Physical and mechanical characterization of cement-mortars internally cured with hybrid nanocomposites based on hydrogel and nanoclay

Detalhes bibliográficos
Autor(a) principal: Watanuki Filho, Adhemar
Data de Publicação: 2021
Tipo de documento: Tese
Idioma: eng
Título da fonte: Repositório Institucional da UNESP
Texto Completo: http://hdl.handle.net/11449/214438
Resumo: Cement-based materials are the most produced in civil construction due to their versatility and durability. However, new admixtures have been widely studied and applied for better performance, especially when it comes to curing processes. The hybrid nanocomposite hydrogels, characterized by their hydrophilic characteristics of water absorption and release, stand out as promising agents for internal curing in cementitious matrices. This study proposed to analyze the physical, chemical, and morphological properties of hydrogels based on polyacrylamide, carboxymethylcellulose, and three different concentrations of Cloisite Na+ in two different swelling media (distilled water and filtered solution of water+Portland cement) and to evaluate the effect of applying 0.5% (wt/wtcement) of these presoaked hydrogels on the fresh and hardened state properties of cementitious mortars (1:2.16 and 0.40 w/c ratio). The results showed that the hydrogels provided reductions in slump flow of up to 4.8% for AHN20 mortars and exudation rate for the fresh state. These observations allowed us to evaluate that the increased concentration of nanoclay in the polymer interferes directly in the kinetic parameters of hydrogels and contributes to greater water retention, which may reflect better hydration and reduction of pathologies. As for the results in the hardened state, it was possible to evaluate that the type of curing of the samples was an important factor since there were no variations in densities (2.18+0.02 g/cm³) of all samples, indicating that the hydrogels were partially or fully swollen during the tests. Loss of mechanical strength was observed, but at 28 days for AHN20 mortars, the results were similar to the control, which corroborates the percentage of voids found. In this case, both mortars had a lower rate of voids when compared to AHN0 and AHN10 mortars and consequently better performances in their mechanical properties. The concentration of nanoclay in the hydrogel controls water release, as observed from the results of mass loss and plastic shrinkage that reduced as this concentration increased. The SEM images allowed us to evaluate that the more uniform matrices with higher mechanical properties, with few pores or micro-cracks. It is concluded that hybrid hydrogel nanocomposites can be applied as internal curing agents, especially those produced with 20% (wt/wt of CMC+AAm) nanoclay. Because its more controlled release allowed reducing porosity, water absorption, shrinkage, and significantly acting on the mechanical properties thus, this type of polymeric additive can be an innovative material for water control improvements in cementitious materials technology.
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spelling Physical and mechanical characterization of cement-mortars internally cured with hybrid nanocomposites based on hydrogel and nanoclayCaracterização física e mecânica de argamassas de cimento curadas internamente com nanocompósitos híbridos baseados em hidrogéis e nanoargila.Absorbent polymerPolímero absorventeNanocompósito híbridoConstrução civilCloisita Na+Cura internaHybrid nanocompositeCivil constructionCloisite Na+Internal curingHydrogelCement-based materials are the most produced in civil construction due to their versatility and durability. However, new admixtures have been widely studied and applied for better performance, especially when it comes to curing processes. The hybrid nanocomposite hydrogels, characterized by their hydrophilic characteristics of water absorption and release, stand out as promising agents for internal curing in cementitious matrices. This study proposed to analyze the physical, chemical, and morphological properties of hydrogels based on polyacrylamide, carboxymethylcellulose, and three different concentrations of Cloisite Na+ in two different swelling media (distilled water and filtered solution of water+Portland cement) and to evaluate the effect of applying 0.5% (wt/wtcement) of these presoaked hydrogels on the fresh and hardened state properties of cementitious mortars (1:2.16 and 0.40 w/c ratio). The results showed that the hydrogels provided reductions in slump flow of up to 4.8% for AHN20 mortars and exudation rate for the fresh state. These observations allowed us to evaluate that the increased concentration of nanoclay in the polymer interferes directly in the kinetic parameters of hydrogels and contributes to greater water retention, which may reflect better hydration and reduction of pathologies. As for the results in the hardened state, it was possible to evaluate that the type of curing of the samples was an important factor since there were no variations in densities (2.18+0.02 g/cm³) of all samples, indicating that the hydrogels were partially or fully swollen during the tests. Loss of mechanical strength was observed, but at 28 days for AHN20 mortars, the results were similar to the control, which corroborates the percentage of voids found. In this case, both mortars had a lower rate of voids when compared to AHN0 and AHN10 mortars and consequently better performances in their mechanical properties. The concentration of nanoclay in the hydrogel controls water release, as observed from the results of mass loss and plastic shrinkage that reduced as this concentration increased. The SEM images allowed us to evaluate that the more uniform matrices with higher mechanical properties, with few pores or micro-cracks. It is concluded that hybrid hydrogel nanocomposites can be applied as internal curing agents, especially those produced with 20% (wt/wt of CMC+AAm) nanoclay. Because its more controlled release allowed reducing porosity, water absorption, shrinkage, and significantly acting on the mechanical properties thus, this type of polymeric additive can be an innovative material for water control improvements in cementitious materials technology.Os materiais de base cimentícia são os mais produzidos na construção civil devido a sua versatilidade e durabilidade. Contudo, para melhores desempenhos, novos aditivos vêm sendo amplamente estudados e aplicado, principalmente ao que se refere aos processos de cura. Destacam-se então os hidrogéis nanocompósitos híbridos caracterizados por suas características hidrofílicas de absorção e liberação de água, como promissores agentes de cura interna em matrizes cimentícias. Este estudo se propôs analisar as propriedades físicas, químicas e morfológicas de hidrogéis baseados em poliacrilamida, carboximetilcelulose e três concentrações diferentes de Cloisita-Na+ em dois meios diferentes de intumescimento (água destilada e solução filtrada da mistura de água+cimento Portland), e avaliar o efeito da aplicação de 0,5% (m/mcimento) destes hidrogéis pré-intumescido nas propriedades do estado fresco e endurecido de argamassas cimentícias (1:2,16 e relação a/c=0,40). Os resultados demonstraram que para estado fresco os hidrogéis proporcionaram reduções no slump flow de até 4,8% para argamassas AHN20, além de menor taxa de exsudação. Estas observações permitiram avaliar que o aumento da concentração de nanoargila no polímero interfere diretamente nos parâmetros cinéticos dos hidrogéis e contribui para maior retenção de água, o que pode refletir em melhor hidratação e redução de patologias. Quanto aos resultados no estado endurecido, foi possível avaliar que o tipo de cura das amostras interferiu nos resultados, já que não ocorreram variações nas densidades (2,18 + 0,02 g/cm³) de todas as amostras, indicando que os hidrogéis encontravam-se parcialmente ou totalmente intumescidos durante a realização dos ensaios. A perda de resistência mecânica foi observada, contudo aos 28 dias para as argamassas AHN20 os resultados foram similares ao controle, o que corrobora com a porcentagem de vazios encontrada. Neste caso, ambas argamassas tiveram menor porcentagem de vazios, em relação as argamasssa AHN0 e AHN10, e consequentemente melhores desempenhos em suas propriedades mecânicas. Destaca-se também, que a concentração de nanoargila no hidrogel controla a liberação de água, sendo observado a partir dos resultados de perda de massa e retração plástica que reduziam à medida que esta concentração aumentava. As imagens de SEM permitiram avaliar que as matrizes com maiores propriedades mecânicas são mais uniformes, com poucos poros ou microfissuras. Conclui-se que os hidrogéis híbridos nanocompósitos podem ser potencialmente aplicados como agentes de cura interna, em destaque para os produzidos com 20% (massa/ massa de CMC+AAm) de nanoargila, uma vez que sua liberação mais controlada permitiu reduzir aspectos como porosidade, absorção de água, retração e atuar significativamente nas propriedades mecânicas. Assim, este tipo de aditivo polimérico pode ser um material inovador no para melhorias no controle de água na área da tecnologia de materiais cimentícios.Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)CAPES: 001CAPES: 88882.465988/2019-01Universidade Estadual Paulista (Unesp)Aouada, Fauze Ahmad [UNESP]Universidade Estadual Paulista (Unesp)Watanuki Filho, Adhemar2021-09-16T16:42:59Z2021-09-16T16:42:59Z2021-07-29info:eu-repo/semantics/publishedVersioninfo:eu-repo/semantics/doctoralThesisapplication/pdfapplication/pdfhttp://hdl.handle.net/11449/21443833004099083P9enginfo:eu-repo/semantics/openAccessreponame:Repositório Institucional da UNESPinstname:Universidade Estadual Paulista (UNESP)instacron:UNESP2024-08-05T13:15:07Zoai:repositorio.unesp.br:11449/214438Repositório InstitucionalPUBhttp://repositorio.unesp.br/oai/requestopendoar:29462024-08-05T13:15:07Repositório Institucional da UNESP - Universidade Estadual Paulista (UNESP)false
dc.title.none.fl_str_mv Physical and mechanical characterization of cement-mortars internally cured with hybrid nanocomposites based on hydrogel and nanoclay
Caracterização física e mecânica de argamassas de cimento curadas internamente com nanocompósitos híbridos baseados em hidrogéis e nanoargila.
title Physical and mechanical characterization of cement-mortars internally cured with hybrid nanocomposites based on hydrogel and nanoclay
spellingShingle Physical and mechanical characterization of cement-mortars internally cured with hybrid nanocomposites based on hydrogel and nanoclay
Watanuki Filho, Adhemar
Absorbent polymer
Polímero absorvente
Nanocompósito híbrido
Construção civil
Cloisita Na+
Cura interna
Hybrid nanocomposite
Civil construction
Cloisite Na+
Internal curing
Hydrogel
title_short Physical and mechanical characterization of cement-mortars internally cured with hybrid nanocomposites based on hydrogel and nanoclay
title_full Physical and mechanical characterization of cement-mortars internally cured with hybrid nanocomposites based on hydrogel and nanoclay
title_fullStr Physical and mechanical characterization of cement-mortars internally cured with hybrid nanocomposites based on hydrogel and nanoclay
title_full_unstemmed Physical and mechanical characterization of cement-mortars internally cured with hybrid nanocomposites based on hydrogel and nanoclay
title_sort Physical and mechanical characterization of cement-mortars internally cured with hybrid nanocomposites based on hydrogel and nanoclay
author Watanuki Filho, Adhemar
author_facet Watanuki Filho, Adhemar
author_role author
dc.contributor.none.fl_str_mv Aouada, Fauze Ahmad [UNESP]
Universidade Estadual Paulista (Unesp)
dc.contributor.author.fl_str_mv Watanuki Filho, Adhemar
dc.subject.por.fl_str_mv Absorbent polymer
Polímero absorvente
Nanocompósito híbrido
Construção civil
Cloisita Na+
Cura interna
Hybrid nanocomposite
Civil construction
Cloisite Na+
Internal curing
Hydrogel
topic Absorbent polymer
Polímero absorvente
Nanocompósito híbrido
Construção civil
Cloisita Na+
Cura interna
Hybrid nanocomposite
Civil construction
Cloisite Na+
Internal curing
Hydrogel
description Cement-based materials are the most produced in civil construction due to their versatility and durability. However, new admixtures have been widely studied and applied for better performance, especially when it comes to curing processes. The hybrid nanocomposite hydrogels, characterized by their hydrophilic characteristics of water absorption and release, stand out as promising agents for internal curing in cementitious matrices. This study proposed to analyze the physical, chemical, and morphological properties of hydrogels based on polyacrylamide, carboxymethylcellulose, and three different concentrations of Cloisite Na+ in two different swelling media (distilled water and filtered solution of water+Portland cement) and to evaluate the effect of applying 0.5% (wt/wtcement) of these presoaked hydrogels on the fresh and hardened state properties of cementitious mortars (1:2.16 and 0.40 w/c ratio). The results showed that the hydrogels provided reductions in slump flow of up to 4.8% for AHN20 mortars and exudation rate for the fresh state. These observations allowed us to evaluate that the increased concentration of nanoclay in the polymer interferes directly in the kinetic parameters of hydrogels and contributes to greater water retention, which may reflect better hydration and reduction of pathologies. As for the results in the hardened state, it was possible to evaluate that the type of curing of the samples was an important factor since there were no variations in densities (2.18+0.02 g/cm³) of all samples, indicating that the hydrogels were partially or fully swollen during the tests. Loss of mechanical strength was observed, but at 28 days for AHN20 mortars, the results were similar to the control, which corroborates the percentage of voids found. In this case, both mortars had a lower rate of voids when compared to AHN0 and AHN10 mortars and consequently better performances in their mechanical properties. The concentration of nanoclay in the hydrogel controls water release, as observed from the results of mass loss and plastic shrinkage that reduced as this concentration increased. The SEM images allowed us to evaluate that the more uniform matrices with higher mechanical properties, with few pores or micro-cracks. It is concluded that hybrid hydrogel nanocomposites can be applied as internal curing agents, especially those produced with 20% (wt/wt of CMC+AAm) nanoclay. Because its more controlled release allowed reducing porosity, water absorption, shrinkage, and significantly acting on the mechanical properties thus, this type of polymeric additive can be an innovative material for water control improvements in cementitious materials technology.
publishDate 2021
dc.date.none.fl_str_mv 2021-09-16T16:42:59Z
2021-09-16T16:42:59Z
2021-07-29
dc.type.status.fl_str_mv info:eu-repo/semantics/publishedVersion
dc.type.driver.fl_str_mv info:eu-repo/semantics/doctoralThesis
format doctoralThesis
status_str publishedVersion
dc.identifier.uri.fl_str_mv http://hdl.handle.net/11449/214438
33004099083P9
url http://hdl.handle.net/11449/214438
identifier_str_mv 33004099083P9
dc.language.iso.fl_str_mv eng
language eng
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eu_rights_str_mv openAccess
dc.format.none.fl_str_mv application/pdf
application/pdf
dc.publisher.none.fl_str_mv Universidade Estadual Paulista (Unesp)
publisher.none.fl_str_mv Universidade Estadual Paulista (Unesp)
dc.source.none.fl_str_mv reponame:Repositório Institucional da UNESP
instname:Universidade Estadual Paulista (UNESP)
instacron:UNESP
instname_str Universidade Estadual Paulista (UNESP)
instacron_str UNESP
institution UNESP
reponame_str Repositório Institucional da UNESP
collection Repositório Institucional da UNESP
repository.name.fl_str_mv Repositório Institucional da UNESP - Universidade Estadual Paulista (UNESP)
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