particle packing: an effective approach to optimize design
TRANSCRIPT
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
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
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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)
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Properties We Measure
StabilityFresh and hardened visual stability index
(ASTM C1611 and Shen 2007)Column technique (ASTM C1610)Probes
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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
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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
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Properties We Measure
• Durability propertiesPermeability Water transportGas transportIon transport
Freeze and Thaw ResistanceScalingASR
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Boel et al. 2007
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)
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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
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
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Background
• Continuous packing model development– Fuller model=> A&A model (1968)=>Bolomey
(1947)=>Plum (1950)=>Funk and Dinger(1994)
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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
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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Test Methods
• Mechanical propertiesStrength: tensile, compressive,
bond, shearMOE
• Visco-elastic propertiesShrinkage: free and restrainedcreep
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Test Methods
• DurabilityAir content
40
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