In-Place Testing Without Taking Cores, The Pullout Test
                     In-Place Strength Without  
Testing Cores:
The Pullout Test
Prepared By
Nicholas J. Carino, PhD
Consultant, Chagrin Falls, OH, USA
1 www.sigmatest.org
Current Practice for Acceptance  Testing 
of Concrete
• Standardized testing of specimens made  from concrete 
delivered to the project
 Standard consolidation
 Standard curing
• Provides assurance that correct concrete  was delivered
• Indicates potential strength
 Does not account for actual consolidation and  curing
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Future Performance-Based  Specifications
• Measure in-place properties of concrete to 
 ensure structure will perform as 
intended
• Methods for estimating in-place strength
 Testing drilled cores High cost
 Rebound number method
Requires correlation 
 Probe penetration test  testing for each  
 Ultrasonic pulse concrete mixture
 vPeullolocuitty test Reliable estimates
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Outline
• Explain pullout test
• Strength correlation and failure mechanism
• Describe CAPO-Test
• Case study
• Summary
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Pullout Test
ASTM C 900
Measure force to pullout an insert anchored in  concrete.
 Cast-in-place (CIP): LOK-Test
 Post-installed (PI): CAPO-Test
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CIP-Pullout Test
25 mm
Insert
25 mm
Formwork
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Inser
t
CIP-Pullout Test
ItsneIsrenrt
55 mm
Pullou
Reactio t  
n  Force
Ring
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CIP-Pullout Test
Insert
Pullou
Reactio t  
n  Force
Ring
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Inser
t
Pullout Test
COMA-
meter
Apply Pullout Load
Conical 
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Estimate Concrete Strength
10
0
80
60
40
20
0 0 10 20 30 40 50 60 70
80
Pullout Load, kN
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Compressive Strength, 
MPa
Correlation 
Testing  ACI 
• Prepare cylinde2rs2 (8or. 1cuRbes) for standard 
 compressive strength testing
• Prepare 200-mm cubes with inserts
• Cure all specimens under same conditions
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Correlation Testing
• At ages of 1, 2, 3, 
 7, 14 and 28 
days:
 Test 2 cylinders 200 
 (or cubes) for  
compressive  mm
strength 200 
 Perform 8 pullout mm
 tests (2 cubes)
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Example of Correlation
3
5
3
0
2
5
2
0
1
5 1 1 20 2 3
0 5Pullout Force, kN5 0
1
0
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Cylinder Strength, 
MPa
Why is there a correlation?
• Analytical studies of pullout test have 
 been done
 Plasticity theory
 Compression-strut theory
 Aggregate-interlock theory
• Pullout strength is related fundamentally 
 to concrete strength
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Pullout Failure 
MechCaonmpisremssion strut theory
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Pullout Failure 
MechCaonmpisremssion strut theory
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Compression Strut
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Robust Correlation
Not affected by:
• Type of cementitious materials
• Water-cement ratio
• Age
• Air entrainment
• Types of admixtures
• Shape or size of normal density aggregate 
 up to 40 mm
 Lightweight aggregate, however, produces 
 significantly different correlation
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Cube Strength Correlations
12
0 Johansen - LOK 
core  Gerhard - f = 0.76 1.16
LOK  Winden - LOK cub
10  Winden - LOK Fe
0 Bellander - CAPO 
core  Bellander - 
LOK core  Bellander 
8 - CAPO  Bellander - 
0 LOK  Worthers - 
CAPO  Moczko - 
CAPO core
6
PPrricicee -  -L OK  
0   General 
LOK
Correlation
4
0
2
0
0 1 2 30 40 50 6 7 8
0 0 0 Pullout Force, kN 0 0 0
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Cube or Core Strength, 
MPa
Cylinder Strength Correlations
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0
10 f = 0.69 
0 cyF1.12l Gay - LOK
8 Bick ley - LOK  
Krenchel - LOK  
0 Krenchel - CAPO 
 Krenchel - LOK  
Jensen - LOK  
Drake - LOK  
6 Drake - LOK  
Poulsen - LOK  
0 Kierkegaard - 
LOK  Lekso - 
LOK  Lekso - 
LOK  Krenchel - 
4 LOK  Krenchel - CAPO  McGee - 
0 LOK  Bickley - 
LOK
AEC - LOK & 
CAPO
0 Obla - LOK  2 General 
0 0 2 40 60 8 Correlatio1n0
0Pullout Force, kN 0 0
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0
Cylinder Strength, 
MPa
Manufacturer’s  General Correlations
10
0
8 f = 0.76 
0 F1.16
cube
6
0
f = 0.69 
c
F1
y.12
4 l
0
2 General Correlations for 
0    Cylinder and Cube 
Strength
0
0 10 20 30 40 50 60 70
80
Pullout Load, kN
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Compressive Strength, 
MPa
Post-Installed Pullout Test  CAPO-Test
• Does not require pre-planning test 
 locations
• Can perform test at any accessible 
 location
• Permits testing of existing 
structures
• Immediate test results compared with 
 cores
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Prepare Concrete
Plane 
surface
Drill hole
25 18 
mm mm
Cut 
slot
25 
23 mm www.sigmatest.org
Surface  
Planing
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Cut 
Slot
3.5 mm
25 mm
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Cut 
Slot
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Cut 
Slot
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Insert Expansion Cone  and Coiled 
Split-Ring
Coiled 
ring
Cone
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Ring Expansion Hardware
Bevel
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Expand 
Ring
Nu
t
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Pullout the Expanded Ring
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CAPO-Test vs LOK-Test
7
0
CAPO = 
6 b*LOVaKlue Error
0 b 1.0038 0.0051703
Chisq 112.19 1.3 kN
5 R 0.99593
0
4
0
Krenchel  
Bellander 
2
3  Best-fit 0
0 line
1
0
0
0 1 2 30 40 5 6 7
0 0 0 0 0
LOK-Test Load, 
kN
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CAPO-Test Load, 
kN
Case 
Study
November/December 
2016
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Polish Bridge Study
• Tested 15 bridges: ages 25 to 52 years
• Measured depth of carbonation (2 to 35 mm)
• Tested drilled cores with L/D = 1 to represent  cube 
strength
• Conducted companion CAPO tests
• Used manufacturer’s correlation to estimate
cube strength from CAPO-Test
• Investigated effect of carbonation depth
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Correlation
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Core 
Strength
Best fit curve: f = 
5 0.77F1.15 core
0 Upper Confidence 
Limit  Lower 
4 Confidence Limit
0 General Correlation: 
f
3 = 0.76F1.16
c
0 u
b
e
2
0
10 15 20 25
0 0 5 1 CAPO-TEST, 3 3 4
0 0 5 0
kN
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7 g
Core Strength, 
MPa
Relative Error
 Estimated Cube Strength  Core Strength CT  100 
%
Core Strength
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Summary for 15 Bridges
Bridge Carbonatio Average core Average Estimated Relative 
No. n strength, MPa CAPO-TEST, compressiv error,
depth, kN e  strength, αCT, %
mm MPa
1 2 34.2 28.1 36.4 6.4
2 4 24.7 21.4 26.6 7.7
3 5 46.4 37.3 50.6 9.1
4 5 34.2 28.7 37.3 9.1
5 7 37.1 27.5 35.5 -4.3
6 7 42.0 30.1 39.4 -6.2
7 7 37.5 29.2 38.1 1.6
8 8 35.4 28.3 36.7 3.7
9 10 42.4 30.6 40.2 -5.2
10 19 33.3 24.9 31.7 -4.8
11 20 29.7 24.6 31.2 5.1
12 20 28.5 24.3 30.8 8.1
13 22 31.7 26.1 33.4 5.4
14 26 31.7 26.5 34.0 7.3
15 35 19.6 16.4 19.5 -0.5
3
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Error vs. Carbonation Depth
2
0
1
5
1
0
5
0 Linear 
- Fit Valu Erro
10 Interce 3
e.2683 r
- pt Slop - 2.5763 0.1592
- 5 Sq.e 0.0434311.15 3 NA
15 Error R 6 6 NA
- 0.05758815 20 25
20 0 5 1 3 3 4
0 Carbonation Depth, 0 5 0
4 mm www.sigmatest.org
0
Relative Error, 
%
Summary
• Pullout test offers the possibility of estimating  in-
place concrete with acceptable reliability
• Stress state created by reaction ring leads to a  
compression strut that explains the good  correlation 
with compressive strength
• CAPO-Test allows testing without pre-placing  
inserts
• Polish bridge study
 On average, CAPO-Test estimate was 3 % greater 
 than core strength
 Carbonation did not appear to affect CAPO-Test 
results
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1
Thank You !
 Sigma Test and Research Centre 
Regd. Office: 99, Badli Industrial 
Area, Phase 2, Delhi 110042
Call +91 - 9560222333
www.sigmatest.org
[email protected]
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