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Numerical Simulation of Fresh SCC Flow: Applications
Swedish Cement and Concrete Research Institute.
Swedish Cement and Concrete Research Institute.ORCID iD: 0000-0002-1526-9331
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.

Place, publisher, year, edition, pages
2011. Vol. 44, no 4, 805-813 p.
Keyword [en]
Numerical simulation, SCC, Fresh concrete, Rheology, Concrete flow
National Category
Civil Engineering
Identifiers
URN: urn:nbn:se:kth:diva-25205DOI: 10.1617/s11527-010-9666-9ISI: 000289002400006OAI: oai:DiVA.org:kth-25205DiVA: diva2:356454
Note
QC 20101012. Updated from submitted to published, 20120315Available from: 2010-10-12 Created: 2010-10-12 Last updated: 2017-12-12Bibliographically approved
In thesis
1. Numerical Modelling of Self-Compacting Concrete Flow: Discrete and Continuous Approach
Open this publication in new window or tab >>Numerical Modelling of Self-Compacting Concrete Flow: Discrete and Continuous Approach
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
SCC, rheology, Simulation of Flow, Simulering, Flöde, Självkompakterande Betong, Reologi
National Category
Other Materials Engineering
Identifiers
urn:nbn:se:kth:diva-10288 (URN)
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
2. Modelling of Bingham Suspensional Flow: Influence of Viscosity and Particle Properties Applicable to Cementitious Materials
Open this publication in new window or tab >>Modelling of Bingham Suspensional Flow: Influence of Viscosity and Particle Properties Applicable to Cementitious Materials
2015 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

Simulation of fresh concrete flow has spurged with the advent of Self-Compacting Concrete, SCC. The fresh concrete rheology must be compatible with the reinforced formwork geometry to ensure complete and reliable form filling with smooth concrete surfaces. Predicting flow behavior in the formwork and linking the required rheological parameters to flow tests performed on the site will ensure an optimization of the casting process.

In this thesis, numerical simulation of concrete flow and particle behaviour is investigated, using both discrete as well as a continuous approach. Good correspondence was achieved with a Bingham material model used to simulate concrete laboratory tests (e.g. slump flow).

It is known that aggregate properties such as size, shape and surface roughness as well as its grading curve affect fresh concrete properties. An increased share of non-spherical particles in concrete increases the level of yield stress, τ0, and plastic viscosity, µpl. The yield stress level may be decreased by adding superplasticizers, however, the plastic viscosity may not. An explanation for the behaviour of particles is sought after experimentally, analytically and numerically. Bingham parameter plastic viscosity is experimentally linked to particle shape. It was found that large particles orient themselves aligning their major axis with the fluid flow, whereas small particles in the colloidal range may rotate between larger particles. The rotation of crushed, non-spherical fine particles as well as particles of a few microns that agglomorate leads to an increased viscosity of the fluid.

Generally, numerical simulation of large scale quantitative analyses are performed rather smoothly with the continuous approach. Smaller scale details and phenomena are better captured qualitatively with the discrete particle approach. As computer speed and capacity constantly evolves, simulation detail and sample volume will be allowed to increase.

A future merging of the homogeneous fluid model with the particle approach to form particles in the fluid will feature the flow of concrete as the physical suspension that it represents. One single ellipsoidal particle in fluid was studied as a first step.

 

 

Place, publisher, year, edition, pages
Stockholm: KTH Royal Institute of Technology, 2015. xiii, 53 p.
Series
TRITA-BKN. Bulletin, ISSN 1103-4270 ; 128
Keyword
Self-Compacting Concrete, SCC, Fresh concrete flow, Numerical simulation, Viscosity, Open channel flow
National Category
Materials Engineering
Identifiers
urn:nbn:se:kth:diva-163040 (URN)
Public defence
2015-04-10, Kollegiesalen, Brinellvägen 8, KTH, Stockholm, 10:00 (English)
Opponent
Supervisors
Note

QC 20150326

Available from: 2015-03-26 Created: 2015-03-26 Last updated: 2015-03-26Bibliographically approved

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