Global analysis of DEF damage to concretes with and without fly-ash
Autor(a) principal: | |
---|---|
Data de Publicação: | 2022 |
Outros Autores: | , , |
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. |
id |
IBRACON-1_6276ec5eb99bfcb43ba1ac51b7e08011 |
---|---|
oai_identifier_str |
oai:scielo:S1983-41952022000300206 |
network_acronym_str |
IBRACON-1 |
network_name_str |
Revista IBRACON de Estruturas e Materiais |
repository_id_str |
|
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 |
dc.type.status.fl_str_mv |
info:eu-repo/semantics/publishedVersion |
format |
article |
status_str |
publishedVersion |
dc.identifier.uri.fl_str_mv |
http://old.scielo.br/scielo.php?script=sci_arttext&pid=S1983-41952022000300206 |
url |
http://old.scielo.br/scielo.php?script=sci_arttext&pid=S1983-41952022000300206 |
dc.language.iso.fl_str_mv |
eng |
language |
eng |
dc.relation.none.fl_str_mv |
10.1590/s1983-41952022000300005 |
dc.rights.driver.fl_str_mv |
info:eu-repo/semantics/openAccess |
eu_rights_str_mv |
openAccess |
dc.format.none.fl_str_mv |
text/html |
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) instacron:IBRACON |
instname_str |
Instituto Brasileiro do Concreto (IBRACON) |
instacron_str |
IBRACON |
institution |
IBRACON |
reponame_str |
Revista IBRACON de Estruturas e Materiais |
collection |
Revista IBRACON de Estruturas e Materiais |
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 |
_version_ |
1754193606786154496 |