd och tjocklek. Samtidigt togs ändring av konstruktionens längd som en påverkande faktor. Slutligen gjordes sprickviddsberäkningar avseende böjande moment och krympning i analys 3 för att få fram armeringsmängderna som skulle klara sprickviddskravet för vattentäta betongkonstruktioner. Detta åstadkoms enligt två olika beräkningsmetoder: Eurokodens och Engströms (2014). Dessa beräkningar visade även en jämförelse i armeringsmängd vid användning av tvångsfaktorer hämtad från eurokoden och tvångsfaktorer framräknad enligt FE-analyserna. Resultaten från analys 1 visade att variationen av beräknade tvångsfaktorer inte motsvarade helt den variationen som anges i SS-EN 1992–3 men avvek inte alldeles för mycket. Det fanns dock några enstaka fall där avvikelser var märkbara och därmed erfordras en noggrannare undersökning. Analys 2 visade att ökning av väggens volym minskar tvånget mot plattan men att en motsatt effekt fås för ökning av plattans volym. Det visade sig dessutom att en längre konstruktion orsakar större tvång mellan själva konstruktionsdelar. Slutsatsen från analys 3 var att skillnaden i genererad armeringsmängd var nästan proportionell i procentsats mot skillnaden i tvångsfaktor. Olika beräkningsmetoder resulterade dock i armeringsmängder som inte var jämförbara. Jämförelsen mellan de två beräkningsmetoderna var inte heller syftet med detta examensarbete utan endast ett försök att få en insyn i hur de olika metoderna är uppbyggda. / Concrete is one of the most widely used building materials in society today. Some of the reasons for this are that it has a long life, is a natural material that is 100% recyclable and non-flammable material. It has many advantages, but it is not entirely ideal due to its low tensile strength. A concrete structure may crack due to restrained movements which creates tensile stresses. Restrained movements are called restraint which can be described in the form of restraint factor. In this thesis, restraint factor is defined as a ratio between the actual imposed stress and the imposed stress at full restraint. The degree of fixity, movement possibility and stiffness relation between the newly casted element and the adjacent old structure are crucial parameters in the calculation of restraint and a typical case is, for example, a wall-on-slab cast. A completely restrained construction has a restraint factor equal to 1, while a structure that can move freely has a restraint factor equal to 0. However, a relative lower restraint factor is obtained if the creep effect is considered, since it has a positive influence on the restraint. The concrete may crack due to the restraint and if the crack is not expected or is larger than the expected for the dimensioned load then it is considered as damage. Preventing water penetration or leakage also means that through cracks in waterproof concrete structures should be avoided. Therefore, it is important to consider the restraint on fracture risk analyzes of waterproof concrete structures. The purpose of this thesis was to investigate the restraint based on several aspects, which meant that the work was divided into 3 analyses. Analysis 1 had as purpose to confirm typical cases specified in Eurocode SS-EN 1992–3 and to evaluate the stated restraint factors that the Eurocode proposes should be used in calculations of restraint deformations. For that matter, finite element program was used for modeling the cases from the Eurocode and at the same time hand calculations were made to supplement the analysis. Analysis 2 consisted of examining how the restraint between structural parts is affected by changing dimensions of the structure. The construction being studied was wall-on-slab cast. Variable parameters were the width and thickness of the slab, as well as the height and thickness of the wall. At the same time, changing the length of the construction was taken as an affecting factor. Lastly, crack width calculations for bending moments and shrinkage were made in analysis 3 to obtain the amount of reinforcement that meet the crack width requirement for waterproof concrete structures. This was done according to two different calculation methods: Eurocodes and Engström’s (2014). These calculations also showed a comparison in the amount of reinforcement when using restraint factors derived from Eurocode and restraint factors calculated according to the FE analyses. The results from analysis 1 showed that the variation of restraint factors calculated did not completely correspond to the variation stated in SS-EN 1992–3 but did not deviate too much. However, there were a few cases where deviations were noticeable and therefore a more detailed examination is required. Analysis 2 showed that increasing the volume of the wall reduces the restraint against the slab, but an opposite effect was obtained by increasing the volume of the slab. At the same time, it was found that a longer construction causes greater restraint between the actual components. The conclusion from analysis 3 was that the difference in generated amount of reinforcement was almost proportional in percentage to the difference in restraint factor. However, using different calculation methods resulted in amounts of reinforcement that were not comparable. Comparison between the two calculation methods was not the purpose of this thesis, but merely an attempt to gain an insight into how the different methods are structured.

En svensk standard, SS 812310­ – Dimensionering av fiberbetongkonstruktioner, har nyligen tagits fram som skall säkerhetsställa kvalitén och underlätta dimensioneringen av stålfiberbetongkonstruktioner. Tidigare har det inte funnits en dimensioneringsstandard som täcker in området stålfiberbetong. Det har varit upp till enskilda konstruktörer att dimensionera utifrån metoder angivna ur ”Svenska Betongföreningens rapport nr 13”. Materialdata har hämtats från stålfiberleverantörer eller balkprovning. Detta har ibland medfört felaktiga dimensioneringar och en osäkerhet till användandet av stålfiberbetong som material. Förhoppningen med den nyutkomna standarden är att den skall underlätta dimensioneringen av konstruktioner med stålfiberbetong och därigenom att materialet börjar användas i bredare utsträckning. Syftet med examensarbetet är att granska den nyutkomna standarden genom att applicera dess beräkningsmetoder på en konkret dimensioneringsuppgift. I examensarbetet har två olika fält av ett bostadsbjälklag, med olika randvillkor, undersökts. Dimensionering med hänsyn till moment- och tvärkraftskapacitet har utförts i brottgränstillstånd, och med hänsyn till sprickbredd och deformationer i bruksgränstillstånd. Dimensioneringen har utförts dels med enbart traditionell armering och dels i en kombination av traditionell armering och stålfibrer. Resultatet av arbetet visar att användandning av stålfibrer i kombination med armeringsjärn ger en betydande minskning av sprickbredden, deformationerna blir mindre och tvärkraftskapaciteten ökar. Vi kunde dra slutsatsen att det är bra att en svensk standard för stålfiberbetong har tagits fram så att konstruktionsföretag i Sverige har något att förhålla sig till. Den behöver dock förtydligas i vissa avseenden samt revideras där vi upptäckte några brister. / A Swedish standard, SS 812310 – Design of Fibre Concrete Structures, have recently been developed to ensure the quality and facilitate the design of steel fiber concrete. Previously, there was no design standard that covered the material steel fiber concrete. It was up to the individual engineer to design the constructions based methods from the Swedish report “Svenska Betongföreningens rapport nr 13”. Material data was gathered from the steel fibre suppliers or beam test. This sometimes led to incorrect designs and also an uncertainty to the use of steel fiber concrete as a material. The expectation with the newly published standard is to ease the process of designing the constructions of steel fiber concrete and thereby the material will be used in a wider extent. The purpose of this thesis is to examine the recently published standard by applying its calculation methods on a design task. In this thesis, two different slab panels of a residential floor, with different boundary conditions, was investigated. Design with respect to moment- and shear force capacity has been carried out in the ultimate limit state, and with respect to crack width and deflections at serviceability limit state. The dimensioning has been performed partly with only traditional reinforcement and partly with traditional reinforcement in combination (Svenska Betongföreningen, 2008) with steel fibers. The result of this thesis shows that the use of steel fibers combined with reinforcing bar provides a significant reduction in crack width, the deformations become smaller and the shear resistance increases. We could conclude that it is good that a Swedish standard for steel fiber concrete has been developed so that construction companies in Sweden have something to relate to. However, it needs to be clarified at some aspects and revised because of some deficiencies we discovered.

Detta examensarbete är ett samarbete med Peab och deras dotterbolag Swerock. Idén som lagtgrunden till denna rapport är att undersöka vilken effekt inblandning av polypropylen har påtvå utvalda betongsammansättningar som används som anläggningsbetong med högexponeringsklass. De två utvalda betongsammansättningarna är dels en konventionellanläggningsbetong med hög exponeringsklass (benämns ”standardbetong” i denna studie) samten motsvarande variant med SweRocks nylanserande ”Eko-betong”. I eko-betongen har en delav cementen ersatts med masugnsslagg (restprodukt från stålindustrin) för att minimerautsläppen av koldioxid vid tillverkning av cementen. Syftet med detta examensarbete är attbehandla och undersöka huruvida inblandning av polypropylenfiber med olika doseringarpåverkar krympningen för anläggningsbetong. Målet med studien är att öka kunskapen omkrympning i anläggningsbetong. Frågeställningarna som beaktas i denna rapport innefattarsåledes hur de två specifika anläggningsbetongrecepten påverkas vid två olika doseringar avpolypropylen med avseende på krympning. Metoden för att kunna besvara frågeställningarnahar uteslutande varit insamling av empiri som i sin tur har möjliggjorts genom att gjutabetongprovkroppar av dessa två recept med olika doseringar av polypropylen. Totalt göts tolvstycken provkroppar fördelat på sex provkroppar per betongrecept. Vidare göts två provkropparper betongrecept och dosering av polypropylen. Provkropparna mättes och vägdes vid tiotillfällen under en period på ca 35 dagar och resultatet på krympningen för respektivebetongsammansättning blev ca: 1,3% utan polypropylen, 0,6% med normaldosering avpolypropylen och 1,4% för dubbelnormaldosering av polypropylen. Teoretiska värden påkrympningen för båda betongrecept beräknades fram med hjälp av modeller från Eurocode 2:Dimensionering av betongkonstruktioner och Betonghandboken: Material. De faktiska värdenasom mättes upp blev ca 20 gånger större än de teoretiska värdena för respektive betong.Viktiga felkällor som tas upp och behandlas i denna rapport är okontrollerade temperatur- ochfuktförhållanden vid förvaring av provkropparna, risken för felmätningar vid mättillfällena,varje provkropps unika betongsammansättning med mera. Betongsammansättningen i varjeenskild provkropp behandlas särskilt då en provkropp kan ha betydligt mer ballast(stenmaterial) än annan vilket i sin tur resulterar i en mindre uppmätt krympning. Därmedbedöms det att studien hade behövt ett större antal provkroppar av varje betongrecept för att påså sätt minska omfattningen av felkällor och erhålla ett mer tillförlitligt resultat. Dock visar deresultat som erhölls i denna studie på att polypropylen kan medföra en minskad krympning förde recept där polypropylen använts kontra de recept där polypropylen inte använts samt att ekobetongenkrymper generellt sätt mindre än standardbetongen. Dock går det inte att se någottydligt gemensamt samband mellan de två olika betongtyperna om huruvida en enkel- ellerdubbeldosering av polypropylen i betongen medför en mindre krympning än den andra utanendast att polypropylen medför en minskad krympning. Slutsatserna och svaren påfrågeställningarna blir således för denna studie är att inblandning av polypropylen medför engenerellt minskad krympning för båda anläggningsbetongrecepten men inget samband sompåvisar att dubbeldosering av polypropylen medför ytterligare krympningsminskning än vad ennormaldosering medför. / This thesis is a collaboration with Peab and their subsidiary Swerock. The idea behind thisreport is to investigate the effect of blending polypropylene on two selected concretecompositions used as construction concrete with a high exposure class. The two selectedconcrete compositions are partly a conventional construction concrete with a high exposureclass (referred to as "standard concrete" in this study) and a corresponding variant withSweRock's newly launched "Eko-betong". In eko-betong, part of the cement has been replacedwith blast furnace slag (residual product from the steel industry) to minimize carbon dioxideemissions during the production of the cement. The purpose of this thesis is to treat andinvestigate whether admixture of polypropylene fibers with different dosages affects theshrinkage of construction concrete. The aim of the study is to increase knowledge aboutshrinkage in fixed concrete. The issues considered in this report thus include how the twospecific construction concrete recipes are affected at two different dosages of polypropylenewith respect to shrinkage. The method for being able to answer the questions has exclusivelybeen the collection of empirical data, which in turn has been made possible by casting concretesamples of these two recipes with different dosages of polypropylene. A total of twelve testspecimens were cast, divided into six test specimens per concrete recipe. Furthermore, two testspecimens were cast per concrete recipe and dosage of polypropylene. The specimens weremeasured and weighed on ten occasions over a period of about 35 days and the result of theshrinkage for each concrete composition was about: 1.3% without polypropylene, 0.6% withnormal polypropylene dosing and 1.4% for double normal polypropylene dosing. Theoreticalvalues for the shrinkage for both concrete recipes were calculated using models from Eurocode2: Dimensioning of concrete structures and the Concrete Handbook: Materials. The actualvalues measured were about 20 times greater than the theoretical values for each concrete.Important sources of error that are addressed and treated in this report are uncontrolledtemperature and humidity conditions when storing the specimens, the risk of erroneousmeasurements at the time of measurement, the unique concrete composition of each specimenand more. The concrete composition in each individual specimen is treated especially as onespecimen may have significantly more aggregate (stone material) than another, which in turnresults in a less measured shrinkage. Thus, it is judged that the study would have needed a largernumber of specimens of each concrete recipe in order to reduce the extent of sources of errorand obtain a more reliable result. However, the results obtained in this study show thatpolypropylene can lead to a reduced shrinkage for the recipes where polypropylene has beenused versus the recipes where polypropylene has not been used and that the eco-concretegenerally shrinks less than the standard concrete. However, it is not possible to see any clearcommon connection between the two different types of concrete as to whether a single or doubledosing of polypropylene in the concrete causes a smaller shrinkage than the other, but only thatpolypropylene causes a reduced shrinkage. The conclusions and answers to the questions thusbecome for this study are that admixture of polypropylene entails a generally reduced shrinkagefor both fixed concrete recipes, but no connection that shows that double dosing ofpolypropylene entails further reduction of shrinkage than a normal dosing entails.

Concrete structures are in general expected to be subjected to cracking during its service life. This is the reason why concrete is reinforced, where the reinforcement is only activated after cracks occur. However, cracks may be a concern in large concrete structures, such as dams, since it may result in reduced service life. The underlying mechanisms behind crack formations are well known at present day. On the other hand, information concerning the crack condition over time and its influence on the structure is limited, such as the influence of water pressure within the cracks. The aim of this project is to study crack propagation influenced by water pressure and to define an experimental test setup that allows for crack propagation due to this load. Numerical analyses have been performed on an initial cracked specimen to study the pressure along the crack propagation. The finite element method has been used as the numerical analysis tool, through the use of the software ABAQUS. The finite element models included in these studies are based on linear or nonlinear material behavior to analyze the behavior during a successively increasing load. The numerical results show that a crack propagates faster if the water is keeping up with the crack extension, i.e. lower water pressure is required to open up a new crack. When the water does not have time to develop within the crack propagation, more pressure is required to open up a new crack. The experimental results show that the connection between the water inlet and the specimen is heavily affected by the bonding material. In addition, concrete quality and crack geometry affects the propagation behavior.

Impelled by the increase in the number of tunnel fires in the last decade alone, wide spread attention has been drawn towards tunnel fire safety studies. Many of these fires occurred in road and railway tunnels involving vehicles and trains. These fire incidents have claimed lives, caused structural damages to the tunnel infrastructure and even economic losses to the government, businesses and communities concerned. When there is a fire in a tunnel, the temperature inside the tunnel increases rapidly to magnitudes as high as 1500°C. At such high temperatures costly damages to the tunnel structure is inevitable. Having an understanding of the detrimental effects of such high temperatures is essential and valuable when carrying out preliminary assessment of the type and extent of damage in the tunnel. This would in turn provide useful information in determining the appropriate remedial measures required to make the tunnel safe and usable again in the aftermath of a tunnel fire. In most tunnel fire safety studies, the focus has been on the behaviour of concrete, since of course concrete is one of the major support elements in tunnels. However, in several cases, such as in Scandinavia for example, where the rock mass is competent enough to support itself only a thin layer of shotcrete is used usually on tunnel walls. In such cases the rock will be fully exposed to heat in an instance of fire. In this case, whether it is prevention or maintenance of the tunnel, it would require knowledge on the effect of elevated heat on the rock mass. Hence, it is line with this thinking that a study was initiated by the Swedish Transport Administration (Trafikverket), Kärnbränslehantering AB, SKB and Vattenfall to study the effect of heat on the physical and mechanical properties of some common rock types, and hence the focus of this thesis. This thesis presents the results of a series of laboratory studies which was carried out to investigate the effect of heat on the physical and mechanical properties of selected rock types, namely; diabase, granite and quartzitic schist. Samples from these rock types were heat treated at temperature levels of 400°C, 750°C and 1100°C, before investigating their mechanical and physical properties through mechanical testing and microscopic investigations of thin sections. Because the effect of heat on rock can be affected by the heating rate and exposure time, the test were conducted under controlled conditions in order to avoid significant variation in the results. The results clearly show that the rock types behave differently at different temperature levels, which tend to depend on the mineral composition and micro cracks distribution. As the temperature increases the rock forming minerals undergo changes in their chemical structure thus causing them to alter from the original phase they had existed in. With these phase changes different reactions take place such as re-crystallization, the loss of crystal bound water, thermal expansion and micro cracking of mineral grains as well as the development of voids. These microscopic changes were manifested in the macro-scale by the variations observed in the behaviour of strength and stiffness of the samples in the mechanical tests.

This thesis is meant to serve as part of a competence platform for future product development projects at Sandvik Coromant AB, Solid Round Tools Department, Västberga, Sweden. The project objective is to gain generic knowledge of the wear mechanisms that restrict tool lifetime when drilling austenitic stainless steel. Thus, identifying if the weakest link of the tool is located within the coating, the coating adherence or in the strength of the substrate. A theoretical review of the work-piece and tool materials has been conducted as a background, along with definition of tool geometry and process parameters. Furthermore, the review includes chemical and process design effect on mechanical properties of the austenitic stainless steel, TiAlN coatings and cemented carbide substrates. Additionally, the basic principles of the wear mechanisms and wear types that are specific to drilling have been reviewed. During the experimental procedures both solid and exchangeable tip drills from cemented carbide with multilayered PVD TiAlN coatings were tested. Two series of tests were conducted, the first series aimed to identify wear type dependency on cutting speed, focusing on wear of the tool margin. The second test series was performed to map the wear progression depending on distance. Analyses including identification the main wear mechanism, quantification the amount of wear, identify wear location on the tool, crack investigation and WDS analysis of chemical wear. Adhesive coating wear was found on the tool margin at an early stage. The adhesive wear rapidly progressed into a stable intermediate stage. Leaving the substrate exposed and more susceptible to other wear types resulting in crack and oxide layer formation.

[pt] As pelotas de minério de ferro são produzidas a partir de um processo de aglomeração de finos de minério denominado pelotização, e possuem granulometria adequada para utilização em fornos siderúrgicos. Nesta dissertação dois fenômenos associados às superfícies das pelotas foram estudados: a formação de trincas e a presença de recobrimento (coating). Durante a pelotização, as pelotas são submetidas a diversos esforços compressivos e mudanças bruscas de temperatura. Desta forma, são geradas trincas em sua superfície, que são prejudiciais à resistência e ao desempenho nos fornos de redução. Já durante o processo de redução pode ocorrer a formação de pontes de ferro entre as pelotas, que se aglomeram formando clusters que comprometem o fluxo de gases no interior dos fornos. Este problema pode ser minimizado recobrindo as pelotas com uma mistura a base de óxidos de magnésio, o coating, que inibe a formação das pontes. Tendo em vista a importância de caracterizar trincas e coating na superfície das pelotas, a presente dissertação desenvolveu metodologias de aquisição, processamento e análise digital de imagens adquiridas com um estereoscópio. Foram desenvolvidos porta-amostras ajustáveis que permitiram a aquisição de imagens 2D de pelotas aproximadamente esféricas de diferentes tamanhos, cobrindo a maior parte da superfície e evitando a sobreposição de regiões de análise. A rotina de análise de trincas comparou dois métodos de segmentação e forneceu atributos como espessura média, fração de área e comprimento. A rotina de análise de coating utilizou segmentação por limiarização e mediu a fração de área ocupada em cada pelota. O uso dos porta-amostras foi fundamental para o sucesso do procedimento de aquisição. As rotinas de análise de trincas ou de coating se mostraram robustas para diferentes amostras. / [en] Iron ore pellets are produced from an ore fines agglomeration process called pelletizing, and are suitable for use in steel furnaces. In this dissertation two phenomena associated with the pellet surfaces were studied: crack formation and the presence of coating. During pelletizing, the pellets undergo various compressive forces and sudden changes in temperature. In this way, cracks are generated on its surface, which are detrimental to strength and performance in reduction furnaces. Already during the reduction process the formation of iron bridges can occur between the pellets, which clump forming clusters that compromise the flow of gases inside the furnaces. This problem can be minimized by coating the pellets with a magnesium oxide coating, which inhibits the formation of bridges. Given the importance of characterizing cracks and coating on the surface of the pellets, this dissertation developed methodologies for acquisition, processing and digital analysis of images acquired with a stereoscope. Adjustable sample holders were developed which allowed the acquisition of 2D images of approximately spherical pellets of different sizes, covering most of the surface and avoiding overlapping analysis regions. The crack analysis routine compared two segmentation methods and provided attributes such as mean thickness, area fraction and length. The coating analysis routine used threshold segmentation and measured the fraction of area occupied in each pellet. The use of the sample holders was fundamental to the success of the acquisition procedure. Crack analysis or coating routines were robust for different samples.

<p>Aging public infrastructure in North America continues to challenge engineers and scientists to develop repair and rehabilitation strategies that are practical, durable and cost effective. Of specific interest is the state of concrete and concrete repair in buildings and civil engineering infrastructures that are in deteriorating condition. In particular, cracks pose a threat to the durability and ultimately the structural integrity of concrete. Cracks in concrete may form for several reasons, e.g. plastic shrinkage, thermal contraction, mechanical loading or as a result of overloading. Once formed, cracks present a combination of problems to the service life and performance of the structure. Therefore cracks must be repaired for the following reasons: to prevent the ingress of deleterious agents such as water, other liquids, vapour, gas, chemicals and biological agents; to either restore or increase the structural load-bearing capacity of the cracked concrete member; to restore the aesthetic condition of the structure.</p> <p>The effectiveness of two different repair methods, crack injections and cementitious overlays, were examined. Two repair materials, a low viscosity epoxy and polyurethane were injected into the cracks, and a thin polymer-modified cementious overlay was applied on the cracked surface. Two types of cement were used, an ordinary Portland cement and a blended cement with 8% silica fume. The specimen properties were evaluated using non-destructive testing, prior to being subjected to a series of freeze-thaw conditioning regimes. From the experimental program, it was determined that the epoxy injection repair was more effective in restoring the air tightness than the thin overlay. The polyurethane material was unsuccessful. Following the freeze-thaw regimes, an overall improvement of conditions for all three repairs was observed, with the cementitious overlay seeing the greatest improvement in air tightness. These results indicate that the on-going cement hydration mechanism had a greater effect on the performance in comparison to the deleterious effects of the environmental loads.</p> / Master of Applied Science (MASc)