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Doctoral Thesis
DOI
10.11606/T.3.2011.tde-31052011-164232
Document
Author
Full name
Cleber Marcos Ribeiro Dias
E-mail
Institute/School/College
Knowledge Area
Date of Defense
Published
São Paulo, 2011
Supervisor
Committee
John, Vanderley Moacyr (President)
Agopyan, Vahan
Barboza, Aline da Silva Ramos
Isaia, Geraldo Cechella
Silva, Emílio Carlos Nelli
Title in Portuguese
Fibrocimentos com gradação funcional.
Keywords in Portuguese
Desempenho mecânico
Elementos finitos
Extrusão
Fibrocimentos com gradação funcional
Processo Hatschek
Projeto de mistura
Abstract in Portuguese
O presente estudo mostra que o conceito de materiais com gradação funcional (MGF) pode ser aplicado no desenvolvimento de componentes de fibrocimento mais econômicos e com desempenho mecânico melhorado. Primeiramente, este trabalho estabelece o conceito de fibrocimento com gradação funcional. Depois, modelam-se, em elementos finitos, as tensões em telhas onduladas sob flexão estática e cargas de vento e mostra-se que, para esses tipos de carregamento, regiões específicas das telhas são submetidas a tensões de baixa intensidade justificando a aplicação do conceito de MGF para a otimização da distribuição da resistência em tais componentes. A parte experimental deste trabalho é constituída de quatro estudos: a) produção de fibrocimentos com o teor de fibras variando ao longo da espessura; b) desenvolvimento de um método de escolha de formulações para fibrocimentos com gradação funcional; c) desenvolvimento de compósitos cimentícios para extrusão em altas velocidades, destinados a gradação de fibrocimentos; e d) aplicação pré-industrial para avaliar a aplicabilidade de técnica de modificação local das propriedades de telhas com gradação funcional. Mostra-se, experimentalmente, que fibrocimentos contendo 1,0% de fibras de PVA, em massa, estrategicamente distribuídas ao longo da espessura, apresentam módulo de ruptura (MOR) similar ao dos fibrocimentos homogêneos com 1,8% de fibras, comprovando a eficácia deste tipo de gradação na redução do custo de placas de fibrocimento. O segundo trabalho experimental avalia formulações de fibrocimento constituídas de seis matérias-primas empregando-se a estratégia screening, uma metodologia promissora para gerar regras de mistura, otimizar custos e desempenho e facilitar a escolha de formulações locais para fibrocimentos com gradação funcional. Compósitos cimentícios com fibras de PVA ou vidro álcali resistente (AR), destinadas à extrusão em altas velocidades, foram desenvolvidos para aplicação pré-industrial. Aqueles contendo 4,0% de fibra de vidro, em volume, apresentaram resistência à tração média igual a 12,0 MPa, enquanto compósitos com 3,0% de fibras de PVA apresentaram resistência igual a 7,5 MPa. A aplicação destas misturas entre as camadas de telhas onduladas de fibrocimento, durante o experimento pré-industrial, resultou em melhoras substanciais do desempenho local.
Title in English
Functionally graded fiber cements.
Keywords in English
Extrusion
Finite elements
Functionally graded fiber cement
Hatschek process
Mechanical performance
Mixture design
Abstract in English
The present study applies the functionally graded materials (FGM) concept on the development of fiber cements as an alternative to improve the mechanical performance and reduce cost of production of asbestos-free corrugated sheets. Primarily, this work establishes the concept of functionally graded fiber cement. Then, finite element modeling (FEM) is applied in the evaluation of the stresses distributions in corrugated sheets under bending and static wind loads. The simulations show that for these load cases, some regions of corrugated sheets are submitted to low stress intensities what justify the application of FGM concept for optimization of the strength distribution in such components. The experimental part of this work consists of four different studies: a) production of functionally graded fiber cements with gradation through thickness; b) development of a method for choosing formulations in functionally graded fiber cements; c) development of fiber reinforced cementitious composites for high speed extrusion and; d) pre-industrial application to evaluate the suitability of functionally graded fiber cements production. The first experimental study shows that functionally graded cementitious composites with 1.0% of PVA fibers, in mass, strategically distributed through thickness, presented similar modulus of ruptures (MORs) to that homogeneous ones with 1.8% of PVA fibers what proves that gradation of fiber content through thickness is a good approach to reduce cost of fiber cement pads without affecting the mechanical performance of the composite. The second experimental work examines sixcomponent fiber cement formulations employing the screening strategy which is a promising methodology to generate coherent mixture rules, optimize cost and performance and even facilitate the choosing of formulations for functionally graded fiber cements. PVA fibers and glass fiber reinforced cementitious composites for high speed extrusion were developed forpre-industrial application. Composites with 4.0% of alkali-resistant (AR) glass fiber, in volume, presented average tensile strength of 12.0 MPa while composites with 3.0% of PVA fibers presented 7.5 MPa. The application of these mixtures between layers of fiber cement corrugated sheets results in improvement of the performance of the product.
 
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Publishing Date
2011-06-29
 
WARNING: The material described below relates to works resulting from this thesis or dissertation. The contents of these works are the author's responsibility.
  • DIAS, C. M. R., SAVASTANO JR, H., e John, V.M. Exploring the potential of functionally graded materials concept for the development of fiber cement [doi:10.1016/j.conbuildmat.2008.01.017]. Construction & Building Materials [online], 2010, vol. 24, p. 140-146.
  • Tanaca, H.K., et al. Discoloration and fungal growth on three fiber cement formulations exposed in urban, rural and coastal zones [doi:10.1016/j.buildenv.2010.07.025]. Building and Environment [online], 2010, vol. 46, p. 324-330.
  • DIAS, C. M. R., et al. Long-term aging of fiber-cement corrugated sheets The effect of carbonation, leaching and acid rain [doi:10.1016/j.cemconcomp.2007.11.001]. Cement & Concrete Composites [online], 2008, vol. 20, p. 255-265.
  • DIAS, C. M. R., et al. Mixture screening design to choose formulations for functionally graded fiber cements [doi:10.4028/www.scientific.net/MSF.631-632.65]. Materials Science Forum [online], 2010, vol. 631-2, p. 65-70.
  • TONOLI, G. H. D., et al. Hybrid Reinforcement of Sisal and Polypropylene Fibers in Cement-Based Composites [doi:10.1061/(ASCE)MT.1943-5533.0000152]. Journal of Materials in Civil Engineering [online], 2011, vol. 23, p. 177-187.
  • DIAS, C. M. R., SAVASTANO JR, H., and JOHN, V. M. The FGM concept in the development of fiber cement components [doi:10.1063/1.2896834]. In MULTISCALE AND FUNCTIONALLY GRADED MATERIALS 2006: (M&FGM 2006);, HONOLULU, 2006. AIP Conf. Proc..Melville, NY : American Institute of Physics, 2008.
  • NITA, C., et al. Effect of Metakaolin on the Performance of PVA and Cellulose Reinforced cement. In The Ninth International Conference Inorganic-Bonded Composite Materials, Vancouver, 2004. The Ninth International Conference Inorganic-Bonded Composite Materials.Moscow : University of Idaho, 2004.
  • DIAS, C. M. R., et al. Effects of Wet and Dry Cycles on the Performance and Microstructure of Asbestos-free Fiber Cement. In 11 DBMC International Conference on Durability of Building Materials and Components, Istanbul, 2008. Proceedings of 11 DBMC International Conference on Durability of Building Materials and Components.Istanbul : Cenkler Matbaacilik Tic. Ltd. Sti., 2008.
  • DIAS, C. M. R., and JOHN, V. M. Performance of PVA and cellulose reinforced fiber cement in different Brazilian climates. In XII Int. Conf. on Durability of Building Materials and Components, Porto, 2011. XI DBMC.Porto : FEUP Edições, 2011.
  • DIAS, C. M. R., JOHN, V. M., e SAVASTANO JR, H. Efeitos dos ciclos de molhagem e secagem nas propriedades de fibrocimentos com fibras de celulose e PVA. In Conferência Brasileira de Materiais e Tecnologias Não-Convencionais: Habitações e Infra-Estrutura de Interesse Social, Pirassununga, 2004. Anais da Conferência Brasileira de Materiais e Tecnologias Não-Convencionais: Habitações e Infra-Estrutura de Interesse Social. : Brasil NOCMAT, 2004.
  • DIAS, C. M. R., SAVASTANO JR, H., and JOHN, V. M. Functionally graded fiber cement: concept and preliminaries experiments. In Conferência Brasileira de Materiais e Tecnologias Não-Convencionais:, Salvador, 2006. BRASIL NOCMAT 2006.Rio de Janeiro : ABTENC, 2006. Available from: http://www.abetenc.org.br.
  • DIAS, C. M. R., SAVASTANO JR, H., e JOHN, V. M. Metodologia de avaliação dos efeitos do envelhecimento nas propriedades dos fibrocimentos. In XI ENCONTRO NACIONAL DE TECNOLOGIA DO AMBIENTE CONSTRUIDO, Florianopolis, 2006. ENTAC 2006.Porto Alegre : ANTAC, 2006. Dispon?vel em: http://www.infohab.org.br.
  • MARANHÃO, F. L., et al. Performance of Silicone Water Repellent for FRC Corrugated Roof Tiles. In 11 DBMC International Conference on Durability of Building Materials and Components, Istanbul, 2008. Proceedings of 11 DBMC International Conference on Durability of Building Materials and Components.Istanbul : Cenkler Matbaacilik Tic. Ltd. Sti., 2008.
  • NITA, C., DIAS, C. M. R., and JOHN, V. M. Natural aging of asbestos free fiber cement with pozzolans. In The Eighth International Summer Symposium of JSCE, Nagoya, 2006. Proceedings The Eighth International Summer Symposium.Tokyo : Japan Society of Civil Engineers, 2006. Available from: http://www.jsce-int.org/events/iss/iss2006.htm.
  • SANTOS, S. F., et al. Evaluation of the mechanical behaviour by measuring the energy of fracture and impact energy of fibre-cements. In 11th IBCC - Int. Inorganic-Bonded Fiber Composites Conference, São Paulo, 2008. 11th IBCC - Int. Inorganic-Bonded Fiber Composites Conference.Madrid : Universidad Complutense, U. Idaho, 2008. Available from: http://www.iibcc.net.
  • SHIRAKAWA, M. A., et al. Influence of carbonation in accelerated chamber previous to biocalcification on fiber cement surface. In 1st BioGeoCivil Engineering Conference, 2008. Proceedings of 1st BioGeoCivil Engineering Conference., 2008.
  • DIAS, C. M. R., FIGUEIREDO, A. D., e JOHN, V. M. Avaliação comparativa do comportamento pós-fissuração de concretos com fibras de aço e com fibras de polipropileno de alto módulo de elasticidade. In 48 Congresso Brasileiro do Concreto CBC. 48 Congresso Brasileiro do Concreto CBC.SAO PAULO : IBRACON, 2006. Dispon?vel em: http://www.ibracon.org.br.
  • SHIRAKAWA, M. A., et al. Fungal colonization on fiber cement exposed to the elements in a tropical climate. In 11 DBMC International Conference on Durability of Building Materials and Components, Istanbul, 2008. Proceedings of 11 DBMC International Conference on Durability of Building Materials and Components., 2008.
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