Utrjanje betona z zakasnelo tvorbo etringita

doktorska disertacija

Samo Lubej (Author), Ivan Anžel (Mentor), Ladislav Kosec (Co-mentor)

Abstract

Zakasnela tvorba etringita (Delayed Ettringite Formation - DEF) je kemična reakcija z dokazano škodljivim vplivom na hidratizirani beton. Kristali, ki pri tej kemicni 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 mehurcki 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 razpada betona, temveč v fazi stabilizacije strukture doprinese 6% poveanje tlačne trdnosti ob minimalnem znižanju gostote hidratiziranega drobno zrnatega betona.

Keywords

zakasnela tvorba etringita;DEF;kontrolirana DEF;kristali etringita;aerirani beton;utrjanje;

Data

Language:	Slovenian
Year of publishing:	2011
Source:	Maribor
Typology:	2.08 - Doctoral Dissertation
Organization:	UM FS - Faculty of Mechanical Engineering
Publisher:	[S. Lubej]
UDC:	691.332.5:666.972(043.3)
COBISS:	15902742
Views:	2734
Downloads:	139
Average score:	0 (0 votes)
Metadata:

Other data

Secondary language:	English
Secondary title:	Strength improvement with delayed ettringite formation
Secondary 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.
Secondary keywords:	delayed ettringite formation;DEF;controlled DEF;ettringite crystals;aerated concrete;strength improvement;Beton;Disertacije;
URN:	URN:SI:UM:
Type (COBISS):	Dissertation
Thesis comment:	Univ. v Mariboru, Fak. za gradbeništvo
Pages:	191 str.
Keywords (UDC):	applied sciences;medicine;technology;uporabne znanosti;medicina;tehnika;building (construction) trade;building materials;building practice and procedure;gradbeništvo;gradbeni materiali;gradbene obrti in dela;building materials;building components;gradiva;gradbeni [konstrukcijski] deli;applied sciences;medicine;technology;uporabne znanosti;medicina;tehnika;chemical technology;chemical and related industries;kemijska tehnologija;kemijske in sorodne industrije;glass industry;ceramics;cement and concrete;industrija stekla;keramika;cement in beton;gypsum;lime and cement industries;hard-setting materials;plasters and compositions;mortar and concrete;industrije mavca;apna in cementa;vezivni materiali;ometi in sestavne zmesi;malta in beton;
ID:	998198