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Publications (4 of 4) Show all publications
Lundgren, M., Babaahmadi, A. & Mueller, U. (2018). Exposure experiments in sulfate containing solution, including exposure at low temperature.
Open this publication in new window or tab >>Exposure experiments in sulfate containing solution, including exposure at low temperature
2018 (English)Report (Other academic)
Abstract [en]

This report describes results of an investigation on the sulfate resistance of dual blended binder of mortar and concrete specimens over a period of 1 year. The focus is on showing the importance of the chemistry of the components when discussing sulfate resistance and the relation of that to the hydrate phase assemblage. Moreover the importance of the test method for evaluations is pointed out.

Publisher
p. 30
Series
RISE Rapport ; 2018:09
Keywords
Cement, Supplementary Cementitious Materials (SCM), Testing, Sulfate ingress
National Category
Materials Chemistry Civil Engineering
Identifiers
urn:nbn:se:ri:diva-34868 (URN)978-91-88695-44-4 (ISBN)
Available from: 2018-08-21 Created: 2018-08-21 Last updated: 2019-06-18Bibliographically approved
Lundgren, M., Helsing, E., Babaahmadi, A. & Mueller, U. (2018). State-of-the-Art Report on: Material Type, Requirements and Durability aspects of Sprayed Concrete in Tunnels.
Open this publication in new window or tab >>State-of-the-Art Report on: Material Type, Requirements and Durability aspects of Sprayed Concrete in Tunnels
2018 (English)Report (Other academic)
Abstract [en]

The report summarizes a state-of-the-art for sprayed concrete applied for ground support in tunnel environments, in Sweden and several European countries, with focus on the components, the mix design and the guidelines and specifications. It focuses also on the addition of supplementary cementitious materials (SCM), where the use, the common practice and the long-term experience vary from country to country. The report presents numerous examples of applications in Sweden and seven other European countries. It also gives an overview about the possible exposure risks and summarizes the relevant durability issues. Along with specifications in international standards and guidelines it also reviews the national requirements in Sweden, Norway, Finland, Austria, France, Germany and Switzerland.

Publisher
p. 64
Series
RISE Rapport ; 2018:08
Keywords
sprayed concrete, underground constructions, mix design, applications in Sweden and other countries, requirements in standards, guidelines, durability
National Category
Civil Engineering Infrastructure Engineering
Identifiers
urn:nbn:se:ri:diva-34865 (URN)978-91-88695-43-7 (ISBN)
Available from: 2018-08-21 Created: 2018-08-21 Last updated: 2019-06-18Bibliographically approved
Mueller, U., Lundgren, M. & Babaahmadi, A. (2017). Hydration of concrete binders blended with ground granulated blast furnace slag, fly ash and metakaolin.
Open this publication in new window or tab >>Hydration of concrete binders blended with ground granulated blast furnace slag, fly ash and metakaolin
2017 (English)Report (Other academic)
Abstract [en]

This report describes a study on the effects of ground granulated blast furnace slag, low calcium fly ash and metakaolin on the hydration behavior of different binder pastes blended with these SCM. The study investigated early heat development, phase assemblages at different ages, strength gain, changes in porosity and pore sizes, pore water OH-concentration, development of the microstructure and the micro chemistry of the binder pastes.It was shown that all SCM impact the pore size distribution of pastes of different ages. Compared to a reference paste without SCM, SCM containing pastes shift their pore size range to smaller sizes, the more SCM the pastes contain. The total porosity depends on the type of SCM. With slag, there was a tendency to decrease the total porosity with increasing SCM content. With fly ash, total porosity was increased with increasing fly ash content. The strength development of slag and fly ash containing mortars is under that of a Portland cement reference mortar within the first 28 days. However, after 28 d strength gain, in particular with fly ash is considerable compared to the reference. With metakaolin already at early ages a strong increase in strength was observed. After that, the strength development was parallel the one of the reference mortar. Aluminum containing SCM contribute to the formation of AFm phases. AFm phases increase the chloride binding in seawater or deicing salt exposed concretes. In particular metakaolin and fly ash contribute, due to their high alumina content, to the formation of AFm phases but also increase the aluminum content in the C-S-H phases.

Abstract [sv]

Rapporten beskriver en studie om inverkan av tillsatsmaterial (SCM) som mald granulerad masugnslagg, kiselhaltig flygaska och metakaolin på hydratationsförloppet hos cementpastor med sammansatta bindemedel, dvs en blandning av cement och en av dessa SCM.Studien undersökte den tidiga värmeutvecklingen, vilka cementhydratfaser som utvecklas vid olika ålder, hållfasthetsutvecklingen, förändringarna i porositet och porstorlekar, porvattnets OH-koncentration och utvecklingen av mikrostruktur och mikrokemi i cementpastan, beroende bindemedlets sammansättning.Studien visar att samtliga tillsatsmaterial (SCM) påverkar porstorleksfördelningen i cementpastan. Jämfört med en referenspasta med enbart cement, sker i cementpastor med blandcement (cement plus SCM) en ändring mot finare porstorlekar, dvs mindre pordiameter, ju högre andelen SCM i blandningen är. Den totala porositeten beror på vilken typ av SCM som används i blandningen. Slagg visade tendensen att leda till minskad total porositet med ökande slagghalt. Med flygaska ökade däremot den totala porositeten med ökande halt flygaska.Hållfastheten som utvecklas hos bruk med bindemedel med slagg och flygaska är lägre än den hos referensbruk med enbart Portland cement, under de första 28 dygnen. Efter 28 dygn märks däremot en mer markant hållfasthetsutveckling jämfört med referensbruket, i synnerhet hos bruk med flygaska. Med metakaolin noterades en markant ökning av hållfastheten redan under de första dygnen, men hållfasthetsutvecklingen fortsatte därefter i samma takt som (parallellt med) referensbruket.Aluminiumhaltiga SCM leder vid hydratation till bildning av hydratfaser av typen AFm.AFm-faser bidrar till ökad kloridbindning i cementpastan, en fördel för betong som utsätts för t ex havsvatten eller avisningssalter på vintervägar. I synnerhet metakaolin och flygaska, tack vare den höga aluminiumhalten, leder till cementhydrater av typen AFm, samtidigt som de även ökar aluminiumhalten i kalciumsilikathydraten (C-S-H-faser).

Publisher
p. 78
Series
CBI rapport, ISSN 0346-8240 ; 2017:6
Keywords
blended binders, hydration, phase assemblages, slag, fly ash, metakaolin, cement
National Category
Other Materials Engineering Civil Engineering
Identifiers
urn:nbn:se:ri:diva-33622 (URN)978-91-980851-6-7 (ISBN)
Available from: 2018-04-11 Created: 2018-04-11 Last updated: 2019-06-18Bibliographically approved
Babaahmadi, A., Tang, L., Abbas, Z., Zack, T. & Mårtensson, P. (2015). Development of an electro-chemical accelerated ageing method for leaching of calcium from cementitious materials (ed.). Materials and Structures, 49(1-2), 705-718
Open this publication in new window or tab >>Development of an electro-chemical accelerated ageing method for leaching of calcium from cementitious materials
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2015 (English)In: Materials and Structures, ISSN 1359-5997, E-ISSN 1871-6873, Vol. 49, no 1-2, p. 705-718Article in journal (Refereed) Published
Abstract [en]

To facilitate the long term durability predictions of nuclear waste repositories, acceleration methods enhancing calcium leaching process from cementitious materials are needed, even though mechanisms not necessarily comparable to those predominant in a natural leaching process may be developed. In the previously published acceleration methods the samples are very small, which limits further physical or mechanical tests. In this paper, a new acceleration method based on electro-chemical migration is presented. The method although not driven with the same kinetics as in natural leaching, was designed in such a way that unnecessarily destructive by-effects could be minimized while promoting a higher leaching rate for a sample size suitable for further testing the mechanical and physical properties. It is shown that approximately 1 × 106C of electrical charge per paste specimen of size Ø50 × 75 mm (approximately 230 g) is required to leach out the total amount of Portlandite. The chemical and mineralogical properties of leached samples are characterized by various techniques. It is concluded that aged samples are comparable to those leached in a natural leaching process as both are characterized by a layered system comprising an unaltered core delineated by total dissolution of Portlandite followed by a progressive decalcification of the calcium silicate hydrate gel.

Keywords
Acceleration method, Calcium leaching, Mineralogical properties, Nuclear waste management, Service life
National Category
Other Materials Engineering
Identifiers
urn:nbn:se:ri:diva-2686 (URN)10.1617/s11527-015-0531-8 (DOI)4800 (Local ID)4800 (Archive number)4800 (OAI)
Available from: 2016-09-07 Created: 2016-09-07 Last updated: 2019-07-03Bibliographically approved
Organisations
Identifiers
ORCID iD: ORCID iD iconorcid.org/0000-0002-4422-0430

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