At an average age of 42 years, 10% of the nation’s over 607,000 bridges are posted for load restrictions, with an additional 15% considered structurally deficient or functionally obsolete. While there are major concerns with decks in 75% of structurally deficient bridges, often weight and geometry of the deck further limit the load rating and functionality of the bridge. Traditional deck systems and construction methods usually lead to prolonged periods of traffic delays, limiting options for transportation agencies to replace or widen a bridge, especially in urban areas. The purpose of this study was to develop a new generation of ultra-lightweight super shallow solid deck systems to replace open grid steel decks on movable bridges and as well serve as a viable alternative in bridge deck replacements across the country. The study has led to a lightweight low-profile asymmetric waffle deck made with advanced materials. The asymmetry comes from the arrangement of primary and secondary ribs, respectively perpendicular and parallel to the direction of traffic. The waffle deck is made with ultrahigh performance concrete (UHPC) reinforced with either high-strength steel (HSS) or carbon fiber reinforced polymer (CFRP) reinforcement. With this combination, the deck weight was limited to below 21 psf and its overall depth to only 4 inch, while still meeting the strength and ductility demands for 4 ft. typical stringer spacing. It was further envisioned that the ultra-high strength of UHPC is best matched with the high strength of HSS or CFRP reinforcement for an efficient system and the ductile behavior of UHPC can help mask the linear elastic response of CFRP reinforcement and result in an overall ductile system. The issues of consideration from the design and constructability perspectives have included strength and stiffness, bond and development length for the reinforcement, punching shear and panel action. A series of experiments were conducted to help address these issues. Additionally full-size panels were made for testing under heavy vehicle simulator (HVS) at the accelerated pavement testing (APT) facility in Gainesville. Detailed finite element analyses were also carried out to help guide the design of this new generation of bridge decks. The research has confirmed the superior performance of the new deck system and its feasibility.

It is important to ensure that vulnerable structures (federal and provincial offices, military structures, embassies, etc) are blast resistant to safeguard life and critical infrastructure. In the wake of recent malicious attacks and accidental explosions, it is becoming increasingly important to ensure that columns in structures are properly detailed to provide the ductility and continuity necessary to prevent progressive collapse. Research has shown that steel fibre reinforced concrete (SFRC) can enhance many of the properties of concrete, including improved post-cracking tensile capacity, enhanced shear resistance, and increased ductility. The enhanced properties of SFRC make it an ideal candidate for use in the blast resistant design of structures. There is limited research on the behaviour of SFRC under high strain rates, including impact and blast loading, and some of this data is conflicting, with some researchers showing that the additional ductility normally evident in SFRC is absent or reduced at high strain loading. On the other hand, other data indicates that SFRC can improve toughness and energy-absorption capacity under extreme loading conditions. This thesis presents the results of experimental research involving tests of scaled reinforced concrete columns exposed to shock wave induced impulsive loads using the University of Ottawa Shock Tube. A total of 13 half-scale steel fibre reinforced concrete columns, 8 with normal strength steel fibre reinforced concrete (SFRC) and 5 with an ultra high performance fibre reinforced concrete (UHPFRC), were constructed and tested under simulated blast pressures. The columns were designed according to CSA A23.3 standards for both seismic and non-seismic regions, using various fibre amounts and types. Each column was exposed to similar shock wave loads in order to provide direct comparisons between seismic and non-seismically detailed columns, amount of steel fibres, type of steel fibres, and type of concrete. The dynamic response of the columns tested in the experimental program is predicted by generating dynamic load-deformation resistance functions for SFRC and UHPFRC columns and using single degree of freedom dynamic analysis software, RCBlast. The analytical results are compared to experimental data, and shown to accurately predict the maximum mid-span displacements of the fibre reinforced concrete columns under shock wave loading.

The application of advanced materials in infrastructure has grown rapidly in recent years mainly because of their potential to ease the construction, extend the service life, and improve the performance of structures. Ultra-high performance concrete (UHPC) is one such material considered as a novel alternative to conventional concrete. The material microstructure in UHPC is optimized to significantly improve its material properties including compressive and tensile strength, modulus of elasticity, durability, and damage tolerance. Fiber-reinforced polymer (FRP) composite is another novel construction material with excellent properties such as high strength-to-weight and stiffness-to-weight ratios and good corrosion resistance. Considering the exceptional properties of UHPC and FRP, many advantages can result from the combined application of these two advanced materials, which is the subject of this research. The confinement behavior of UHPC was studied for the first time in this research. The stress-strain behavior of a series of UHPC-filled fiber-reinforced polymer (FRP) tubes with different fiber types and thicknesses were tested under uniaxial compression. The FRP confinement was shown to significantly enhance both the ultimate strength and strain of UHPC. It was also shown that existing confinement models are incapable of predicting the behavior of FRP-confined UHPC. Therefore, new stress-strain models for FRP-confined UHPC were developed through an analytical study. In the other part of this research, a novel steel-free UHPC-filled FRP tube (UHPCFFT) column system was developed and its cyclic behavior was studied. The proposed steel-free UHPCFFT column showed much higher strength and stiffness, with a reasonable ductility, as compared to its conventional reinforced concrete (RC) counterpart. Using the results of the first phase of column tests, a second series of UHPCFFT columns were made and studied under pseudo-static loading to study the effect of column parameters on the cyclic behavior of UHPCFFT columns. Strong correlations were noted between the initial stiffness and the stiffness index, and between the moment capacity and the reinforcement index. Finally, a thorough analytical study was carried out to investigate the seismic response of the proposed steel-free UHPCFFT columns, which showed their superior earthquake resistance, as compared to their RC counterparts.

Atualmente, um dos principais problemas ligados às estruturas de concreto armado é a corrosão da armadura, especialmente devido à ação dos íons cloreto. Sua incidência no contexto das principais manifestações patológicas encontradas nas construções é bastante significativa, chegando a atingir índices de 50% em algumas regiões brasileiras. Além disso, o custo do reparo ou da reabilitação das estruturas deterioradas, em alguns casos, pode ser superior ao de uma estrutura nova. Com o objetivo de aumentar a vida útil das estruturas de concreto e diminuir o índice de ocorrência da corrosão de armaduras, esta pesquisa verifica o comportamento de concretos com adições minerais quanto à eficiência na proteção do aço contra a corrosão induzida por íons cloreto, em relação ao concreto sem adição. Para a produção dos concretos de alto desempenho (CAD), foram utilizados dois tipos de adições: a sílica de Fe-Si ou silício metálico (SFS), já comercialmente disponível, e a sílica extraída da casca de arroz (SCA), produzida em laboratório. Assim, além de proporcionar uma barreira física à entrada de agentes agressivos na camada de cobrimento, a utilização desses concretos contribui para a diminuição da poluição ambiental, uma vez que as adições estudadas são resíduos. Para tanto, foram realizados ensaios mecânicos e relacionados à durabilidade, tais como: absorção de água, resistência à penetração de cloretos, frente de penetração, teor total de cloretos e resistividade elétrica dos concretos. Na análise do processo de corrosão, duas técnicas foram empregadas: potencial de corrosão e espectroscopia por impedância eletroquímica. Em relação à microestrutura, foram realizados ensaios de porosimetria por intrusão de mercúrio, difratometria de raios X, termogravimetria e microscopia eletrônica de varredura. Os resultados obtidos no controle da corrosão pelo ataque de íons cloreto foram favoráveis ao uso das adições em substituição ao cimento Portland, uma vez que os concretos com adições superam os resultados obtidos nos concretos sem sílica (ainda que a SFS tenha proporcionado melhor desempenho em algumas propriedades), indicando alta capacidade dos CAD em proteger o aço frente à ação de íons cloreto. Dentre os tipos de cimento utilizados, o CP V ARI RS mostrou-se mais eficiente que o CP V ARI Plus, bem como apresentou melhor sinergia com a SCA. A técnica de espectroscopia eletroquímica pode ser utilizada em CAD, porém deve-se minimizar os efeitos da alta resistividade do material, especialmente quando se utiliza a SFS. / Nowadays, one of the main problems in reinforced concrete structures is steel corrosion, especially due to the action of chloride ions. Its incidence among the main pathologies is quite significant, reaching indexes of 50% in some Brazilian areas. Besides, the cost of repair or rehabilitation of deteriorated structures, in some cases, can be higher than a new structure. To increase the service life of concrete structures and reduce the occurrence of steel corrosion, this work verifies the behavior of concretes with mineral additions in protecting the steel against the corrosion induced by chloride ions, in comparison to concretes without addition. For the production of high performance concretes (HPC), two addition types were used: silica fume (SF), already commercially available, and silica extracted from rice husk (SRH), produced in laboratory. Thus, besides providing a physical barrier to the aggressive agents in the concrete cover, the use of such concretes contribute to decrease the environmental pollution, since the additions studied are residues. Mechanical and durability tests were accomplished, such as water absorption, chloride penetration resistance, chloride penetration depth and concentration and electric resistivity of concretes. In the analysis of corrosion process, two techniques were used: open circuit potential and electrochemical impedance spectroscopy. Regarding the microstructure, tests of mercury intrusion porosimetry, X-ray diffraction, termogravimetry and scanning electron microscopy were conducted. The results obtained in the control of steel corrosion by chloride ions were favorable to the use of the additions in substitution to the portland cement. Both concretes with additions showed better performances than the concretes without silica, indicating high capacity of HPC to protect against the steel corrosion in reinforced concrete structures. Concerning the types of cement used, CP V ARI RS showed to be more efficient than CP V ARI Plus and presented better synergy with SRH. The electrochemical impedance spectroscopy technique can be used in HPC, however the effects of the high resistivity of the material should be minimized, especially when silica fume is used.

This diploma thesis deals with the concept of use of nanotechnology for cement composites and UHPC. In the theoretical part of this diploma thesis there are theoretical principles described for successful design of high performance concrete and characteristics of main feedstock and its production. Furthermore, there is a focus on nanoparticles, especially the ones with carbon base in the form of carbon nanotubes CNT, in addition to that, graphenes GN that are new on the market, moreover, graphene oxide GO and its application in cement composites to mechanical characteristics and its durability. The first part of the practical part devotes in trying to find out an optimal parameter for ultrasonic mix with a suitable surface active substance of three graphenes. The other two parts of the practical part are about influence of graphenes on mechanical characteristics, cement paste microstructure, and application in the mix of concrete C 35/45 and UHPC

Thesis describes properties of HPC compared to concretes of normal and high strength. It further describes the input materials and the procedure for designing the composition of the mixture. It gives examples of already completed structures made of HPC. The experimental part describes the optimization of concrete mix and production of specimens. In the end results of testing the properties of the developed mixes from tests of dynamic and static modulus of elasticity, compressive strength and tensile strength by bending are described.

The goal of this work was to create a method for improving the dispersion of silica fumes for use in high performance concrete. Traditional methods used to design and manufacture high performance concrete emphasize the removal of coarse aggregates. Use of specially sorted fine aggregates at relatively low doses, the use of super-plasticizers and siliceous excrement. The low water content was achieved by using superplasticizer on a polycarboxylate basis. The standard ultrasound technology found in each laboratory was selected for the dispersion of silica fume. For experiments were we used dry silica fume powder and aqueous stabilized suspension. For comparison, were prepared different mixtures which showed the effects of the treatment prior to the use of silica fume.

Användandet av betong som ersättare för stål vid produktionen av vindkraftverkstorn har ökat den senaste tiden. Betongtorn är betydligt billigare än ståltorn men problem som sprickbildningar, frostsprängningar och följaktligen armeringskorrosion har uppstått bl a på grund av vibrationer från rotorn. I fundamentet i vindkraftverk kan ovan nämnda problem också uppstå och det uppfyller således inte alltid funktionskraven. Det här examensarbetet undersöker möjligheten att eliminera dessa problem genom att använda en sorts högpresterande betong kallad UHPC 2.2 med syntetfiberarmeringen, STRUX. Jämförelser mellan tidigare empiri om högpresterande betong och laborativa tester på UHPC 2.2 visar att den senare är beständigare och ger möjligheter till en större sprickfrihet. Sammanfattningsvis har den högpresterande betongen med fiberarmeringen STRUX visat sig vara en konkurrenskraftig möjlighet på marknaden. / The use of concrete has recently increased as a replacement to steel for the construction of towers for wind power plants. However there are problems such as cracking or frost scaling and finally corrosion of reinforcement, partly due to vibrations caused by the power plants' blades. In the foundation of power plants, the above problems also occur and do not always fulfill the functional requirements. This thesis investigates the possibility to eliminate these problems by using a special kind of high-performance concrete called UHPC 2.2 with synthetic fiber reinforcement, STRUX. When comparing previous empirics about regular concrete with laboratory tests on this high-performance concrete, we find that the later is more durable. In summary, the high-performance concrete with fiber reinforcement STRUX is shown to be a competitive market opportunity.

It is a well-known problem that concrete needs to be made more efficient and that it is the large consumption of cement that is the major contributing factor to the nearby need. There is a zero vision of a climate-neutral concrete where all CO2 emissions in the life cycle of the concrete are to be reset by 2050. It is a question of improving, above all, the process of handling CO2 in the production of cement. This study tackles CO2 emissions from the concrete from a holistic perspective, by exploring optimization possibilities when implementing a newly developed concrete in residential buildings, called Ultra High Performance Concrete (UHPC). While it should be a better alternative for the climate, it should also require less material consumption and be more cost-effective in order to create a competitive alternative to the conventional alternative today, called Normal Concrete (NC). UHPC is during a development phase regarding optimization opportunities and it has been proven in several studies to be able to relate better to a sustainable design, based on a total life cycle progression. This applies above all to large and robust bridge structures where large volume differences are available. The idea behind this study is to highlight the question of whether there is an opportunity to get similar results in the construction of less robust components in residential buildings, since the problem with the mix design for UHPC has been the overall high cost in relation to NC. In recent years, this cost has been reduced and now there are opportunities to effectively introduce UHPC into another segment.In this study, columns and beams were dimensioned in a residential NC building and a residential UHPC building with ETABS (CSI 2019). Furthermore, the components of the buildings were compared, based on the aspect of a sustainable design from a total LCA. What was investigated were the differences in total material consumption, CO2 emissions, and costs.The study showed that the UHPC components were better based on all aspects after its total LCA. The total cement consumption was larger, but the building received at the same time an estimated double the lifespan of the NC- building. The total material consumption in the form of total component volumes became smaller, the total annual CO2 emissions became smaller and the total annual costs became smaller as well. / Det är ett välkänt problem att betong behöver klimateffektiviseras och att det är den storacementkonsumtionen som är den stora bidragande faktorn till det närliggande behovet. Detfinns en nollvision om en klimatneutral betong där alla CO2- utsläpp under betongenslivscykel (LCA), ska nollställas fram till år 2050. Det är en fråga om att framför allt förbättraprocessen gällande hantering av CO2 vid produktion av cement. Den här studien angriperCO2- utsläppen från betongen ur ett helhetsperspektiv, genom att undersökaoptimeringsmöjligheter vid implementering av en nyutvecklad betong i bostadshus, kalladUltra High Performance Concrete (UHPC). Samtidigt som den ska vara ett bättre alternativför klimatet, ska den också kräva mindre materialåtgång och vara mer kostnadseffektiv föratt kunna skapa ett konkurrenskraftigt alternativ till det konventionella alternativet idag,kallad Normal Concrete (NC). UHPC är under en optimeringsfas och den har bevisats i flerastudier kunna förhålla sig bättre till en hållbar design, utifrån en total LCA. Det gäller framförallt stora och robusta brokonstruktioner där stora volymskillnader är disponibla. Tankenmed den här studien är att lyfta fram frågan om det finns möjlighet att få liknande resultatvid byggnation av mindre robusta komponenter i bostadshus, i ju med att problemet medmix-designen för UHPC, har varit den generella höga kostnaden i förhållande till NC. Påsenare år har den kostnaden kunnat reduceras och nu finns möjligheterna att effektivtkunna införa UHPC till ytterligare ett segment.I studien jämfördes pelare och balkar i ett UHPC- hus med motsvarande komponenter i ettNC- hus utifrån aspekten en hållbar design, ur en total LCA. Husen dimensionerades i ETABS(CSI 2019) utefter samma förutsättningar med hänsyn till kravet på bärförförmågorna. Detutgjorde skillnader hos volymerna på komponenterna, som således påvisade hurmaterialåtgången förändrades. CO2- utsläppen och kostnaderna påverkades avbetongkompositionerna och skillnaderna hos de materiella egenskaperna av respektivebetongtyp. I slutändan redovisades vilken betongtyp som genererade minsta och störstaårliga CO2- utsläpp och kostnader.Resultatet visade att UHPC- komponenterna minskade den totala betongåtgången underbyggprocessen med 27,1%, samt minskade armeringsåtgången med 12,0%, men attcementåtgången nästan fördubblades och motsvarade en ökning på 99,4%. CO2- utsläppenvart således betydligt större efter byggprocessen, men i förhållande till ett totaltlivcykelförlopp, minskade de totala årliga utsläppen med 18,8%. Det fanns en kritisk punktdär UHPC- komponenterna måste ha en LCA på minst 97,5 år i förhållande till NCkomponenternas LCA på 60 år, för att vara mer lönsamma utifrån totala CO2- utsläpp.Kostnaderna vart också betydligt större för UHPC- komponenterna efter byggprocessen,men efter en total LCA, minskade de totala kostnaderna med 39,0%. Det fanns en kritiskpunkt, där LCA- förloppet måste uppgå till minst 73,2 år i förhållande till NCkomponenternas LCA på 60 år, för att vara mer lönsamma utifrån totala kostnader.Enligt det framtagna resultatet fanns det goda möjligheter för pelare och balkar i UHPChuset att förhålla sig bättre utifrån en hållbar design, än vad motsvarande komponenter förNC- huset gjorde, efter en total LCA. Pelare och balkar i bostadshus kan bli ett nytt segmentatt introducera UHPC till, även om pålitligheten för studien är begränsad av betydelsefullafelkällor och tillgängliga kunskaper inom området för närvarande.

The main objective of this thesis is the verification of the buckling strength of the composite compression members which were made from high-strength materials. This thesis is divided into four main chapters which are interconnected. The first chapter summarizes the current state of the problem of the compression members. The basis of this part is the elementary theories and researches, the task of this text is attempted to understand and obtain normative procedures which are important for practical use. The second part deals with the theoretical analysis of composite column, mainly with the examination of the individual effects on the buckling strength. The result of the first and the second parts is analytical algebraic equations which determine the buckling strength of the member. The third part contains the numerical analysis, which leads to create a numerical model of the compression column. The numerical model is used for the verification of the theoretical analysis and for the investigation of the behaviour of the column loaded by axial force. The last part deals with the experimental verification of the previous analyses. There are tested various types of the composite columns, which were made of steel with a yield strength up to 455 MPa and of the concrete with a cube compression strength up to 102 MPa. Experimental results confirmed the high reliability of centrally loaded column and every tested columns failed by flexural buckling. The final step is evaluation and comparison of the results obtained from previous four parts. It was founded that design criteria for centrally loaded steel-concrete column are too conservative and design relationships doesn´t use the positive properties of high-strength materials for economic design.