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Title:Utrjanje betona z zakasnelo tvorbo etringita
Authors:ID Lubej, Samo (Author)
ID Anžel, Ivan (Mentor) More about this mentor... New window
ID Kosec, Ladislav (Comentor)
Files:.pdf DR_Lubej_Samo_2012.pdf (26,01 MB)
MD5: B51D36653A5D1CC225411AD0450493FE
PID: 20.500.12556/dkum/2f0c3dac-d23d-47b2-8a03-29757ebb8295
 
Language:Slovenian
Work type:Dissertation
Organization:FGPA - Faculty of Civil Engineering, Transportation Engineering and Architecture
Abstract:Zakasnela tvorba etringita (Delayed Ettringite Formation - DEF) je kemična reakcija z dokazano škodljivim vplivom na hidratizirani beton. Kristali ki pri tej kemični reakciji nastanejo lahko povzročijo nastanek razpok. Pozitivne spremembe prostornine, ki je posledica nastalih produktov prav tako poveča pritiske na stene razpok in poroznih mestih. Zaradi rasti kristalov etringita ima lahko mlad hidratizirani beton višje trdnosti, kar pa navadno pomeni spremljajoč pojav nastanek razpok in razpad betona. V disertaciji smo raziskali možnosti kako izkoristiti pozitivne volumensko spremembo, ki je posledica DEF za izboljšanje trdnostnih lastnosti drobno zrnatega betona.. Ugotovili smo, da z dodajanjem aeranta in zelo kratkim časom vibriranja betona dosežemo takšno strukturo betona, kjer zračni mehurčki v hidratiziranem betonu predstavljajo nukleacijska mesta. Zakasnela tvorba etringita je z razpršenimi zračnimi mehurčki, ki so nastali od aeranta kontrolirana. Rast kristalov etringita ne povzroči hitrega povečanja trdnosti in razapada betona temveč v fazi stabilizacije strukture doprinese 6% povečanje tlačne trdnosti ob minimalnem znižanju gostote hidratiziranega drobno zrnatega betona.
Keywords:Zakasnela tvorba etringita (DEF), kontrolirana DEF, kristali etringita, aerirani beton, utrjanje
Place of publishing:Maribor
Publisher:[S. Lubej]
Year of publishing:2011
PID:20.500.12556/DKUM-22543 New window
UDC:691.332.5:666.972(043.3)
COBISS.SI-ID:15902742 New window
NUK URN:URN:SI:UM:DK:SBNXQZTE
Publication date in DKUM:11.04.2012
Views:3568
Downloads:318
Metadata:XML DC-XML DC-RDF
Categories:KTFMB - FG
:
LUBEJ, Samo, 2011, Utrjanje betona z zakasnelo tvorbo etringita [online]. Doctoral dissertation. Maribor : S. Lubej. [Accessed 22 January 2025]. Retrieved from: https://dk.um.si/IzpisGradiva.php?lang=eng&id=22543
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Secondary language

Language:English
Title:STRENGTH IMPROVEMENT WITH DELAYED ETTRINGITE FORMATION
Abstract:Delayed ettringite formation (DEF) is a chemical reaction with proven damaging effects on hydrated concrete. Ettringite crystals can cause cracks and their widening due to pressure on crack walls caused by the positive volume difference in the reaction. Concrete may show improvements in strength at early ages but further growth of cracks causes widening and spreading of these cracks through the concrete structure. In this study, a potential to utilise the positive volume difference in DEF in order to improve mechanical properties of hydrated fine grained concrete is investigated. Finely dispersed crystallization nuclei achieved by adding air-entraining agent (AEA) and short vibration of specimens is presented as the main prerequisite for such improvements. The study presents the method and mechanism for obtaining the required crystallisation nuclei. Controlling long-term DEF by providing AEA-induced crystallisation nuclei prevented excessive and rapid initial strength improvements, and resulted in a 6% increase of compressive strength of fine grained concrete with only marginally lower density.
Keywords:Delayed Ettringite Formation (DEF), controlled DEF, ettringite crystals, aerated concrete, strength improvement


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