Please use this identifier to cite or link to this item: http://repositorio.lnec.pt:8080/jspui/handle/123456789/18178
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dc.contributor.authorMatos, L.pt_BR
dc.contributor.authorSantos Silva, A.pt_BR
dc.contributor.authorSoares, D.pt_BR
dc.contributor.authorSalta, M. M.pt_BR
dc.contributor.authorMirão, J.pt_BR
dc.contributor.authorCandeias, A.pt_BR
dc.contributor.editorTrans Tech Publicationspt_BR
dc.date.accessioned2010-04-08T09:22:54Zpt_BR
dc.date.accessioned2010-04-27T07:26:20Zpt_BR
dc.date.accessioned2014-10-20T16:32:20Zpt_BR
dc.date.accessioned2017-04-12T14:55:45Z-
dc.date.available2010-04-08T09:22:54Zpt_BR
dc.date.available2010-04-27T07:26:20Zpt_BR
dc.date.available2014-10-20T16:32:20Zpt_BR
dc.date.available2017-04-12T14:55:45Z-
dc.date.issued2010pt_BR
dc.identifier.urihttp://repositorio.lnec.pt:8080/jspui/handle/123456789/18178-
dc.description.abstractThe degradation of concrete structures caused by delayed ettringite formation (DEF) is a problem that nowadays affects many concrete structures worldwide. This pathology is due to the formation of an expansive compound – ettringite - inside the material. This is a hydrated calcium sulphoaluminate produced by the chemical reaction between sulphate ions, calcium hydroxide and alumina present in the Portland cement paste. This product, normally formed during the hydration of cement, presents an acicular morphology (needles) that can be observed by scanning electron microscopy (SEM). However, DEF can also be formed after the setting of the cement causing, in this case, a deleterious expansion of the concrete. This secondary ettringite can also be produced after an excessive heating of the concrete, caused by a high amount of cement or by the use of heat cure. SEM has been used to distinguish between expansive and non expansive ettringite based normally in morphology analysis, since the former is characterized by a compressed or compact nature where the needle shapes disappear or are welded together. Furthermore, the use of other techniques, like X-ray diffraction or micro-XRF, has been limited because the compressed or compact ettringite is badly crystallized or even amorphous and the elemental composition is similar and therefore it is difficult to detect. This article presents a methodology for the diagnosis of DEF using polished concrete thin sections and combining polarised and fluorescence light optical microscopy with SEM-EDS.pt_BR
dc.description.sponsorshipThe authors wish to acknowledge the Foundation for Science and Technology (FCT) for the financial support under project EXREACT (Mitigação de reacções deletérias expansivas internas em estruturas de betão, PTDC/CTM/65243/2006) and project DURATINET (Durable Tranport Infrastructures in the Atlantic Area Network) for Transnational Programme Atlantic Area 2007- 2013, co-financed by FEDER.pt_BR
dc.format.extent3261952 bytespt_BR
dc.format.mimetypeapplication/pdfpt_BR
dc.language.isoengpt_BR
dc.publisherMaterials Science Forumpt_BR
dc.rightsopenAccesspt_BR
dc.subjectDelayed ettringite formation (def)pt_BR
dc.subjectScanning electron microscopy (sem)pt_BR
dc.subjectPetrographic examinationpt_BR
dc.subjectFluorescence microscopypt_BR
dc.subjectConcretept_BR
dc.titleThe Application of Fluorescence Microscopy and Scanning Electron Microscopy in the Detection of Delayed Ettringite Formation in Concretept_BR
dc.typearticlept_BR
dc.description.figures4pt_BR
dc.description.tables1pt_BR
dc.description.pages6pt_BR
dc.identifier.seminarioMATERIAIS 2009pt_BR
dc.identifier.localIST, LISBOApt_BR
dc.description.volume636-637pt_BR
dc.description.sectorDM/NMMpt_BR
dc.description.year2009pt_BR
dc.description.data5 a 8 de Abrilpt_BR
Appears in Collections:DM/NMM - Comunicações a congressos e artigos de revista

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