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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

Caractérisation de la microstructure et comportement à court et long terme d'un Béton de Poudre Réactive extrudable / Caracterization of microstructure and early age/long term behaviour of extrudable Reactive Powder concrete

Cherkaoui, Khalid 15 October 2010 (has links)
Les Bétons de Poudre Réactive (BPR) sont connus pour leur résistance très élevée et leur bonne durabilité, mais aussi pour leur prix élevé. L’objectif de cette étude concerne la mise au point d’une formulation de BPR extrudable (BPR). Des essais préliminaires d’écoulement au mini cône d’Abrams ont été réalisés avec des teneurs variées en superplastifiant et en substituant partiellement la fumée de silice par du quartz broyé. Cinq mélanges ont été retenus et caractérisés de façon systématique au microscope électronique à balayage et en diffraction des Rayons X. Une étude complète de retrait au jeune âge, de résistance mécanique et de durabilité face à l’azote et aux ions chlorure a été menée. Un montage expérimental d’extrusion a été mis au point. Un mélange incorporant du quartz broyé en remplacement d’une fraction de la fumée de silice et une composition optimisée en superplastifiant montre des propriétés intéressantes : extrudabilité, très bonne durabilité, performances mécaniques améliorées et retrait diminué. Sur cette composition, l’étude microstructurale met en évidence le rôle que joue le superplastifiant sur la chimie d’hydratation avec une forte consommation en bélite. Ce mélange permet ainsi de diminuer le coût de fabrication pour un BPR en permettant d’économiser la fumée de silice coûteuse et en ne nécessitant aucun traitement thermique. / Reactive Powder Concrete (RPC) is well known for ultra-high mechanical performances and very good durability as well as for a high cost. The aim of this study is to find an extrudable RPC. Abrams cone preliminary tests were made with various contents of superplasticizer and a partial substitution of silica fume by crushed quartz. Then, fives concrete samples were chosen and systematically characterized by scanning electron microscopy and X-ray diffraction. Then, a complete study was made including early-age shrinkage, mechanical strength, gas permeability and chloride diffusion measurements. An experimental extruder was build. Among the five compositions, one of them, where crushed quartz replaces a part of silica fume, exhibits very good properties: good extrudability, very good durability, and better mechanical strength with an improvement of shrinkage. The microstructural study of this composition highlights the effect of the superplasticizer on hydration, with high belite consumption. This composition allows a lower cost of RPC with a decreasing of silica fume content, without thermal treatment.
2

Short-term and time-dependent flexural behaviour of steel fibre-reinforced reactive powder concrete

Warnock, Robyn Ellen, Civil & Environmental, UNSW January 2006 (has links)
This thesis presents an experimental and theoretical study of the material and structural behaviour of a Steel-Fibre reinforced Reactive Powder Concrete (SF-RPC). The experimental program consisted of three phases. Phase 1 involved the development of a design mix for use throughout the remainder of the study. Phase 2 consisted of an in-depth investigation into the material properties of the mix. The final phase of the experimental component was the testing of 16 plain and prestressed SF-RPC beams. Twelve beams were tested under short-term loading to determine their cracking and ultimate moment capacity. The remaining 4 beams were used to investigate the time-dependent flexural behaviour of prestressed SF-RPC slabs. The material properties were measured using a range of short-term tests and included the compressive and flexural behaviour, static chord modulus of elasticity and crack mouth opening. In addition to the short-term tests, investigation into the time-dependent material behaviour was undertaken and included the creep and shrinkage characteristics of the material. The response of the material to various curing conditions was also investigated. The structural behaviour investigated included the short-term flexural moment-curvature response and load-deflection behaviour of beams and slabs along with the crack patterns of both plain and prestressed SF-RPC members. In addition to the investigations into the short-term flexural behaviour, a study into the time-dependent flexural behaviour was also undertaken. There are currently 2 available models for predicting the flexural response of plain and prestressed RPC cross-sections. The analytical phase of this investigation involved an evaluation of these models. Based on the experimental findings and analysis, a modified model was proposed for calculating the short-term flexural behaviour of plain and prestressed SF-RPC beams. The applicability of an age-adjusted effective modulus method for calculating the time-dependent deformations of prestressed SF-RPC slabs under various levels of sustained loads was also evaluated and found to be adequate with minor refinements.
3

Hydration characteristics, hydration products and microstructure of reactive powder concrete

Ge, W., Zhang, Z., Ashour, Ashraf, Li, W., Jiang, H., Hu, Y., Shuai, H., Chuanzhi, S., Li, S., Liu, W. 16 March 2023 (has links)
Yes / Reactive Powder Concrete (RPC) is a new type of cementitious materials with a complex hydration mechanism, and active admixtures greatly influence the hydration reaction, formation of hydration products, and evolution of microstructure. In order to comprehensively study the quantitative effects of active admixtures contents, namely silica fume, slag and fly ash, on hydration characteristics, hydration products, and microstructure of RPCs, tests of workability, setting time, electrical conductivity, bound water and mechanical properties were conducted. Furthermore, a series of properties including morphology and micro-structure characteristics of RPCs were analyzed by thermogravimetric (TG) analysis, X-ray diffraction (XRD), fourier transform infrared spectroscopy (FTIR), mercury intrusion porosimetry (MIP), Brunauer-Emmet-Teller (BET), and scanning electron microscope (SEM). The results indicate that the initial hydration reaction rate of RPCs is reduced by partly replacing cement with active admixtures. The pozzolanic effect created by the active admixtures enhances hydration and improves RPC's compressive and flexural strength. RPCs made of cement-silica fume mixture exhibit the best macroscopic properties. The adoption of silica fume promotes the production of C-S-H gel during hydration and exerts pozzolanic and crystal nucleation effects to promote cement hydration. RPCs made of pure cement exhibit 15.3% porosity after 28 days of hydration, with the largest proportion of less harmful pores in the microstructure. The porosity is reduced to 5.2% when cement is partially replaced with silica fume, and the microstructure is dominated by harmless pores. When replacement of silica fume is kept at 25%, using slag powder or fly ash substitute part of cement also reduces the number of less harmful pores. It is beneficial to add slag powder to increase the number of gel pores, whereas fly ash reduces the number of gel pores. The investigation presented in this paper would contribute to the production of low cost and environmentally-friendly RPCs, and accelerate the wider applications of ultra-high performance concrete (UHPC) in engineering structures.
4

Análise experimental do concreto de pós reativos: dosagem e propriedades mecânicas / Experimental analysis of reactive powder concrete: mix and mechanical properties

Vanderlei, Romel Dias 27 August 2004 (has links)
A tecnologia dos materiais a base de cimento Portland vem se desenvolvendo rapidamente, onde a melhoria das propriedades mecânicas vem sendo alcançada, eliminando os agregados graúdos e estudando a composição granulométrica da mistura, procurando preencher os vazios utilizando materiais finos e ultrafinos, como pó de quartzo e a sílica ativa. Esta pesquisa tem como objetivos: desenvolver concreto de pós reativos com resistência à compressão próxima de 200 MPa e módulo de elasticidade acima de 45 GPa; propor uma relação constitutiva para o material, considerando o volume de fibras; especificar as deformações máximas na tração e na compressão; e verificar a influência das fibras nas resistências à compressão e à tração na flexão. Para isso, foi utilizado o método de empacotamento das partículas sólidas, com o intuito de definir composições granulométricas, e desenvolveu-se técnicas necessárias para a moldagem, adensamento e cura térmica. A análise experimental compreendeu o estudo das seguintes propriedades: resistência à compressão, módulo de elasticidade, resistência à tração na flexão, deformações e ductilidade. As fibras metálicas melhoraram as propriedades mecânicas e aumentaram a ductilidade do concreto. A temperatura de cura e o tempo de submissão ao tratamento térmico, tornou o material mais resistente. A deformação específica máxima na compressão foi definida experimentalmente como 4,3%. O limite elástico para as deformações de tração ficou em 0,28%. Foi proposta uma relação constitutiva para tensões de compressão, que pode ser utilizada para concretos de pós reativos, com resistência à compressão próxima de 200 MPa e taxa de fibras até 4% em volume. Os resultados obtidos indicam que o concreto de pós reativos desenvolvido apresentou altas resistências à compressão e à tração na flexão, onde a microestrutura do material mostrou-se com baixíssima porosidade e interface pasta - agregado praticamente suprimida. A tecnologia desenvolvida nesta pesquisa pode ser considerada um grande avanço na tecnologia de materiais a base de cimento Portland que, com maiores aperfeiçoamentos, espera-se a aplicação desse material em situações que tirem proveito das excelentes propriedades mecânicas e durabilidade / The technology of Portland cement materials has developed quickly, where the improvement of the mechanical properties has been reached, eliminating the coarse aggregates and studying the granular mixture, in order to fill the emptiness with fine and ultra-fine materials, like crushed quartz and silica fume. The present paper aimed: develop reactive powder concrete with compressive strength close to 200 MPa and module of elasticity above 45 GPa; propose a strength x strain relationship in compression for the material considering the volume of fibers; specify the maximum strain in the traction and in the compression; and to verify the influence of the fibers in the compression strength and in the bending strength. It went using the method of packing of the solid particles to define the grain size distribution, and necessary techniques were developed for the preparation and thermal cure. The experimental analysis understood the study of the following properties: compression strength, module of elasticity, bending strength, strain and ductility. The metallic fibers improved the mechanical properties and they increased the ductility of the concrete. The cure temperature and the time of submission to the thermal treatment, improved the compression strength. The maximum strain in the compression was defined experimentally as 4,3%. The elastic limit for the traction strain was 0,28%. A strength x strain relationship in compression was proposed, and can be used in reactive powders concrete, with compression strength of around 200 MPa and rate of fibers of up to 4% of volume. The results indicate that the reactive powders concrete developed presented excellent compression strength and bending strength, and the material presented a microestrutura with low porosity. The technology developed in this research can be considered a great progress in the technology of materials with Portland cement, and the application of that material is expected in situations that use advantage of the excellent mechanical properties and durability
5

Análise experimental do concreto de pós reativos: dosagem e propriedades mecânicas / Experimental analysis of reactive powder concrete: mix and mechanical properties

Romel Dias Vanderlei 27 August 2004 (has links)
A tecnologia dos materiais a base de cimento Portland vem se desenvolvendo rapidamente, onde a melhoria das propriedades mecânicas vem sendo alcançada, eliminando os agregados graúdos e estudando a composição granulométrica da mistura, procurando preencher os vazios utilizando materiais finos e ultrafinos, como pó de quartzo e a sílica ativa. Esta pesquisa tem como objetivos: desenvolver concreto de pós reativos com resistência à compressão próxima de 200 MPa e módulo de elasticidade acima de 45 GPa; propor uma relação constitutiva para o material, considerando o volume de fibras; especificar as deformações máximas na tração e na compressão; e verificar a influência das fibras nas resistências à compressão e à tração na flexão. Para isso, foi utilizado o método de empacotamento das partículas sólidas, com o intuito de definir composições granulométricas, e desenvolveu-se técnicas necessárias para a moldagem, adensamento e cura térmica. A análise experimental compreendeu o estudo das seguintes propriedades: resistência à compressão, módulo de elasticidade, resistência à tração na flexão, deformações e ductilidade. As fibras metálicas melhoraram as propriedades mecânicas e aumentaram a ductilidade do concreto. A temperatura de cura e o tempo de submissão ao tratamento térmico, tornou o material mais resistente. A deformação específica máxima na compressão foi definida experimentalmente como 4,3%. O limite elástico para as deformações de tração ficou em 0,28%. Foi proposta uma relação constitutiva para tensões de compressão, que pode ser utilizada para concretos de pós reativos, com resistência à compressão próxima de 200 MPa e taxa de fibras até 4% em volume. Os resultados obtidos indicam que o concreto de pós reativos desenvolvido apresentou altas resistências à compressão e à tração na flexão, onde a microestrutura do material mostrou-se com baixíssima porosidade e interface pasta - agregado praticamente suprimida. A tecnologia desenvolvida nesta pesquisa pode ser considerada um grande avanço na tecnologia de materiais a base de cimento Portland que, com maiores aperfeiçoamentos, espera-se a aplicação desse material em situações que tirem proveito das excelentes propriedades mecânicas e durabilidade / The technology of Portland cement materials has developed quickly, where the improvement of the mechanical properties has been reached, eliminating the coarse aggregates and studying the granular mixture, in order to fill the emptiness with fine and ultra-fine materials, like crushed quartz and silica fume. The present paper aimed: develop reactive powder concrete with compressive strength close to 200 MPa and module of elasticity above 45 GPa; propose a strength x strain relationship in compression for the material considering the volume of fibers; specify the maximum strain in the traction and in the compression; and to verify the influence of the fibers in the compression strength and in the bending strength. It went using the method of packing of the solid particles to define the grain size distribution, and necessary techniques were developed for the preparation and thermal cure. The experimental analysis understood the study of the following properties: compression strength, module of elasticity, bending strength, strain and ductility. The metallic fibers improved the mechanical properties and they increased the ductility of the concrete. The cure temperature and the time of submission to the thermal treatment, improved the compression strength. The maximum strain in the compression was defined experimentally as 4,3%. The elastic limit for the traction strain was 0,28%. A strength x strain relationship in compression was proposed, and can be used in reactive powders concrete, with compression strength of around 200 MPa and rate of fibers of up to 4% of volume. The results indicate that the reactive powders concrete developed presented excellent compression strength and bending strength, and the material presented a microestrutura with low porosity. The technology developed in this research can be considered a great progress in the technology of materials with Portland cement, and the application of that material is expected in situations that use advantage of the excellent mechanical properties and durability
6

Caracterização mecânica de material compósito cimentício avançado à base de pós reativos / Mechanical Characterization of Advanced Reactive Powder Cementitious Composite Material

Fávero, Rafael Burin January 2016 (has links)
O compósito de pós reativos é um material formado basicamente por uma argamassa de matriz cimentícia ricamente refinada em termos de granulometria e com a inclusão de fibras, como forma de reforço. Entretanto, duas características principais o definem em termos de composição: a quase ausência de armaduras em estruturas construídas com o material e o fato de dispensar o uso de agregados com diâmetro máximo superior a 1 mm, sendo constituído basicamente por pós. O CPR possui características únicas que lhe conferem resistências à compressão de seis a oito vezes superiores ao concreto convencional, e tração e flexão cerca de dez vezes maior, podendo competir diretamente com estruturas em aço. As dificuldades para sua obtenção e utilização residem no fato de ser um material que demanda grande precisão em sua dosagem e também nos custos diretos para sua produção, bem como o desconhecimento em relação ao seu desempenho. O presente estudo comparou três diferentes traços de CPR a um traço de concreto convencional de uso comum na indústria de préfabricados, de forma a caracterizá-lo mecanicamente e buscando viabilizar sua produção e aplicação na indústria de pré-fabricados nacional, utilizando cinza volante como alternativa de aglomerante e a hibridização de fibras. Efetuou-se também um estudo comparativo dos custos de sua obtenção em relação ao concreto convencional, levando-se em conta o desempenho mecânico. Os resultados indicam que para todos os traços estudados, em relação ao concreto convencional estabelecido como parâmetro, as principais propriedades mecânicas contemplam uma resistência à compressão até quatro vezes superior; módulo de elasticidade longitudinal 50% superior; resistência à tração na flexão até sete vezes superior e resistência à tração direta cerca de três vezes superior. Com relação aos custos, ao se considerar o seu comportamento mecânico, o CPR se mostrou mais competitivo frente ao concreto convencional, demonstrando que a sua implantação, dentro da indústria de pré-fabricados nacional, pode e deve ser explorada. / Reactive powder composite is a material formed by a richly refined cementitious mortar matrix in terms of grain size and the inclusion of fibers, such as reinforcement. However, two main features define it in terms of composition: the almost absence of reinforcement steel and the use of aggregates with a maximum diameter greater than 1 mm, consisting basically by powder materials. RPC has unique characteristics which confer compressive strength six to eight times higher than conventional concrete and tensile and flexural strength about ten times higher, and may compete directly with steel structures. Difficulties in obtaining and use the material lie in the fact that it requires a great precision in the dosage and also the direct costs for its production, as well as the lack of knowledge about its performance. This study compared three different CPR mixes to a conventional concrete mix, commonly used in the precast industry, in order to characterize it mechanically and intending to disseminate its production and use in the national precast industry by using fly ash as a binder and alternative fiber hybridization. It also made a comparative study between the costs of obtaining CPR compared to conventional concrete, taking into account the mechanical performance. The results indicate that for all mixes studied in relation to conventional concrete set as a parameter, the primary mechanical properties include a compressive strength up to four times higher; longitudinal elastic modulus exceeding 50%; bending tensile strength up to seven times and resistance to direct tension about three times higher. Considering the costs compared to the mechanical behavior, CPR was found more competitive against the conventional concrete, demonstrating that its implementation within the national precast industry can and should be explored.
7

Maîtrise de la texturation des poudres céréalières réactives : étude des mécanismes d'agglomération humide et de séchage. : Application à la semoule de blé dur / Control of texturation of granular medium. study of the dynamics of structuration and consolidation : application to reactive powders

Hafsa, Inés 09 June 2015 (has links)
Le sujet de thèse concerne la maîtrise de la texturation de milieux granulaires par l'étude des dynamiques de structuration et de consolidation et l'application aux poudres céréalières réactives. La démarche s'appuie sur la confrontation d'approches scientifiques complémentaires (physique, physico-chimiques, génie des procédés et technologiques) pour étudier les dynamiques (i.e. évolutions cinétiques sous contraintes mécaniques) de structuration, de croissance, de rétraction et de consolidation. La méthodologie s'appuie sur la mise en œuvre d'une approche multi échelles. (i) À l'échelle des procédés, avec une approche technologique (basée sur une étude paramétrique avec des expérimentations à l'échelle pilote) et avec la construction d'un modèle de description des processus. (ii) À l'échelle des mécanismes pour étudier la génération de contacts (i.e. mécanismes de croissance) et la consolidation des interfaces (i.e. mécanismes de solubilisation & de séchage), avec des approches physico-chimiques expérimentales et le développement de modèles mécanistiques. (iii) À l'échelle de la structure : description de la microstructure interne (distribution de la compacité) et des caractéristiques texturales locales des structures formées. La thèse de doctorat prend en compte la réactivité des poudres pour la construction de modèles mécanistiques de croissance et de consolidation des milieux granulaires. Ces travaux trouvent des applications évidentes pour la filière céréales. / The PhD thesis subject concerns the control of the structures of granular matters, by the study of the dynamics of structuring and consolidation, and the application in reactive cereal powders. The approach leans on the confrontation of complementary scientific approaches (physical, physico-chemical, process engineering and technological) to study the dynamics (i.e. kinetic evolutions under mechanical stresses) of structuring, growth, shrinkage and consolidation. The experimental methodology is based on a multi-scales approach. (i) On the scale of the processes, with a technological approach (based on a parametric study with experiments using pilot scales equipments) and with the construction of a descriptive model of the reactions. (ii) On the scale of mechanisms, to study the generation of contacts (i.e. mechanisms of growth) and the consolidation of the interfaces (i.e. mechanisms of solubilization and drying), with experimental physico-chemical approaches and development of mechanistic models. (iii) On the scale of the structure, with the description of the intern microstructure (distribution of the compactness) and the measurement of local characteristics of the structures. The PhD thesis takes into account the reactivity of powders for the construction of mechanistic models to describe the growth and the consolidation mechanisms of the granular matter. These works find obvious applications for the cereal sector.
8

Mix Design and Impact Response of Fibre Reinforced and Plain Reactive Powder Concrete

Gao, Xiang, S3090502@student.rmit.edu.au January 2008 (has links)
Concrete is the most broadly used material in construction worldwide and Reactive Powder Concrete (RPC, a type of ultra high performance concrete) is a relatively new member of the concrete family. In this work the critical parameters of RPC mix design are investigated and the mix design is explored through a program of concrete casting and testing. Owing to the enhanced microstructure of RPC, porosity and permeability can be significantly decreased in the concrete matrix. This benefits the durability characteristics of RPC elements resulting in a longer service life with less maintenance costs than conventional concrete. It has been used for high integrity radiation waste material containers because of its low permeability and durability. Fibre reinforced RPC is also ideal for use in long span and thin shell structural elements without traditional reinforcement because of its advantageous flexural strength. Moreover, due to improved impact resistance, RPC can be widely employed in piers of bridges, military construction and blast protection. There is no standard approach to assessing the impact resistance of concrete. This investigation utilises relatively well accepted impact equipment to evaluate the mechanical properties of RPC under dynamic loading. The compressive and flexural tensile strengths of plain and fibre reinforced RPC are investigated using a variety of specimens and apparatus. The dynamic increase factor (DIF) is evaluated to indicate the strain rate sensitivity of the compressive and flexural strength.
9

Caracterização mecânica de material compósito cimentício avançado à base de pós reativos / Mechanical Characterization of Advanced Reactive Powder Cementitious Composite Material

Fávero, Rafael Burin January 2016 (has links)
O compósito de pós reativos é um material formado basicamente por uma argamassa de matriz cimentícia ricamente refinada em termos de granulometria e com a inclusão de fibras, como forma de reforço. Entretanto, duas características principais o definem em termos de composição: a quase ausência de armaduras em estruturas construídas com o material e o fato de dispensar o uso de agregados com diâmetro máximo superior a 1 mm, sendo constituído basicamente por pós. O CPR possui características únicas que lhe conferem resistências à compressão de seis a oito vezes superiores ao concreto convencional, e tração e flexão cerca de dez vezes maior, podendo competir diretamente com estruturas em aço. As dificuldades para sua obtenção e utilização residem no fato de ser um material que demanda grande precisão em sua dosagem e também nos custos diretos para sua produção, bem como o desconhecimento em relação ao seu desempenho. O presente estudo comparou três diferentes traços de CPR a um traço de concreto convencional de uso comum na indústria de préfabricados, de forma a caracterizá-lo mecanicamente e buscando viabilizar sua produção e aplicação na indústria de pré-fabricados nacional, utilizando cinza volante como alternativa de aglomerante e a hibridização de fibras. Efetuou-se também um estudo comparativo dos custos de sua obtenção em relação ao concreto convencional, levando-se em conta o desempenho mecânico. Os resultados indicam que para todos os traços estudados, em relação ao concreto convencional estabelecido como parâmetro, as principais propriedades mecânicas contemplam uma resistência à compressão até quatro vezes superior; módulo de elasticidade longitudinal 50% superior; resistência à tração na flexão até sete vezes superior e resistência à tração direta cerca de três vezes superior. Com relação aos custos, ao se considerar o seu comportamento mecânico, o CPR se mostrou mais competitivo frente ao concreto convencional, demonstrando que a sua implantação, dentro da indústria de pré-fabricados nacional, pode e deve ser explorada. / Reactive powder composite is a material formed by a richly refined cementitious mortar matrix in terms of grain size and the inclusion of fibers, such as reinforcement. However, two main features define it in terms of composition: the almost absence of reinforcement steel and the use of aggregates with a maximum diameter greater than 1 mm, consisting basically by powder materials. RPC has unique characteristics which confer compressive strength six to eight times higher than conventional concrete and tensile and flexural strength about ten times higher, and may compete directly with steel structures. Difficulties in obtaining and use the material lie in the fact that it requires a great precision in the dosage and also the direct costs for its production, as well as the lack of knowledge about its performance. This study compared three different CPR mixes to a conventional concrete mix, commonly used in the precast industry, in order to characterize it mechanically and intending to disseminate its production and use in the national precast industry by using fly ash as a binder and alternative fiber hybridization. It also made a comparative study between the costs of obtaining CPR compared to conventional concrete, taking into account the mechanical performance. The results indicate that for all mixes studied in relation to conventional concrete set as a parameter, the primary mechanical properties include a compressive strength up to four times higher; longitudinal elastic modulus exceeding 50%; bending tensile strength up to seven times and resistance to direct tension about three times higher. Considering the costs compared to the mechanical behavior, CPR was found more competitive against the conventional concrete, demonstrating that its implementation within the national precast industry can and should be explored.
10

Caracterização mecânica de material compósito cimentício avançado à base de pós reativos / Mechanical Characterization of Advanced Reactive Powder Cementitious Composite Material

Fávero, Rafael Burin January 2016 (has links)
O compósito de pós reativos é um material formado basicamente por uma argamassa de matriz cimentícia ricamente refinada em termos de granulometria e com a inclusão de fibras, como forma de reforço. Entretanto, duas características principais o definem em termos de composição: a quase ausência de armaduras em estruturas construídas com o material e o fato de dispensar o uso de agregados com diâmetro máximo superior a 1 mm, sendo constituído basicamente por pós. O CPR possui características únicas que lhe conferem resistências à compressão de seis a oito vezes superiores ao concreto convencional, e tração e flexão cerca de dez vezes maior, podendo competir diretamente com estruturas em aço. As dificuldades para sua obtenção e utilização residem no fato de ser um material que demanda grande precisão em sua dosagem e também nos custos diretos para sua produção, bem como o desconhecimento em relação ao seu desempenho. O presente estudo comparou três diferentes traços de CPR a um traço de concreto convencional de uso comum na indústria de préfabricados, de forma a caracterizá-lo mecanicamente e buscando viabilizar sua produção e aplicação na indústria de pré-fabricados nacional, utilizando cinza volante como alternativa de aglomerante e a hibridização de fibras. Efetuou-se também um estudo comparativo dos custos de sua obtenção em relação ao concreto convencional, levando-se em conta o desempenho mecânico. Os resultados indicam que para todos os traços estudados, em relação ao concreto convencional estabelecido como parâmetro, as principais propriedades mecânicas contemplam uma resistência à compressão até quatro vezes superior; módulo de elasticidade longitudinal 50% superior; resistência à tração na flexão até sete vezes superior e resistência à tração direta cerca de três vezes superior. Com relação aos custos, ao se considerar o seu comportamento mecânico, o CPR se mostrou mais competitivo frente ao concreto convencional, demonstrando que a sua implantação, dentro da indústria de pré-fabricados nacional, pode e deve ser explorada. / Reactive powder composite is a material formed by a richly refined cementitious mortar matrix in terms of grain size and the inclusion of fibers, such as reinforcement. However, two main features define it in terms of composition: the almost absence of reinforcement steel and the use of aggregates with a maximum diameter greater than 1 mm, consisting basically by powder materials. RPC has unique characteristics which confer compressive strength six to eight times higher than conventional concrete and tensile and flexural strength about ten times higher, and may compete directly with steel structures. Difficulties in obtaining and use the material lie in the fact that it requires a great precision in the dosage and also the direct costs for its production, as well as the lack of knowledge about its performance. This study compared three different CPR mixes to a conventional concrete mix, commonly used in the precast industry, in order to characterize it mechanically and intending to disseminate its production and use in the national precast industry by using fly ash as a binder and alternative fiber hybridization. It also made a comparative study between the costs of obtaining CPR compared to conventional concrete, taking into account the mechanical performance. The results indicate that for all mixes studied in relation to conventional concrete set as a parameter, the primary mechanical properties include a compressive strength up to four times higher; longitudinal elastic modulus exceeding 50%; bending tensile strength up to seven times and resistance to direct tension about three times higher. Considering the costs compared to the mechanical behavior, CPR was found more competitive against the conventional concrete, demonstrating that its implementation within the national precast industry can and should be explored.

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