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A New Test Method to Measure
the Freeze Thaw Durability of
Fresh Concrete
Braden Tabb, Robert Felice, John Michael
Freeman, Robert Frazier, David Welchel
Tyler Ley, P.E., Ph. D

Acknowledgements
• Oklahoma Transportation Center
• CP Tech Center
• Portland Cement Association

Summary
• Some basics of air entrained concrete…
• The Super Air Meter
• The future

What is…
Air-entrained concrete

Why Do We Add Air to Concrete?
• Air-entrained bubbles are the key to
the freeze-thaw resistance of concrete
Air volume = Freeze Thaw Performance
• Smaller bubbles are more effective in
providing freeze-thaw resistance than
larger bubbles

• Volume of air provided is the same for both circumstances.
• Case B has a lower spacing factor and a higher specific surface.
A B
What Do You Want in an Air-Void System?

A B
• Volume of air provided is the same for both circumstances.
• Case B has a lower spacing factor and a higher specific surface.
What Do You Want in an Air-Void System?

Current Measuring Techniques
PCA photo
ASTM C 231
PCA photo
ASTM C 173 ASTM C 138
These only measure volume!!!

Hardened Air Void Analysis
From Hover

Open symbols
failed ASTM
C666
0.004
0.006
0.008
0.010
0.012
0.014
0.016
0.018
0.020
0.022
0.024
2.0% 3.0% 4.0% 5.0% 6.0% 7.0% 8.0% 9.0%
SpacingFactor(in)
Air Content of Concrete (Pressure)
No Polycarboxylate
Open symbols
failed ASTM
C666
Freeman et al., 2012

0.004
0.006
0.008
0.010
0.012
0.014
0.016
0.018
0.020
0.022
0.024
2.0% 3.0% 4.0% 5.0% 6.0% 7.0% 8.0% 9.0%
SpacingFactor(in)
Air Content of Concrete (Pressure)
No Polycarboxylate
Polycarboxylate
Open symbols
failed ASTM
C666

0%
1%
2%
3%
4%
5%
6%
7%
8%
9%
10% 0-10
10-20
20-30
30-40
40-50
50-60
60-70
70-80
80-90
90-100
100-110
110-120
120-130
130-140
140-150
150-160
160-170
170-180
180-190
190-200
200-210
210-220
220-230
230-240
240-250
250-260
260-270
270-280
280-290
290-300
300-310
310-320
320-330
330-340
340-350
350-360
360-370
370-380
380-390
390-400
400-410
410-420
420-430
430-440
440-450
450-460
460-470
470-480
480-490
490-500
500-550
550-600
600-650
650-700
700-750
750-800
800-850
850-900
900-950
950-1000
1000-1200
1200-1400
1400-1600
1600-1800
1800-2000
2000+
normalizedAirContentFraction
Chord Size, microns
WROS Only
PC1 + WROS
small voids large voids

0%
1%
2%
3%
4%
5%
6%
7%
8%
9%
10% 0-10
10-20
20-30
30-40
40-50
50-60
60-70
70-80
80-90
90-100
100-110
110-120
120-130
130-140
140-150
150-160
160-170
170-180
180-190
190-200
200-210
210-220
220-230
230-240
240-250
250-260
260-270
270-280
280-290
290-300
300-310
310-320
320-330
330-340
340-350
350-360
360-370
370-380
380-390
390-400
400-410
410-420
420-430
430-440
440-450
450-460
460-470
470-480
480-490
490-500
500-550
550-600
600-650
650-700
700-750
750-800
800-850
850-900
900-950
950-1000
1000-1200
1200-1400
1400-1600
1600-1800
1800-2000
2000+
normalizedAirContentFraction
Chord Size, microns
WROS Only
PC1 + WROS
Look at the
difference in
the volume of
the air voids!!!
small voids large voids

Summary
• It is common to require a certain
volume of air in concrete in order to
obtain freeze thaw durability
• The volume of air does not equal air
void system quality
• Although, a hardened air void analysis
(ASTM C 457) can measure the air-
void quality it is not practical to run
regularly

What do we need?
• We need a test that can quantify air-
void systems quickly in fresh concrete
• Investigate a sample of significant size
• Economical
• Field ready

Super Air Meter (SAM)
• We have modified a typical ASTM C
231 pressure meter so that it can hold
larger pressures
• We have replaced the typical gage
with a digital one
• The test takes 8 minutes

How does it work?
• Use ASTM C 231 procedures to fill the
measurement bowl
• Secure the lid
• Add water through the petcocks

0
15
30
45
60
75
90
0
AppliedPressure(psi)
Time
Top Chamber, Pc1
Bottom Chamber, Pa1
Equilibrium Pressure, P2
When both chambers
are in contact with
one another
Top Chamber
Bottom Chamber

0
15
30
45
60
75
90
0
Time
Top Chamber, Pc1
Bottom Chamber, Pa1
When both chambers
are in contact with
one another

0
15
30
45
60
75
90
0
Time
Top Chamber, Pc1
Bottom Chamber, Pa1
When both chambers
are in contact with
one another
release
pressure in both
chambers

0
15
30
45
60
75
90
0
Time
Top Chamber, Pc1
Bottom Chamber, Pa1

How does it work?
• We use an algorithm to find a SAM
number.
• The SAM number correlates to air
void distribution
• The meter also measures air volume

How can we prove it?
• We made 95 concrete mixtures
• Different AEAs
• Combinations of AEAs and PCs
• Different w/cm (0.39 - 0.53)
• Slumps from 0.25” to 10”
• Air contents from 1.25% to 10%
• Hardened air void analysis (ASTM C
457) was completed on each mixture
• Values were compared to the SAM
number

0%
10%
20%
30%
40%
50%
60%
70%
80%
90%
100%
0 0.1 0.2 0.3 0.4 0.5 0.6 0.7
Modulus(%)
SAM Number
SAM Number
PASS
FAIL

Observations
• When the SAM number is below 0.2
then the spacing factor is below
0.008” for 90% of the samples and
98% of the samples had a spacing
factor below 0.010”
• The SAM number seems to correlate
with the amount of small bubbles in
the sample

How Consistent Is It?
• We ran the following on each of the 95
mixtures with two separate SAMs:
– Air contents
– SAM numbers
– ASTM C 457 hardened air void analysis
– Unit Weight

y = 1.015x - 0.0227
R² = 0.9932
0
1
2
3
4
5
6
7
8
9
0 1 2 3 4 5 6 7 8 9
SAM2AirContent(%)
SAM 1 Air Content (%)
Mean Difference -0.005%
Standard dev. 0.064%

Mean Difference 0.006
Standard dev. 0.049

y = 0.9982x + 0.2504
R² = 0.9668
y = 0.9965x + 0.3611
R² = 0.9651
0
1
2
3
4
5
6
7
8
9
10
0 1 2 3 4 5 6 7 8 9 10
SuperAir(%)
Gravimetric Calculated Air (%)

Conclusions
• The SAM test can be completed in
about 10 minutes with fresh concrete
• A SAM number of 0.20 seems to
correlate with the ASTM C 457
spacing factor of 0.008” and freeze
thaw durability as per ASTM C 666
• Two SAMs have been shown to
provide consistent results.

www.superairmeter.com
SAMs should be available
April 2014

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