Alterações na microestrutura, causadas pela exposição às altas temperaturas, de argamassas com potencial formação de etringita tardia
Autor(a) principal: | |
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Data de Publicação: | 2022 |
Tipo de documento: | Dissertação |
Idioma: | por |
Título da fonte: | Manancial - Repositório Digital da UFSM |
Texto Completo: | http://repositorio.ufsm.br/handle/1/27419 |
Resumo: | The delayed ettringite formation (DEF) is a pathological manifestation that can occur in concretes and mortars when cement with high sulfate content in the production process and thermal cure in temperatures high up to 70 ºC. The DEF causes cracks which can shorten the lifespan and aggravate the damage suffered in atypical situations such as a fire. This work aimed to evaluate the microstructural changes due to high-temperature exposure in mortars with potential delayed ettringite formation. For this, a reference mixture was compared with a mixture in which the SO3/Al2O3 molar ratio was changed to 1.1 to favor the occurrence of DEF. After the production of the specimens, they were subjected to an initial wet cure for 12 hours at 23 or 80 °C, followed by a wet cure at room temperature for 96 days to simulate deterioration and subsequent recrystallization from ettringite. Subsequently, the CPs were kept for 56 days in a controlled environment at 23 ± 2 ºC and 50 ± 5 % humidity to stabilize the internal humidity and avoid possible detachment during heating due to moisture evaporation. After the moisture conditioning period, the CPs were heated at a rate of 1 °C/min to levels of 200, 400, 600, and 900 °C. Using X-ray diffraction and scanning electron microscopy techniques, it was verified that mortars with a SO3/ Al2O3 molar ratio equal to 1.1 had a higher incidence of ettringite with type II morphology, which has an expansive character. In addition, the curing process resulted in the decomposition of the ettringite. Regarding heating, for the specimens submitted to 200 ºC, it was observed that there was no increase in the intensity of portlandite peaks in the thermally cured samples. As for the change in the SO3/Al2O3 molar ratio, its influence was evident in the samples heated to levels of 600 and 900 ºC in which the presence of anhydrite was observed, which can make it difficult to recover the material in a post-fire scenario. Therefore, it is concluded that the mortar with more significant potential for the occurrence of DEF can also present greater damage when subjected to high temperatures, such as in the event of a fire. |
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Alterações na microestrutura, causadas pela exposição às altas temperaturas, de argamassas com potencial formação de etringita tardiaMicrostructural behavior in mortars with potential delayed ettringite formation exposed to high temperaturesFormação de etringita tardiaAltas temperaturasArgamassaMicroestruturaDelayed ettringite formationHigh temperaturesMortarMicrostructuralCNPQ::ENGENHARIAS::ENGENHARIA CIVILThe delayed ettringite formation (DEF) is a pathological manifestation that can occur in concretes and mortars when cement with high sulfate content in the production process and thermal cure in temperatures high up to 70 ºC. The DEF causes cracks which can shorten the lifespan and aggravate the damage suffered in atypical situations such as a fire. This work aimed to evaluate the microstructural changes due to high-temperature exposure in mortars with potential delayed ettringite formation. For this, a reference mixture was compared with a mixture in which the SO3/Al2O3 molar ratio was changed to 1.1 to favor the occurrence of DEF. After the production of the specimens, they were subjected to an initial wet cure for 12 hours at 23 or 80 °C, followed by a wet cure at room temperature for 96 days to simulate deterioration and subsequent recrystallization from ettringite. Subsequently, the CPs were kept for 56 days in a controlled environment at 23 ± 2 ºC and 50 ± 5 % humidity to stabilize the internal humidity and avoid possible detachment during heating due to moisture evaporation. After the moisture conditioning period, the CPs were heated at a rate of 1 °C/min to levels of 200, 400, 600, and 900 °C. Using X-ray diffraction and scanning electron microscopy techniques, it was verified that mortars with a SO3/ Al2O3 molar ratio equal to 1.1 had a higher incidence of ettringite with type II morphology, which has an expansive character. In addition, the curing process resulted in the decomposition of the ettringite. Regarding heating, for the specimens submitted to 200 ºC, it was observed that there was no increase in the intensity of portlandite peaks in the thermally cured samples. As for the change in the SO3/Al2O3 molar ratio, its influence was evident in the samples heated to levels of 600 and 900 ºC in which the presence of anhydrite was observed, which can make it difficult to recover the material in a post-fire scenario. Therefore, it is concluded that the mortar with more significant potential for the occurrence of DEF can also present greater damage when subjected to high temperatures, such as in the event of a fire.A formação de etringita tardia (DEF) é uma manifestação patológica que pode ocorrer em concretos e em argamassas quando são empregados cimento com altos teores de sulfatos no processo de fabricação e cura térmica em temperaturas superiores a 70 ºC. A DEF causa fissurações que podem diminuir a vida útil do material e agravar os danos sofridos em situações atípicas como um incêndio. Este trabalho teve como objetivo avaliar as alterações microestruturais causadas pela exposição a altas temperaturas em argamassas com potencial formação de etringita tardia. Para isso, comparou-se traço de referência com traço em que a razão molar SO3/Al2O3 foi alterada para 1,1, para favorecer a ocorrência de DEF. Após a produção dos corpos de prova (CPs), esses foram submetidos a uma cura úmida inicial, por 12 horas, a 23 ou 80 ºC, seguida de uma cura úmida a temperatura ambiente, durante 96 dias, para simular a deterioração e posterior recristalização da etringita. Na sequência, os CPs foram mantidos por 56 dias em ambiente controlado a 23 ± 2 ºC e umidade de 50 ± 5 %, para estabilizar a umidade interna e evitar possíveis desplacamentos durante o aquecimento devido a evaporação da umidade. Após o período de condicionamento da umidade, os CPs foram aquecidos a uma taxa de 1 ºC/min até os patamares de 200, 400, 600 e 900 ºC. Verificou-se, por meio das técnicas de difração de raios-x e microscopia eletrônica de varredura, que as argamassas com razão molar SO3/Al2O3 igual a 1,1 apresentaram maior incidência de etringita com morfologia do tipo II, que possui caráter expansivo. Além disso, o processo de cura acarretou em decomposição da etringita. Em relação ao aquecimento, para os corpos de prova submetidos a 200 ºC, observou-se que não houve aumento de intensidade dos picos de portlandita nas amostras curadas termicamente. Quanto à alteração da razão molar SO3/Al2O3, sua influência ficou evidente nas amostras aquecidas aos patamares 600 e 900 ºC em que se observou a presença de anidrita, que pode dificultar a recuperação do material em um cenário pós incêndio. Portanto, conclui-se que a argamassa com maior potencialidade para a ocorrência de DEF pode, também, apresentar maiores danos quando submetida a altas temperaturas, como por exemplo, na ocorrência de um incêndio.Universidade Federal de Santa MariaBrasilEngenharia CivilUFSMPrograma de Pós-Graduação em Engenharia CivilCentro de TecnologiaLima, Rogerio Cattelan Antocheves dehttp://lattes.cnpq.br/5518587537986438Vargas, Alexandre Silva dePacheco, FernandaVenquiaruto, Simone DornellesKramer, Henrique dos Santos2022-12-28T13:26:14Z2022-12-28T13:26:14Z2022-11-01info:eu-repo/semantics/publishedVersioninfo:eu-repo/semantics/masterThesisapplication/pdfhttp://repositorio.ufsm.br/handle/1/27419porAttribution-NonCommercial-NoDerivatives 4.0 Internationalhttp://creativecommons.org/licenses/by-nc-nd/4.0/info:eu-repo/semantics/openAccessreponame:Manancial - Repositório Digital da UFSMinstname:Universidade Federal de Santa Maria (UFSM)instacron:UFSM2022-12-28T13:26:15Zoai:repositorio.ufsm.br:1/27419Biblioteca Digital de Teses e Dissertaçõeshttps://repositorio.ufsm.br/ONGhttps://repositorio.ufsm.br/oai/requestatendimento.sib@ufsm.br||tedebc@gmail.comopendoar:2022-12-28T13:26:15Manancial - Repositório Digital da UFSM - Universidade Federal de Santa Maria (UFSM)false |
dc.title.none.fl_str_mv |
Alterações na microestrutura, causadas pela exposição às altas temperaturas, de argamassas com potencial formação de etringita tardia Microstructural behavior in mortars with potential delayed ettringite formation exposed to high temperatures |
title |
Alterações na microestrutura, causadas pela exposição às altas temperaturas, de argamassas com potencial formação de etringita tardia |
spellingShingle |
Alterações na microestrutura, causadas pela exposição às altas temperaturas, de argamassas com potencial formação de etringita tardia Kramer, Henrique dos Santos Formação de etringita tardia Altas temperaturas Argamassa Microestrutura Delayed ettringite formation High temperatures Mortar Microstructural CNPQ::ENGENHARIAS::ENGENHARIA CIVIL |
title_short |
Alterações na microestrutura, causadas pela exposição às altas temperaturas, de argamassas com potencial formação de etringita tardia |
title_full |
Alterações na microestrutura, causadas pela exposição às altas temperaturas, de argamassas com potencial formação de etringita tardia |
title_fullStr |
Alterações na microestrutura, causadas pela exposição às altas temperaturas, de argamassas com potencial formação de etringita tardia |
title_full_unstemmed |
Alterações na microestrutura, causadas pela exposição às altas temperaturas, de argamassas com potencial formação de etringita tardia |
title_sort |
Alterações na microestrutura, causadas pela exposição às altas temperaturas, de argamassas com potencial formação de etringita tardia |
author |
Kramer, Henrique dos Santos |
author_facet |
Kramer, Henrique dos Santos |
author_role |
author |
dc.contributor.none.fl_str_mv |
Lima, Rogerio Cattelan Antocheves de http://lattes.cnpq.br/5518587537986438 Vargas, Alexandre Silva de Pacheco, Fernanda Venquiaruto, Simone Dornelles |
dc.contributor.author.fl_str_mv |
Kramer, Henrique dos Santos |
dc.subject.por.fl_str_mv |
Formação de etringita tardia Altas temperaturas Argamassa Microestrutura Delayed ettringite formation High temperatures Mortar Microstructural CNPQ::ENGENHARIAS::ENGENHARIA CIVIL |
topic |
Formação de etringita tardia Altas temperaturas Argamassa Microestrutura Delayed ettringite formation High temperatures Mortar Microstructural CNPQ::ENGENHARIAS::ENGENHARIA CIVIL |
description |
The delayed ettringite formation (DEF) is a pathological manifestation that can occur in concretes and mortars when cement with high sulfate content in the production process and thermal cure in temperatures high up to 70 ºC. The DEF causes cracks which can shorten the lifespan and aggravate the damage suffered in atypical situations such as a fire. This work aimed to evaluate the microstructural changes due to high-temperature exposure in mortars with potential delayed ettringite formation. For this, a reference mixture was compared with a mixture in which the SO3/Al2O3 molar ratio was changed to 1.1 to favor the occurrence of DEF. After the production of the specimens, they were subjected to an initial wet cure for 12 hours at 23 or 80 °C, followed by a wet cure at room temperature for 96 days to simulate deterioration and subsequent recrystallization from ettringite. Subsequently, the CPs were kept for 56 days in a controlled environment at 23 ± 2 ºC and 50 ± 5 % humidity to stabilize the internal humidity and avoid possible detachment during heating due to moisture evaporation. After the moisture conditioning period, the CPs were heated at a rate of 1 °C/min to levels of 200, 400, 600, and 900 °C. Using X-ray diffraction and scanning electron microscopy techniques, it was verified that mortars with a SO3/ Al2O3 molar ratio equal to 1.1 had a higher incidence of ettringite with type II morphology, which has an expansive character. In addition, the curing process resulted in the decomposition of the ettringite. Regarding heating, for the specimens submitted to 200 ºC, it was observed that there was no increase in the intensity of portlandite peaks in the thermally cured samples. As for the change in the SO3/Al2O3 molar ratio, its influence was evident in the samples heated to levels of 600 and 900 ºC in which the presence of anhydrite was observed, which can make it difficult to recover the material in a post-fire scenario. Therefore, it is concluded that the mortar with more significant potential for the occurrence of DEF can also present greater damage when subjected to high temperatures, such as in the event of a fire. |
publishDate |
2022 |
dc.date.none.fl_str_mv |
2022-12-28T13:26:14Z 2022-12-28T13:26:14Z 2022-11-01 |
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 |
http://repositorio.ufsm.br/handle/1/27419 |
url |
http://repositorio.ufsm.br/handle/1/27419 |
dc.language.iso.fl_str_mv |
por |
language |
por |
dc.rights.driver.fl_str_mv |
Attribution-NonCommercial-NoDerivatives 4.0 International http://creativecommons.org/licenses/by-nc-nd/4.0/ info:eu-repo/semantics/openAccess |
rights_invalid_str_mv |
Attribution-NonCommercial-NoDerivatives 4.0 International http://creativecommons.org/licenses/by-nc-nd/4.0/ |
eu_rights_str_mv |
openAccess |
dc.format.none.fl_str_mv |
application/pdf |
dc.publisher.none.fl_str_mv |
Universidade Federal de Santa Maria Brasil Engenharia Civil UFSM Programa de Pós-Graduação em Engenharia Civil Centro de Tecnologia |
publisher.none.fl_str_mv |
Universidade Federal de Santa Maria Brasil Engenharia Civil UFSM Programa de Pós-Graduação em Engenharia Civil Centro de Tecnologia |
dc.source.none.fl_str_mv |
reponame:Manancial - Repositório Digital da UFSM instname:Universidade Federal de Santa Maria (UFSM) instacron:UFSM |
instname_str |
Universidade Federal de Santa Maria (UFSM) |
instacron_str |
UFSM |
institution |
UFSM |
reponame_str |
Manancial - Repositório Digital da UFSM |
collection |
Manancial - Repositório Digital da UFSM |
repository.name.fl_str_mv |
Manancial - Repositório Digital da UFSM - Universidade Federal de Santa Maria (UFSM) |
repository.mail.fl_str_mv |
atendimento.sib@ufsm.br||tedebc@gmail.com |
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1805922138664730624 |