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Numerical Modelling of Self-Compacting Concrete Flow: Discrete and Continuous Approach
KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Structural Design and Bridges (name changed 20110630).
2009 (English)Licentiate thesis, comprehensive summary (Other academic)
Abstract [en]

With the advent of Self-Compacting Concrete (SCC) that flows freely, under the soleinfluence of gravity, the wish for hassle-free and predictable castings even in complexcases, spurged the simulation of concrete flow as a means to model and predictconcrete workability. To achieve complete and reliable form filling with smoothsurfaces of the concrete, the reinforced formwork geometry must be compatible withthe rheology of the fresh SCC. Predicting flow behavior in the formwork and linkingthe required rheological parameters to flow tests performed on the site will ensurean optimization of the casting process.In this thesis, numerical simulation of concrete flow is investigated, using both discreteas well as continuous approaches.The discrete particle model here serves as a means to simulate details and phenomenaconcerning aggregates modeled as individual objects. The here presented cases aresimulated with spherical particles. However, it is possible to make use of nonsphericalparticles as well. Aggregate surface roughness, size and aspect ratio maybe modeles by particle friction, size and clumping several spheres into forming thedesired particle shape.The continuous approach has been used to simulate large volumes of concrete. Theconcrete is modeled as a homogeneous material, particular effects of aggregates,such as blocking or segregation are not accounted for. Good correspondence wasachieved with a Bingham material model used to simulate concrete laboratory tests(e.g. slump flow, L-box) and form filling. Flow of concrete in a particularly congestedsection of a double-tee slab as well as two lifts of a multi-layered full scale wall castingwere simulated sucessfully.A large scale quantitative analysis is performed rather smoothly with the continuousapproach. Smaller scale details and phenomena are better captured qualitativelywith the discrete particle approach. As computer speed and capacity constantlyevolves, simulation detail and sample volume will be allowed to increase.A future merging of the homogeneous fluid model with the particle approach to formparticles in the fluid will feature the flow of concrete as the physical suspension thatit represents. One single ellipsoidal particle falling in a Newtonian fluid was studiedas a first step.

Abstract [sv]

Med uppkomsten av självkompakterande betong (SKB) och dess möjligheter att flyta ut under inverkan av endast gravitation uppstod ett behov av att kunna förutsäga och kontrollera även mer komplicerade gjutningar. Numerisk simulering av SKBs flöde kan kommma att utgöra ett kraftfullt verktyg för att optimera gjutprocessen, ge möjlighet att förutsäga nödbvändig arbetbarhet och säkerställa kompatibilitet mellan den armerade formen och betongens reologi. I föreliggande avhandling undersöks betongens flöde med både diskreta och kontinuumbaserade simuleringsmetoder. Den diskreta partikelmodellen används för att simulera detaljer och fenomen hos t.ex. ballast i betong. I de här presenterade simuleringarna används sfäriska partiklar, men det är även möjligt att skapa ballastkorn av olika form. Ballastens ytråhet och storlek kan modelleras med parametrar för friktion och storlek medan sammanfogning av ett flertal partiklar kan ge ekvivalent form. Den kontinuumbaserade ansatsen används för att simulera större flödesmängder. Betongen modelleras som ett homogent material, eventuella effekter av ballastens inverkan, till exempel blockering eller separation, ingår ej. God överensstämmelse har uppnåtts med Binghams materialmodell som applicerats på några av SKBs provningsmetoder (bl a flytsättmått och L-låda) liksom även för större gjutningar. Formfyllnad av en hårt armerad sektion av ett STT-element, liksom två pumpade betongleveranser till en hög vägg, har framgångsrikt simulerats. En kvantitativ övergripande analys av betongflödet i formen kan göras med den kontinuumbaserade ansatsen för att upptäcka zoner med eventuella svårigheter. En högupplöst detaljstudie kompletterar sedan analysen på valda delar av och kring dessa zoner för att fånga partikelfenomen kvalitativt med hjälv av den diskreta modellen. Då datorkapaciteten ökar kommer även större volymer med högre detaljrikedom att kunna simuleras. En framtida modell simulerar med stor sannolikhet partiklar i flöde, vilket till fullo kan fånga betongens egenskaper som suspension. Som ett första steg på vägen har en fallande ellipsoid i en newtonsk vätska simulerats.

Place, publisher, year, edition, pages
Stockholm: US-AB , 2009. , xii, 60 p.
Series
Trita-BKN. Bulletin, ISSN 1103-4270 ; 99
Keyword [en]
SCC, rheology, Simulation of Flow
Keyword [sv]
Simulering, Flöde, Självkompakterande Betong, Reologi
National Category
Other Materials Engineering
Identifiers
URN: urn:nbn:se:kth:diva-10288OAI: oai:DiVA.org:kth-10288DiVA: diva2:214194
Presentation
2009-05-04, L1, KTH, Stockholm, 13:15 (English)
Opponent
Supervisors
Available from: 2009-05-07 Created: 2009-05-04 Last updated: 2012-02-21Bibliographically approved
List of papers
1. Computer-aided modelling and simulation of self-compacting concrete flow
Open this publication in new window or tab >>Computer-aided modelling and simulation of self-compacting concrete flow
2007 (English)In: Proceedings pro054: Self-Compacting Concrete - SCC 2007 / [ed] G. De Schutter and V. Boel, RILEM Publications SARL , 2007, 455-460 p.Conference paper, Published paper (Refereed)
Abstract [en]

 The flow behaviour of SCC is currently being investigated as an ongoing PhD project. This paper presents a development of the Distinct Element Method using the commercial software PFC3D to model the flow of SCC. A good correspondence was obtained between laboratory test and numerical result for the slump flow test.

Place, publisher, year, edition, pages
RILEM Publications SARL, 2007
National Category
Other Materials Engineering
Identifiers
urn:nbn:se:kth:diva-25201 (URN)978-2-35158-047-9 (ISBN)
Conference
5th International RILEM Symposium on Self-Compacting Concrete, SCC 2007, Ghent, Belgium, 3-5 September 2007
Note
QC 20101012Available from: 2010-10-12 Created: 2010-10-12 Last updated: 2010-10-12Bibliographically approved
2. Computer simulation of SCC flow
Open this publication in new window or tab >>Computer simulation of SCC flow
2007 (English)In: Betonwerk und Fertigteil-Technik/Concrete Plant and Precast Technology, ISSN 0373-4331, Vol. 73, no 8, 40-48 p.Article in journal (Refereed) Published
Abstract [en]

Starting in 1993, Sweden was, inspired by Japanese research in the concrete field, the first European country to develop the revolutionary material called Self Compacting Concrete (SCC). The Swedish Cement and Concrete Research Institute (CBI) was one of the pioneer research environments on SCC in Europe; f. i. the first European SCC bridges were cast in Sweden in 1998. Furthermore, an SCC flow a simulation project was started; in 2000 at CBI. The used particle based software is icalled Particle Flow Code (PFC) and is based on the Distinct Element Method (DEM).

Keyword
Compaction, Computer simulation, Computer software, Numerical methods
National Category
Other Materials Engineering
Identifiers
urn:nbn:se:kth:diva-25204 (URN)2-s2.0-34548257776 (Scopus ID)
Note

QC 20101012

[Computersimulation des fließverhaltens von SVB]

Available from: 2010-10-12 Created: 2010-10-12 Last updated: 2014-11-11Bibliographically approved
3. Numerical Simulation of Fresh SCC Flow: Applications
Open this publication in new window or tab >>Numerical Simulation of Fresh SCC Flow: Applications
2011 (English)In: Materials and Structures, ISSN 1359-5997, E-ISSN 1871-6873, Vol. 44, no 4, 805-813 p.Article in journal (Refereed) Published
Abstract [en]

Numerical simulation of self-compacting concrete (SCC) flow shows great potential for developing into a powerful tool for prediction of SCC form filling. Numerical simulation is also of interest for modelling small scale material phenomena. This paper presents three different applications useful for modelling different phenomena on different scales: (i) particles, each representing an aggregate in the concrete, (ii) fluid, modelling concrete as a homogeneous liquid and (iii) particle in fluid, studying details of flow. The methods are compared and evaluated in order to give the reader a quick guidance into the world of possibilities that open up with numerical simulation.

Keyword
Numerical simulation, SCC, Fresh concrete, Rheology, Concrete flow
National Category
Civil Engineering
Identifiers
urn:nbn:se:kth:diva-25205 (URN)10.1617/s11527-010-9666-9 (DOI)000289002400006 ()
Note
QC 20101012. Updated from submitted to published, 20120315Available from: 2010-10-12 Created: 2010-10-12 Last updated: 2017-12-12Bibliographically approved
4. Linking Numerical Simulation of Fresh Concrete Flow to On-Site Casting
Open this publication in new window or tab >>Linking Numerical Simulation of Fresh Concrete Flow to On-Site Casting
2009 (English)In: Cement and Concrete Research, ISSN 0008-8846, E-ISSN 1873-3948Article in journal (Refereed) Submitted
National Category
Civil Engineering
Identifiers
urn:nbn:se:kth:diva-25207 (URN)
Note
QS 20120315Available from: 2010-10-12 Created: 2010-10-12 Last updated: 2017-12-12Bibliographically approved

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