Student Number : 0218148W - MSc Dissertation - School of Civil Engineering - Faculty of Engineering and the Built Environment / Self-compacting concrete (SCC) is becoming a popular form of concrete usage in a range of applications throughout the world. This investigation considers the development of the technology and use of SCC. Importantly, the investigation aims to highlight the opportunities for using SCC in South Africa. A mixture design model is proposed and has been found to work well using local materials. The advantage of this model is the simplicity and the adaptability to any aggregate type. This method should be more acceptable to SCC producers who do not have special facilities and testing equipment An overview concerning concrete rheology is included to explain the mechanisms used to describe the flow and deformation of both the concrete and mortar mixtures. Included is a comparison between concrete, mortar and paste rheology. The Tattersall Two Point Tester was used to measure the shear resistance at two shear deformation rates. From the test results it was found that SCC can be made using South African materials and that it is possible to design a mixture with a lower cementitious content. The results from the Tattersall Two Point Tester gave additional information about the flowability of SCC.

Self-Compacting Concrete (SCC) is a material which under its own self-weight flows to form and fill any shape, attains full compaction, without external energy input, to create a dense homogenous mass (based on Holton, 2003; The Concrete Society and BRE, 2005; Damtoft et al, 2008). It is, in respect to the history of concrete, a relatively new development, with its first UK application occurring in the late 1990s. Since then a significant amount of research has sought to understand its physical and structural properties, but there is a lack of a knowledge base on its practical application and performance in construction projects. Where it does exist, such research lacks robust and transparent data, particularly relating to the claimed attributes of the material (such as better surface finish, faster construction and lower overall costs). Using a combination of qualitative and quantitative research methods, this research investigates the construction practices employed when pouring SCC and presents new data on its practical applications. Interviews with a range of building contractors, ranging from multinationals to small UK businesses (SMEs), show that current perceptions of SCC limit its use to specific applications because practitioners see SCC as just another type of concrete . A critical examination of these attitudes led to the identification of three distinct scenarios for the use of SCC: 1. Reactive selection: in which a particular attribute of SCC provokes its use to solve a particular problem, often as a last minute substitution for conventional concrete the most common scenario. 2. Strategic change: in which the material is chosen on the basis of a balanced assessment of all its benefits and on the understanding that such benefits can only be attained if the contractor appreciates that there may be implications for the construction process a rarely experienced scenario. 3. Specification: in which there is complete acceptance of SCC as a method, not just as a material; a significant amount of early project involvement with knowledge holders, such as contractors and material suppliers, optimises the construction process. A rigorous work measurement study of live construction projects has made it possible to quantify the as-built costs of SCC for selected UK residential slab and multi-storey flat slab applications and compare this with the equivalent conventional concrete slab construction. On-site use of self-compacting concrete vi The results indicate that SCC can reduce construction times of structural topping layers of residential slabs by up to 73%, and has shown that SCC can also match, if not reduce, total as-built concrete placement costs in multi-storey applications. This new data will enable contractors, designers and specifiers to better understand the practical implications of using SCC for on-site applications, thereby leading to more potential instances of its early and planned specification, hence resulting in more of its full benefits being realised.

This research studies the properties of self-compacting concrete by applying bamboo-charcoal to improve the fresh concrete property, physical property and micro-scale property.Conventionally, the Pozzolanic materials used in the self-compacting concrete are fly ash and slag. They are used to replace part of the cement such that the flowing property and compacting property can reach the requirement of the self-compacting concrete. According to previous research the bamboo-charcoal can absorb part of water, and enhance the early strength of concrete. In this study, we use bamboo-charcoal to replace parts of the fine-aggregate in the mixture of self-compacting concrete. The replacement ratio is designed as 0‰,2‰,3‰,3.5‰,4‰ and 5‰. From the experimental test of fresh concrete property, we can evaluate whether the concrete mix design can achieve the requirements of self-compacting concrete. Test for the compressive strength development, water absorption and rapid chloride penetration test are performed to evaluate the physical property of concrete. In addition, the scanning electronic microscope photos are taken to examine the microstructure of the concrete. In our results, it is found that the best proportion of replacement is 3‰. The requirements of self-compacting concrete can be satisfied, and the development of strength is also good.

Thesis submitted in fulfilment of the requirements for the degree Master of Technology: Civil Engineering in the Faculty of Engineering at the Cape Peninsula University of Technology / Self-compacting concrete (SCC) is a flowable self-consolidating concrete which can fill formwork without any external vibration. A self-compacting concrete mix requires the addition of superplasticiser (SP), which allows it to become more workable without the addition of excessive water to the mixture. The effect of different CEM I 52.5N cements produced by one company at different factories on self-compacting concrete was investigated. The properties of SCC are highly sensitive to changes in material properties, water content and addition of admixtures. For self-compacting concrete to be more accepted in South Africa, the effect that locally sourced materials have on SCC, partially replaced with extenders, needs to be investigated. The European guidelines for SCC (2005) determined the standard, through an extensive study, for the design and testing of self-compacting concrete. Using these guidelines, the properties of self-compacting concrete with the usage of local materials were investigated. The effect on SCC mixes was studied by using four cements; two types of SPs – partially replaced with two types of fly ash; and one type of slag. Mix design and tests were done according to the European Specification and Guidelines for Self-Compacting Concrete (2005). Using locally sourced materials (different cements, sand, coarse aggregate, fly ashes and slag), mixes were optimised with different SPs. Optimisation was achieved when self-compacting criteria, as found in the European guidelines, were adhered to, and the binders in these required mixes were then partially replaced with fly ash and slag at different concentrations. Tests done were the slump flow, V-funnel, L-box, sieve segregation resistance as well as the compressive strength tests. The results obtained were then compared with the properties prescribed by the European guidelines. The cements reacted differently when adding the SPs, and partially replacing fly ash and slag. According to the tests, replacing cement with extenders – in order to get a sufficient SCC – seemed to depend on the chemical and physical properties of each cement type, including the soluble alkali in the mixture, C3A, C3S and the surface area. The range, in which the concentration of these chemical and physical cement compounds should vary – in order to produce an acceptable SCC partially replaced by extenders – was determined and suggested to the cement producer. The main conclusion of this project is that cement properties vary sufficiently from factory to factory so as to influence the performance of an SCC mix. The problem becomes even bigger when such cements are extended with fly ash or slag, and when different SPs are used. When designing a stable SCC mix, these factors should be taken into account.

L'industrie du béton est une source importante d'émissions de gaz CO2 lors de la production de ciment. Une des solutions proposées à l'industrie de la construction est de remplacer le ciment par des matières premières secondaires moins polluantes (ex : filler calcaire, fumée de silice), qui peuvent également améliorer les caractéristiques rhéologiques du liant et accroître la durabilité du béton.Le but principal de cette thèse est donc de : (1) standardiser la formulation de béton issue des différents travaux de recherche publiés tout en assurant une bonne compréhension de ses propriétés rhéologiques; (2) adapter ces principes aux conditions de réalisation (prise en compte des caractéristiques des matériaux locaux utilisés); et (3) vérifier dans le laboratoire ou sur le terrain la viscosité plastique et le seuil d’écoulement des bétons.Outre les moyens expérimentaux classiques nous avons utilisé, dans notre étude, un autre moyen de caractérisation rhéologique : c’est l’écoulement de béton dans un V-Funnel couplé à un canal horizontal en plexiglas. Dans un premier temps nous cherchons à comprendre la corrélation entre la viscosité et les paramètres rhéologiques de béton en se basant sur des modèles proposés dans la littérature. À partir de là, nous cherchons à présenter le modèle qui décrit le comportement de béton. Pour ce faire, nous proposons une corrélation théorique entre la viscosité plastique du béton frais et le temps d’écoulement dans le V-Funnel, puis nous comparons cette solution théorique avec des mesures expérimentales rapportées dans la littérature. / The concrete industry is an important source of carbon dioxide gas emissions during cement production. One of the proposed solutions to the construction industry is to replace the cement by less polluting secondary raw materials (e.g. limestone filler, silica fume), which can also improve the rheological properties of binder and increase the concrete durability.Thus, the development of self-compacting concrete can be seen as an attempt to reduce the environmental impact of the construction. Similarly, the structure optimization also aims at reducing the quantity (in volume) of concrete and is reflected in the use of high performance concrete and ultra performance fiber-reinforced concrete (HPC and UPFRC).The most widely adopted approach to quantify these rheological properties is to experimentally measured the shear stress versus strain rate using a concrete rheometer.In addition to traditional experimental tests such as the V-funnel, spread, sieve stability and L box, in our study we used another test of rheological characterization: it is the flow of concrete in a V-Funnel and then in a horizontal channel Plexiglas.The main purpose of this thesis is to: (1) standardize the concrete formulation outcome of various research works published while ensuring a good understanding of its rheological properties, (2) adapt these principles to the realization conditions (taking into account characteristics of local materials used), and (3) check, in the laboratory or in the field, the plastic viscosity and the flow threshold of concrete.

O concreto autoadensável (CAA) é um concreto especial com a capacidade de fluir e preencher completamente todos os espaços das fôrmas pela ação de seu peso próprio, sem que haja ocorrência de bloqueio e segregação da mistura. Contudo, para alcançar essas características, normalmente esse concreto é dosado com um maior teor de materiais finos e/ou com aditivo modificador de viscosidade. Os agregados provenientes de Resíduos de Construção e Demolição (RCD) já estão sendo utilizados na produção de concretos, porém o uso dos materiais finos de agregados reciclados não é recomendado para a produção de concretos convencionais. Entretanto, acredita-se que em CAA esses materiais finos podem ser uma oportunidade interessante, tanto para a questão da reutilização desses resíduos, conseguindo uma destinação nobre para esses materiais com baixa demanda no mercado, como na manutenção das propriedades deste concreto, sendo os principais agentes do controle de segregação. Desta forma, o presente trabalho consistiu em estudar a influência da utilização de finos de RCD (concretos, argamassas e tijolos cerâmicos), separadamente, em substituição parcial ao agregado miúdo natural, nas principais propriedades do concreto autoadensável no estado fresco (fluidez, habilidade passante e resistência à segregação) e no estado endurecido (resistência à compressão e módulo de elasticidade), bem como avaliar seu desempenho quanto à durabilidade (absorção de água e penetração de íons cloretos). Os resultados demostraram perda de fluidez e boa coesão nos concretos autoadensáveis que empregaram agregados reciclados. No entanto, ainda conferem boas características de autoadensabilidade, atendendo as condições normativas para uso em estruturas correntes de engenharia. No que tange às propriedades mecânicas, foi observado aumento de resistência à compressão e decréscimo do módulo de resistência para concretos com finos de RCD. No quesito de durabilidade, os concretos com agregados reciclados apresentaram valores mais elevados para absorção de água por capilaridade e penetração de íons cloretos em comparação aos concretos de referência. / Self-compacting concrete (SCC) is a special concrete with the ability to flow into and completely fill all spaces within the formworks only by the action of their own weight, without blocking and segregation of the mixture. However, to achieve these characteristics, normally this concrete needs to be mixed with more content of fine materials and/or viscosity modifiers additives. The aggregates from Construction and Demolition Wastes (CDW) are used for concrete production, but the use of fine recycled aggregate is not recommended for the production of conventional concrete. Although, it is believed that in SCC these fine aggregates can be an interesting opportunity for the reuse of these wastes, achieving a noble destination for these materials with low demand in the market, as for the maintenance of the properties of this concrete, being the main agents of segregation control. So, the present research consisted in studying the influence of the use of CDW fines aggregates (concretes, mortars and ceramic bricks, separately) to replace the natural sand in the main properties of the self-compacting concrete in the fresh state (flowability, passing ability and segregation resistance) and in the hardened state (compressive strength and modulus of elasticity), as well as to evaluate its performance in terms of durability (water absorption and chloride penetration). The study results showed loss of flowability and increased cohesion in the self-compacting concretes that used recycled aggregates. However, they still confer good characteristics for self-compacting concrete, taking into account the normative conditions for using current engineering structures. With respect to the mechanical properties, it was observed an increase of compressive strength and decrease of the modulus of elasticity for concrete with CDW fines aggregates. In terms of durability, concretes with recycled aggregates presented higher values for capillarity water absorption and penetration of chloride ions compared to the references concretes.

Submitted by Cátia Araújo (catia.araujo@unipampa.edu.br) on 2017-01-26T11:47:11Z No. of bitstreams: 2 license_rdf: 1232 bytes, checksum: 66e71c371cc565284e70f40736c94386 (MD5) Avaliação do potencial do uso da sílica de casca de arroz obtida através da queima controlada como substituição parcial ao cimento Portland na produção de concretos au.pdf: 5610666 bytes, checksum: 59bf1f9b8c485e95150b2a114381adde (MD5) / Approved for entry into archive by Cátia Araújo (catia.araujo@unipampa.edu.br) on 2017-01-26T11:47:27Z (GMT) No. of bitstreams: 2 license_rdf: 1232 bytes, checksum: 66e71c371cc565284e70f40736c94386 (MD5) Avaliação do potencial do uso da sílica de casca de arroz obtida através da queima controlada como substituição parcial ao cimento Portland na produção de concretos au.pdf: 5610666 bytes, checksum: 59bf1f9b8c485e95150b2a114381adde (MD5) / Made available in DSpace on 2017-01-26T11:47:27Z (GMT). No. of bitstreams: 2 license_rdf: 1232 bytes, checksum: 66e71c371cc565284e70f40736c94386 (MD5) Avaliação do potencial do uso da sílica de casca de arroz obtida através da queima controlada como substituição parcial ao cimento Portland na produção de concretos au.pdf: 5610666 bytes, checksum: 59bf1f9b8c485e95150b2a114381adde (MD5) Previous issue date: 2016-09-01 / O presente estudo tem como objetivo avaliar o potencial uso da Sílica de Casca de Arroz (SCA), obtida de queima controlada, como material de substituição parcial em massa ao Cimento Portland (CP) na produção de concretos autoadensáveis (CAA). A SCA empregada neste trabalho foi produzida em condições controladas em um sistema de combustão com leito fluidizado, tendo como resultado uma sílica altamente amorfa e de boa qualidade. Foram avaliados os resultados do comportamento reológico do CAA no estado fresco e a resistência mecânica no estado endurecido de um concreto de referência, sem o uso de SCA, e de cinco concretos produzidos a partir de substituições parciais de 5%, 10%, 15%, 20% e 25% de SCA em relação à quantidade de massa do cimento. Em todos os traços foram utilizado 15% de cinza volante (CV) adicionada à massa do material aglomerante, a fim de auxiliar na diminuição do atrito entre as partículas dos agregados com o cimento. O traço do concreto de referência foi obtido utilizando o procedimento de caráter experimental proposto pelo Método de Gomes. Este traço foi analisado também pelo Método do Empacotamento Compressível, sendo assim, definidos os outros traços com substituições. As amostras foram caracterizadas no estado fresco de acordo com a norma brasileira ABNT NBR 15823/2010, através de: ensaios de espalhamento no cone de Abrans e Anel “J”, de fluidez no funil “V” e habilidade passante na caixa “L” e caixa “U”. Os resultados mostram que os concretos produzidos com SCA possuem boa capacidade de fluidez. No estado endurecido foram verificadas as resistências mecânicas de compressão axial e tração por compressão diametral dos CAAs nas idades de 7, 28, 56 e 91 dias. Os resultados dos ensaios indicam que é possível substituir CP por SCA sem que haja prejuízo às características mecânicas dos CAAs e ainda obter ganhos técnicos e econômicos. O melhor concreto, levando em conta todos os aspectos estudados, foi com 15% de substituição de CP por SCA. / This study aims to evaluate the potential use of rice husk silica (RHS), obtained under controlled burning conditions, such as partial replacement material to the Portland Cement (PC) in the production of self-compacting concrete (SCC). The RHS employed in this study was produced under controlled conditions in a fluidized bed combustion system, resulting in highly amorphous silica and of good quality. We evaluated the results of the rheological behavior of SCC in the fresh state and strength in the hardened state of a reference concrete without the use of RHS and five concrete made from partial substitution 5%, 10%, 15%, 20% and 25% in RHS relative to the amount of concrete mass. In all traces were used 15% of Fly Ash (FA) is added to the mass of the binder material to assist in reducing friction between particles of the aggregates with cement. The trace of the reference concrete was obtained using the experimental procedure proposed by Gomes method. This trait was also analyzed by the method of packaging compressible and based on this method are defined partial strokes with other PC for RHS substitutions. After obtaining the characteristics of the materials and dosages of SCCs, these were featured in the fresh according to the Brazilian standard NBR 15823/2010, as follows: Spreading tests on cone Abrans and "J-ring", pour in "V-Funnel" and passing ability in the "L-box" and "U-box". The results shows that concrete made with RHS have good flow capacity. In the hardened state the mechanical resistances were checked axial compression and tension by diametrical compression of SCCs at the ages of 7, 28, 56 and 91 days. The test results indicate that it is possible to replace PC with RHS without prejudice to the characteristics of SCCs and still get technical and economic gains. The best concrete, taking into account all the points studied, was the one with replacement of 15% of PC for RHS.

O concreto auto adensável (CAA) é um material novo cujas propriedades mecânicas precisam ser estudadas. Ele apresenta em sua composição maior quantidade de argamassa e agregados graúdos de menores dimensões, que podem torná-lo mais deformável que o concreto convencional. Em contrapartida, o melhor empacotamento das partículas no estado fresco do CAA e a sua maior resistência (para uma mesma relação a/c) pode atuar no sentido oposto. Além disso, os modelos de previsão disponíveis na norma brasileira não levam em consideração os concretos especiais. O objetivo deste trabalho é verificar se modelos de previsão disponíveis na literatura são adequados para prever a fluência e a retração do CAA. Este estudo envolve aspectos de sua caracterização por meio de ensaios em laboratório, de retração, de fluência e de outras propriedades mecânicas como resistência à compressão, resistência á tração e módulo de elasticidade. Para o ensaio de fluência foram avaliadas as influências das condições ambientais (através de corpos de prova mantidos em ambiente controlado e sem controle de umidade e temperatura) e idade de carregamento. A partir dos resultados obtidos experimentalmente, foi feita a sua comparação com os modelos de previsão do ACI, EC2, NBR, B3 e GL. O estudo da deformação do CAA também foi feito por meio da monitoração de uma viga protótipo protendida, seguida da comparação das deformações medidas com as obtidas por um programa de elementos finitos. A partir dos resultados experimentais, observa-se que dentre os modelos de previsão de fluência e retração estudados, o que mais se adéqua aos resultados obtidos experimentalmente, é o fornecido pelo ACI e GL. A utilização do modelo de previsão do ACI pelo programa de elementos finitos gerou bons resultados de previsão de deformações quando comparados com os resultados medidos. Em relação à função de fluência, nota-se que a norma brasileira é adequada para o concreto estudado. / Self-compacting concrete (SCC) is a new material and its mechanical properties have yet to be studied. It has a higher amount of mortar and smaller coarse aggregates which make it more deformable. On the other hand, the packing of the particles in fresh SCC and its larger strength (at a constant water/cement ratio) may act in the opposite way. Besides, the prediction models provided by the Brazilian Code do not take special concretes into account. The main objective of this work is to verify if the creep and shrinkage prediction models available in the literature can predict those properties of a SCC. This study involves aspects of its characterization by tests in laboratory of creep, shrinkage and other mechanical properties, such as compressive strength, splitting tensile strength and modulus of elasticity. For the creep test, the influence of environmental conditions (for specimens kept in an environment with and without temperature and humidity controlled) and age at loading were evaluated. From the obtained experimental results, a comparison was made to the values obtained from the ACI, EC2, NBR, B3 and GL prediction models. The deformability of SCC was analyzed by monitoring a post-tensioned beam prototype followed by the comparison of the measured deflection and strain long the time to those obtained from a finite element model. From the obtained experimental results of creep and shrinkage, the most adequate prediction models are the ACI and GL models. The use of the ACI model with the finite element method produced good results when compared to the experimental measurements of deflection and strain of the prototype beam. With respect to the compliance creep function, it can be noticed that the model provided by the Brazilian Code is adequate to the studied SCC.

Made available in DSpace on 2015-04-22T22:08:45Z (GMT). No. of bitstreams: 1 Marcio Bartholomei.pdf: 2499347 bytes, checksum: 6b31cbfe2379597e5c48f869551b9c94 (MD5) Previous issue date: 2013-01-15 / Conselho Nacional de Desenvolvimento Científico e Tecnológico / Currently concrete performs a very important role in contemporary society´s development. Their benefits to society come from its variety of applications, being used in diverse types of constructions. Among the many kinds of existing concretes, the self-compacting one is highlighted once it is of a superior technology if compared to the ordinary one, once it doesn´t need a specific equipment to be compacted, having a self-compacting ability due to gravity. The aim of this work was studying the use of materials commercialized in Manaus and nearby locations for the production of self-compacting concrete with addition of ground glass´ waste. In this process great and tiny aggregates, cement, viscosity modifier of physical effect (ground glass´ waste) and superplasticizer additive were characterized according to Brazilian Standards (NBR). It was also analyzed the best dosage method for the ordinary concrete´s production, which also was adapted to the self-compacting production. 10 After choosing the best method for the ordinary concrete, this work developed a method so that self-compacting concrete could be produced using ground glass´ waste and local materials from Manaus city. The results showed that it is possible to obtain a self-compacting concrete from materials commercialized in Manaus and nearby locations, moreover, that the ground glass´ waste is a material which holds the self-compacting concrete properties in the cured stage having gains in resistance, and in the fresh state with viscosity increase, in which shortens its static and dynamic segregation. / Atualmente o concreto desempenha um papel muito importante no desenvolvimento de uma sociedade moderna. Seus benefícios para a sociedade vêm de sua ampla faixa de aplicações, sendo este usado em diversos tipos de construção. Dentre os diversos tipos de concretos existentes, destaca-se o concreto auto-adensável, que é uma tecnologia superior ao concreto convencional, pois o mesmo não necessita de nenhum equipamento para ser compactado, tendo uma capacidade de auto-compactação através da força da gravidade. O objetivo deste trabalho foi estudar a utilização de materiais comercializados na região de Manaus para a produção de concreto auto-adensável com adição de resíduo moído de vidro. Neste processo de estudo foram caracterizados os agregados miúdos, agregados graúdos, cimento, modificador de viscosidade de efeito físico (resíduo moído de vidro) e aditivo superplastificante conforme as Normas Brasileiras (NBR). Também foi analisado o melhor método de dosagem para a produção do concreto convencional, o qual 8 também se adaptava a produção do concreto auto-adensável. Após a escolha do melhor método para a produção do concreto convencional, foi desenvolvido neste trabalho um método para a produção do concreto auto-adensável utilizando resíduo de vidro moído e materiais regionais da cidade de Manaus. Os resultados mostraram que é possível obter um concreto auto-adensável empregando materiais comercializados na região de Manaus, além disso, que o resíduo moído de vidro é um material que mantêm as propriedades do concreto auto-adensável no estado endurecido com ganhos de resistência e no estado fresco com o aumento de viscosidade, a qual diminui a sua segregação estática e dinâmica.

Self compacting concrete (SCC) is first developed in Japan in the late 1980s in order to overcome the consolidation problems associated with the presence of congested reinforcement. It is also termed as a high performance concrete, as it can flow under its own weight and completely fill the formworks. As the fresh properties of SCC are quite important, mix design of a SCC is performed by considering various workability related fresh properties. Therefore, a well designed SCC should satisfy all requirements of a hardened concrete, besides its superior workability properties. The aim of this research is to assess the effects of some basic ingredients of SCC on the fresh properties of SCC. This will be performed by applying design of experiment techniques and obtaining significant statistical models, which will give valuable information about the effects of the model parameters on the rheology and fresh state characteristics of SCC. In this research program, four different variables / use of fly ash replacement, use of high range water reducing admixture (HRWRA), use of viscosity modifying admixtures (VMA) and water-cementitious material ratio, are considered as the variables of the experimental design. Central Composite Design (CCD), a design of experiment technique, is employed throughout the experimental program and a total of 21 mixtures of concrete are cast. Slump flow, V-funnel, L-box, sieve segregation, initial and final setting time tests are performed, furthermore / to investigate the effects of these variables to the rheology of SCC, relative plastic viscosity and relative yield stress, which are the parameters of Bingham Model are measured with the help of a concrete rheometer. As a result of the experimental program, the fresh state properties of SCC are expressed by mathematical equations. Those equations are then used in order to explain the effects of fly ash replacement, HRWRA and VMA concentration, and the w/cm ratio on the fresh state properties of SCC. According to the derived models, it is stated that the water-cementitious material ratio of the concrete mixture is the most effective parameter on the flowability and passing ability of SCC beside the other parameters utilized in this research as its coefficient was the highest in the related models.