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Magnel Laboratory for Concrete Research – Department of Structural Engineering
Self-Compacting Concrete:State-of-the-artGeert DE SCHUTTER
21 March 2012, Ghent
Magnel Laboratory for Concrete Research 2
Self-Compacting Concrete
Magnel Laboratory for Concrete Research 3
Self-compacting concrete
• Fills the formwork like a liquid• No external compaction energy• Substantial ecological benefits
Magnel Laboratory for Concrete Research 4
SCC – Two Decades (?)
‘Modern’ SCC Japan, 1980’s
‘Parents’ Underwater concrete + Highly flowable concrete
‘Great great grandfather’ System ‘Non Plus’First developed in 1906 in Germany, and applied in Germany, the
Netherlands and Belgium in the 1910’s and 1920’sConsisted of liquid concrete poured into the formwork, without any
further compaction. Successfully applied for house construction, in spite of the heavy
competition of the more traditional approach relying on masonry. Due to problems related to the complex and expensive formworks, the
‘Non Plus’ system gradually faded away.
Magnel Laboratory for Concrete Research
System ‘Non Plus’
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SCC – Two Decades (?)
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SCC – Two Decades (?)
System ‘Non Plus’
Magnel Laboratory for Concrete Research
SCC - Two decades of research and practice
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Magnel Laboratory for Concrete Research
Selection of materials and mix design
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Magnel Laboratory for Concrete Research
Selection of materials and mix design
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State-of-the-artStandard materials for use in concrete are suitable for SCCA wide range of mix proportions exists to produce SCCCommon practice:
Powder-type SCC, VMA-type SCC, Mixed-type SCCBottleneck:Designing ROBUST SCC mixesFurther developments:Tailor made systems based on ternary or quaternary blends,Including synergetic effects.
Magnel Laboratory for Concrete Research
Selection of materials and mix design
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Porous interface
limestone
Dilution effect
Che
mic
al e
ffect P
hysical effectFi
ller e
ffect
Time
Isot
herm
al h
eat p
rodu
ctio
n ra
te Increasing limestone
filler content
Possible occurrence of new
hydration peak
Effect of limestone filler on cement hydration
Portland cement
Portland cement + limestone filler
Magnel Laboratory for Concrete Research
Selection of materials and mix design
11
State-of-the-art Bottlenecks Futuredevelopments
Selection of materials and mix design
Partly covered in STAR Reports:RILEM TC 174-SCCRILEM TC 188-CSC
Robustness RobustnessTailor-made blends
Magnel Laboratory for Concrete Research
Mixing process
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Magnel Laboratory for Concrete Research
2011
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Magnel Laboratory for Concrete Research
Mixing process
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(Schiessl, Mazanec, Lowke,2007).
Magnel Laboratory for Concrete Research
Mixing process
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• New development: vacuum mixing
Mortar/paste level Concrete level
Magnel Laboratory for Concrete Research
Mixing process
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Ongoing fundamental research project on vacuummixing (Ghent University & University College):
• Conventional Concrete, SCC, UHPC• Pore structure / Air void system• Rheology• Mechanical properties• Durability
Magnel Laboratory for Concrete Research
Mixing process
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State-of-the-art Bottlenecks Futuredevelopments
Mixing process Partly covered in STAR Reports:RILEM TC 188-CSC
Influence of mixingprocess oftenneglected or notunderstood
More fundamentalstudies of mixingprocess, includingadvanced mixingtechniques likevacuum mixing
Magnel Laboratory for Concrete Research
Pumping
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Magnel Laboratory for Concrete Research 19
Pumping
Precast industry – automated production process
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Pumping – Belgian Concrete pipe factory• High quality concrete pipes• Diameter up to 1.6 m• Length up to 3.2 m
Shift to more environment friendly production method?
Experiencedproblems: Noise, Vibration, Energy
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Pumping – Belgian Concrete pipe factory
Energy saving: about 60% of actual energy consumption
Estimated energy saving
Current productionmethod
Pumping SCC
Mixing Energy 0.4 GWh 0.6 GWhTransport Energy 0.2 GWh 0.042 GWhCompaction Energy 1.0 GWh 0.0 GWhFinishing Energy Neglected NeglectedTotal Energy 1.6 GWh 0.642 GWh
Magnel Laboratory for Concrete Research
Pumping on-site
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WFC Shanghai
SCC was applied for - foundation slab- central core- perimeter walls- mega-columns
SCC was pumped
Magnel Laboratory for Concrete Research
0
50
100
150
200
250
300
350
400
0 5 10 15
Yield stress:
SCC < TC
Viscosity
SCC > TC
Shear thickening
SCC is more fluid than TC.
RHEOLOGICAL RESULTSShear stress (Pa)
Shear rate (1/s)
TC
SCC
Pumping: fundamental study
Magnel Laboratory for Concrete Research
0
5
10
15
20
25
30
35
40
45
0 5 10 15 20 25
PUMPING RESULTS Pumping pressures for SCC are higher, especially at the higher discharges.
This is the opposite to the rheological results !!
The paradox of pumping SCCDischarge (l/s)
Pressure loss (kPa/m)
SCC
TC
Pumping: fundamental study
Magnel Laboratory for Concrete Research
Extrapolation of rheometer results, based on the measured shear stresses:
Viscosity (and shear-thickening) influences pumping pressures significantly, yield stress does not.
0
200
400
600
800
1000
1200
0 10 20 30 40 50
Shear stress (Pa)
Shear rate (1/s)
TC
SCC
Pumping: fundamental study
Magnel Laboratory for Concrete Research
Theoretical prediction of pressure losses
Bingham: Modified Bingham:
Overestimation with factor 2 to 5
Overestimation with factor 4 to 10
Conditions of use for (extended) Poiseuille formula:
No slippageHomogeneity
Pumping: fundamental study
γµττ &⋅+= p0 ²0 γγµττ && ⋅+⋅+= c
MAGNEL LABORATORY FOR CONCRETE RESEARCHHYDRAULICS LABORATORY
Theoretical prediction of pressure losses
Homogeneity ?
Pipe wall
Pipe centre-line
Lower concentration of aggregates
Pumping: fundamental study
MAGNEL LABORATORY FOR CONCRETE RESEARCHHYDRAULICS LABORATORY
Theoretical prediction of pressure losses
Homogeneity: geometrical wall effect
Pipe wall Shear stress: FIXED !!
Rheological properties
Shear rate
Velocity
Lower concentration of aggregates
Pipe centre-line
Pumping: fundamental study
MAGNEL LABORATORY FOR CONCRETE RESEARCHHYDRAULICS LABORATORY
Theoretical prediction of pressure losses
Homogeneity: geometrical wall effect + structural breakdown
Pipe wall
Pipe centre-line
Shear stress: FIXED !!Shear rate
Velocity
Pumping: fundamental study
MAGNEL LABORATORY FOR CONCRETE RESEARCHHYDRAULICS LABORATORY
Theoretical prediction of pressure losses
Homogeneity: G.W.E. + S.B. + dynamic segregation
Pipe wall
Pipe centre-line
Shear stress: FIXED !!Shear rate
Velocity
Lower concentration of aggregates
Pumping: fundamental study
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Pumping: fundamental study
Slip or no slip? That’s the question!
Ongoing research…
Magnel Laboratory for Concrete Research 32
Pumping: fundamental study
Slip or no slip? That’s the question!
Ongoing research…
Magnel Laboratory for Concrete Research
Pumping
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State-of-the-art Bottlenecks Futuredevelopments
Pumping Partly covered in STAR Reports:RILEM TC 188-CSC
Surface layer?Slip conditions?
Real velocitymeasurements, in order to understandsurface and slip conditions
Magnel Laboratory for Concrete Research
Filling of formwork
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Magnel Laboratory for Concrete Research
Filling of formwork
Magnel Laboratory for Concrete Research
Filling of formwork
Example:
Villa Gistel
(Belgium)
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Filling of formwork
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Simulation tools needed, in order to avoid non-appropriate filling,taking into account complex rheological behaviour of SCC/
Magnel Laboratory for Concrete Research
Filling of formwork
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Large scale testing at Ghent University
Magnel Laboratory for Concrete Research
Wall type A
•Dimensions 4 m x 2 m x 0.21 m
•SCC inlet: at the base on the short side
Filling of formwork
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Wall type B
•Dimensions 4 m x 2 m x 0.21 m
•SCC inlet: at the base and central
Magnel Laboratory for Concrete Research
Filling of formworkCFD + VOF techniques
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Governing equations – Navier-Stokes equations
•Conservation of mass (continuity equation):
•Conservation of momentum:
•Constitutive equation – Herschel-Bulkley:
Free surface flows – Volume of Fluid Method
Magnel Laboratory for Concrete Research
Filling of formwork
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Simulation results for wall A
Simulation results for wall B
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Filling of formwork
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New development: automatic connection valve
Patent pending
Magnel Laboratory for Concrete Research
Filling of formwork
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New development: automatic connection valve
Magnel Laboratory for Concrete Research
Video of casting operation
Filling of wall formwork Uncoupling of pipes
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Magnel Laboratory for Concrete Research
Filling of formwork
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State-of-the-art Bottlenecks Futuredevelopments
Filling of formwork
Partly covered in STAR Reports:RILEM TC 188-CSC
Complex behaviour, e.g. thixotropy.
Formwork pressure
Advancedmodelling, includingCFD.
Industrial development, e.g. valves.
Magnel Laboratory for Concrete Research
Hydration process
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Magnel Laboratory for Concrete Research
Hydration process
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Time
Isot
herm
al h
eat p
rodu
ctio
n ra
te Increasing limestone
filler content
Possible occurrence of new
hydration peak
Effect of limestone filler on cement hydration
Portland cement
Portland cement + limestone filler
Magnel Laboratory for Concrete Research
Hydration process
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Analytical modelling
Magnel Laboratory for Concrete Research
Hydration process
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embeddedparticles
outer product
inner product
expansion caused byembedded particles
δin;x
x/2 δx
HYMOSTRUC MODEL
Magnel Laboratory for Concrete Research
Hydration process
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Thermodynamic equilibrium calculations (Lothenbach et al)
Magnel Laboratory for Concrete Research
Hydration Process
51
State-of-the-art Bottlenecks Futuredevelopments
Hydrationprocess
Partly covered in STAR Reports:RILEM TC 205-DSC
Interaction cement-fillers-plasticizer notalways fullyunderstood, especially in ternary and quaternary blends
Advancedhydration modellingincludingthermodynamicmodelling and multi-scaleapproach to predictproperties.
Tailor made binders
Magnel Laboratory for Concrete Research
Mechanical properties
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Magnel Laboratory for Concrete Research
Mechanical properties
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BondCompression Shear
Magnel Laboratory for Concrete Research
Mechanical properties
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Compression
0
Peak strain [‰]
10
20
30
40
50
60
70
80
90
f c,cy
l [N
/mm
²]
CVC1CVC2CVC3SCC1SCC2SCC5SCC7
1.50 1.75 2.00 2.25 2.50 2.75 3.00
28211470.00Time [days]
0.01
0.02
0.03
0.04
0.05
0.06
0.07
SCC LSSCC BFSSCC FASCC SFSCC BFS+LSSCC FA+LS
Peak strain limestone-SCC higher than peak strain of CVC for same compressive strength
Influence filler type on peak strainLargest strains for limestone filler
Magnel Laboratory for Concrete Research
Mechanical properties
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Bond
Top-bar effect:
1700
200250450
150
200
150
200
500
500
0
250
500
750
1000
1250
1500
1750
1.00.5 1.5 2.0 2.5
Hei
ght [
mm
]
CVC1SCC1SCC2
16 mm
Smaller top-bar effect for SCC
Magnel Laboratory for Concrete Research
Mechanical properties
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Shear
ITZ qualityInterlock - dmax Bond
Shear strength
Influence limited
± 2-3%
Influence limited
± 2%
Influence significant
Around 8%
Magnel Laboratory for Concrete Research
Mechanical properties
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Adjusting models =
Taking benefit of better performance
Applying existing models =
Safe
Take-home message
Magnel Laboratory for Concrete Research
Mechanical properties
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State-of-the-art Bottlenecks Futuredevelopments
Mechanicalproperties
Partly covered in STAR Reports:RILEM TC 228-MPS
Some remainingissues like fatigueand tensionstiffening
Smarter use of (steel) fibers, takingprofit of alignmentdue to casting, combined withadvanced CFD modelling
TC 228-MPS: STAR report expected by end of 2012
Magnel Laboratory for Concrete Research
Durability
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Durability
Transport propertiesImportant factors (as for TVC):
‣W/C‣Degree of hydration‣Mineral additions
More general parameter:‣Capillary porosity‣More general and more accurate than W/C!
y = 1.8394x - 2.7394R2 = 0.8899
02468
101214161820
4 6 8 10 12
f cap [%]K
[10
-12 m
/s]
SCC
TC
Water permeability vs. capillary porosity in case of SCC and traditional concrete (TC)
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Durability of SCC
More details: State-of-the-art report of RILEM TC 205-DSC ‘Durability of Self-Compacting Concrete’, Published by RILEM, 2007.
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Durability in practice
EN 206 – 1 (2001): ‘Concrete – Specification, performance, production and conformity’- Only applicable to vibrated concrete SCC??- Exposure classes:
- XC4: ‘Cyclic wet and dry – concrete surfaces exposed to water contact’ - XS3: ‘Tidal, splash and spray zones – parts of marine structures’
- Concrete types: - minimum cement content- maximum W/C ratio- minimum compressive strength class additional requirement
Concrete type e.g. T(0.45)
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Durability in practice
As some general and practical conclusion it can be mentioned that the durability of SCC is at least as good as the durability of traditional concrete with similar W/C and cement content.
However, when the comparison is made based on strength, SCC might show a somewhat inferior durability.
New developments concerning practical durability issues:- Equivalent Concrete Performance Concept- Durability indicators
Magnel Laboratory for Concrete Research
Durability
64
State-of-the-art Bottlenecks Futuredevelopments
Durability Partly covered in STAR Reports:RILEM TC 205-DSC
Code prescription(similar as forTVC): ‘deemed to satisfy’
Durability indicators
ECPC
Magnel Laboratory for Concrete Research
Conclusion
During the last decades, concrete technology has shown a significant evolution
Self-compacting Concrete is a further step towards a tailor-made environment friendly concrete
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Acknowledgement
Dr. K. AudenaertDr. V. BoelDr. X. LiuDr. A.-M. PoppeDr. G. YeDr. D. FeysDr. B. CraeyeDr. P. Desnerck
(Former) co-workers of the Magnel Laboratory for Concrete Research
Ir. K. Lesage (KUL)Ir. J. DilsIr. S. TichkoIr. H.D. LeIr. I. PopIr. Y. GaoIr. Z. TanIr. S. Mu
Magnel Laboratory for Concrete Research
BBG Module SCC, avondcursus5, 12, 19 en 26 november 2012
Session 1: General introduction to SCC and constituent materials
Prof. Dr. Ir. G. De Schutter (UGent)
Session 2: Properties of fresh self-compacting concrete mixes
Ir. K. Lesage (KU Leuven)
Session 3: Mix design Dr. Ir.-Arch. P. Van Itterbeeck (WTCB)Session 4: Construction process Prof. Dr. Ir. G. De Schutter (UGent)Session 5: Hydration and microstructure
Prof. Dr. Ir. G. De Schutter (UGent)
Session 6: Engineering properties Dr. Ir. P. Desnerck (UGent)Session 7: Durability Prof. Dr. Ir. V. Boel (HoGent)Session 8: Standards, specifications and practical applications
Dr. Ir.-Arch. P. Van Itterbeeck (WTCB)
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