Lignosulfonatos de sódio e magnésio: uma avaliação comparativa entre matérias-primas fundamentais para aditivos plastificantes

Detalhes bibliográficos
Autor(a) principal: Torres, Igor Ferraz
Data de Publicação: 2019
Tipo de documento: Dissertação
Idioma: por
Título da fonte: Biblioteca Digital de Teses e Dissertações da UFPB
Texto Completo: https://repositorio.ufpb.br/jspui/handle/123456789/20021
Resumo: Motivated by low cost, lignosulfonate based plasticizers are the most widely used type of admixtures in the concrete industry worldwide. Due to the plurality of types of lignosulphonates and consequent variations in their chemical, structural and compositional characteristics, this study evaluated the influence of basic admixtures consisting of sodium lignosulphonates (LS-Na) and magnesium (LS-Mg) combined in different dosages, (0.40% and 0.80%) to two different types of cement: CP II F 40 and CP III 40 RS. The following tests were carried out: determination of adsorption curves, isothermal calorimetry in cement pastes, hydration kinetics through microstructural tests (TG/DTG and XRD) and, finally, concrete applications - comparison of properties obtained in the fresh state (reduction of water, loss of slump, entrained air content) and hardened (compressive strength and tensile strength by diametral compression, modulus of elasticity). The results clearly demonstrated that there was difference in the performance of each lignosulfonate, influenced especially by intrinsic characteristics such as sugar content, molar mass and free sulfate content. In the presence of lignosulphonates, different rates of hydration of both cements were observed, impacting on delayed dissolution of silicate phases (C3S and C2S) and consequent portlandite contents. At 90 minutes of hydration, for both cements the amount of water combined chemically and accumulated heat were increased with the increase in lignosulfonate content, being globally higher for LSMg at the dose of 0.80%, indicating the accelerated development of the ettringite. No adsorption curve was fitted into the Langmuir model, with linear behavior, being higher for LSMg (lower sulphate and molar mass) and the most pronounced difference when combined with CP III 40 RS. In the concrete application, the LSMg obtained higher compressive strength, tensile strength and modulus of elasticity, although the LSNa obtained better performance in the fresh state - greater reduction of water, less loss of slump, but greater development of entrained air. It is evident to the chain of the concrete admixtures industry the importance of optimization through the appropriate and specific choice of types of lignosulfonates as raw material.
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spelling Lignosulfonatos de sódio e magnésio: uma avaliação comparativa entre matérias-primas fundamentais para aditivos plastificantesLignosulfonatoCimento PortlandPastaConcretoEnsaios microestruturaisLignosulfonatePortland cementPasteConcreteMicrostructural testsCNPQ::ENGENHARIASMotivated by low cost, lignosulfonate based plasticizers are the most widely used type of admixtures in the concrete industry worldwide. Due to the plurality of types of lignosulphonates and consequent variations in their chemical, structural and compositional characteristics, this study evaluated the influence of basic admixtures consisting of sodium lignosulphonates (LS-Na) and magnesium (LS-Mg) combined in different dosages, (0.40% and 0.80%) to two different types of cement: CP II F 40 and CP III 40 RS. The following tests were carried out: determination of adsorption curves, isothermal calorimetry in cement pastes, hydration kinetics through microstructural tests (TG/DTG and XRD) and, finally, concrete applications - comparison of properties obtained in the fresh state (reduction of water, loss of slump, entrained air content) and hardened (compressive strength and tensile strength by diametral compression, modulus of elasticity). The results clearly demonstrated that there was difference in the performance of each lignosulfonate, influenced especially by intrinsic characteristics such as sugar content, molar mass and free sulfate content. In the presence of lignosulphonates, different rates of hydration of both cements were observed, impacting on delayed dissolution of silicate phases (C3S and C2S) and consequent portlandite contents. At 90 minutes of hydration, for both cements the amount of water combined chemically and accumulated heat were increased with the increase in lignosulfonate content, being globally higher for LSMg at the dose of 0.80%, indicating the accelerated development of the ettringite. No adsorption curve was fitted into the Langmuir model, with linear behavior, being higher for LSMg (lower sulphate and molar mass) and the most pronounced difference when combined with CP III 40 RS. In the concrete application, the LSMg obtained higher compressive strength, tensile strength and modulus of elasticity, although the LSNa obtained better performance in the fresh state - greater reduction of water, less loss of slump, but greater development of entrained air. It is evident to the chain of the concrete admixtures industry the importance of optimization through the appropriate and specific choice of types of lignosulfonates as raw material.NenhumaMotivado pelo baixo custo, os plastificantes à base de lignosulfonatos são o tipo de aditivos mais consumido mundialmente pela indústria do concreto. Diante da disponibilidade plural de tipos de lignosulfonatos, e consequentes variações nas características químicas, estruturais e composicionais desses, este estudo avaliou a influência de aditivos básicos constituídos por lignosulfonatos de sódio (LS-Na) e magnésio (LS-Mg) combinados em diferentes dosagens (0,40% e 0,80%) a dois tipos distintos de cimento: CP II F 40 e CP III 40 RS. Foram conduzidos os seguintes testes: determinação das curvas de adsorção, calorimetrias isotérmicas em pastas, cinética de hidratação por meio de ensaios microestruturais (TG/DTG e DRX) e por fim, aplicações em concreto – comparação de propriedades obtidas no estado fresco (redução de água, perda de abatimento, teor de ar incorporado) e endurecido (resistências à compressão e tração por compressão diametral, módulo de elasticidade). Os resultados obtidos demonstraram claramente que houve diferença no desempenho de cada lignosulfonato, influenciado especialmente por características intrínsecas tais como o teor de açúcares, massa molar e conteúdo de sulfatos livres. Na presença de lignosulfonatos, foram constatadas diferentes taxas de hidratação de ambos cimentos, impactando em atraso na dissolução de fases silicatos (C3S e C2S) e consequentes teores de portlandita. Aos 90 minutos de hidratação, para ambos cimentos a quantidade de água combinada quimicamente e o calor acumulado foram incrementados com o aumento no teor de lignosulfonatos, sendo globalmente maior para o LSMg na dose de 0,80%, indicando o desenvolvimento acelerado da etringita. Nenhuma curva de adsorção se enquadrou no modelo de Langmuir, tendo comportamentos lineares, sendo maior para o LSMg (teor de sulfatos e massa molar inferiores) e a diferença mais acentuada quando combinado ao CP III 40 RS. Na aplicação em concretos, o LSMg obteve maiores resistências mecânicas à compressão, tração e módulo de elasticidade, embora o LSNa tenha obtido melhor desempenho no estado fresco – maior redução de água, menor perda de abatimento, porém maior desenvolvimento de ar incorporado. Fica evidente para a cadeia da indústria de aditivos para concreto a importância da otimização por meio da escolha adequada e específica de tipos de lignosulfonatos como matéria-prima.Universidade Federal da ParaíbaBrasilEngenharia de MateriaisPrograma de Pós-Graduação em Ciência e Engenharia de MateriaisUFPBTorres, Sandro Mardenhttp://lattes.cnpq.br/1050045022082025Torres, Igor Ferraz2021-05-11T18:42:38Z2020-02-262021-05-11T18:42:38Z2019-02-26info:eu-repo/semantics/publishedVersioninfo:eu-repo/semantics/masterThesishttps://repositorio.ufpb.br/jspui/handle/123456789/20021porhttp://creativecommons.org/licenses/by-nd/3.0/br/info:eu-repo/semantics/embargoedAccessreponame:Biblioteca Digital de Teses e Dissertações da UFPBinstname:Universidade Federal da Paraíba (UFPB)instacron:UFPB2021-06-21T14:31:35Zoai:repositorio.ufpb.br:123456789/20021Biblioteca Digital de Teses e Dissertaçõeshttps://repositorio.ufpb.br/PUBhttp://tede.biblioteca.ufpb.br:8080/oai/requestdiretoria@ufpb.br|| diretoria@ufpb.bropendoar:2021-06-21T14:31:35Biblioteca Digital de Teses e Dissertações da UFPB - Universidade Federal da Paraíba (UFPB)false
dc.title.none.fl_str_mv Lignosulfonatos de sódio e magnésio: uma avaliação comparativa entre matérias-primas fundamentais para aditivos plastificantes
title Lignosulfonatos de sódio e magnésio: uma avaliação comparativa entre matérias-primas fundamentais para aditivos plastificantes
spellingShingle Lignosulfonatos de sódio e magnésio: uma avaliação comparativa entre matérias-primas fundamentais para aditivos plastificantes
Torres, Igor Ferraz
Lignosulfonato
Cimento Portland
Pasta
Concreto
Ensaios microestruturais
Lignosulfonate
Portland cement
Paste
Concrete
Microstructural tests
CNPQ::ENGENHARIAS
title_short Lignosulfonatos de sódio e magnésio: uma avaliação comparativa entre matérias-primas fundamentais para aditivos plastificantes
title_full Lignosulfonatos de sódio e magnésio: uma avaliação comparativa entre matérias-primas fundamentais para aditivos plastificantes
title_fullStr Lignosulfonatos de sódio e magnésio: uma avaliação comparativa entre matérias-primas fundamentais para aditivos plastificantes
title_full_unstemmed Lignosulfonatos de sódio e magnésio: uma avaliação comparativa entre matérias-primas fundamentais para aditivos plastificantes
title_sort Lignosulfonatos de sódio e magnésio: uma avaliação comparativa entre matérias-primas fundamentais para aditivos plastificantes
author Torres, Igor Ferraz
author_facet Torres, Igor Ferraz
author_role author
dc.contributor.none.fl_str_mv Torres, Sandro Marden
http://lattes.cnpq.br/1050045022082025
dc.contributor.author.fl_str_mv Torres, Igor Ferraz
dc.subject.por.fl_str_mv Lignosulfonato
Cimento Portland
Pasta
Concreto
Ensaios microestruturais
Lignosulfonate
Portland cement
Paste
Concrete
Microstructural tests
CNPQ::ENGENHARIAS
topic Lignosulfonato
Cimento Portland
Pasta
Concreto
Ensaios microestruturais
Lignosulfonate
Portland cement
Paste
Concrete
Microstructural tests
CNPQ::ENGENHARIAS
description Motivated by low cost, lignosulfonate based plasticizers are the most widely used type of admixtures in the concrete industry worldwide. Due to the plurality of types of lignosulphonates and consequent variations in their chemical, structural and compositional characteristics, this study evaluated the influence of basic admixtures consisting of sodium lignosulphonates (LS-Na) and magnesium (LS-Mg) combined in different dosages, (0.40% and 0.80%) to two different types of cement: CP II F 40 and CP III 40 RS. The following tests were carried out: determination of adsorption curves, isothermal calorimetry in cement pastes, hydration kinetics through microstructural tests (TG/DTG and XRD) and, finally, concrete applications - comparison of properties obtained in the fresh state (reduction of water, loss of slump, entrained air content) and hardened (compressive strength and tensile strength by diametral compression, modulus of elasticity). The results clearly demonstrated that there was difference in the performance of each lignosulfonate, influenced especially by intrinsic characteristics such as sugar content, molar mass and free sulfate content. In the presence of lignosulphonates, different rates of hydration of both cements were observed, impacting on delayed dissolution of silicate phases (C3S and C2S) and consequent portlandite contents. At 90 minutes of hydration, for both cements the amount of water combined chemically and accumulated heat were increased with the increase in lignosulfonate content, being globally higher for LSMg at the dose of 0.80%, indicating the accelerated development of the ettringite. No adsorption curve was fitted into the Langmuir model, with linear behavior, being higher for LSMg (lower sulphate and molar mass) and the most pronounced difference when combined with CP III 40 RS. In the concrete application, the LSMg obtained higher compressive strength, tensile strength and modulus of elasticity, although the LSNa obtained better performance in the fresh state - greater reduction of water, less loss of slump, but greater development of entrained air. It is evident to the chain of the concrete admixtures industry the importance of optimization through the appropriate and specific choice of types of lignosulfonates as raw material.
publishDate 2019
dc.date.none.fl_str_mv 2019-02-26
2020-02-26
2021-05-11T18:42:38Z
2021-05-11T18:42:38Z
dc.type.status.fl_str_mv info:eu-repo/semantics/publishedVersion
dc.type.driver.fl_str_mv info:eu-repo/semantics/masterThesis
format masterThesis
status_str publishedVersion
dc.identifier.uri.fl_str_mv https://repositorio.ufpb.br/jspui/handle/123456789/20021
url https://repositorio.ufpb.br/jspui/handle/123456789/20021
dc.language.iso.fl_str_mv por
language por
dc.rights.driver.fl_str_mv http://creativecommons.org/licenses/by-nd/3.0/br/
info:eu-repo/semantics/embargoedAccess
rights_invalid_str_mv http://creativecommons.org/licenses/by-nd/3.0/br/
eu_rights_str_mv embargoedAccess
dc.publisher.none.fl_str_mv Universidade Federal da Paraíba
Brasil
Engenharia de Materiais
Programa de Pós-Graduação em Ciência e Engenharia de Materiais
UFPB
publisher.none.fl_str_mv Universidade Federal da Paraíba
Brasil
Engenharia de Materiais
Programa de Pós-Graduação em Ciência e Engenharia de Materiais
UFPB
dc.source.none.fl_str_mv reponame:Biblioteca Digital de Teses e Dissertações da UFPB
instname:Universidade Federal da Paraíba (UFPB)
instacron:UFPB
instname_str Universidade Federal da Paraíba (UFPB)
instacron_str UFPB
institution UFPB
reponame_str Biblioteca Digital de Teses e Dissertações da UFPB
collection Biblioteca Digital de Teses e Dissertações da UFPB
repository.name.fl_str_mv Biblioteca Digital de Teses e Dissertações da UFPB - Universidade Federal da Paraíba (UFPB)
repository.mail.fl_str_mv diretoria@ufpb.br|| diretoria@ufpb.br
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