Particle Packing: An Effective Approach to Optimize Design of Self

Consolidating Concrete

Dr. Xuhao Wang

SCC: The Good, the Bad, and the Ugly

• The Good,Labor cost savingsAesthetic finishRapid placementSelf-consolidating through heavy

reinforced structures

2Boehm, 2008

SCC: The Good, the Bad, and the Ugly

• The Bad,SegregationFormwork pressure

3Khrapko, 2007

SCC: The Good, the Bad, and the Ugly

• The ugly,Early age crackingRobustness

4Sludge Soup

Dosage

Background

• Developed in Japan (~1990s)• Aim at flow without vibration or

mechanical consolidation• Features:High-range water reducer admixture

(polycarboxylate)Viscosity modifying admixture (VMA)High cementitious materials or powder

content Smaller coarse aggregate for flowability

5ACI 237 report

SCC Strategies

6

SCC Strategies– High paste content– VMA (thickeners)– Smaller aggregate &

controlled gradation– HRWR, SP– Mineral fillers & additives

Properties– Stability– Shrinkage and

creep– Strength and

Stiffness

Performance– Segregation– Early age cracking– Deformation– Prestress Loss– Long Term Durability

Lange et al. 2007

Properties We Measure

• Fresh SCCFlow/filling abilitySlump flow and T50 (ASTM 2009)V-funnel (Omoto 1999)Orimet test (Bartos 1998)

Passing abilityJ-ring, L or U-box (ASTM C1621)Filling vessel test (Khayat 1999)

7

Properties We Measure

StabilityFresh and hardened visual stability index

(ASTM C1611 and Shen 2007)Column technique (ASTM C1610)Probes

8

Properties We Measure

• Physical propertiesFormwork pressure

Cementitious material type and contentCoarse aggregateViscosity-modifying admixturesCasting rate and temperatureWall friction

Shape retentionSlip-form SCC development (Wang et al.)

PumpabilityRheometer testsFull-scale pumping test

9

Feys et al. 2010

Properties We Measure• Hardened SCCMechanical properties

Compressive strengthTensile strengthBond strength – pull out testMOEShear strength

Visco-elastic propertiesShrinkage Creep

Heat of hydration (Setting)Adiabatic isothermal

10

Properties We Measure

• Durability propertiesPermeability Water transportGas transportIon transport

Freeze and Thaw ResistanceScalingASR

11

Boel et al. 2007

What Do We Care?

• The owner wants:SafetyCost effective DurableStrongAesthetic

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What Do We Care?• The contractor wants:Cost effectiveWorkmanshipCrack freeSafeNo challenges for cast-in-place

applicationsCalculate form pressure through full liquid head to

design formworkProper sizing of lines and equipment (mix design,

pipe network and operator error)Shape stability for cross slopes, i.e., SFSCCClean forms and good timing (setting time)

13

What Do We Care?

• The researcher wants:Make contractor and owner

happier

14Burrows 1998

Motivation• Essential for mix designAggregate systemPaste quality Paste quantity

• Minimizing void content among aggregate particlePermit more paste to cover aggregate

surfaces in a given concrete system Improve workabilityReduce capillary poresEnhance concrete strength and

durability15

Koehler

Key Point

16

17

Particle Packing Theory

18Wong and Kwan 2005

Background

• Particle packing in mix designMotivation:To minimize void fraction while ensuring

sufficient workability and performanceFurther reduce w/cmDensify pre-hydrated mixtureDensify hydration product

Particle packing modelsContinuous Discrete

19

Background

• Continuous packing model development– Fuller model=> A&A model (1968)=>Bolomey

(1947)=>Plum (1950)=>Funk and Dinger(1994)

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Background

• Discrete element solution

21

He et al. (2009)

Pre-Proportioning Testing Methods

• Packing densityDry conditionRodded or unrodded unit weight to find out void

fractionWet conditionRealisticSuperplasticizer effectVibration can be simulatedBlending effect

22Brouwers and Radix 2005

Proposed Proportioning Method

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Note:Fix valueChange in accordance with applications and materials

Cast-in-Place Bridge ComponentSCC ClassesFlowability 1Segregation Resistance 1Viscocity 1Passingability 1Aggregates InformationMaximum Nominal Aggregate Size (NMSA) 3/4"Coarse Aggregate Type and S.G. Crushed limestone 2.74Fine Aggregate Type and S.G. Natural sand 2.68Cement Type and S.G. Type I/II 3.15SCM Type, S.G., and % Replacement Fly Ash C 2.4 25%Air Content 5‐8%Water Content, lb/cy Use shown TableDistribution modulus q 0.25 0.2-0.45

Proposed Proportioning Method

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Percentage PassingDiameter (um)Coarse Fine Cement C Ash Target Mix Sq. errorMin D (um) 1Max D (um) 19000

25400 100.00% 100.00% 100.00% 100.00% 100.00% 100.00% 019000 92.00% 100.00% 100.00% 100.00% 100.00% 96.42% 0.00127940712500 58.00% 100.00% 100.00% 100.00% 89.14% 81.22% 0.0062643669500 41.00% 100.00% 100.00% 100.00% 82.61% 73.62% 0.0080780394750 9.20% 98.27% 100.00% 100.00% 67.98% 58.77% 0.0084913022360 1.00% 87.81% 100.00% 100.00% 55.58% 51.28% 0.0018538611180 0.00% 72.30% 100.00% 100.00% 45.26% 45.16% 1.01565E‐06600 0.00% 43.30% 100.00% 100.00% 36.77% 34.55% 0.000493109300 0.00% 14.08% 100.00% 100.00% 29.44% 23.86% 0.003113648150 0.00% 0.63% 100.00% 100.00% 23.27% 18.94% 0.00187919990 0.00% 0.01% 100.00% 96.45% 19.37% 18.51% 7.38148E‐0575 0.00% 0.52% 99.92% 95.19% 18.09% 18.61% 2.75761E‐0563 0.00% 0.00% 99.44% 93.65% 16.92% 18.27% 0.00018299553 0.00% 0.00% 98.32% 91.77% 15.81% 18.02% 0.00048808745 0.00% 0.00% 96.58% 89.64% 14.80% 17.67% 0.00082281138 0.00% 0.00% 93.93% 87.09% 13.81% 17.18% 0.00114005532 0.00% 0.00% 90.07% 84.00% 12.83% 16.50% 0.00134712225 0.00% 0.00% 83.69% 79.65% 11.51% 15.43% 0.00153482620 0.00% 0.00% 76.00% 74.97% 10.38% 14.16% 0.00142889516 0.00% 0.00% 67.53% 70.09% 9.31% 12.78% 0.00120289310 0.00% 0.00% 50.52% 60.05% 7.25% 9.99% 0.0007547857 0.00% 0.00% 39.22% 52.42% 5.83% 8.09% 0.000508413 0.00% 0.00% 19.52% 34.34% 2.94% 4.50% 0.0002410671 0.00% 0.00% 4.56% 10.72% 0.00% 1.20% 0.000144907

Sum of sq. error: 0.041352189

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Ingredient Recommendation ReferenceVolume (m3)

Coarse 0.346 ACI 237Fine 0.283Cement 0.101Water 0.167Additive 0.044AdmixtureAir 0.060 F/TTotal 1.000Water:powder ratio 0.395S/A 0.450Vp 0.372 ACI 237

0.32‐0.45S/A= 0.4‐0.5

Vp=(Vc+Vw+Vadd+Vair) = 0.34‐0.40

Constraints

0.28‐0.38

0.05‐0.08

Proposed Proportioning Method

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Applications

• All about “q”

Ingredient Type q value 0.23 0.25 0.29

CA, kg/m3 Limestone 892 927 965

FA, kg/m3 River sand 735 764 796

C I,II, kg/m3 336 311 285 SCM, kg/m3 Class C 112 104 95 Water, kg/m3 177 164 150

Air, % 5 5 5 Total weight, kg/m3 2251 2270 2290

Cementitious material content,

kg/m3 448 415 380 w/cm 0.40 0.40 0.40

FA/Total Aggregate 0.45 0.45 0.45 Paste volume, % 39.0 36.6 34.0

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Applications

• Why choose proposed design method?Save up to 8% of paste volume

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Test Methods

• Check:performance

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Test Methods

• Fresh properties

30

Test Methods

• Rheology

31

Test Methods

• Workability

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Test Methods

• Workability

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Test Methods

• Workability

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Visual rate: 0 Visual rate: 1

Test Methods

• Formwork pressure

35

Test Methods

• Calorimetry

36

Test Methods

• Setting time

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Test Methods

• Hardened properties

38

Test Methods

• Mechanical propertiesStrength: tensile, compressive,

bond, shearMOE

• Visco-elastic propertiesShrinkage: free and restrainedcreep

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Test Methods

• DurabilityAir content

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0.0

3.0

6.0

9.0

12.0

15.0

18.0

21.0

24.0

27.0

Surfa

ce Resistivity (k

Ω‐cm

)

Limestone Mixtures

Gravel Mixtures

SCC + class C fly ash

CVC + class F fly ash

SCC + class F fly ash

SCC + class F fly ash + LSP

SCC +GGBFS

Test Methods

• DurabilityScaling?Freeze and thaw?

• QC

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Guide Specification

• More SCC applications• More guidelines are coming soon

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Closing

• Performance engineered SCC mixtures work

• How can we make it work better…?

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Questions?