Academic literature on the topic 'Fibrous Cementitious Composites'
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Journal articles on the topic "Fibrous Cementitious Composites"
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Signorini, Cesare. "Durable and Highly Dissipative Fibrous Composites for Strengthening Coastal Military Constructions." Key Engineering Materials 893 (July 20, 2021): 75–83. http://dx.doi.org/10.4028/www.scientific.net/kem.893.75.
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Reinforced concrete strategic structures for military purposes are often established in coastalor offshore areas, widely subjected to chemical attacks, mainly due to an aggressive saline and acidenvironments. Porosity of cementitious conglomerates favour penetration of chlorides, which tend tocorrode the internal metallic rebar. The reinforcement of structures with fibrous composite materialsis a viable solution to restore the initial requirements of the building, especially when it exerts defence purposes. Among synthetic fibres, polyphenylenebenzobisoxazole (PBO) is an organic fibre based on linked aromatic structures with high elastic modulus and tensile strength and highly dissipative attitudes. In this work, the assessment of durability of continuous fibrereinforced cementitious mortar (FRCM) composites is carried out comparing the mechanical performance of laminates subjected to uniaxial tensile tests. It is found that PBOFRCM presents high resistance against aggressive environments and specifically preserve its mechanical strength in the presence of saltwater, where other reinforcing materials undergo to a dramatic degradation process.
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Murali, G., Sallal R. Abid, Hakim S. Abdelgader, Y. H. Mugahed Amran, Mohammad Shekarchi, and Krzysztof Wilde. "Repeated Projectile Impact Tests on Multi-Layered Fibrous Cementitious Composites." International Journal of Civil Engineering 19, no. 6 (2021): 635–51. http://dx.doi.org/10.1007/s40999-020-00595-4.
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Dutkiewicz, Maciej, Hasan Erhan Yücel, and Fatih Yıldızhan. "Evaluation of the Performance of Different Types of Fibrous Concretes Produced by Using Wollastonite." Materials 15, no. 19 (2022): 6904. http://dx.doi.org/10.3390/ma15196904.
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Production of cement and aggregate used in cement-based composites causes many environmental and energy problems. Decreasing the usage of cement and aggregate is a crucial and currently relevant challenge to provide sustainability. Inert materials can also be used instead of cement and aggregates, similar to pozzolanic materials, and they have positive effects on cement-based composites. One of the inert materials used in cement-based composites is wollastonite (calcium metasilicate-CaSiO3), which has been investigated and attracted attention of many researchers. This article presents state-of-the-art research regarding fibrous concretes produced with wollastonite, such as mortars, conventional concrete, engineered cementitious composites, geopolymer concrete, self-compacting concrete, ultra-high-performance concrete and pavement concrete. The use of synthetic wollastonite, which is a novel issue, its high aspect ratio and allowing the use of waste material are also evaluated. Studies in the literature show that the use of wollastonite in different types of concrete improves performance properties, such as mechanical/durability properties, and provides environmental–economic efficiency. It has been proven by studies that wollastonite is a material with an inert structure, and, therefore, its behavior is similar to that of a fiber in cementitious composites due to its acicular particle structure.
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Sreenath, Sreekumaran, Kaliyaperumal Saravana Raja Mohan, and Gunasekaran Murali. "Fracture Toughness of Reactive Powder Fibrous Concrete Composites under Pure and Mixed Modes (I/III)." Buildings 12, no. 5 (2022): 599. http://dx.doi.org/10.3390/buildings12050599.
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Reactive Powder Concretes (RPC) are well known for their exceptional strength properties and durability properties. The use of Supplementary Cementitious Materials (SCM) is the best way to enhance the strength and durability characteristics of RPCs further. Among various SCMs, the potential of Ground Granulated Blast-furnace Slag (GGBS) is proven by many researchers. However, the effect of GGBS on the fracture toughness of RPCs, especially under the tearing mode, is not explored. This study investigates the effect of partial replacement of OPC with GGBS in non-fibrous and fibrous RPCs, on its mode I (pure opening), mode III (pure tearing), and mixed-mode I/III fracture behaviour. A significant improvement in mode I, mode III, and mixed-mode I/III fracture toughness was observed due to incorporating GGBS and fibres in RPCs. The fibrous mix with 30% OPC, replaced with GGBS, exhibited the highest values of mode I and mode III fracture toughnesses, which were 2.35 MPa·m0.5 and 0.98 MPa·m0.5, respectively, and significantly high compared to the control non-fibrous and fibrous RPC mixes. The study reveals the ability of GGBS as an SCM to improve the fracture toughness of RPC mixes, thereby delaying the failure of the process of structural components.
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Lancellotti, Isabella, Federica Piccolo, Hoang Nguyen, et al. "The Effect of Fibrous Reinforcement on the Polycondensation Degree of Slag-Based Alkali Activated Composites." Polymers 13, no. 16 (2021): 2664. http://dx.doi.org/10.3390/polym13162664.
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Alternative cementitious binders, based on industrial side streams, characterized by a low carbon footprint, are profitably proposed to partially replace Portland cement. Among these alternatives, alkali-activated materials have attracted attention as a promising cementitious binder. In this paper, the chemical stability of the matrix, in fiber-reinforced slag-based alkali-activated composites, was studied, in order to assess any possible effect of the presence of the reinforcement on the chemistry of polycondensation. For this purpose, organic fiber, cellulose, and an inorganic fiber, basalt, were chosen, showing a different behavior in the alkaline media that was used to activate the slag fine powders. The novelty of the paper is the study of consolidation by means of chemical measurements, more than from the mechanical point of view. The evaluation of the chemical behavior of the starting slag in NaOH, indeed, was preparatory to the understanding of the consolidation degree in the alkali-activated composites. The reactivity of alkali-activated composites was studied in water (integrity test, normed leaching test, pH and ionic conductivity), and acids (leaching in acetic acid and HCl attack). The presence of fibers does not favor nor hinder the geopolymerization process, even if an increase in the ionic conductivity in samples containing fibers leads to the hypothesis that samples with fibers are less consolidated, or that fiber dissolution contributes to the conductivity values. The amorphous fraction was enriched in silicon after HCl attack, but the structure was not completely dissolved, and the presence of an amorphous phase is confirmed (C–S–H gel). Basalt fibers partly dissolved in the alkaline environment, leading to the formation of a C–N–A–S–H gel surrounding the fibers. In contrast, cellulose fiber remained stable in both acidic and alkaline conditions.
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Querido, Victor A., José Roberto M. d’Almeida, and Flávio A. Silva. "Development and analysis of sponge gourd (Luffa cylindrica L.) fiber-reinforced cement composites." BioResources 14, no. 4 (2019): 9981–93. http://dx.doi.org/10.15376/biores.14.4.9981-9993.
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Sponge gourd (Luffa cylindrica L.) fiber-reinforced cement composites were developed and analyzed. Dried sponge gourd fruit’s fibrous vascular system forms a natural 3D network that can reinforce matrices in composite materials, diverting cracks along the complex array of 3D interfaces between the fibers and the cementitious matrix. To avoid fiber deterioration, the cement paste was modified by incorporating pozzolanic materials. The fibers were mechanically characterized by tensile testing of strips of the 3D natural fiber array and of single fibers extracted from the array. The fibers had an average tensile strength of 140 MPa and an average Young’s modulus up to 28 GPa. Image analysis showed that the fiber spatial distribution inside the 3D network was random. The modified cement paste was characterized by its workability (flow table test) and mechanical behavior (compression and three-point bending tests), with average results of 430 mm, 62.7 MPa, and 6.2 MPa, respectively. Under bending, the cement matrix collapsed after the first crack. The sponge gourd-cement composite manufactured with 1 wt% of fibers showed an average flexural strength of 9.2 MPa (approximately 50% greater than the unreinforced matrix). Importantly, the composite also presented a limited deflection-hardening behavior. These results support sponge gourd’s possible use as reinforcement in cement matrix composites.
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Malchiodi, Beatrice, Erika Iveth Cedillo-González, Cristina Siligardi, and Paolo Pozzi. "A Practical Valorization Approach for Mitigating Textile Fibrous Microplastics in the Environment: Collection of Textile-Processing Waste Microfibers and Direct Reuse in Green Thermal-Insulating and Mechanical-Performing Composite Construction Materials." Microplastics 1, no. 3 (2022): 393–405. http://dx.doi.org/10.3390/microplastics1030029.
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Microplastic (MP) contamination is an urgent environmental issue to address. Fibrous microplastics (FMPs) are the principal MP type in the air and have already been found in human stool and lung tissues. FMPs are generated from the lifecycle of synthetic and blended textiles and are expected to increase due to fast fashion. Among textile processes, the finishing of fabrics is estimated to generate 5000 t/year of textile waste fibers in Italy, including FMPs. To limit FMPs spread, this paper suggests, for the first time, the direct collection of blended finishing textile waste microfibers and reuse in designing thermal-insulating and mechanical-performing fiber-reinforced cementitious composites (FRCs). The microfibers were thoroughly characterized (size, morphology, composition, and density), and their use in FRCs was additionally evaluated by considering water absorption and release capacity. Untreated, water-saturated, and NaOH-treated microfibers were considered in FRCs up to 4 wt%. Up to a +320% maximum bending load, +715% toughness, −80% linear shrinkage, and double-insulating power of Portland cement were observed by increasing microfiber contents. NaOH-treated and water-saturated microfibers better enhanced toughness and linear shrinkage reduction. Therefore, green and performant composite construction materials were obtained, allowing for the mitigation of more than 4 kg FMPs per ton of cement paste. This is a great result considering the FMP contamination (i.e., 2–8 kg/day fallout in Paris), and that FRCs are promising and shortly-widely used construction materials.
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Rizzo, Valeria, Antonio Bonati, Francesco Micelli, Marianovella Leone, and Maria Antonietta Aiello. "Influence of Alkaline Environments on the Mechanical Properties of FRCM/CRM and their Materials." Key Engineering Materials 817 (August 2019): 195–201. http://dx.doi.org/10.4028/www.scientific.net/kem.817.195.
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Fabric Reinforced Mortar (FRCM) used as Externally Bonded Reinforcements (EBR), provide a sustainable solution for retrofitting and repair of existing masonry structures. They are commonly made by fibrous meshes embedded in a cementitious/hydraulic lime matrix. This technique represents a valid alternative to the well-known FRP (Fiber Reinforced Polymer) composites, which show some limitations in heritage masonry applications. In this scenario, a new system known as CRM (Composite Reinforced Mortar) has been developed in the last years. In this system, a pre-cured FRP grid is utilized as internal reinforcement in a mortar layer. The system reproduces the traditional technique of reinforced plaster, where the steel grid is substituted by a non-metallic one. In masonry applications high compatibility with the substrate, sustainability and removability are commonly required in heritage construction. These goals are not easily achieved by using fibers immersed into a polymeric resin. Moreover, the inorganic matrix ensures the transpiration of substrates and consequently a higher durability of the whole strengthened system is expected. On the other hand, the recent use of these new materials in civil engineering needs appropriate design guidelines. The proposed paper focuses attention on the initial results of a large experimental study on the durability of FRCM/CRM systems and their single components (dry glass fibers, resin, pre-cured FRP grid and mortar). In particular, the influence of three alkaline environments solutions was studied. Exposure conditions were stressed by increasing the temperature of the three aqueous solutions. The mechanical retention of tensile properties was measured by performing direct tensile tests after different exposure times.
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Adamu, Musa, Yasser E. Ibrahim, and Hani Alanazi. "Evaluating the Influence of Elevated Temperature on Compressive Strength of Date-Palm-Fiber-Reinforced Concrete Using Response Surface Methodology." Materials 15, no. 22 (2022): 8129. http://dx.doi.org/10.3390/ma15228129.
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Due to its availability and affordable processing, date palm fiber (DPF) is among the natural and sustainable fibers used in cementitious composites. Furthermore, DPF is an agricultural, organic, and fibrous material that when subjected to higher temperature can easily degrade and cause reduction in strength. Therefore, the influence of elevated temperatures on the unit weight and strengths of DPF-reinforced concrete needs to be examined. Under this investigation, DPF is used in proportions of 0–3% weight of binder to produce a DPF-reinforced concrete. Silica fume was utilized as a supplemental cementitious material (SCM) in various amounts of 0%, 5%, 10%, and 15% by weight to enhance the heat resistance of the DPF-reinforced concrete. The concrete was then heated to various elevated temperatures for an hour at 200 °C, 400 °C, 600 °C, and 800 °C. After being exposed to high temperatures, the weight loss and the compressive and relative strengths were examined. The weight loss of DPF-reinforced concrete escalated with increments in temperature and DPF content. The compressive and relative strengths of the concrete improved when heated up to 400 °C, irrespective of the DPF and silica fume contents. The heat resistance of the concrete was enhanced with the replacement of up to 10% cement with silica fume when heated to a temperature up to 400 °C, where there were enhancements in compressive and relative strengths. However, at 800 °C, silica fume caused a significant decline in strength. The developed models for predicting the weight loss and the compressive and relative strengths of the DPF-reinforced concrete under high temperature using RSM have a very high degree of correlation and predictability. The models were said to have an average error of less than 6% when validated experimentally. The optimum DPF-reinforced concrete mix under high temperature was achieved by adding 1% DPF by weight of binder materials, replacing 12.14% of the cement using silica fume, and subjecting the concrete to a temperature of 317 °C. The optimization result has a very high desirability of 91.3%.
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Abbas, Al-Ghazali Noor, Farah Nora Aznieta Abdul Aziz, Khalina Abdan, Noor Azline Mohd Nasir, and Mohd Nurazzi Norizan. "Kenaf Fibre Reinforced Cementitious Composites." Fibers 10, no. 1 (2022): 3. http://dx.doi.org/10.3390/fib10010003.
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Increased environmental awareness and the demand for sustainable materials have promoted the use of more renewable and eco-friendly resources like natural fibre as reinforcement in the building industry. Among various types of natural fibres, kenaf has been widely planted in the past few years, however, it hasn’t been extensively used as a construction material. Kenaf bast fibre is a high tensile strength fibre, lightweight and cost-effective, offering a potential alternative for reinforcement in construction applications. To encourage its use, it’s essential to understand how kenaf fibre’s properties affect the performance of cement-based composites. Hence, the effects of KF on the properties of cementitious composites in the fresh and hardened states have been discussed. The current state-of-art of Kenaf Fibre Reinforced Cement Composite (KFRCC) and its different applications are presented for the reader to explore. This review confirmed the improvement of tensile and flexural strengths of cementitious composites with the inclusion of the appropriate content and length of kenaf fibres. However, more studies are necessary to understand the overall impact of kenaf fibres on the compressive strength and durability properties of cementitious composites.
Dissertations / Theses on the topic "Fibrous Cementitious Composites"
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Garcez, Estela Oliari. "Investigação do comportamento de Engineered Cementitious Composites reforçados com fibras de polipropileno como material para recapeamento de pavimentos." reponame:Biblioteca Digital de Teses e Dissertações da UFRGS, 2009. http://hdl.handle.net/10183/28642.
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Uma parcela substancial das rodovias do país apresenta processos de deterioração graves de seus pavimentos, fato que acarreta sérios impactos econômicos, sociais e ambientais, resultando em aumento do consumo de combustível, dos gastos com manutenção dos veículos, da frequência de engarrafamentos e do tempo gasto em deslocamentos. A utilização de recapeamentos ou overlays de concreto tem demonstrado ser uma alternativa sustentável e econômica para a reabilitação de pavimentos. No entanto, em muitos casos, os overlays de concreto não tem conseguido prevenir a ocorrência de fissuração por reflexão. Os Engineered Cementitious Composite (ECCs) são um tipo especial de compósitos cimentícios de alto desempenho reforçados com fibras, cuja principal característica é a altíssima ductilidade. Esta propriedade faz com que os mesmos sejam capazes de superar muitas das limitações dos overlays de concreto tradicionais. Fibras de PVA com uma camada superficial modificada foram especialmente desenvolvidas para serem empregadas no reforço de ECCs (ou PVAECC). O custo de tais fibras é o principal responsável pelo elevado custo dos ECCs, o que pode inviabilizar seu emprego em alguns casos. Buscando alternativas, este estudo se focou na investigação da possibilidade de uso de fibras de polipropileno (PP) de alto desempenho. Estas fibras, com custo mais atraente, já são produzidas comercialmente no Brasil, e usadas na produção de fibrocimento. As mesmas se demonstraram adequadas para uso como reforço em ECCs (ou PPECC), sendo capazes de garantir que se atinja um comportamento dúctil através do desenvolvimento de um processo de múltipla fissuração. Um resultado importante foi que a dimensão média da abertura das fissuras nos PPECC foi de 10 m, enquanto nos PVAECC a mesma era 60 m. Este resultado pode resultar em incrementos na durabilidade de estruturas. Além disto, o trabalho investigou o comportamento à flexão e fadiga dos ECCs reforçados com fibras de polipropileno. Os resultados demonstraram que os compósitos produzidos com cimento Portland tipo V-ARI não se comportam adequadamente à fadiga, uma vez que ocorre a deterioração das fibras. Por outro lado, os compósitos produzidos com cimento tipo I, já usualmente empregado em ECCs, apresentaram resultados satisfatórios. Um modelo de previsão de vida útil foi gerado para recapeamentos de PPECC, PVAECC e concreto, em função das espessuras dos revestimentos. O mesmo indicou que os ECCs requerem camadas 1,5 a 2,5 vezes mais finas que as usuais de concreto. O material foi, então, testado especificamente quanto à resistência à fissuração por reflexão. Os resultados demonstraram que o PPECC pode modificar o modo de ruptura frágil dos recapeamentos através do processo de múltipla fissuração. Na última etapa do trabalho foi realizada uma análise do ciclo de vida e dos custos do ciclo de vida de quatro diferentes sistemas de recapeamento – concreto, asfalto, PVAECC e PPECC. Os resultados mostram que os overlays de ECCs são bastante atrativos, pois diminuem tanto o consumo de energia associado aos processos de projeto, construção e manutenção do recapeamento, bem como reduzem a liberação de emissões gasosas à atmosfera, constituindo uma alternativa mais sustentável que as demais. Os sistemas de recapeamento com ECC também resultaram em vantagens econômicas. Apesar do alto custo inicial, a menor frequência de atividades de manutenção resulta em uma redução do custo total ao longo do período de 40 anos considerado. Isto representa uma importante economia em termos de custos diretos para os responsáveis pelas rodovias. De forma geral, o trabalho evidenciou a viabilidade de uso dos PPECCs para reabilitação de pavimentos.<br>Many old pavements in service today are approaching the end of their design service lives. Others are in dire need of major repair to continue serving, resulting in economical, environmental and social impacts by increasing vehicle fuel consumption and maintenance costs, traffic jam and delays. For pavements subject to moderate and heavy traffic, concrete overlays are increasingly being used as a cost effective and sustainable rehabilitation technique. However, concrete overlays have some physical limitations that contribute to durability concerns, which increase the probability of pavement overlay failure and maintenance frequency. Consequently, alternative materials are being developed to improve overlay performance. Engineered Cementitious Composites (ECC) are a special type of high performance fiber reinforced cementitious composites, designed for high ductility and damage tolerance which may overcome concrete overlay limitations. Polyvinylalcohol (PVA) fibers with special coating are typically used as reinforcement of ECC. Although some successful field application of PVAECC, the use of ECC is restrained by the high cost of the material, consequence of high PVA fibers cost. This research is focused on the investigation of using high tenacity polypropylene fibers as reinforcement of engineered cementitious composites (PPECC). Those fibers are produced and available in Brazil for fibrocement industry by less than half price of PVA fibers. PP fibers have demonstrated good performance in reinforcing ECC, assuring composite strain-hardening behavior through the development of multiple cracking processes. An important finding was the tinier crack opening of PPECC – 10 m average- comparing to PVAECC – 60 m average. This result may result in higher material durability. Furthermore, flexural and fatigue behavior or ECCs reinforced with PP fibers were investigated. Results have shown that Portland cement type V (high early strength) is not adequate for PPECCs subject to fatigue loading, resulting in fiber deterioration and premature rupture. By the other hand, promising results were found with cement ordinary type I, usually used in ECC production. A model of service life prediction was developed for PPECC, PVAECC and concrete overlays correlated to overlay thickness. Results have shown that ECCs may reduce overlay thickness in 1.5 to 2.5 times the usual thickness of overlay concrete. Reflective cracking resistance of PPECC was also testes. From the results it is possible to deduce that PPECC may modify typical rupture mode of concrete overlays through the development of multiple cracking. In the last stage of this work, life cycle analyses and life cycle cost analyses of four different overlays systems – concrete, hot mix asphalt, PVAECC and PPECC – were carried out. The results of this study have shown that an ECC overlay system have lower environmental burdens, reducing the energy consumption related to design, construction and maintenance activities, reducing green house effect as well. Life cycle costs analyses over a 40 years service life revealed that PPECC is the most economical overlay system compared to concrete, hot mix asphalt and PVAECC overlay systems. Agency costs are significantly reduced by adopting PPECC overlays. PPECC is a feasible alternative for pavement rehabilitation.
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Abdallah, Sadoon Mushrif. "Bonding mechanisms and strength of hooked-end steel fibre reinforced cementitious composites." Thesis, Brunel University, 2017. http://bura.brunel.ac.uk/handle/2438/15827.
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Concrete is a strong material as to its compressive strength. However, it is a material with a low tensile and shear strength, and brittleness at failure. Concrete has to be reinforced with appropriate materials. Steel fibre is one of the most common materials currently being used to develop reinforced concrete, which may replace partially or completely conventional steel reinforcement. Successful reinforcement of concrete composite is closely related to the bond characteristics between the reinforcing fibre and matrix. The effective utilisation of steel fibre reinforced concrete (SFRC) requires in-depth and detailed understanding of bonding mechanisms governing the tensile behaviour. In response to this demand, this study embraced two main areas: understanding the reinforcing mechanisms of fibres in SFRC and material's post-cracking behaviour. Comprehensive experimental and theoretical programmes have therefore been developed: the experimental work is subdivided into three parts. The first part was to investigate the effect of various physical parameters, such as fibre characteristics (i.e. geometry, inclination angle, embedded length, diameter and tensile strength) and matrix strength which controls the pull-out behaviour of steel fibres. The second part is concerned with the assessment of the bond mechanisms of straight and hooked end fibres after exposure to elevated temperatures and varying matrix strength. The third part is devoted to gain further insight on the bond mechanisms governing the post-cracking behaviour through uniaxial and bending tests. It was found that the varying hook geometry and matrix strength each had a major influence on the pull-out response of hooked end fibres. As the number of the hook's bends increased, the mechanical anchorage provided by fibre resulted in significant improvement of mechanical properties of SFRC. The reduction in bond strength at elevated temperatures is found to be strongly related to the degradation in properties of the constituent materials, i.e. the fibre and concrete. The most effective combination of matrix strength and fibre geometry was found to be as follows: 3DH (single bend) fibre with normal-medium strength matrix, 4DH (double bend) fibre with high strength matrix and 5DH (triple bend) fibre with ultra-high performance matrix. Two analytical models to predict the pull-out behaviour of hooked end fibres were developed. Both models were able to predict the pull-out response of SFRC made from a variety of fibre and matrix characteristics at ambient temperature. This work has established a comprehensive database to illustrate the bonding mechanisms of SFRC and anchorage strengthening of various hooked end fibres, and this should contribute towards an increasing interest and growing number of structural applications of SFRC in construction.
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Muñoz, Rodriguez Camilo Andrés. "Avaliação do comportamento mecânico de um ECC (Engineered Cementitious Composites) com fibras de polipropileno no recapeamento de pavimentos." reponame:Biblioteca Digital de Teses e Dissertações da UFRGS, 2018. http://hdl.handle.net/10183/179406.
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O Engineered Cementitious Composite ou ECC é um compósito cimentício de elevada capacidade de deformação, concebido na Universidade de Michigan. Constituído por agregados miúdos, cimento e fibras, o compósito apresenta elevada ductilidade associada com a capacidade de gerar microfissuras quando submetido a carregamentos, num comportamento conhecido como strain-hardening. As pesquisas previamente desenvolvidas no Laboratório de Ensaios e Modelos Estruturais (LEME) da UFRGS objetivaram caracterizar um ECC adaptado aos materiais do Brasil, adicionando-se fibras de polipropileno na elaboração do compósito, e estudando-se alternativas para a substituição parcial de cimento. Na pesquisa aqui relatada, adotou-se o traço de referência definido previamente (ECCRef) e também foi utilizado um traço alternativo com 30% (em volume) de cinza de casca de arroz moída por 4 horas, em substituição parcial do cimento (ECCCCA). A pesquisa foi dividida em duas abordagens. A primeira consistiu na caracterização das propriedades mecânica dos traços em laboratório com a realização de ensaios de resistência à tração na flexão, à compressão simples, avaliação da aderência por cisalhamento direto e da trabalhabilidade, bem como ensaios de fadiga em viga quatro pontos. Em ensaios monotônicos o ECCCCA apresentou uma resistência à tração na flexão média (ft,f) de 8,2 MPa e resistência à compressão simples média (fc) de 50 MPa; já o ECCRef teve valores médios de 6,8 MPa e 36 MPa, respetivamente. Nos ensaios de aderência obtiveram-se resistências ao cisalhamento de 2050 kPa (ECCCCA) e 1900 kPa (ECCRef) A avaliação da trabalhabilidade permitiu estabelecer critérios para aprimorar o processo de mistura e manuseio do material em estado fresco, desta forma obteve-se adequada trabalhabilidade no ensaio de flow table, que aumentou de 44 para 90, possibilitando a utilização de betoneiras de tombo e obter os volumes de material necessários. Com os resultados dos ensaios dinâmicos foram estabelecidos modelos de fadiga em termos da deformação específica de extensão inicial (εti), deformação específica de extensão inicial normalizada (ti/εtP) e tração inicial (σti), assim como da energia dissipada (DE), igualmente foi possível estudar o processo de degradação dos compósitos. A segunda abordagem da pesquisa consistiu na realização de ensaios em verdadeira grandeza, com a utilização do simulador de tráfego do Laboratório de Pavimentação (LAPAV). Foram construídos dois recapeamentos (de 50 e 30 mm de espessura) sobre pavimentos flexíveis que apresentavam idêntico padrão de trincamento. Em cada recapeamento foram aplicados 100 mil ciclos da carga de semi-eixo de 5,5 toneladas. Foram acompanhados, visualmente, o surgimento e evolução de fissuras e outras manifestações patológicas, bem como o desgaste superficial, por meio dos ensaios de Pêndulo Britânico e Altura de Mancha de Areia. Após o fim do tráfego, foram serradas placas das seções trafegadas para verificar a propagação das fissuras e a aderência entre o compósito e o pavimento. Concluiu-se que o controle de qualidade na mistura é fundamental para garantir a qualidade da superfície. Além disso, percebeu-se que a aparição de fissuras está associada com possíveis problemas de aderência ECC-pavimento asfáltico, e em menor escala reflexão de fissuras. Globalmente, constatou-se que é possível produzir ECC’s com materiais disponíveis no estado e que este material pode ser aplicado na restauração de pavimentos.<br>Engineered Cementitious Composite or ECC is a material with a high deformation capacity, designed at the University of Michigan. Composed of fine aggregates, cement and fibres, the composite presents high ductility associated with the ability to generate microcracks when loaded, in a behavior known as strain-hardening. The research previously developed in the Laboratory of Structural Models and Tests (LEME) of UFRGS aimed to characterize an ECC adapted to the materials of Brazil, adding polypropylene fibres in the preparation of the composite, and studying alternatives for the partial replacement of cement. In the research reported here, the previously defined reference mix proportion (ECCRef) was adopted and an alternative mix proportion was used with 30% (by volume) of unprocessed rice-husk ash grinded for 4 hours, in partial replacement of the cement (ECCCCA). The research was divided into two approaches. The first one consisted in the characterization of the mechanical properties of the ECC’s in the laboratory with the execution of tests of flexural behavior and compressive strength, evaluation of adhesion by direct shear tests and the workability, as well as fatigue tests in four point configuration. In monotonic tests ECCCCA showed a resistance to flexural strength of 8.2 MPa and average compression strength of 50 MPa; ECCRef had mean values of 6.8 MPa and 36 MPa, respectively. In the adhesion tests, shear strengths of 2050 kPa (ECCCCA) and 1900 kPa (ECCRef) were obtained The evaluation of the workability allowed for the determination of criteria to improve the process of mixing and handling of the material in fresh state, in this way, adequate workability was obtained in the flow table test, which increased from 44 to 90, permitting the use of concrete mixer machines and to obtain the required volumes of material. With the results of the dynamic tests, fatigue models were stipulated in terms of initial tensile strain (εti), normalized initial tensile strain (ti/εtP) and initial traction (σti), as well as the dissipated energy (DE), it was also possible to study the process of degradation of the composites. The second approach of the research consisted in the accomplishment of tests in true greatness, with the use of the Accelerated Loading Facility of the Laboratory of Pavements (LAPAV). Two overlays (50 and 30 mm thick) were built over flexible pavements that had the same cracking pattern. At each overlay, 100 thousand cycles of the semi-axle load of 5.5 tons were applied. The appearance and evolution of cracks and other pathologies were monitored visually, as well as surface wear through the British Pendulum and Sand Patch tests. After the end of the traffic simulator, plates of the trafficked sections were sawn to verify the propagation of the cracks and the adhesion between the composite and the pavement. It was concluded that the quality control in the mixture is fundamental to guarantee the quality of the surface. In addition, it was noticed that the appearance of cracks is associated with possible problems of adhesion ECC-asphalt pavement, and to a lesser extent reflective cracking. Overall, it has been found that it is possible to produce ECC's with Brazilian materials and the ECC can be applied in the restoration of pavements.<br>El ECC (Engineered Cementitious Composites) es un compósito cementicio de elevada capacidad de deformación desarrollado en la Universidad de Michigan. Conformado por agregados finos, cemento y fibras poliméricas, presenta una alta ductilidad asociada con la capacidad de generar microfisuras durante la aplicación de cargas, comportamiento conocido como strain-hardening. Las investigaciones previamente desarrolladas en el Laboratório de Ensaios e Modelos Estruturais (LEME) de la UFRGS se direccionaron para caracterizar un ECC adaptado a los materiales brasileros, utilizando fibras de polipropileno y estudiando alternativas para la sustitución parcial del cemento. En la presente investigación se adoptó el trazo de referencia definido previamente (ECCRef), también fue utilizado un trazo alternativo con 30% (en volumen) de ceniza de cáscara de arroz molida por 4 horas como substituto parcial del cemento (ECCCCA). La investigación fue dividida en dos abordajes. La primera consistió en la caracterización de las propiedades mecánicas en laboratorio con la realización de ensayos de resistencia a tracción por flexión e compresión simple, evaluación de la adherencia por corte directo y de la trabajabilidad, además de ensayos de fatiga en viga cuatro puntos. En ensayos monotónicos el ECCCCA presentó una resistencia a la tracción por flexión media (ft,f) de 8,2 MPa y resistencia a la compresión simple media (fc) de 50 MPa; ya el ECCRef tuvo valores medios de 6,8 MPa y 36 MPa, respectivamente. En los ensayos de adherencia se obtuvieron resistencias al corte de 2050 kPa (ECCCCA) y 1900 kPa (ECCRef). La evaluación de la trabajabilidad permitió establecer criterios para mejorar el proceso de mezcla y manipulación del material en estado fresco, de esa forma se obtuvo una adecuada trabajabilidad en el ensayo de flow table, que aumentó de 44 para 90, posibilitando la utilización de mezcladoras de tambor y la obtención de los volúmenes de material necesarios. Con los resultados de los ensayos dinámicos fueron establecidos modelos de fatiga en términos de la deformación específica de extensión inicial (εti), de la deformación específica de extensión inicial normalizada (ti/εtP), de la tracción inicial (σti) y de la energía disipada (DE), igualmente fue posible estudiar el proceso de degradación de los compósitos El segundo abordaje de la investigación consistió en la realización de ensayos en verdadera grandeza con la utilización del simulador de tráfico del Laboratório de Pavimentação (LAPAV). Fueron construidos dos recapeamentos (de 50 y 30 mm de altura) sobre pavimentos flexibles que presentaban idéntico patrón de fisuración. En cada recapeamento fueron aplicados 100 mil ciclos da carga de semi-eje de 5,5 toneladas. Fueron acompañados, visualmente, la aparición y evolución de fisuras y otras patologías, así como el desgaste superficial por medio de los ensayos de Péndulo Británico y Altura de Mancha de Arena. Una vez terminados los ciclos de carga, fueron extraídas placas de las secciones ensayadas para verificar la propagación de las fisuras y la adherencia entre el compósito y el pavimento. Se concluyó que el control de calidad durante el proceso de mezcla es fundamental para garantizar la calidad superficial. Además, fue percibido que la aparición de fisuras está asociada con posibles problemas de adherencia ECC-pavimento asfáltico y en menor escala reflexión de fisuras. Globalmente, se constató que es posible producir ECC’s con materiales disponibles a nivel local y que este material puede ser aplicado en la restauración de pavimentos.
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Dolores, Gonzalo Mármol de los. "Low-alkalinity matrix composites based on magnesium oxide cement reinforced with cellulose fibres." Universidade de São Paulo, 2017. http://www.teses.usp.br/teses/disponiveis/74/74133/tde-17082017-113846/.
Full textAbstract:
A lower-alkalinity cement based on MgO and SiO2 blends is analysed to develop clinker-free Fibre Reinforced Cementitious Composites (FRCC) with cellulosic fibres in order to solve the durability problems of this type of fibres when used in FRCC with Portland cement. Hydration evolution from 7 to 28 days of different MgO-SiO2 formulations is assessed. The main hydration products are Mg(OH)2 and M-S-H gels for all the formulations studied regardless of age. Hardened pastes are obtained with pH values < 11 and good mechanical properties compared to conventional Portland cement. 60% MgO-40% SiO2 system is chosen as optimal for the development FRCC since is the most mechanical resistant and is less alkaline compared with 70% MgO-30% SiO2. FRCC based on magnesium oxide and silica (MgO-SiO2) cement with cellulose fibres are produced to study the durability of lignocellulosic fibres in a lower pH environment than the ordinary Portland cement (PC). Flexural performance and physical tests (apparent porosity, bulk density and water absorption) of samples at 28 days and after 200 accelerated ageing cycles (aac) are compared. Two types of vegetable fibres are utilised: eucalyptus and pine pulps. MgO-SiO2 cement preserves cellulosic fibres integrity after ageing, so composites made out of MgO-SiO2 exhibit significant higher performance after 200 cycles of accelerated ageing than Portland cement composites. High CO2 concentration environment is evaluated as a curing treatment in order to optimise MgO- SiO2 matrices in FRCC. Samples are cured under two different conditions: 1) steam water curing at 55°C and 2) a complementary high CO2 concentration (20% by volume). In carbonated samples, Mg(OH)2 content is clearly lowered while new crystals of hydromagnesite [Mg5 (CO3)4⋅(OH) 2⋅4H2O] are produced. After carbonation, M-S-H gel content is also reduced, suggesting that this phase is also carbonated. Carbonation affects positively to the composite mechanical strength and physical properties with no deleterious effects after ageing since it increases matrix rigidity. The addition of sepiolite in FRCC is studied as a possible additive constituent of the binding matrix. Small cement replacement (1 and 2% wt.) by sepiolite is introduced and studied in hardened cement pastes and, later, in FRCC systems. When used only in cement pastes, it improves Dynamic Modulus of Elasticity over time. Bending tests prove the outcome of this additive on the mechanical performance of the composite: it improves composite homogeneity. Ageing effects are reported after embedding sisal fibres in MgO-SiO2 and PC systems and submitting them to different ageing conditions. This comparative study of fibre degradation applied in different cementitious matrices reveals the real compatibility of lignocellulosic fibres and Mg-based cements. Sisal fibres, even after accelerated ageing, do neither suffer a significant reduction in cellulose content nor in cellulose crystallinity and crystallite size, when exposed to MgO-SiO2 cement. Fibre integrity is preserved and no deposition of cement phases is produced in MgO-SiO2 environment.<br>Um cimento de baixa alcalinidade à base de blendas de MgO e SiO2 é analisado para o desenvolvimento de Compósitos Cimentícios Reforçados com Fibras (CCRF) celulósicas sem clínquer para resolver os problemas de durabilidade de este tipo de fibras quando são usadas em CCRF com cimento Portland. A evolução da hidratação, desde 7 aos 28 dias, das diferentes formulações é avaliada. Os principais produtos hidratados são o Mg(OH)2 e o gel M-S-H para todas as formulações independentemente da idade estudada. As pastas endurecidas apresentam valores de pH < 11 e bom desempenho mecânico comparado com o cimento Portland convencional. O sistema 60% MgO-40% SiO2 é escolhido como a formulação ótima para o desenvolvimento de CCRF já que é a mais resistente e menos alcalina comparada com 70% MgO-30% SiO2. CCRF com cimento à base de óxido de magnésio e sílica (MgO-SiO2) e fibras celulósicas são produzidos para a análise da durabilidade das fibras lignocelulósicas em ambientes com valores de pH mais baixos comparados com o cimento Portland (PC). O desempenho mecânico a flexão e os ensaios físicos (porosidade aparente, densidade aparente e absorção de água) são comparados aos 28 dias e após de 200 ciclos de envelhecimento acelerado. O cimento à base de MgO-SiO2 preserva a integridade das fibras após o envelhecimento. Os compósitos produzidos com este cimento exibem melhores propriedades após 200 ciclos de envelhecimento acelerado que os compósitos produzidos com cimento Portland. Ambientes com alta concentração de CO2 são avaliados como tratamento de cura para otimizar as matrizes MgO- SiO2 nos CCRF. As amostras são curadas sob 2 condições diferençadas: 1) cura com vapor de água a 55oC e 2) cura com alta concentração de CO2 (20% do volume). As amostras carbonatadas apresentam teores reduzidos de Mg(OH)2 enquanto é produzida uma nova fase cristalina: hidromagnesita [Mg5 (CO3)4⋅(OH) 2⋅4H2O]. Após a carbonatação, o conteúdo de gel M-S-H é reduzido também, indicando uma carbonatação desta fase. A carbonatação aumenta a rigidez da matriz o que influi positivamente no desempenho mecânico e as propriedades físicas dos compósitos sem efeitos prejudiciais ao longo prazo. A adição de sepiolita em CCRF é estudada como possível adição na composição da matriz aglomerante. Baixos teores (1 e 2% em massa) de cimento são substituídos por sepiolita para o estudo das pastas de cimento hidratado e, posteriormente, dos compósitos. O Módulo Elástico Dinâmico das pastas é incrementado com o tempo pela adição de sepiolita. Os ensaios a flexão demostram que a adição de sepiolita melhora a homogeneidade dos compósitos. Reportam-se os efeitos das fibras de sisal após da exposição a sistemas MgO-SiO2 e PC e submetidas a diferentes condições de envelhecimento. Este estudo comparativo da degradação das fibras expostas a diferentes matrizes cimentícias mostra a compatibilidade das fibras lignocelulósicas com os cimentos à base de Mg. As fibras de sisal, inclusive após o envelhecimento acelerado, não apresentam nem redução significativa no conteúdo de celulose nem na cristalinidade da celulose assim como do tamanho de cristalito, quando expostas a cimentos MgO-SiO2.
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Sultangaliyeva, Fariza. "Formulation of fluid fire-resistant fiber-reinforced cementitious composite : Application to radioactive waste disposal." Thesis, Pau, 2020. http://www.theses.fr/2020PAUU3041.
Full textAbstract:
Le but de ce travail est de développer un béton fluide résistant au feu renforcé en fibres de polypropylène pour les colis de stockage des déchets radioactifs de moyenne activité à vie longue. Le défi de ce travail consiste à utilizer des fibres de polypropylène qui, même ajoutées en petite quantité, améliorent la résistance au feu mais diminuent de manière significative la maniabilité des bétons frais. Des essais à l’échelle du laboratoire sont effectués afin d’évaluer les comportements rhéologique et à haute température des matériaux cimentaires contenant des fibres de polypropylène. Dans la première partie, une étude du comportement rhéologique des matériaux cimentaires avec des fibres de polypropylène a été réalisée. Le but de cette étude est d’étudier l’influence de ces fibres sur le seuil d’écoulement des pâtes de ciment et des mortiers. Un modèle qui permet d’évaluer la quantité de pâte supplémentaire nécessaire pour compenser l’effet des fibres de polypropylène en fonction de la fluidité du béton frais a été développé.Ensuite, une étude expérimentale et numérique sur le comportement des matériaux cimentaires avec des fibres de polypropylène à haute température a été réalisée afin d’optimiser le choix des fibres pour améliorer la stabilité thermique d’un matériau cimentaire. Des essais de perméabilité résiduelle radiale et des essais feu sur les trois matériaux avec squelettes granulaires différents contenant des fibres de polypropylène de différentes géométries et dosages ont été réalisés dans un but de sélectionner une géométrie et un dosage optimal des fibres. Puis, des simulations thermomécaniques ont été développées à l’échelle macroscopique et mésoscopique. Le choix du diamètre, de la longueur et du dosage des fibres a été fait en fonction de la taille maximale des granulats.Finalement, une méthode de formulation du béton autoplaçant avec des fibres de polypropylène optimisé à la fois du point de vue de la rhéologie et de la résistance au feu a été présentée. Avec cette méthode, la conformité aux critères imposés sur les propriétés à l’état frais et à l’état durci du béton est vérifiée. Des éprouvettes de bétons sont testées sous chargement mécanique uniaxial et, en fonction des résultats, les formulations finales sont sélectionnées pour les futurs essais feu à l’échelle plus importante<br>The aim of the thesis is to design a self-compacting concrete with polypropylene fibers resistant to fire for a use in storage containers of medium activity long-lived waste. The challenge of the work is presented by the use of polypropylene fibers that enhance fire resistance but drastically diminish workability of concrete even when added at small volume fractions. Tests on laboratory scale are conducted with a purpose of evaluating rheological behavior and high temperature behavior of cementitious materials containing polypropylene fibers.In the first part, a study of rheological behavior of cement-based materials containing polypropylene fibers was done. The aim of this study is to investigate the influence of polypropylene fibers on the yield stress of cement pastes and mortars. A model is proposed to be able to evaluate the quantity of paste necessary to compensate the addition of polypropylene fibres according the fluidity of fresh concrete.Then an experimental and numerical investigation of behavior of cementitious materials with polypropylene fibers at high temperature was done so as to optimize the choice of polypropylene fibers for cementitious material to improve its thermal stability. Three different cementitious materials with three different granular skeleton containing various polypropylene fiber geometries and dosages were tested (residual radial permeability test and fire test) in order to select an optimal fiber geometry and dosage. Then thermomechanical computations was developped at maco and meso scale. Then, a choice of diameter, length and dosage of fibres is proposed according to the maximum size of gravels.Finally, a method of concrete formulation with polypropylene fibers optimized from perspectives of rheology and resistance to fire is presented. In this method, fresh and hardened state properties are verified to ensure an accordance with performance criteria specified by the project. At the end, designed mixes were tested in fire tests conducted on uniaxially compressed prisms and, based on outcomes, final mixes are selected for further fire tests on higher scale concrete
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Costa, Fernanda Bianchi Pereira da. "Análise da durabilidade de compósitos cimentícios de elevada capacidade de deformação reforçados com fibras." reponame:Biblioteca Digital de Teses e Dissertações da UFRGS, 2015. http://hdl.handle.net/10183/130203.
Full textAbstract:
Apesar do avanço tecnológico crescente na construção civil, a falta de durabilidade das estruturas de concreto, tanto em edificações como pavimentação, tem sido constatada com acentuada assiduidade e proporção. O compósito cimentício de elevada deformação, também conhecido como Engineered Cementitious Composites (ECC), foi difundido a partir do conceito de concretos de alto desempenho reforçado com fibras, visando suprir o comportamento frágil do concreto convencional e problemas relacionados à falta de durabilidade gerada, principalmente, devido à propagação de fissuras. Neste contexto, o Laboratório de Ensaio de Modelos Estruturais (LEME) da Universidade Federal do Rio Grande do Sul (UFRGS) consolidou, nos últimos cinco anos, um grupo de pesquisa voltado ao estudo do ECC aliado a utilização de materiais nacionais. A concepção tem sido baseada na aplicação de materiais que proporcionem custos mais baixos e fomentem questões de sustentabilidade ambiental. Assim, foram incorporados ao material, fibra de polipropileno (2% em volume) e substituição parcial do cimento por 30% (em volume) de cinza de casca de arroz residual. O presente trabalho visa analisar questões de durabilidade destes compósitos (com e sem a incorporação de cinza), e compará-los a concretos convencionais, através de ensaios relacionados ao estudo da estrutura de poros (absortividade, absorção e índice de vazios, absorção e água por capilaridade, absorção de água pelo método do cachimbo e microscopia eletrônica de varredura), penetração e difusão de íons cloretos, retração livre e restringida, e, por fim, resistência à abrasão. Os resultados obtidos indicam que a incorporação de cinza de casca de arroz melhorou significativamente as propriedades do compósito relacionadas à conexão e solução dos poros, dificultando a passagem de cloretos, além de apresentar resistência à abrasão semelhante ao compósito de referência. Sua desvantagem está relacionada às maiores aberturas de fissuras ocasionadas devido à retração restringida. Entretanto, o trabalho evidencia a viabilidade e vantagem do uso de cinza de casca de arroz na produção do compósito, em termos de durabilidade.<br>Despite the increasing technological advances in construction, the lack of concrete structures durability, both in buildings and pavement, have been found with severe attendance and proportion. The high strain cementitious composite, also known as Engineered Cementitious Composites (ECC), was widespread from the concept of high performance fiber reinforced concrete, in order to supply the fragile behavior of conventional concrete and problems related to lack of durability generated mainly due to crack propagation. In this context, the Laboratório de Ensaios e Modelos Estruturais (LEME) of the Federal University of Rio Grande do Sul (UFRGS) consolidated over the last five years, a research group focused on the ECC study allied with the use of national materials. The design has been based on the application materials that provide lower costs and promote environmental sustainability issues. Thus, they were incorporated into the material polypropylene fibers (2% by volume) and partial cement replacement of 30% (by volume) of residual rice husk ash. This study aims to examine durability issues of these composites (with and without rice husk ash), and compare them to conventional concretes, through tests related to the study of pore structure (absorptivity, absorption and void ratio, water absorption by capillarity, water absorption by the pipe method and scanning electron microscopy), penetration and diffusion of chloride ions, free and restrained shrinkage, and, finally, abrasion resistance. The results indicate that the incorporation of rice husk ash significantly improved material properties related to connection and pores solution, hindering the chloride ingress, and presents abrasion resistance similar to the reference composite. Its disadvantage is related to the larger cracks due to restrained shrinkage. However, the work demonstrates the viability and advantage of use rice husk ash in the composite production in terms of durability.
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Teixeira, Ronaldo Soares. "Efeito das fibras de curauá e de polipropileno no desempenho de compósitos cimentícios produzidos por extrusão." Universidade de São Paulo, 2015. http://www.teses.usp.br/teses/disponiveis/18/18158/tde-04022016-100910/.
Full textAbstract:
O emprego de compósitos na construção civil, como os de matriz cimentícia e pasta reforçada com fibras, tem se disseminado consideravelmente nos últimos anos. Uma grande variedade de fibras sintéticas, como o polipropileno, tem sido utilizada com sucesso para reforçar compósitos cimentícios. No entanto, o interesse mundial na utilização de produtos com menor impacto ambiental estimula a busca por materiais para substituir fibras sintéticas. As fibras vegetais, biodegradáveis, pode ser ótima alternativa devido à abundância, ao baixo custo, ao menor consumo de energia para sua produção e às propriedades mecânicas apropriadas. Fibra de curauá, planta nativa do estado do Amazonas, com plantações em escala comercial, é usada na fabricação de cordas, cestos ou como reforço em matrizes orgânicas. Suas propriedades mecânicas são semelhantes às de polipropileno. A tecnologia de extrusão é viável nas indústrias de fibrocimento, pois produz compósitos com matriz de alta densidade e ótimo empacotamento, baixa permeabilidade e boa adesão fibra matriz. No entanto, o processo de extrusão bem-sucedido de produtos cimentícios depende principalmente das propriedades reológicas do cimento fresco reforçado com fibras. As fibras vegetais podem promover o sequestro de água e interferir fortemente no escoamento, na coesão e no fluxo de pasta de cimento fresco. A incorporação de fibras vegetais influencia os materiais à base de cimento no estado fresco e afeta propriedades no estado endurecido. Neste contexto, o objetivo da pesquisa é avaliar a influência das fibras de curauá e de polipropileno em propriedades reológicas e em propriedades mecânicas da pasta de cimento fresco. Foram preparadas formulações sem fibras, como referência, e com 1 e 2% de reforço em massa, fibras com comprimento de 6 e 10 mm. Utilizaram-se duas técnicas reológicas: Squeeze flow e reômetro extrusor para analisar o fluxo de pastas cimentícias. Por meio de dados experimentais, como força/deslocamento, e de análise numérica da pressão do reômetro extrusor, foram determinados: tensão inicial de cisalhamento (σ0), limite de cisalhamento (τ0), tensão de escoamento (α) e tensão de cisalhamento (β). As propriedades mecânicas foram determinadas em máquina de ensaio MTS. Módulo de ruptura (MOR), tenacidade à fratura (TFT) e energia de fratura (EF) foram calculados. Os resultados reológicos indicam que a pasta cimentícia reforçada com fibras de curauá apresentou maior força, menor deslocamento e aumento da pressão de extrusão em fibras de curauá em relação às pastas cimentícias reforçadas com fibras de polipropileno. O comprimento das fibras influenciou mais o fluxo da mistura do que o teor de fibra. Compósitos cimentícios reforçados com fibra de polipropileno apresentaram melhores resultados mecânicos de MOR, TFT e EF em relação aos compósitos reforçados com curauá. Após os 200 ciclos de envelhecimento, os resultados mecânicos dos compósitos reforçados com as fibras de curauá diminuíram devido a mineralização das fibras. Os resultados de nanoindentação, como dureza e módulo elástico, aumentaram após os 200 ciclos. As metodologias aplicadas para avaliar o comportamento reológico e mecânico do fibrocimento durante a extrusão facilitará a futura transferência dessa tecnologia ao setor produtivo, com produtos potencialmente de melhor qualidade.<br>The use of composites in construction, as matrix and paste cement reinforced with fibers, has spread considerably in recent years. A wide variety of synthetic fibers such as polypropylene have been successfully used to reinforce cementitious composites. However, worldwide interest in the use of products with lower environmental impact stimulates the search for materials to replace synthetic fiber. Vegetable fiber, biodegradable, can be a great alternative because of the abundance, low cost, the lowest energy consumption for its production, appropriate mechanical properties. Curauá fiber, native plant from Amazon, with crops on a commercial scale, is used in the manufacture of ropes, baskets or as reinforcement in organic matrix. Its mechanical properties are similar to those of polypropylene. Extrusion technology is feasible in the fibercement industry, because it produces composites with high density matrix and great packaging, low permeability and good adhesion fiber matrix. However, successful extrusion process of cementitious products mainly depends on the rheological properties of fresh cement reinforced with fibers. The vegetable fibers can promote water kidnapping and strongly interfere in the flow, cohesion and fresh cement slurry flow. The incorporation of vegetable fibers influences the based cementitious materials in the fresh state and affects properties in the hardened state. In this context, the objective of the research is to evaluate the influence of curauá and polypropylene fiber in rheological and mechanical properties of fresh cement paste. Formulations without fiber, used as reference, 1 and 2% content by weight of reinforcement, fibers with a length of 6 to 10 mm were prepared. Two rheological techniques were used: Squeeze flow and extruder rheometer to analyze the flow of cement pastes. Through experimental data, as strength/displacement and numerical analysis of the pressure extruder rheometer were determined: yield stress corresponding to zero velocity (σ0), initial shear stress (τ0), effect of the velocity on yield stress (α) and effect of velocity in the shear stress (β). The mechanical properties were determined in MTS testing machine. Modulus of rupture (MOR), fracture toughness (TFT) and fracture energy (EF) were calculated. The rheological results indicate that the cement paste reinforced with curauá fiber showed higher strength, smaller displacement and increased extrusion pressure with curauá fibers compared to cementitious paste reinforced with polypropylene fibers. The length of the fibers influence the flow of the mixture more than the fiber content. Composites reinforced with polypropylene fibers presented higher values of MOR, TFT and EF compared to composites reinforced with curauá fiber. After 200 ageing cycles, the mechanical results of composites reinforced with curauá fibers decreased due to mineralization of the fibers. The nanoindentation results, as hardness and elastic modulus, increased after 200 cycles. The methodologies used to assess the rheological and mechanical behavior of fibercement during extrusion facilitate future transfer of this technology to the productive sector, with potentially higher quality products.
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Monteiro, André Oliveirinha. "Development of a multifunctional carbon black/cement composite for traffic monitoring." Doctoral thesis, Universidade de Aveiro, 2018. http://hdl.handle.net/10773/23030.
Full textAbstract:
Doutoramento em Engenharia Civil<br>As sociedades modernas estão fundadas em sistemas infraestruturais como
redes de abastecimento de água, electricidade, comunicação e transporte.
Com o aumento da procura global pela eficiência, imposto pelo século XXI, o
desempenho esperado das estruturas segue inevitavelmente a mesma
tendência. Esta busca de performance tem levado às infraestruturas físicas e à
tecnologia digital se fundirem no conceito de “infraestruturas inteligentes”,
através de vastas redes de monitorização, aliadas a subsistemas de
informação. A disciplina de gestão de tráfego é talvez aquela que mais tem
beneficiado destes avanços, com a implementação dos chamados Sistemas
Inteligentes de Transporte (ITS).
Avanços recentes na área dos materiais têm permitido o desenvolvimento de
materiais de construção “inteligentes”, capazes de desempenhar tarefas
autónomas. Os compósitos cimentícios piezoresistivos são um exemplo. Estes
podem ser utilizados como sistemas de monitorização, graças às suas
propriedades intrínsecas de sensitividade a estímulos mecânicos. A presente
dissertação visa fazer a ponte entre o conceito de materiais cimentícios
multifuncionais e a disciplina de monitorização de tráfego. Deste modo, um
compósito piezoresistivo foi desenvolvido para aplicação em pavimentos, com
base na adição de partículas de negro de fumo (CB), com o objectivo de
avaliar dados de tráfego em tempo real.
Numa primeira abordagem experimental foi determinada uma composição
cimentícia sensitiva, concluindo que a incorporação de 7% de CB (em relação
à massa de cimento) oferecia a melhor resposta resistiva a estímulos de
compressão. Numa segunda campanha experimental, composição, ergonomia
dos sensores cimentícios, tipologia de ensaios e sistema de aquisição foram
otimizados e adequados, de acordo com a finalidade de monitorização de
tráfego. Ciclos de compressão estáticos e dinâmicos demonstraram fatores de
sensitividade médios (GF) de 60 e uma excelente resposta linear, não afetada
por variações de temperatura, ao contrário da sensitividade piezoresistiva que
registou diminuições até 30%.
Em resumo, os resultados desta dissertação demonstram que a incorporação
de elementos de betão sensitivo com adição de CB à superfície de pavimentos
pode vir a constituir uma alternativa às soluções tradicionais de monitorização
de tráfego, dado as suas vantagens como: baixo custo, simplicidade de
implementação, propriedades estruturais, durabilidade e sensitividade<br>Today’s society is founded on infrastructure systems such as water, electricity,
communication and transport networks. The global efficiency demand of the
21st century is growing rapidly and the expected performance of infrastructures
follows the same trend. This pursuit for efficiency has led digital technology and
physical urban infrastructures to fuse into the concept of ‘smart infrastructures’,
relying on large monitoring networks coupled to information subsystems. Traffic
logistics has been one of the fields which has benefited the most of such
advances, with the implementation of the so-called Intelligent Transportation
Systems (ITS).
Over the last years, advances in materials science have enabled the
development of a wide range of “smart” construction materials capable of
autonomous tasks. An example of these are the piezoresistive cementitious
composites, some of which may be used as monitoring systems, thanks to their
self-sensing properties. The present dissertation aims to bridge the concept of
multifunctional cement-based materials to the traffic monitoring discipline. Here,
a stress-sensitive cementitious composite, based on the addition of carbon
black (CB) particles, was developed for application in pavement surfaces with a
view to perform permanent real-time evaluation of traffic data.
In a first experimental approach, a sensitive CB-based cementitious
composition was determined and results concluded that mixtures containing
7% of CB by mass of cement offered the most favourable piezoresistive
response. In a second experimental campaign, materials, specimens design
and measurement setup were reviewed, towards traffic monitoring
requirements. Quasi-static and dynamic compressive load cycles showed
gauge factors (GF) as high as 60 and a response linearity inaffected by
temperature variations, despite registered reductions in sensitivity up to 30%.
Taken together, results demonstrated that embedding conductive CB-based
concrete elements in pavement surfaces may become a prospective alternative
to conventional traffic monitoring solutions given their numerous advantages,
including: low-cost, simplicity of implementation, structural properties, durability
and good sensitivity.
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Guimar?es, Elvio Antonino. "Efeito da adi??o de fibras da palma do licuri (syagrus coronata) no comportamento f?sico e mec?nico de comp?sitos de matriz ciment?cia." Universidade Federal do Rio Grande do Norte, 2013. http://repositorio.ufrn.br:8080/jspui/handle/123456789/12859.
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Previous issue date: 2013-12-20<br>Coordena??o de Aperfei?oamento de Pessoal de N?vel Superior<br>This research was motivated by the requirement of asbestos s replacement in
building systems and the need to generate jobs and income in the country side of the
state of Bahia, Brazil. The project aimed at using fibers from licuri leaves (syagrus
coronata), an abundant palm in the region, to produce composites appropriate for the
sustainable production of cement fibre reinforced products in small plants. The
composites were produced in laboratory using Portland cement CP-II-F32, sand,
water, licuri palm fiber contents of 1.0, 1.5 and 2.0% by weight of binder (two different
fiber length) and metakaolin. The latter was chosen as an additional binder for its
efficiency to reduce the alkalinity of cementitious matrixes therefore preventing the
degradation of vegetable fibers. The characterization of the composite components
was carried out by sieving and laser particle size analyses, thermal analysis,
fluorescence and X-ray diffraction. The composites performance was evaluated by 3-
point-bending tests, compressive strength, ultrasound module of elasticity, free and
restrained shrinkage, water capillarity absorption and apparent specific gravity. It has
been found that the addition of fibers increased the time to onset of cracking over
200.00% and a 25% reduction in cracks opening in the restrained shrinkage test. The
capillary absorption reduced about 25% when compared to fiber-free composites. It
was also observed with regard to flexural strength, compressive strength and specific
gravity, that the addiction of fibers did not affect the composite performance
presenting similar results for compounds with and without fibers. In general it can be
stated that the reinforced composite fibers of palm licuri presents physical and
mechanical characteristics which enable them to be used in the intended proposals
of this research<br>A exig?ncia da substitui??o do amianto em sistemas construtivos em conjunto com a
necessidade de gera??o de renda no sert?o da Bahia fez nascer o projeto do
aproveitamento da fibra da palma do licuri (syagrus coronata), palmeira abundante
na regi?o, na produ??o de comp?sitos para a fabrica??o artefatos de cimento
refor?ados com fibras para a constru??o civil de maneira sustent?vel, em pequenas
unidades fabris. Os comp?sitos foram produzidos em laborat?rio utilizando cimento
Portland CP II-F32, areia, ?gua, metacaulinita e fibra da palma do licuri. As fibras
foram adicionadas em teores de 1,0, 1,5 e 2,0% da massa do aglomerante e com
dois comprimentos de fibra diferentes. A metacaulinita foi selecionada como
aglomerante suplementar de forma a agir na redu??o da alcalinidade da matriz
ciment?cia na perspectiva de diminuir ou at? mesmo eliminar a degrada??o das
fibras vegetais em meio alcalino. Foram realizados ensaios de caracteriza??o dos
componentes do comp?sito, incluindo granulometria, an?lise t?rmica, fluoresc?ncia e
difratometria de Raios-X. A verifica??o do desempenho dos comp?sitos foi feita com
ensaios de flex?o em tr?s pontos, resist?ncia ? compress?o axial, m?dulo de
elasticidade por ultrassom, retra??o livre e restringida, absor??o de ?gua por
capilaridade e massa espec?fica aparente. Verificou-se que a presen?a das fibras de
licuri aumentou o tempo para o surgimento da fissura??o acima de 200,00% e
redu??o de 25% na abertura das fissuras no ensaio de retra??o restringida. Com
rela??o ? absor??o capilar ocorreu uma redu??o de 25%, quando comparados com
os materiais sem fibras. Observou-se que, com rela??o ? resist?ncia a flex?o,
compress?o axial e massa espec?fica aparente, a adi??o de fibras n?o afeta o
desempenho dos materiais, apresentando resultados similares para materiais com e
sem fibras. De uma maneira geral pode-se afirmar que os comp?sitos refor?ados
com fibras da palma do licuri apresentam caracter?sticas f?sicas e mec?nicas que
viabilizam sua aplica??o dentro das condi??es estabelecidas neste trabalho
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Arquez, Ana Paula. "Aplicação de laminado de polímero reforçado com fibras de carbono (PRFC) inserido em substrato de microconcreto com fibras de aço para reforço à flexão de vigas de concreto armado." Universidade de São Paulo, 2010. http://www.teses.usp.br/teses/disponiveis/18/18134/tde-29062010-114146/.
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O reforço de elementos estruturais de concreto armado com uso de polímeros reforçados com fibras de carbono (PRFC) está cada vez mais conhecido, seguro e acessível. Em todo o mundo, a aplicação do PRFC vem sendo estudada sob diversas técnicas. Características como elevada resistência à tração e à corrosão, baixo peso, facilidade e rapidez de aplicação são os principais fatores para essa disseminação. Em particular, a técnica aqui estudada é conhecida como Near Surface Mounted (NSM), que consiste na inserção de laminados de PRFC em entalhes realizados no concreto de cobrimento de elementos de concreto armado. Com dupla área de aderência, ela vem a suprir uma deficiência comum no reforço colado externamente, que é o seu destacamento prematuro. Como nas demais técnicas de reforço à flexão, o material é colado na região do concreto tracionado. Sabe-se que, na prática da intervenção, essa região frequentemente encontra-se danificada por razões diversas, como fissuração causada por ações externas, corrosão da armadura e deterioração do concreto, o que exige a sua prévia reparação. Considerando que a boa qualidade desse reparo é imprescindível à eficiência do reforço, propõe-se uma inovação técnica pela reconstituição da face tracionada da viga com um compósito cimentício de alto desempenho, que sirva como substrato para aplicação do PRFC e elemento de transferência de esforços à estrutura a ser reforçada. Produzido à base de cimento Portland, fibras e microfibras de aço, o compósito tem também potencial para retardar a abertura de fissuras e aumentar a rigidez da viga, melhorando o aproveitamento do reforço. Com apoio da mecânica do fraturamento, foi possível encontrar as taxas de fibras e microfibras de aço a serem adicionadas a uma matriz cimentícia especialmente desenvolvida. Foram realizados ensaios de aderência para estudar o processo de transferência de tensões cisalhantes do laminado para o compósito na zona de ancoragem da viga. Uma vez conhecido o comportamento do sistema, foram ensaiadas vigas de concreto armado de tamanho representativo de estruturas reais, em três diferentes versões de ancoragem do laminado, sendo duas delas com uso do compósito cimentício. Comprovou-se a eficiência da inovação proposta, constatando-se o aumento da rigidez e da capacidade de carga da viga reforçada, com excelente aproveitamento do laminado. Além disso, as fibras e microfibras diminuíram a abertura das fissuras em estágios mais avançados de carregamento, sem que se observasse fissuras horizontais próxima ao reforço, que poderiam indicar destacamento iminente do laminado de PRFC.<br>Strengthening of reinforced concrete elements with carbon fiber reinforced polymer (CFRP) is increasingly well known, safe and accessible. The application of CFRP has been studied worldwide using various techniques. Features like high tensile strength, corrosion resistance, lightweightness and easy and speedy application are the main factors for dissemination. In particular, the technique here analyzed is known as Near Surface Mounted (NSM), which involves inserting CFRP strips into grooves made on the concrete cover of reinforced concrete elements. With double bonding area, this technique avoids the premature peeling-off that usually takes place in externally bonded CFRP reinforcement. As in others flexural strengthening techniques, the material is bonded in the concrete tension region. It is known in strengthening practice that this region usually requires prior repair. Often it shows up damaged by several reasons such as cracking caused by external actions, reinforcement corrosion and deterioration of the concrete. Whereas the good quality of this repair is essential to strengthening efficiency, an innovative technique is proposed. A high-performance cementitious composite is used as a transition layer for insertion of CFRP strips. The composite is made of Portland cement, steel fibers and microfibers of steel. It also has the potential to delay crack opening and to increase the beam stiffness. Based on fracture mechanics, it was possible to find suitable volume fractions of steel fibers and microfibers to be added to the cementitious matrix. Bonding tests were performed to analyze the shear stress transferring from the CFRP laminate to the beam anchorage zone. Once known the system behavior, real size reinforced concrete beams were tested in three different versions of the anchorage conditions, two of them with use of cementitious composites. The efficiency of the proposed innovation was proved by confirming increased stiffness and load capacity of the strengthened beam. In addition, fibers and microfibers allowed the decrease of the crack opening in later loading steps. No horizontal cracks near to the reinforcement were noticed, which means that CFRP laminate peeling-off was not likely to occur.
Books on the topic "Fibrous Cementitious Composites"
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Sidney, Mindess, ed. Fibre reinforced cementitious composites. Elsevier Applied Science, 1990.
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Sidney, Mindess, ed. Fibre reinforced cementitious composites. 2nd ed. Taylor & Francis, 2007.
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3
Ozyildirim, H. Celik. Exploratory investigation of high-performance fiber-reinforced cementitious composites for crack control. Virginia Transportation Research Council, 2008.
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Sidney, Mindness, Skalny Jan, and Materials Research Society, eds. Fiber-reinforced cementitious materials: Symposium held November 26-28, 1990, Boston, Massachusetts, U.S.A. Materials Research Society, 1991.
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Mindess, Sidney, and Arnon Bentur. Fibre Reinforced Cementitious Composites. Taylor & Francis Group, 2003.
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Mindess, Sidney, and Arnon Bentur. Fibre Reinforced Cementitious Composites. Taylor & Francis Group, 1990.
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7
Mindess, Sidney, and Arnon Bentur. Fibre Reinforced Cementitious Composites. Taylor & Francis Group, 2006.
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8
Mindess, Sidney, and Arnon Bentur. Fibre Reinforced Cementitious Composites. Taylor & Francis Group, 2019.
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9
Mindess, Sidney, Routledge, and Arnon Bentur. Fibre Reinforced Cementitious Composites. Taylor & Francis Group, 2006.
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Mindess, Sidney, Routledge, and Arnon Bentur. Fibre Reinforced Cementitious Composites. Taylor & Francis Group, 2006.
Find full textBook chapters on the topic "Fibrous Cementitious Composites"
1
Barros, Joaquim A. O., Cristina Frazão, Antonio Caggiano, et al. "Cementitious Composites Reinforced with Recycled Fibres." In Recent Advances on Green Concrete for Structural Purposes. Springer International Publishing, 2017. http://dx.doi.org/10.1007/978-3-319-56797-6_8.
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Ferrara, Liberato, Saulo Rocha Ferreira, Visar Krelani, Paulo Lima, Flavio Silva, and Romildo Dias Toledo Filho. "Cementitious Composites Reinforced with Natural Fibres." In Recent Advances on Green Concrete for Structural Purposes. Springer International Publishing, 2017. http://dx.doi.org/10.1007/978-3-319-56797-6_9.
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Lukasenoks, Arturs, Andrejs Krasnikovs, Arturs Macanovskis, Olga Kononova, and Videvuds Lapsa. "Short Composite Fibres for Concrete Disperse Reinforcement." In Short Fibre Reinforced Cementitious Composites and Ceramics. Springer International Publishing, 2019. http://dx.doi.org/10.1007/978-3-030-00868-0_6.
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Figueiredo, Stefan Chaves, Oğuzhan Çopuroğlu, Branko Šavija, and Erik Schlangen. "Piezoresistive Properties of Cementitious Composites Reinforced by PVA Fibres." In Strain-Hardening Cement-Based Composites. Springer Netherlands, 2017. http://dx.doi.org/10.1007/978-94-024-1194-2_81.
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Jolly, C. K. "The Stiffness and Strength of Small Diameter Steel Fibres in Cementitious Composites." In Composite Structures 3. Springer Netherlands, 1985. http://dx.doi.org/10.1007/978-94-009-4952-2_19.
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Baričević, Ana, Katarina Didulica, Branka Mrduljaš, and Antonija Ocelić. "Production Waste Fibres as a Sustainable Alternative for Strengthening Cementitious Composites." In International RILEM Conference on Synergising Expertise towards Sustainability and Robustness of Cement-based Materials and Concrete Structures. Springer Nature Switzerland, 2023. http://dx.doi.org/10.1007/978-3-031-33211-1_53.
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Salvador Filho, J. A. A., D. Lavorato, A. V. Bergami, J. R. Azeredo, C. Nuti, and S. Santini. "Influence of Polyethylene and Stainless Steel Fibres on Compressive and Tensile Behaviour of High-Performance Fibre-Reinforced Cementitious Composites." In GCEC 2017. Springer Singapore, 2018. http://dx.doi.org/10.1007/978-981-10-8016-6_1.
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Halvaei, Mana. "Fibers and textiles reinforced cementitious composites." In Engineered Polymeric Fibrous Materials. Elsevier, 2021. http://dx.doi.org/10.1016/b978-0-12-824381-7.00001-9.
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"Steel fibres." In Fibre Reinforced Cementitious Composites. CRC Press, 2006. http://dx.doi.org/10.1201/9781482267747-16.
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"Glass fibres." In Fibre Reinforced Cementitious Composites. CRC Press, 2006. http://dx.doi.org/10.1201/9781482267747-17.
Full textConference papers on the topic "Fibrous Cementitious Composites"
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"Durability of Glass / Polymer Fibrous Mesh-Reinforced Thin Cementitious Composites Durability of Glass / Polymer Fibrous Mesh-Reinforced Thin Cementitious Composites." In SP-190: High-Performance Fiber-Reinforced Concrete Thin Sheet Products. American Concrete Institute, 2000. http://dx.doi.org/10.14359/5724.
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Ramli, Mahyuddin, Cheah Chee Ban, and Muhamad Fadli Samsudin. "Flexural behavior of the fibrous cementitious composites (FCC) containing hybrid fibres." In INTERNATIONAL CONFERENCE ON ENGINEERING AND TECHNOLOGY (IntCET 2017). Author(s), 2018. http://dx.doi.org/10.1063/1.5022946.
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Ajouguim, Soukaina, Jonathan Page, Chafika Djelal, Mohamed Waqif, and Latifa Saadi. "Performance of Alfa Fibres in Cementitious Materials Exposed to Diverse Surface Treatments." In 4th International Conference on Bio-Based Building Materials. Trans Tech Publications Ltd, 2022. http://dx.doi.org/10.4028/www.scientific.net/cta.1.660.
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Alfa plant presents a great ecological and socio-economic interest in the Maghreb countries. It is used in several fields of applications such as craft production and paper industry. However, a few research work has been realized on the valorisation of Alfa fibres in the construction sector. The main objective of this work is to develop an Alfa fibre-reinforced mortar with significant mechanical properties for the facade panel’s manufacturing. It was highlighted that Alfa fibres enhance the flexural strength of reinforced mortars. Therefore, a decrease in the flexural strength of the composite after 90 days of curing. In addition, the incorporation of Alfa fibres reduced the compressive strength of the composite. In this regard, to enhance the mechanical properties of the composite, various treatments were explored: alkaline treatment with sodium hydroxide, hydrothermal treatment by water boiling, and coating with sulfoaluminate cement. It was noted that the treatments could provide a partial elimination of the non-cellulosic components and enhance the Alfa fibre roughness. Raw and treated Alfa fibres were incorporated into cement mortars at different lengths of the (10 and 20 mm) with an addition ratio of 1 %vol.. Compared to untreated fibres, fibres treated chemically provide an improvement of 38 % of the flexural strength at 28 days for both fibres length. Unlike the coated fibres, the efficiency of treatment was noted at 90 days of curing. Otherwise, a slight increase in compressive strength was observed compared to the untreated fibres mortar. These results were approved by porosity accessible to water and calorimetric tests.
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Tao, Zhong, Richard Shuaibu, Zhu Pan, Md Kamrul Hassan, and Jian Zhou. "Compressive behaviour of steel tubes filled with strain hardening cementitious composites." In 12th international conference on ‘Advances in Steel-Concrete Composite Structures’ - ASCCS 2018. Universitat Politècnica València, 2018. http://dx.doi.org/10.4995/asccs2018.2018.6968.
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This paper presents the compressive behaviour of steel tubes filled with strain hardening cementitious composites (SHCC) through experimental and numerical investigations. The main parameters considered in the experimental study include type (SHCC and normal concrete) and strength (normal and high strength) of the in-fill material, steel tube thickness (2 and 4 mm) and cross-section type (circular and square). To develop the SHCC material, 2% of polyvinyl alcohol fibres by volume were used. The test results indicate that the performance of SHCC-filled steel tubes is generally similar to that of the counterparts filled with normal concrete. A finite element (FE) model was then developed to predict the load–deformation curves of the test specimens. In general, a reasonably good match is obtained between the predicted and measured curves.
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Guilarduci, Viviane V. S., Patricia B. Martelli, Honória de F. Gorgulho, and Pablo R. Oliveira. "INCORPORATION OF REUSED SUGARCANE FIBRES APPLIED IN THE TREATMENT OF EFFLUENTS CONTAMINATED WITH ENGINE OIL AS REINFORCEMENT OF CEMENTITIOUS COMPOSITES." In Brazilian Conference on Composite Materials. Pontifícia Universidade Católica do Rio de Janeiro, 2018. http://dx.doi.org/10.21452/bccm4.2018.02.23.
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"Using Steel Fibres to Increase the Projectile Impact Resistance of Cementitious Composites." In SP-347: Recent Developments in High Strain Rate Mechanics and Impact Behavior of Concrete. American Concrete Institute, 2021. http://dx.doi.org/10.14359/51732657.
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Mercedes, Luis, Lluis Gil, and Ernest Bernat. "Comportamiento mecánico de compuestos de matriz cementicia y tejidos de fibras vegetales." In HAC2018 - V Congreso Iberoamericano de Hormigón Autocompactable y Hormigones Especiales. Universitat Politècnica València, 2018. http://dx.doi.org/10.4995/hac2018.2018.5501.
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Los compuestos cementicios reforzados con fibras en forma de tejidos (fibre reinforced cementitious composite: FRCC) han demostrado ser un material de refuerzo con un prometedor futuro, debido a su facilidad de aplicación, resistencia al fuego y su capacidad de disipar energía a través de un patrón de multifisuras. El auge que viene desarrollando el uso de fibras vegetales como refuerzo dentro de los materiales compuestos debido a su bajo costo, baja densidad, reciclabilidad y biodegradabilidad, hace que estas fibras se presenten como una opción de refuerzo a considerar dentro los compuestos cementicios. En este estudio se han elaborado especímenes FRCC de diferentes fibras vegetales (lino, cáñamo, sisal y algodón), utilizando un tratamiento a base de poliéster para evitar la degradación de las fibras y mejorar su eficacia dentro de la matriz alcalina de los compuestos cementicios. Los resultados han mostrado una excelente interacción entre los tejidos y la matriz utilizada, pues el poliéster además mejorar las propiedades mecánicas de los hilos y proteger las fibras frente a la alcalinidad de la matriz, aumenta la adherencia con esta, y con ello mejora las prestaciones mecánicas del FRCC. Donde los resultados presentan las fibras de lino y cáñamo (por sus mejores propiedades mecánicas frente a otras fibras vegetales) como las fibras vegetales con mayor futuro dentro de los materiales compuestos.DOI: http://dx.doi.org/10.4995/HAC2018.2018.5501
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LOVICHOVÁ, ROMANA, KRISTÝNA TAKÁČOVÁ, KAREN KÜNZEL, et al. "DIRECTED ORIENTATION OF STEEL FIBRES IN ULTRA-HIGH-PERFORMANCE CEMENTITIOUS COMPOSITE USING THE MAGNETIC FIELD." In HPSM/OPTI 2020. WIT Press, 2020. http://dx.doi.org/10.2495/hpsm200051.
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Cheng, Jin, Kang Hai, and Hongcun Guo. "Compressive stress-strain relationship of strain-hardening cementitious composite with hybrid fibres after high temperature exposure." In The International Conference of Applications of Structural Fire Engineering (ASFE 2017). CRC Press, 2017. http://dx.doi.org/10.1201/9781315107202-43.
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Ocelić, Antonija, Ana Baričević, and Marina Frančić Smrkić. "POSSIBLITIES OF USING UHPC AS A REPAIR MATERIAL." In 2nd Croatian Conference on Earthquake Engineering. University of Zagreb Faculty of Civil Engineering, 2023. http://dx.doi.org/10.5592/co/2crocee.2023.111.
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More and more buildings need to be repaired and strengthened, both for durability and for the effects of natural disasters such as earthquakes. The repair material should ensure compatibility with the substructure materials and contribute to their improvement. The continuous development of materials has led to their excellent properties and application possibilities. In addition, the new generation of materials offers more environmentally friendly solutions, which is certainly in line with repair as part of sustainable development. In an effort to meet all these requirements, the use of mortars with exceptional properties and environmental efficiency can be the key to solving repair works. Materials such as ultra-high performance concrete (UHPC) are characterised by exceptional mechanical and durability properties. In its usual composition, it contains large amounts of cement, which can be reduced by using waste materials to improve its environmental performance. One of the properties of UHPC worth highlighting is its toughness, which is achieved through the use of fibres that ensure a cement composite with ductile behaviour. Therefore, this paper presents a general overview of UHPC and the possibility of its application as a repair material. The evaluation of UHPC as a repair material is based on the studies carried out. These are divided into tests of interfacial properties, which include bond strength, microstructure, and permeability. The influence of additional cementitious materials on the interfacial microstructure is presented. Finally, the importance of fibres and the potential self-healing effect of UHPC in repair are highlighted and opportunities for new studies are identified.