self compacting concrete - state of the art

8/10/2019 Self compacting concrete - State of the Art

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Magnel Laboratory for Concrete Research Department of Structural Engineering

Self-Compacting Concrete:

State-of-the-art

Geert DE SCHUTTER

21 March 2012, Ghent


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Magnel Laboratory for Concrete Research 2

Self-Compacting

Concrete


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Self-compacting concrete

Fills the formwork like a liquid

No external compaction energy

Substantial ecological benefits


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SCC Two Decades (?)

Modern SCC Japan, 1980 s

ParentsUnderwater concrete + Highly flowable concrete

Great great grandfatherSystem Non Plus

First developed in 1906 in Germany, and applied in Germany, theNetherlands and Belgium in the 1910 s and 1920 s

Consisted of l iquid 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.


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Magnel Laboratory for Concrete Research

System Non Plus

5

SCC Two Decades (?)


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SCC Two Decades (?)

System Non Plus


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SCC - Two decades of research and practice

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Selection of materials and mix design

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State-of-the-art

Standard materials for use in concrete are suitable for SCC

A wide range of mix proportions exists to produce SCC

Common practice:

Powder-type SCC, VMA-type SCC, Mixed-type SCC

Bottleneck:

Designing ROBUST SCC mixes

Further developments:

Tailor made systems based on ternary or quaternary blends,

Including synergetic effects.


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Porous

interface

limestone

Dilutioneffect

Chemicaleffec

t Physicaleffect

Filler

effect

Time

Isothermalheatproductionrate Increasing

limestone

filler content

Possibleoccurrence of new

hydration peak

Effect of limestone filler on cement hydration

Portland cement

Portland cement +

limestone filler


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Mixing process

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Mixing process

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(Schiessl, Mazanec, Lowke,2007).


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Mixing process

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New development: vacuum mixing

Mortar/paste level Concrete level


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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


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Mixing process

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State-of-the-art Bottlenecks Future

developments

Mixing process Partly covered in

STAR Reports:RILEM TC 188-CSC

Influence of mixing

process oftenneglected or not

understood

More fundamental

studies of mixingprocess, including

advanced mixing

techniques like

vacuum mixing


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Pumping

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Pumping

Precast industry automated production process


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Pumping Belgian Concrete pipe factory

Energy saving: about 60% of actual energy consumption

Estimated energy saving

Current production

method

Pumping SCC

Mixing Energy 0.4 GWh 0.6 GWh

Transport Energy 0.2 GWh 0.042 GWh

Compaction Energy 1.0 GWh 0.0 GWh

Finishing Energy Neglected Neglected

Total Energy 1.6 GWh 0.642 GWh


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Pumping on-site

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WFC Shanghai

SCC was applied for

- foundation slab

- central core- perimeter walls

- mega-columns

SCC was

pumped


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0

5

10

15

20

25

30

35

40

45

0 5 10 15 20 25

PUMPING RESULTS Pumpingpressures 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


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MAGNEL LABORATORY FOR CONCRETE RESEARCH

HYDRAULICS 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



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Homogeneity: geometrical wall effect + structural breakdown

Pipe wall

Pipe centre-line

Shear stress: FIXED !!Shear rate

Velocity



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Homogeneity: G.W.E. + S.B. + dynamic segregation

Pipe wall

Pipe centre-line

Shear stress: FIXED !!Shear rate

Velocity

Lower concentration

of aggregates



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Slip or no slip? Thats the question!

Ongoing research


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Slip or no sl ip? Thats the question!

Ongoing research


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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


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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


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Filling of formwork

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New development: automatic connection valve


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Video of casting operation

Filling of wall formwork Uncoupling of pipes

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Filling of formwork

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developments

Filling of

formwork

Partly covered in

STAR Reports:RILEM TC 188-CSC

Complex

behaviour, e.g.thixotropy.

Formwork pressure

Advanced

modelling, includingCFD.

Industrial

development, e.g.

valves.


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Hydration process

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Hydration process

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Time

Is

othermalheatpro

ductionrate Increasing

limestone

filler content

Possible

occurrence of new

hydration peak

Effect of limestone filler on cement hydration

Portland cement

Portland cement +

limestone filler


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Hydration process

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Analytical modelling


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Hydration process

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Thermodynamic equilibrium calculations (Lothenbach et al)


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Hydration Process

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developments

Hydration

process

Partly covered in

STAR Reports:RILEM TC 205-DSC

Interaction cement-

fillers-plasticizer notalways fully

understood,

especially in

ternary and

quaternary blends

Advanced

hydration modellingincluding

thermodynamic

modelling and

multi-scale

approach to predict

properties.

Tailor made binders


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BondCompression Shear


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Compression

0

Peak strain []

10

20

30

40

50

60

70

80

90

fc,cyl

[N/mm]

CVC1CVC2

CVC3SCC1SCC2

SCC5

SCC7

1.50 1.75 2.00 2.25 2.50 2.75 3.00

28211470.00

Time [days]

0.01

0.02

0.03

0.04

0.05

0.06

0.07

SCC LSSCC BFS

SCC FASCC SF

SCC BFS+LS

SCC FA+LS

Peak strain limestone-

SCC higher than peak

strain of CVC for same

compressive strength

Influence filler type on peak strain

Largest strains for limestone filler


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Bond

Top-bar effect:

1700

200250

450

150

200

150

200

500

500

0

250

500

750

1000

1250

1500

1750

1.00.5 1.5 2.0 2.5

Height[mm]

CVC1

SCC1

SCC2

16 mm

Smaller top-bar effect for SCC


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Shear

ITZ qualityInterlock - dmax Bond

Shear strength

Influence limited

2-3%

Influence limited

2%

Influence significant

Around 8%


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Adjusting models

=Taking benefit of better performance

Applying existing models

=

Safe

Take-home message


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Durability

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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 mentionedthat 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


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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. Boel

Dr. X. Liu

Dr. A.-M. Poppe

Dr. G. Ye

Dr. D. Feys

Dr. B. Craeye

Dr. P. Desnerck

(Former) co-workers of the Magnel Laboratory forConcrete Research

Ir. K. Lesage (KUL)Ir. J. Dils

Ir. S. Tichko

Ir. H.D. Le

Ir. I. PopIr. Y. Gao

Ir. Z. Tan

Ir. S. Mu


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BBG Module SCC, avondcursus

5, 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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self compacting concrete - state of the art

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