Global analysis of DEF damage to concretes with and without fly-ash

Detalhes bibliográficos
Autor(a) principal: Hasparyk,Nicole Pagan
Data de Publicação: 2022
Outros Autores: Schovanz,Dioice, Tiecher,Francieli, Kuperman,Selmo Chapira
Tipo de documento: Artigo
Idioma: eng
Título da fonte: Revista IBRACON de Estruturas e Materiais
Texto Completo: http://old.scielo.br/scielo.php?script=sci_arttext&pid=S1983-41952022000300206
Resumo: Abstract Delayed Ettringite formation (DEF) is an internal expansive reaction that can damage concrete. DEF is strongly influenced by the temperature, above about 60-65°C, and other factors involving cement chemistry especially, but also its physical characteristics. The exposure environment over time also promotes a condition to increase deterioration from DEF. Expansions results from secondary ettringite formation are progressive and can lead concrete to microcracking impacting its performance and durability over time. Several concrete structures are pointed to be severely attacked by DEF, and test method as well a better comprehension on this pathology is necessary to promote specific and proper preventive measures to avoid future damages. Furthermore, compared to alkali-silica reaction, DEF occurs more readily and aggressively, and sometimes prematurely, depending on several factors, such as type of cement, concrete mix design, exposure conditions, among others. This paper involves an overall analysis of the behavior of concretes with two types of Portland cements (High early-strength cement and a Portland pozzolanic cement, with fly-ash) in relation to DEF process. Several data from a laboratory study where DEF was induced through a specific thermal curing procedure are presented and discussed. The analyses involved the assessment of physical, mechanical, and expansive properties besides microstructural monitoring of samples from concretes over time. These experiments allowed detecting high values of expansions from DEF (up to 1.2%) in the concrete without fly ash. The mechanical properties were severely impacted from this deleterious process; as expansions increased, losses in the mechanic and elastic properties were verified. Expansion levels in the order of 0.5% prompted remarkably high reductions and, at about 1% the losses were relevant for both strengths (tensile and compressive) and modulus of elasticity, of 60% and 80%, respectively, in the presence of cement without fly-ash. Concrete microstructure has indicated massive formations of ettringite as well as micro-cracking and the fragility of the cement matrix because of DEF. On the other hand, expansion up to 0.2% did not promote important negative effects on the properties of concrete, especially with the pozzolanic cement tested. Furthermore, an overall approach with several correlations between physical and mechanical properties was taken to obtain different levels of deterioration for a concrete presenting DEF.
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spelling Global analysis of DEF damage to concretes with and without fly-ashconcretedelayed ettringite formation (DEF)expansionmechanical and physical propertiesmicrostructurefly-ashdamageAbstract Delayed Ettringite formation (DEF) is an internal expansive reaction that can damage concrete. DEF is strongly influenced by the temperature, above about 60-65°C, and other factors involving cement chemistry especially, but also its physical characteristics. The exposure environment over time also promotes a condition to increase deterioration from DEF. Expansions results from secondary ettringite formation are progressive and can lead concrete to microcracking impacting its performance and durability over time. Several concrete structures are pointed to be severely attacked by DEF, and test method as well a better comprehension on this pathology is necessary to promote specific and proper preventive measures to avoid future damages. Furthermore, compared to alkali-silica reaction, DEF occurs more readily and aggressively, and sometimes prematurely, depending on several factors, such as type of cement, concrete mix design, exposure conditions, among others. This paper involves an overall analysis of the behavior of concretes with two types of Portland cements (High early-strength cement and a Portland pozzolanic cement, with fly-ash) in relation to DEF process. Several data from a laboratory study where DEF was induced through a specific thermal curing procedure are presented and discussed. The analyses involved the assessment of physical, mechanical, and expansive properties besides microstructural monitoring of samples from concretes over time. These experiments allowed detecting high values of expansions from DEF (up to 1.2%) in the concrete without fly ash. The mechanical properties were severely impacted from this deleterious process; as expansions increased, losses in the mechanic and elastic properties were verified. Expansion levels in the order of 0.5% prompted remarkably high reductions and, at about 1% the losses were relevant for both strengths (tensile and compressive) and modulus of elasticity, of 60% and 80%, respectively, in the presence of cement without fly-ash. Concrete microstructure has indicated massive formations of ettringite as well as micro-cracking and the fragility of the cement matrix because of DEF. On the other hand, expansion up to 0.2% did not promote important negative effects on the properties of concrete, especially with the pozzolanic cement tested. Furthermore, an overall approach with several correlations between physical and mechanical properties was taken to obtain different levels of deterioration for a concrete presenting DEF.IBRACON - Instituto Brasileiro do Concreto2022-01-01info:eu-repo/semantics/articleinfo:eu-repo/semantics/publishedVersiontext/htmlhttp://old.scielo.br/scielo.php?script=sci_arttext&pid=S1983-41952022000300206Revista IBRACON de Estruturas e Materiais v.15 n.3 2022reponame:Revista IBRACON de Estruturas e Materiaisinstname:Instituto Brasileiro do Concreto (IBRACON)instacron:IBRACON10.1590/s1983-41952022000300005info:eu-repo/semantics/openAccessHasparyk,Nicole PaganSchovanz,DioiceTiecher,FrancieliKuperman,Selmo Chapiraeng2021-12-08T00:00:00Zoai:scielo:S1983-41952022000300206Revistahttp://www.revistas.ibracon.org.br/index.php/riemhttps://old.scielo.br/oai/scielo-oai.phpeditores.riem@gmail.com||arlene@ibracon.org.br1983-41951983-4195opendoar:2021-12-08T00:00Revista IBRACON de Estruturas e Materiais - Instituto Brasileiro do Concreto (IBRACON)false
dc.title.none.fl_str_mv Global analysis of DEF damage to concretes with and without fly-ash
title Global analysis of DEF damage to concretes with and without fly-ash
spellingShingle Global analysis of DEF damage to concretes with and without fly-ash
Hasparyk,Nicole Pagan
concrete
delayed ettringite formation (DEF)
expansion
mechanical and physical properties
microstructure
fly-ash
damage
title_short Global analysis of DEF damage to concretes with and without fly-ash
title_full Global analysis of DEF damage to concretes with and without fly-ash
title_fullStr Global analysis of DEF damage to concretes with and without fly-ash
title_full_unstemmed Global analysis of DEF damage to concretes with and without fly-ash
title_sort Global analysis of DEF damage to concretes with and without fly-ash
author Hasparyk,Nicole Pagan
author_facet Hasparyk,Nicole Pagan
Schovanz,Dioice
Tiecher,Francieli
Kuperman,Selmo Chapira
author_role author
author2 Schovanz,Dioice
Tiecher,Francieli
Kuperman,Selmo Chapira
author2_role author
author
author
dc.contributor.author.fl_str_mv Hasparyk,Nicole Pagan
Schovanz,Dioice
Tiecher,Francieli
Kuperman,Selmo Chapira
dc.subject.por.fl_str_mv concrete
delayed ettringite formation (DEF)
expansion
mechanical and physical properties
microstructure
fly-ash
damage
topic concrete
delayed ettringite formation (DEF)
expansion
mechanical and physical properties
microstructure
fly-ash
damage
description Abstract Delayed Ettringite formation (DEF) is an internal expansive reaction that can damage concrete. DEF is strongly influenced by the temperature, above about 60-65°C, and other factors involving cement chemistry especially, but also its physical characteristics. The exposure environment over time also promotes a condition to increase deterioration from DEF. Expansions results from secondary ettringite formation are progressive and can lead concrete to microcracking impacting its performance and durability over time. Several concrete structures are pointed to be severely attacked by DEF, and test method as well a better comprehension on this pathology is necessary to promote specific and proper preventive measures to avoid future damages. Furthermore, compared to alkali-silica reaction, DEF occurs more readily and aggressively, and sometimes prematurely, depending on several factors, such as type of cement, concrete mix design, exposure conditions, among others. This paper involves an overall analysis of the behavior of concretes with two types of Portland cements (High early-strength cement and a Portland pozzolanic cement, with fly-ash) in relation to DEF process. Several data from a laboratory study where DEF was induced through a specific thermal curing procedure are presented and discussed. The analyses involved the assessment of physical, mechanical, and expansive properties besides microstructural monitoring of samples from concretes over time. These experiments allowed detecting high values of expansions from DEF (up to 1.2%) in the concrete without fly ash. The mechanical properties were severely impacted from this deleterious process; as expansions increased, losses in the mechanic and elastic properties were verified. Expansion levels in the order of 0.5% prompted remarkably high reductions and, at about 1% the losses were relevant for both strengths (tensile and compressive) and modulus of elasticity, of 60% and 80%, respectively, in the presence of cement without fly-ash. Concrete microstructure has indicated massive formations of ettringite as well as micro-cracking and the fragility of the cement matrix because of DEF. On the other hand, expansion up to 0.2% did not promote important negative effects on the properties of concrete, especially with the pozzolanic cement tested. Furthermore, an overall approach with several correlations between physical and mechanical properties was taken to obtain different levels of deterioration for a concrete presenting DEF.
publishDate 2022
dc.date.none.fl_str_mv 2022-01-01
dc.type.driver.fl_str_mv info:eu-repo/semantics/article
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dc.language.iso.fl_str_mv eng
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dc.relation.none.fl_str_mv 10.1590/s1983-41952022000300005
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dc.publisher.none.fl_str_mv IBRACON - Instituto Brasileiro do Concreto
publisher.none.fl_str_mv IBRACON - Instituto Brasileiro do Concreto
dc.source.none.fl_str_mv Revista IBRACON de Estruturas e Materiais v.15 n.3 2022
reponame:Revista IBRACON de Estruturas e Materiais
instname:Instituto Brasileiro do Concreto (IBRACON)
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instname_str Instituto Brasileiro do Concreto (IBRACON)
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repository.name.fl_str_mv Revista IBRACON de Estruturas e Materiais - Instituto Brasileiro do Concreto (IBRACON)
repository.mail.fl_str_mv editores.riem@gmail.com||arlene@ibracon.org.br
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