InIInnIn- ---Place Strength by PulloutPlace Strength by ... Jan 2013/Pullout New York JAN 8... ·...

Test smart – Build right

InInInIn----Place Strength by PulloutPlace Strength by PulloutPlace Strength by PulloutPlace Strength by Pullout

The Concrete Industry Board of NYC (CIB)

NYC Chapter of ACI

New YorkJanuary 8th, 2013

Claus Germann Petersen

GERMANN INSTRUMENTS, Inc.


InInInIn----Place Strength by PulloutPlace Strength by PulloutPlace Strength by PulloutPlace Strength by Pullout

Acknowledgement

Dr. Nicholas J. CarinoConcrete Technology Consultant

&

Dr.Andrzej Tadeusz Moczko

Professor, Wroclaw University


InInInIn----Place StrengthPlace StrengthPlace StrengthPlace Strength

• Evaluation by

�Testing cores

�Rebound hammer

�UPV

�Pullout test

�Pull-off test

�Maturity method


Pullout TestPullout TestPullout TestPullout TestASTM C 900ASTM C 900ASTM C 900ASTM C 900

Measure force to pullout an insert anchored in concrete.

� Cast-in-place (CIP): LOK-Test

� Post-installed (PI): CAPO-Test


25 mm 25 mm

55 mm

F

25 mm

25 mm

F 55 mm

LOK-TEST CAPO-TEST


Instrument 1972 and todayInstrument 1972 and todayInstrument 1972 and todayInstrument 1972 and today

0-100 kN, 4 kgAutomatic registration of data

and peak value

0-40 kN, 43 kg


Birth of CAPOBirth of CAPOBirth of CAPOBirth of CAPO----TESTTESTTESTTEST1976197619761976

Drilling from the bottom of a 75 cm thick slab in preparation for LOK-TEST at the top of the slab

1st CAPO-TEST in the world performed adjacent to LOK-TEST


LOKLOKLOKLOK----Test Pullout Test Pullout Test Pullout Test Pullout

Apply Pullout LoadConical Fragment

Failure

COMA-Meter for maturity


CapoCapoCapoCapo----TestTestTestTestPulloutPulloutPulloutPullout


LOKLOKLOKLOK----TEST Insert HardwareTEST Insert HardwareTEST Insert HardwareTEST Insert Hardware

Nailed to Nailed to formworkformwork

Attached toAttached toformwork cutoutsformwork cutouts

Floated Floated into surfaceinto surface


25 mm

25 mm


InsertInsert

Formwork

Steel Plate


LOKLOKLOKLOK----TEST Pullout TEST Pullout TEST Pullout TEST Pullout

InsertInsert

ReactionRing

PulloutForce



Insert

ReactionRing

PulloutForce

Insert

Cut hole in formworkCut hole in formworkCut hole in formworkCut hole in formworkCut hole in formworkCut hole in formworkCut hole in formworkCut hole in formwork

Attach backing plate and fasten insertAttach backing plate and fasten insertAttach backing plate and fasten insertAttach backing plate and fasten insertAttach backing plate and fasten insertAttach backing plate and fasten insertAttach backing plate and fasten insertAttach backing plate and fasten insert

InsertInsert

PlatePlate

•• Attach insert support assembly to formAttach insert support assembly to form

•• Apply sealantApply sealant

•• Place concretePlace concrete

SealantSealant

•• Remove backing plateRemove backing plate

•• Attach loading systemAttach loading system

•• Apply loadApply load

•• Measure pullout strengthMeasure pullout strength

Pressuregage


Ultimate Pullout LoadUltimate Pullout LoadUltimate Pullout LoadUltimate Pullout Load

• At peak load, ≈ 0.5 mm surface displacement

• Gradual decrease in load with continued displacement

Surface Displacement

Pu


0

20

40

60

80

100

0 10 20 30 40 50 60 70 80

Compressive Strength, MPa

Pullout Load, kN

General Correlations forCylinder and Cube Strength

fcube= 0.76 F

1.16

fcyl= 0.69 F

1.12

Estimate Concrete StrengthEstimate Concrete StrengthEstimate Concrete StrengthEstimate Concrete Strength


Strength indication by maturityStrength indication by maturityStrength indication by maturityStrength indication by maturity

Requires pre-established strength-maturity relationship in the lab, and:

• Same concrete quality on-site as in the lab

• Same curing conditions

• Same compaction


Maturity + Pullout TestingMaturity + Pullout TestingMaturity + Pullout TestingMaturity + Pullout Testing

• Use the maturity method to determine when the required strength should have been achieved in the structure

• Verify by using pullout tests to estimate in-place strength

• Combination of maturity and pullout testing can lead to rapid and safe concrete construction


Pullout timed by MaturityPullout timed by MaturityPullout timed by MaturityPullout timed by Maturity

0

10

20

30

40

50

0 5 10 15 20 25 30

Mixture AMixture BMixture C

Compressive Sterngth, MPa

M20, days at 20

oC


Caution !Caution !Caution !Caution !

Tensioning of anchors in bridge girders was made at sufficient maturity, including a safety factor

The concrete failed anyhow at one of the anchors destroying one girder


Subsequent testing by impact-echo (left) and ultrasound echo (right) revealed a large honeycomb in the anchor´s

trumphet zone


Insert HardwareInsert HardwareInsert HardwareInsert Hardware

Floated Floated into surfaceinto surface


Floated Surface InsertsFloated Surface InsertsFloated Surface InsertsFloated Surface Inserts

• Does not require cutting holes into formwork

• Training for proper placement

� Good consolidation around insert head

� Minimum of surface voids

� Ensure representative aggregates in failure zone

• Requires workable concrete


Push insert into concreteMove sideward for aggregates to flow into the failure zoneTilt for air to escape below the insert plate


Correctly installed floating inserts


Correctly performed LOK-Test using floating inserts

Sharp 55 mm dia.edge from the reaction ring

No surface voids


Clearance RequirementsClearance RequirementsClearance RequirementsClearance RequirementsASTM C900ASTM C900ASTM C900ASTM C900

db

>200 mm >100 mm

≥ dbor

NMSA

Edgedistance

Reinforcementclearance

Insert clearance

25 mm


PostPostPostPost----Installed TestsInstalled TestsInstalled TestsInstalled TestsCAPOCAPOCAPOCAPO----TestTestTestTest

• Does not require pre-planning test locations

• Can perform test at any accessible location

• Permits testing of existing structures


CAPOCAPOCAPOCAPO----Test Pullout Test Pullout Test Pullout Test Pullout


Prepare ConcretePrepare ConcretePrepare ConcretePrepare Concrete

Plane surfaceCore hole18 mm dia.

18 mm25 mm

25 mm

Cut slot

25 mm


Core HoleCore HoleCore HoleCore Hole


SurfaceSurfaceSurfaceSurfacePlaningPlaningPlaningPlaning



Cut SlotCut SlotCut SlotCut Slot

25 mm






Insert Expansion ConeInsert Expansion ConeInsert Expansion ConeInsert Expansion Coneand Coiled Splitand Coiled Splitand Coiled Splitand Coiled Split----Ring Ring Ring Ring

Coiled ring

Cone


Ring Expansion HardwareRing Expansion HardwareRing Expansion HardwareRing Expansion Hardware

Coiled ringCoiled ring

ConeCone

NutNut


Expand RingExpand RingExpand RingExpand Ring

Nut


Expand RingExpand RingExpand RingExpand Ring


Pullout the Expanded RingPullout the Expanded RingPullout the Expanded RingPullout the Expanded Ring


ApplyApplyApplyApplyPulloutPulloutPulloutPulloutForceForceForceForce


AcceptableAcceptableAcceptableAcceptableTestTestTestTest

Complete failure ring


UnacceptableUnacceptableUnacceptableUnacceptableTestTestTestTest

Incomplete failure ring


General Approach to General Approach to General Approach to General Approach to InInInIn----Place TestingPlace TestingPlace TestingPlace Testing

• Pre-construction meeting to plan the in-place testing program

• Develop a correlation (strength relationship) for the concrete to be used in construction

• Perform in-place tests on the structure

• Apply statistical methods to estimate in-place strength (ACI 228.1R)

Correlation TestingCorrelation TestingCorrelation TestingCorrelation Testing

• Prepare cylinders (or cubes)

• Prepare cubes with inserts

• Cure under same conditions

2 x LOK-Test 2 x CAPO-Test


Correlation TestingCorrelation TestingCorrelation TestingCorrelation Testing

• Test 2 cylinders (cubes) and perform 8 pullout tests at each test age:

� 1, 2, 3, 7, 14 and 28 days

200 mm

200 mm


Example of CorrelationExample of CorrelationExample of CorrelationExample of Correlation

http://www.nrmca.org/research/HVFAC_Final_Report_final.pdf

0

5

10

15

20

25

30

35

10 15 20 25 30

Cylinder Strength, MPaUpper 95 % CLLower 95 % CLManufacturer

Cylinder Strength, MPa

Pullout Force, kN


CAPOCAPOCAPOCAPO----Test Test Test Test vsvsvsvs LOKLOKLOKLOK----TestTestTestTest

0

10

20

30

40

50

60

70

0 10 20 30 40 50 60 70

CAPO-Test, kN

LOK -Test, kN

Line of Equality


0

20

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60

80

100

120

0 20 40 60 80 100

Cylinder Strength, MPa

Pullout Load, kN

Cylinder Stength Correlations

Cylinder strength relationsCylinder strength relationsCylinder strength relationsCylinder strength relations

16 Cylinder Strength Correlations


Cube Strength CorrelationsCube Strength CorrelationsCube Strength CorrelationsCube Strength Correlations

0

20

40

60

80

100

120

0 10 20 30 40 50 60 70

Cube Strength, MPa

Pullout Load, kN

Cube Strength Correlations8 Cube Strength Correlations


LOKLOKLOKLOK---- / CAPO/ CAPO/ CAPO/ CAPO----TEST TEST TEST TEST General CorrelationsGeneral CorrelationsGeneral CorrelationsGeneral Correlations

0

20

40

60

80

100

0 10 20 30 40 50 60 70 80


Pullout Load, kN


fcube= 0.76 F

1.16

fcyl= 0.69 F

1.12


Robust CorrelationRobust CorrelationRobust CorrelationRobust CorrelationNot affected by:

• Cementitious materials

• Water-cement ratio

• SCC mixtures

• Fibers

• Age

• Air entrainment

• Admixtures

• Curing conditions

• Shape, type or size of aggregate < 40 mm� Lightweight aggregate, however, produces

significantly different correlation


CorrelationCorrelationCorrelationCorrelation

• Pullout strength is related fundamentally to concrete strength

• Studies of test have been done

� Finite element study (Ottosen, 1981)

� Compression strut theory (Krenchel, 1987)


Pullout Failure MechanismPullout Failure MechanismPullout Failure MechanismPullout Failure Mechanism

Compression strut theory


Pullout Failure MechanismPullout Failure MechanismPullout Failure MechanismPullout Failure Mechanism

Compression strut theory


Compression StrutCompression StrutCompression StrutCompression Strut


Variation and duration of testVariation and duration of testVariation and duration of testVariation and duration of test

• Variation on homogeneous concrete is 6-8%, lower for shotcrete 3-5%

• In-place variabilty depends on the type of structure and the position of the test

• Duration of test: LOK-Test 3-4 minutes, CAPO-Test 15-20 minutes

• Results are immediately available on-site


ExamplesExamplesExamplesExamples

Pullout TestingPullout TestingPullout TestingPullout Testing



COMA-Meter for maturity


Comparative study Polish bridgesComparative study Polish bridgesComparative study Polish bridgesComparative study Polish bridgesfor increased loadingfor increased loadingfor increased loadingfor increased loading

• Cores, sawcut, capped, tested after 5 days drying in lab conditions (100 mm dia x 100 mm cores)

• CAPO-Test in-situ, double amount of cores

• Schmidt Hammer in-situ, up to 20 locations, each 6 tests

• Schmidt Hammer on side of cores prior to compression tests

Age of structures: 20-30 yearsDepth of carbonation: 4-35 mm


Bridge

No.

Cores from

structure

Capo-Test

on structure

Schmidt Hammer

on structure

Schmidt Hammer

on cores

MPa Av.

of

MPa αααα(CT) MPa αααα(L) MPa αααα(LM)

1 19.6 4 20.3 +3.4% 36.9 +88.3% 28.4 +44.3%

2 24.7 3 26.9 +8.9% 37.4 +51.4% 28.4 +15.0%

3 29.7 4 31.8 +7.1% 49.5 +66.7% 38.2 +28.6%

4 34.2 3 36.8 +10.5% 56.8 +66.1% 43.1 +26.0%

5 33.3 4 32.3 -3.0% 61.6 +85.0% 49.3 +48.0%

6 34.2 3 37.6 +9.0% 54.5 +59.4% 36.5 +6.7%

7 35.4 4 37.1 +7.1% 66.3 +87.3% 57.0 +61.0%

8 37.1 3 35.9 -3.2% 56.9 +53.4% 46.1 +24.3%

9 37.5 4 36.8 -1.9% 70.9 +89.1% 61.0 +62.7%

10 42.0 3 39.7 -5.5% 68.4 +62.9% 57.4 +36.7%

Avg. 32.8 33.5 +2.5 55.9 +71.0% 44.5 +35.7%Comparative testing, Polish experience, bridges 20-30 years old, ref. A. Mozcko,, Wroclaw University


Capo-Test on shotcrete, Cigar Lake Mining Project, Saskatchewan, Canada


Correlations on mortar (Yun, 1988) and concrete with < 8 mm maximum aggregate size (Krenchel, 1984)

Compressive Strength fc(MPa)

Capo-Test Pullout Load F (kN)

CYL, 150 x 300mm,<8 mm max aggregate size

Cores, 150 x 300mm,mortar



CAPO EquipmentCAPO EquipmentCAPO EquipmentCAPO Equipment

Preparation Kit

DSV Kit

Pullmachine Kit

Capo Inserts


SummarySummarySummarySummary• Pullout test is a reliable method for estimating

in-place compressive strength of the cover layer

• Can be used for new construction and existing construction

• General correlations according to EN 12505-3: 2005

• Following ASTM C 900-06 confirm general correlations for LOK-Test

• For CAPO-Test cores can be drilled out for comparison to the general correlation


When correlating to coresWhen correlating to coresWhen correlating to coresWhen correlating to cores

• Pullout test is testing the outer 25 mm cover layer of the structure, cores the interior

• Moisture conditioning of cores affects core strength (as well as other factors)


Moisture conditioning of coresMoisture conditioning of coresMoisture conditioning of coresMoisture conditioning of cores

• In the past, cores were tested after a period of air drying or after being submerged for at least 40 h

• In high w/c concrete, storage under water for 40 h resulted in saturation

• With modern concrete and lower w/c, storage under water leads to moisture gradient


Research FindingsResearch FindingsResearch FindingsResearch Findings


Moisture GradientsMoisture GradientsMoisture GradientsMoisture GradientsImmediately After Wet DrillingImmediately After Wet DrillingImmediately After Wet DrillingImmediately After Wet Drilling

• Moistened concrete tends to swell

• Swelling is restrained by dry interior

• Results in internal stresses; outer region in compression

• Measured strength is reduced

Compression

Tension


JointJointJointJointIndustry Industry Industry Industry StudyStudyStudyStudy

www.cement.org

CT003


Effect of Core ConditioningEffect of Core ConditioningEffect of Core ConditioningEffect of Core Conditioningon Strengthon Strengthon Strengthon Strength

CT003


Moisture ConditioningMoisture ConditioningMoisture ConditioningMoisture ConditioningASTM C42/C42MASTM C42/C42MASTM C42/C42MASTM C42/C42M

• Wipe off drilling water, surface dry

• Place in watertight containers

• Wait at least 5 days between wetting due to drilling or sawing and testing

• Other procedure permitted when required by the “specifier of tests”


ACI 214.4R for coringACI 214.4R for coringACI 214.4R for coringACI 214.4R for coring

In-place strength Core strength

Correction for L/D

Correction for D Correction for moisture content

Correction for “damage”due to coring

'

,c eq cf Kf=Equivalent specified strength

Average in-place strength

Statistical factor


Other systems correlationsOther systems correlationsOther systems correlationsOther systems correlations

• Rebound Hammer

• UPV


Rebound number to cores,Rebound number to cores,Rebound number to cores,Rebound number to cores,mix specificmix specificmix specificmix specific

0

10

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30

40

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25 30 35 40

Core Strength

Upper 95 % CL

Lower 95 % CL

Core Strength, MPa

Rebound Number

n = 13Ward, M.A. and Langan, B.W., Cement Concrete and Aggregates, 16(2), Dec. 1994, 181-185


Factors Affecting Factors Affecting Factors Affecting Factors Affecting Rebound NumberRebound NumberRebound NumberRebound Number

• Strength and elastic modulus of concrete near to surface

� Aggregate type dependence

• Thickness of carbonation zone

• Surface texture

• Surface moisture condition

• Rigidity of test object


Comparison of RelationshipsComparison of RelationshipsComparison of RelationshipsComparison of Relationships

0

10

20

30

40

50

25 30 35 40 45

Case 1

Case 2Core Strength, MPa

Rebound Number


Strength Relationship UPVStrength Relationship UPVStrength Relationship UPVStrength Relationship UPV

( )4Vfc ∝∴

fc

VelocityFor mature concrete, large increase in strength is accompanied by small increase in velocity.

EV ∝Physics:

cfE ∝Empirically:


Relationship for a specific mixRelationship for a specific mixRelationship for a specific mixRelationship for a specific mix

0

5

10

15

20

25

30

35

2000 2500 3000 3500 4000 4500


Pulse Velocity, m/s

1 day

3 day

7day


Factors Affecting UPV for Factors Affecting UPV for Factors Affecting UPV for Factors Affecting UPV for Given Concrete Strength Given Concrete Strength Given Concrete Strength Given Concrete Strength

• Aggregate type

• Aggregate content

• Moisture content

� Saturated concrete 5 % greater UPV than dry

• Presence of reinforcement

� Perpendicular to pulse path

� Parallel to pulse path

ExampleExampleExampleExampleAggregate TypeAggregate TypeAggregate TypeAggregate Type

Ref: Bungey, 1982


Why is cube strength higher than cylinder strength?


0

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80

100

0 10 20 30 40 50 60 70 80


Pullout Load, kN


fcube= 0.76 F

1.16

fcyl= 0.69 F

1.12

Cube and cylinder strength Cube and cylinder strength Cube and cylinder strength Cube and cylinder strength correlationscorrelationscorrelationscorrelations

150 x 150 cubes

150 x 300 cylinders


Effect of End Friction Effect of End Friction Effect of End Friction Effect of End Friction ––––TriaxialTriaxialTriaxialTriaxial CompressionCompressionCompressionCompression

Frictional Stresses

Zones of triaxial

compression


As L/D DecreasesAs L/D DecreasesAs L/D DecreasesAs L/D Decreases

Strength Increases


Evaluation techniques byEvaluation techniques byEvaluation techniques byEvaluation techniques by

Testing coresRebound hammerUPVPullout testPull-off testMaturity method

are dealt with in detail at our NDT Workshopswww.germann.org


Thank you for your attentionThank you for your attentionThank you for your attentionThank you for your attention

www.germann.org

InIInnIn- ---Place Strength by PulloutPlace Strength by ... Jan 2013/Pullout New York JAN 8... ·...

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