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Modelling of Bingham Suspensional Flow: Influence of Viscosity and Particle Properties Applicable to Cementitious Materials
KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Concrete Structures.
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 [en]
Self-Compacting Concrete, SCC, Fresh concrete flow, Numerical simulation, Viscosity, Open channel flow
National Category
Materials Engineering
Identifiers
URN: urn:nbn:se:kth:diva-163040OAI: oai:DiVA.org:kth-163040DiVA: diva2:798394
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
List of papers
1. 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
2. Simulation of Fresh Concrete Channel Flow: Evaluation of Rheological Parameters
Open this publication in new window or tab >>Simulation of Fresh Concrete Channel Flow: Evaluation of Rheological Parameters
2010 (English)In: 8th fib International PhD Symposium in Civil Engineering, 2010, 389-394 p.Conference paper, Published paper (Other academic)
National Category
Infrastructure Engineering
Identifiers
urn:nbn:se:kth:diva-68334 (URN)
Conference
8th fib International PhD Symposium in Civil Engineering, Lyngby, Denmark, June 20-23
Note
QC 20120424Available from: 2012-01-27 Created: 2012-01-27 Last updated: 2015-03-26Bibliographically approved
3. Obtaining rheological parameters from flow test - Analytical, computational and lab test approach
Open this publication in new window or tab >>Obtaining rheological parameters from flow test - Analytical, computational and lab test approach
2014 (English)In: Cement and Concrete Research, ISSN 0008-8846, E-ISSN 1873-3948, Vol. 63, 29-34 p.Article in journal (Refereed) Published
Abstract [en]

In the mix design process of cementitious suspensions, an adequate rheology of the cement paste is crucial. A novel rheological field test device for cementitious fluids is presented here and investigated theoretically, by computer simulation and by lab tests. A simple flow stoppage test with a timed spread passage point provides accurate rheological parameters according to the Bingham material model. Values for yield stress and plastic viscosity are obtained for a test specimen of no more than 19.75 . 10(-6) m(3) of fluid. This volume is equivalent to 19.75 g of water at room temperature. Such a small volume allows reliable tests even for small amounts of fillers. Promising results show that both yield stress and plastic viscosity can be determined by this simple test. This novel rheological test method also enables the correlation of different rheological equipment used by different laboratories.

Keyword
Simulation, Cement paste, Workability Bingham material model, Rheology, Modeling, Mortar
National Category
Materials Engineering
Identifiers
urn:nbn:se:kth:diva-163037 (URN)10.1016/j.cemconres.2014.03.012 (DOI)000340141300004 ()2-s2.0-84900990005 (Scopus ID)
Note

QC 20150326

Available from: 2015-03-26 Created: 2015-03-26 Last updated: 2017-12-04Bibliographically approved
4. Evaluation of crushed fine materials
Open this publication in new window or tab >>Evaluation of crushed fine materials
(English)Manuscript (preprint) (Other academic)
Identifiers
urn:nbn:se:kth:diva-163038 (URN)
Note

QS 2015

Available from: 2015-03-26 Created: 2015-03-26 Last updated: 2015-03-26Bibliographically approved
5. Particle Motion in Fluid: Analytical and Numerical Study
Open this publication in new window or tab >>Particle Motion in Fluid: Analytical and Numerical Study
(English)Manuscript (preprint) (Other academic)
Identifiers
urn:nbn:se:kth:diva-163039 (URN)
Note

QS 2015

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

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