Influence of the addition sequence of PVA-fibers and water on mixing and rheological behavior of mortars

Detalhes bibliográficos
Autor(a) principal: França,M. S. de
Data de Publicação: 2016
Outros Autores: Cardoso,F. A., Pileggi,R. G.
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=S1983-41952016000200226
Resumo: ABSTRACT The mixing process of fiber-containing cementitious suspensions is a crucial factor to obtaining a good dispersion of fibers and guarantee adequate mechanical performance of the hardened products. The addition of fibers into the suspension causes reduction of the fluidity of the system due to factors inherent to the fibers, the matrix and their interaction. During mixing, these interactions make dispersion and homogenization processes more difficult due to the formation of fibers - particles agglomerates. Conventional techniques to assess workability of mortars are inadequate to evaluate the rheological behavior of fiber-reinforced systems, in which parameters like viscosity and yield stress are not completely taken into account. Therefore, this work employs rotational rheometry to evaluate the influence of fiber and water addition sequences on mixing and rheological behavior of mortars containing Polyvinyl Alcohol (PVA) fibers. Constant test parameters were: mixing time of 317s; impeller velocity 126.5 rpm; water flow 128g/s. A constant mix design was used with a water content of 16%wt, and a 0.2%vol of fibers were added to the reference composition. Four mixing sequences were studied: S1 and S2 are based on the addition of fibers at different stages of the mixing process; while in S3 and S4 not only the fibers are added at different stages, but also the water addition is performed in two steps (25% first and 75% latter).Results showed that it is possible to optimize the mixing step of fiber-containing systems by changing the moment of fiber addition into the mixture. The introduction of fibers after mixing the dry mortar with water, when it already had achieved its fluidity point, demanded a lower mixing effort and produced a more flowable material.
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spelling Influence of the addition sequence of PVA-fibers and water on mixing and rheological behavior of mortarsmixing sequencerheologyPVA fibersABSTRACT The mixing process of fiber-containing cementitious suspensions is a crucial factor to obtaining a good dispersion of fibers and guarantee adequate mechanical performance of the hardened products. The addition of fibers into the suspension causes reduction of the fluidity of the system due to factors inherent to the fibers, the matrix and their interaction. During mixing, these interactions make dispersion and homogenization processes more difficult due to the formation of fibers - particles agglomerates. Conventional techniques to assess workability of mortars are inadequate to evaluate the rheological behavior of fiber-reinforced systems, in which parameters like viscosity and yield stress are not completely taken into account. Therefore, this work employs rotational rheometry to evaluate the influence of fiber and water addition sequences on mixing and rheological behavior of mortars containing Polyvinyl Alcohol (PVA) fibers. Constant test parameters were: mixing time of 317s; impeller velocity 126.5 rpm; water flow 128g/s. A constant mix design was used with a water content of 16%wt, and a 0.2%vol of fibers were added to the reference composition. Four mixing sequences were studied: S1 and S2 are based on the addition of fibers at different stages of the mixing process; while in S3 and S4 not only the fibers are added at different stages, but also the water addition is performed in two steps (25% first and 75% latter).Results showed that it is possible to optimize the mixing step of fiber-containing systems by changing the moment of fiber addition into the mixture. The introduction of fibers after mixing the dry mortar with water, when it already had achieved its fluidity point, demanded a lower mixing effort and produced a more flowable material.IBRACON - Instituto Brasileiro do Concreto2016-04-01info:eu-repo/semantics/articleinfo:eu-repo/semantics/publishedVersiontext/htmlhttp://old.scielo.br/scielo.php?script=sci_arttext&pid=S1983-41952016000200226Revista IBRACON de Estruturas e Materiais v.9 n.2 2016reponame:Revista IBRACON de Estruturas e Materiaisinstname:Instituto Brasileiro do Concreto (IBRACON)instacron:IBRACON10.1590/S1983-41952016000200005info:eu-repo/semantics/openAccessFrança,M. S. deCardoso,F. A.Pileggi,R. G.eng2016-05-06T00:00:00Zoai:scielo:S1983-41952016000200226Revistahttp://www.revistas.ibracon.org.br/index.php/riemhttps://old.scielo.br/oai/scielo-oai.phpeditores.riem@gmail.com||arlene@ibracon.org.br1983-41951983-4195opendoar:2016-05-06T00:00Revista IBRACON de Estruturas e Materiais - Instituto Brasileiro do Concreto (IBRACON)false
dc.title.none.fl_str_mv Influence of the addition sequence of PVA-fibers and water on mixing and rheological behavior of mortars
title Influence of the addition sequence of PVA-fibers and water on mixing and rheological behavior of mortars
spellingShingle Influence of the addition sequence of PVA-fibers and water on mixing and rheological behavior of mortars
França,M. S. de
mixing sequence
rheology
PVA fibers
title_short Influence of the addition sequence of PVA-fibers and water on mixing and rheological behavior of mortars
title_full Influence of the addition sequence of PVA-fibers and water on mixing and rheological behavior of mortars
title_fullStr Influence of the addition sequence of PVA-fibers and water on mixing and rheological behavior of mortars
title_full_unstemmed Influence of the addition sequence of PVA-fibers and water on mixing and rheological behavior of mortars
title_sort Influence of the addition sequence of PVA-fibers and water on mixing and rheological behavior of mortars
author França,M. S. de
author_facet França,M. S. de
Cardoso,F. A.
Pileggi,R. G.
author_role author
author2 Cardoso,F. A.
Pileggi,R. G.
author2_role author
author
dc.contributor.author.fl_str_mv França,M. S. de
Cardoso,F. A.
Pileggi,R. G.
dc.subject.por.fl_str_mv mixing sequence
rheology
PVA fibers
topic mixing sequence
rheology
PVA fibers
description ABSTRACT The mixing process of fiber-containing cementitious suspensions is a crucial factor to obtaining a good dispersion of fibers and guarantee adequate mechanical performance of the hardened products. The addition of fibers into the suspension causes reduction of the fluidity of the system due to factors inherent to the fibers, the matrix and their interaction. During mixing, these interactions make dispersion and homogenization processes more difficult due to the formation of fibers - particles agglomerates. Conventional techniques to assess workability of mortars are inadequate to evaluate the rheological behavior of fiber-reinforced systems, in which parameters like viscosity and yield stress are not completely taken into account. Therefore, this work employs rotational rheometry to evaluate the influence of fiber and water addition sequences on mixing and rheological behavior of mortars containing Polyvinyl Alcohol (PVA) fibers. Constant test parameters were: mixing time of 317s; impeller velocity 126.5 rpm; water flow 128g/s. A constant mix design was used with a water content of 16%wt, and a 0.2%vol of fibers were added to the reference composition. Four mixing sequences were studied: S1 and S2 are based on the addition of fibers at different stages of the mixing process; while in S3 and S4 not only the fibers are added at different stages, but also the water addition is performed in two steps (25% first and 75% latter).Results showed that it is possible to optimize the mixing step of fiber-containing systems by changing the moment of fiber addition into the mixture. The introduction of fibers after mixing the dry mortar with water, when it already had achieved its fluidity point, demanded a lower mixing effort and produced a more flowable material.
publishDate 2016
dc.date.none.fl_str_mv 2016-04-01
dc.type.driver.fl_str_mv info:eu-repo/semantics/article
dc.type.status.fl_str_mv info:eu-repo/semantics/publishedVersion
format article
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dc.identifier.uri.fl_str_mv http://old.scielo.br/scielo.php?script=sci_arttext&pid=S1983-41952016000200226
url http://old.scielo.br/scielo.php?script=sci_arttext&pid=S1983-41952016000200226
dc.language.iso.fl_str_mv eng
language eng
dc.relation.none.fl_str_mv 10.1590/S1983-41952016000200005
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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.9 n.2 2016
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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
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