This thesis evaluates the use of High Strength Lightweight Concrete (HSLW) in bridge girders for the I-85 Ramp "B" Bridge crossing SR-34 in Cowetta County, Georgia. This bridge consisted of four spans; all girders were constructed using lightweight expanded slate aggregate. Spans 2 and 3 had a design strength of 10,000 psi, and span 2 was chosen for this research. The BT-54 girders were 107 ft 11½ inches in length. The prestressing strands used in these girders were 0.6 in diameter, grade 270, low relaxation strands. Material properties and member properties were tested. All 5 girders of span 2 were instrumented with vibrating wire strain gages at midspan, as well as with DEMEC inserts for transfer length measurements and with a deflection measurement system. Transfer length measurements found the transfer length of the girders to be 23% less than the values suggested by AASHTO and ACI equations. The deflection measurements showed 4.26 inches of camber at 56-days while the girders were stored at Standard Concrete Products. The camber measurements matched theoretical predictions within 5%. Mechanical property tests found the concrete to be within all design requirements. A stiffness, load test was performed on each of the 5 girders at Standard Concrete Products. The average stiffness value of 8.428 x 106 kip ft2 is recommend for use by GDOT engineers in designing the deck and road profile. This thesis discusses all short term findings from construction to the end of storage. A later report will address long term issues such as creep and shrinkage, as well as the performance of the girders as part of the bridge.

Autogenous shrinkage is of concern in high performance concrete mixtures, when specific properties like strength and durability are enhanced. Factors like low watercement ratio, low porosity and increased hydration kinetics which are associated with high performance concrete mixtures are also responsible for the development of autogenous shrinkage. With about two decades of research into autogenous shrinkage, uncertainties still exist with testing procedure, effect of supplementary cementitious materials, modelling and prediction of autogenous shrinkage. The primary focus of this study is to understand mechanisms which have been postulated to cause autogenous shrinkage like chemical shrinkage and self desiccation. In addition, this study has considered properties like porosity and internal empty voids in the analysis of the causes of bulk volume deformations of the cementitious paste systems with and without mineral admixtures. The study begins with an experimental investigation of chemical shrinkage in hydrating cementitious paste systems with the addition of fly ash, slag and silica fume using the test method recently accepted by the ASTM. This was followed by the experimental investigation of autogenous shrinkage in cementitious paste. The autogenous shrinkage in paste mixtures is studied from an early age (~1.5 hours after addition of water) for cementitious systems at a water-cementitious ratio of 0.32 (w/c 0.25 for limited mixture proportions). A non-contact measurement method using eddy current sensors were adopted. The hydration mechanism of the cementitious paste systems was then modelled using CEMHYD3D, which is a 3 dimensional numerical modelling method successfully used to study, simulate and present the hydration developments in cementitious systems. Properties like chemical shrinkage, degree of hydration, total porosity and free water content; all of which have been obtained from the CEMHYD3D simulation have been cross correlated with the experimental results in order to more comprehensively understand the mechanism contributing to bulk volume change under sealed conditions. The experimental investigations are extended to study the development in concrete with and without mineral admixtures (i.e., silica fume, fly ash and slag). Self desiccation driving the development of autogenous shrinkage has been used extensively across literature but as an alternative the author has proposed using internal drying factor in modelling autogenous shrinkage. The "internal drying factor" is described as the ratio of the empty voids (due to chemical shrinkage) to the total porosity at any point of time of hydration. Independent of the mixture proportions, a linear trend was observed between the autogenous shrinkage strain and increase in internal drying factor. Thus the internal drying factor could be incorporated into semiempirical models while attempting to predict autogenous shrinkage. An increase in the compressive strength of matured concrete at 1 year had a strong correlation to the observed autogenous shrinkage strains irrespective of the cementitious system. It is believed this could be because of the increase in gel-space ratio which is intern linked to the degree of hydration and porosity of the microstructure. The author has obtained strong evidence that the micro-structural changes associated with high strength and durable concrete have a direct impact on the autogenous shrinkage of concrete. Hence, the author suggests that autogenous shrinkage should be investigated and allowable values be stipulated as design criterion in structures that use high strength-high performance concrete.

Thesis (M.S.)--University of Missouri-Columbia, 2007. / The entire dissertation/thesis text is included in the research.pdf file; the official abstract appears in the short.pdf file (which also appears in the research.pdf); a non-technical general description, or public abstract, appears in the public.pdf file. Title from title screen of research.pdf file (viewed on November 6, 2007) Includes bibliographical references.

Thesis (Ph. D.)--University of New South Wales, 2005. / Also available online.

Made available in DSpace on 2014-06-11T19:27:14Z (GMT). No. of bitstreams: 0 Previous issue date: 2007-12-10Bitstream added on 2014-06-13T18:31:07Z : No. of bitstreams: 1 jacomassi_lmc_me_ilha.pdf: 1853171 bytes, checksum: f9955a37141d1b46cbca1dacc35af9be (MD5) / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / A demanda crescente pela utilização de Concreto de Alta Resistência (CAR) torna necessária a definição de critérios e procedimentos de análise do comportamento estrutural desse material. Nesse sentido, este trabalho apresenta a discussão de resultados experimentais publicados e as simulações numéricas de pilares armados de CAR submetidos à compressão axial simples. Utilizando o Código CASTEM 2000, é feita uma modelagem numérica bidimensional e análise via Método dos Elementos Finitos (MEF) para a reprodução dos diagramas força-deformação obtidos experimentalmente. Após um estudo comparativo dos parâmetros recomendados por normas internacionais de análise do comportamento estrutural do CAR, nota-se que os resultados numéricos obtidos utilizando as especificações da Norma Norueguesa NS 3473 são mais próximos dos experimentais. A modelagem numérica desenvolvida é capaz de reproduzir, com certa precisão, a capacidade de carga de pilares de diversas geometrias, taxas de armadura transversal e longitudinal, tipos de aço e resistência do concreto variando entre 50 MPa e 90 MPa. As taxas mínimas de armadura capazes de promoverem a ductilização dos pilares por desagregação do cobrimento são superiores a 2,5% de armadura longitudinal e 2,0% de armadura transversal, segundo os resultados experimentais. Comparando a esses resultados os obtidos pelas simulações, observa-se como de comportamento dúctil os pilares com capacidade de carga obtida numericamente pelo menos 25% maior que a força máxima teórica obtida de acordo com as recomendações da NS 3743. / The increasing demand of the use of High-Strength Concrete (HSC) makes it necessary to define criteria and procedures analysis to the structural behavior of this material. This work presents the discussion on published experimental results and numerical simulations of HSC reinforced columns submitted to simple axial compression. Bidimensional numerical modeling with Finite Elements Method (FEM) analysis were made to reproduce experimentally force-strain diagrams by using the Code CASTEM 2000. After a comparative study on the internationally recommended HSC structural behavior analysis standards, it may be inferred that the numerical results obtained using specifications of the Standard Norge NS 3473 are the closest to the experimental ones. The adopted numerical modeling could reproduce the force capacity of columns of different shapes, transversal and longitudinal reinforcement rates, types of steel and concrete resistance from 50 MPa to 90 MPa with some precision. The minimal reinforcement rate able to provide columns ductility by confinement effect is higher than 2.5% longitudinal reinforcement and 2.0% transversal reinforcement, according the experimental results. Comparing these results with the simulations, it could be considered the ductility behavior of the columns with the numerical charge capacity at least 25% higher than the maximum teorical force obtained according to recomendations of NS 3743.

Este trabalho tem o objetivo de analisar teórica e experimentalmente o comportamento de consolos de concreto armado. Para tal, foi realizada uma revisão bibliográfica, buscando os artigos mais recentes e as principais normas que tratam deste assunto. Foram analisados mais de trezentos consolos encontrados na literatura. Nesta análise, as forças de ruína experimentais foram comparadas com a forças de ruínas calculadas segundo as normas: ACI-318M-89, CAN3-A23.3-M-84 e NBR-9062/85. Para complementar este estudo, foram ensaiados oito consolos de concreto de alta resistência, os quais apresentavam: as mesmas dimensões, a mesma armadura principal e diferentes taxas de armadura de costura. A resistência do concreto variou de 50 MPa a 80 MPa. Estes consolos tiveram suas forças de ruína comparadas com as previstas pelas normas já citadas. Além disto, foram analisadas: as deformações na armadura, medidas a cada nível de carregamento, e o ângulo de inclinação das tensões principais, medidos no centro geométrico da provável biela comprimida. De acordo com as análises realizadas, pode-se observar que o uso de concreto de alto desempenho na confecção de consolos é bastante eficaz. Entretanto, é necessário o uso de taxas adequadas de armadura, que são basicamente as mesmas indicadas para consolos de concreto de resistência convencional. O dimensionamento de consolos segundo as normas citadas foi bastante satisfatório. Entretanto, no cálculo da força de ruína das peças ensaiadas por outros pesquisadores, os resultados não foram tão satisfatórios, pois estes consolos analisados nem sempre apresentavam o detalhamento conforme recomendam estas normas. / The aim of this work is to analyze theoretically and experimentally the behavior of reinforced concrete corbels. A bibliographic review was done, searching for the most recent papers and the main codes concerning to this subject. It was analyzed more than there hundred corbels found in the literature. In this analysis, the experimental failures forces were compared to the failure forces calculated by the followings codes: ACI-318M-89; CAN3-A23.3-M-84 and NBR-9062/85. To complement this work, eight corbels of high-strength concrete were made with the same dimensions, the same main reinforcement and different rates of secondary reinforcement. The strength of the concrete ranged from 50 MPa to 80 MPa. These corbels had their failure forces compared with the failure forces postulated by the codes. It was also evaluated the deformations of the reinforcement, considered in each level of loading, and the angle of inclination of the main stresses, measured in the geometric center of probable compressed diagonal. By this analysis, it was observed that the use of high-strength concrete in the construction of corbels is quitely efficient. Although, it is necessary the use of proper reinforcement ratios, that are basically the same indicated for corbels with low-strength concrete. The design of corbels by the cited codes was quitely satisfactory. By the way, the calculation of the failure force of corbels made by others researchers were not satisfactory. The probable reason was that the corbels did not present the reinforcement details recomended by these codes.

Malgré les avantages multiples du béton à hautes performances, il reste relativement peu étudiédans les structures en béton armé. Notamment, la servicibilité du matériau et son comportementvis-à-vis de la fissuration nécessitent une investigation profonde. En effet, dans les structures enbéton armé, c’est souvent la servicibilité du matériau qui se détériore et écourte la durée de vied’une construction. Dans le même contexte, le comportement à l’effort tranchant du béton àhautes performances (BHP) reste insuffisamment étudié comparativement à la littératureabondante sur le béton ordinaire (BO). Le principe de l’effort tranchant en béton armé n’estd’ailleurs toujours pas suffisamment explicité avec rationalité et l’on continue à utiliser desméthodes empiriques pour se prémunir contre les effets désastreux de cette sollicitation sur lesstructures en béton armé. Ce manque de compréhension est illustré par des approches de calculdifférentes et parfois contradictoires utilisées dans les principaux règlements de calcul en bétonarmé. L’applicabilité de ces approches de calcul réglementaires au béton à hautesperformances nécessite une evaluation profonde. Cet aspect fait partie des objectifs de laprésente étude. L’utilisation des fibres d’acier comme renforcement en béton en général et enbéton à hautes performances en particulier semble améliorer le comportement structural de cematériau en effort tranchant. Sur ces aspects de comportement structural, un total de 70 poutresen béton armé, ordinaire et de hautes performances, avec et sans fibres d’acier, ont été testéesen flexion quatre-points. Les fibres d’acier ont été utilisées en différentes quantités /f et différentsélancements lf/df. Les essais réalisés dans ce travail ont montré que les fibres d’aciers couturentefficacement les fissures et ainsi permettent aux éléments de structures d’être servicibles à desniveaux de chargement élevés. Cette efficacité se distingue particulièrement dans le matériauBHP qui développe une adhérence relativement meilleure avec l’acier par comparaison au BO.Ces effets de coutures efficaces ne sont, cependant, pas reflétés dans les modèles de calculsutilisés dans les règlements universels. / Despite de multiple advantages of high performances, it is still relatively unknown. It is thusimportant to study this material from all the aspects in the aim of understanding its structuralbehavior and using it as a building material in composition with steel and hence beneficiate fullyfrom its higher compressive strength and denser compactness. In this sense, the serviceability ofthe material, particularly its behaviour towards cracking which affects its integrity, necessitates adeeper investigation. In the same context, the shear behavior of high performances concrete(HPC) is still insufficiently investigated by comparison to the abundant literature for that of ordinaryconcrete (OC). On the aspect of shear behaviour, it is worth noting that such a solicitation inreinforced concrete is a topic which continues to arouse a lot of interest despite the abundanceof the existing literature. The applicability of the different design approaches to high performancesconcrete requires further investigations. This aspect is a part of the objectives of the presentexperimental study. The use of steel fibers as reinforcement for concrete in general and for highperformances concrete in particular seems to improve the structural behavior of this concretematerial, particularly for shearing. On these aspects of structural behaviour, a total of 70 reinforcedconcrete beams, from ordinary concrete and high performances concrete, with and withoutsteel fibers, have been tested in four-point flexural bending. The steel fibers were used in differentquantities /f and different aspect ratios lf/df. The test carried out in this investigation have shownthat fibers stitch up effectively the two faces of a crack and thus enable structural elements to beserviceable at higher loading levels. This efficiency is particularly distinguishable for highperformances concrete (HPC) which develops a relatively better bond with the reinforcement bycomparison to ordinary concrete (OC). These stitching effects are however not reflected in thedesign models presented in the different universal design codes.

In South Africa, as much as 33 million tons of ash, a waste product of burning coal, are produced per year. Of the total ash produced, just over 8% is sold for utilisation, the remainder of which is disposed of in landfills or ash lagoons. Countries like the UK, USA, Germany, Poland and Russia are producing Lightweight Aggregates (LWAs) commercially by using fly ash and clay, however, this technology is not available in many developing countries. The opportunity to utilise the fly ash produced in South Africa for the production of coarse LWA for use in structural concrete has therefore been identified and investigated in this dissertation. This dissertation consists of two phases, firstly to determine a suitable method for the manufacture of a high quality LWA, and secondly to determine the manufactured aggregate’s performance and potential for use in structural concrete. In the first phase, different LWA batches were produced using fly ash as the main constituent and kaolin clay, in contents of 0%, 10%, 20% and 30% by mass, as a binder. Green aggregate particles were produced in a disc granulator and then hardened using sintering at 1200°C for one hour. It was found that the LWA batch containing 20% kaolin produced LWA with the most suitable mechanical properties for use in concrete, and was therefore mass produced for further aggregate testing and for the production of concrete specimens for concrete testing. The final LWA produced was found to have an apparent density of 1600 kg/m3 and 24 hour water absorption of 12% by mass. The produced LWA was also found to have an Aggregate Crushing Value (ACV) and 10% FACT of 24.4% and 185 kN, respectively, which indicated that it would be suitable for use in High Strength Concrete (HSC). The sintering process was found to induce liquid phase sintering and the formation of new phases, mainly mullite, which contributed to the relatively high strengths of the aggregates. In the second phase of this dissertation, the manufactured LWA was then used to produce HSC and Normal Strength Concrete (NSC) specimens for concrete testing, which were compared to control mixes made with normal weight dolomite aggregate. In the HSC testing, concrete with a density of 2300 kg/m3 and compressive strength of 90 MPa was produced with the LWA. In HSC, it was found that internal curing was improved when up to 50% of the normal weight coarse aggregate was replaced by saturated LWA for this specific concrete mix. By using different stiffness relationship models between the concrete constituents, it was found that the manufactured LWA modulus of elasticity was between 8-23 GPa, and had a compressive strength of between 49-60 MPa. The Interface Transition Zone (ITZ) in concrete produced with the LWA was found to be stronger than the LWA as a result of the impregnation of the cement paste within the aggregate, and that the LWA was reactive in an alkaline environment. This resulted in an improved early age strength development, as well as caused the concrete failure surface to occur through the LWA particles rather than at the ITZ. Finally, Lightweight Concrete (LWC), having a dry density below 2000 kg/m3, was produced with the manufactured LWA. The LWC, produced with a water-to-cement ratio of 0.75, 28 day compressive strength of 24 MPa, modulus of elasticity of 21 GPa and dry density of 1800 kg/m3, was found to be suitable for use as structural concrete when assessed in terms of EN 1992-1-1 (2004). / Dissertation (MEng (Structural Engineering))--University of Pretoria, 2020. / Civil Engineering / MEng (Structural Engineering) / Restricted

[pt] A utilização do concreto de alta resistência já é uma realidade e muitos países estão adaptando suas normas para levar em conta as propriedades deste material. No dimensionamento de pilares esbeltos e seções com concreto de alta resistência é importante observar a relação tensão- deformação adotada no cálculo, pois enquanto para o concreto convencional a deformação máxima, ecu, é 0,0035, para o de alta resistência esta deformação depende do valor da resistência do concreto, diminuindo com o aumento do fck. Para um concreto com fck = 80 MPa, por exemplo, ecu é em torno de 0,0022 de acordo com as relações tensão - deformação propostas pelo MC90-CEB. A relação tensão- deformação com ecu dependente de fck irá alterar os diagramas de interação adimensionais para o dimensionamento de pilares esbeltos e concreto de alta resistência. São construídos neste trabalho diagramas de interação força normal - momento fletor - curvatura (n,m,f) e força normal - momento fletor - índice de esbeltez (n,m,l) para o dimensionamento de pilares esbeltos e diagramas de interação (nd,md) e (nd,mdx,mdy) para o dimensionamento de seções submetidas a flexão composta reta e oblíqua. Adotou- se a relação tensão-deformação proposta pelo MC90-CEB e valores de fck de 50 a 80 MPa. Os diagramas para pilares esbeltos foram construídos com auxílio do programa PCFRAME (KRÜGER, 1989) e os diagramas para o dimensionamento de seções foram construídos com um programa desenvolvido neste trabalho. Através dos resultados, observa-se que, como ecu depende de fck, todos os diagramas de interação sofreram diferenças, podendo ser dito ainda que o uso dos diagramas já existentes, construídos com ecu constante e igual a 0,0035, pode conduzir a erros contra a segurança estrutural. / [en] The use of high strength concrete is already a reality and many countries are adapting their design codes to take into account the properties of this material. For the design of slender columns and sections subjected to combined axial force and bending, the most important property is the stress-strain relationship. While for normal concrete the strain at ultimate, ecu, can be considered constant and equal to 0,0035, for high strength concrete ecu depends on the concrete strength, decreasing as the strength increases. For a concrete with fck of 80 MPa, for instance, ecu is around 0,0022 according to the CEB Model Code (1990). Stress-strain relationship with ecu dependent of fck will affect the nondimensional interaction diagrams for the design of slender columns and sections of high strength concretes. Nondimensional interaction diagrams moment-axial load-curvature (m,n,f) and diagrams moment-axial load- slenderness ratio (m,n,l), for the design of slender columns, and nondimensional interaction diagrams (md,nd) and (nd,mdx,mdy) , for compression plus axial and biaxial bending of sections, are constructed in this work. The diagrams were constructed for concretes with strength between 50 MPa and 80 MPa, adopting suitable stress-strain relationships recommended by the CEB Model Code 1990. The diagrams for slender columns were constructed with the aid of an existing computational program developed in an earlier thesis, while the diagrams for the design of sections were constructed with a new program, specially developed in this work. The results have shown that all these diagrams are affected, even when presented in a nondimensional form, when stress-strain diagrams with ecu dependent of fck are adopted. The use of traditional nondimensional interaction diagrams, constructed with ecu constant and equal to 0,0035, may lead to errors against structural safety. / [es] La utilización del concreto de alta resistencia es una realidad actual y muchos países estan adaptando sus normas para tener en cuenta las propiedades de este material. En el dimensionamiento de pilares esbeltos y secciones con concreto de alta resistencia es importante observar la relación tensión-deformación que se adopta en el cálculo, porque mientras para el concreto convencional la deformación máxima, ecu, es 0,0035, para el de alta resistencia esta deformación depende del valor de la resistencia del concreto, diminuyendo con el aumento del fck. Para un concreto con fck = 80 MPa, por ejemplo, ecu es en torno de 0,0022 de acordo con las relaciones tensión - deformación propostas por el MC90-CEB. La relación tensión- deformación con ecu dependente de fck alterará los diagramas de interacción adimensionales para el dimensionamiento de pilares esbeltos y concreto de alta resistencia. En este trabajo se construyen diagramas de interacción fuerza normal - momento flector - curvatura (n,m,f) y fuerza normal - momento flector - índice de esbeltez (n,m,l) para el dimensionamiento de pilares esbeltos y diagramas de interacción (nd,md) y (nd,mdx,mdy) para el dimensionamiento de secciones sometidas a flexión compuesta recta y obliqua. se adoptó la relación tensión-deformación propuesta por el MC90-CEB y valores de fck de 50 la 80 MPa. Los diagramas para pilares esbeltos fueron construidos con auxilio del programa PCFRAME (KRÜGER, 1989) e implementamos un programa para obtener los diagramas para el dimensionamiento de las secciones. A través de los resultados se observa que, como ecu depende de fck, todos los diagramas de interacción sufren diferencias, y puede decirse que el uso de los diagramas construidos con ecu constante e igual la 0,0035, pueden conducir a errores que afectan la seguridad extructural.

Yes / Although several research studies have been conducted on investigating the bond stress – slip behaviour of Glass-Fibre Reinforced Polymer (GFRP) bars embedded in high strength concrete (HSC) using a pull-out method, there is no published work on the bond behaviour of GFRP bars embedded in high strength concrete using a hinged beam. This paper presents the experimental work consisted of testing 28 hinged beams prepared according to RILEM specifications. The investigation of bond performance of GFRP bars in HSC was carried out by analysing the effect of the following parameters: bar diameter (9.5, 12.7 and 15.9 mm), embedment length (5 and 10 times bar diameter), surface configuration (helical wrapping with slight sand coating (HW-SC) and sand coating (SC)) and bar location (top and bottom). Four hinged beams reinforced with 16 mm steel bar were also tested for comparison purposes. The majority of beam specimens failed by pull-out. Visual inspection of the test specimens showed that the bond failure of GFRP (HW-SC) bars usually occurred owing to the bar surface damage, while the bond failure of GFRP (SC) bars was caused due to the detachment of sand coating. The GFRP bars with helical wrapping and sand coated surface configurations showed different bond behaviour and it was found that the bond performance of the sand coated surface was better than that of the helically wrapped surface. Bond strength reduced as the embedment length and bar diameter increased. It was also observed that the bond strength for the bottom bars was higher than that of the top bars. The bond strength was compared against the prediction methods given in ACI-440.1R, CSA-S806 and CSA-S6 codes. All design guidelines underestimated the bond strength of both GFRP re-bars embedded in high strength concrete. / Ministry of Higher Education in Libya for funding.