1. 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

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

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

4. What is…
Concrete
PCA Photo

5. What is…
Air-entrained concrete

6. 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

7. • 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?

8. 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?

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

10. Hardened Air Void Analysis
From Hover

11. Hardened Air Void Analysis
From Hover

12. 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

13. 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
Freeman et al., 2012

14. 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
Freeman et al., 2012
small voids large voids

15. 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!!!
Freeman et al., 2012
small voids large voids

16. 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

17. 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

18. 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

19. digital
gauge
Six
clamps!

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

21. top
chamber
bottom
chamber

22. 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

23. 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

24. 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

25. 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
release
pressure in both
chambers

26. 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

27. 0
15
30
45
60
75
90
0
AppliedPressure(psi)
Time
Top Chamber, Pc1
Bottom Chamber, Pa1
Equilibrium Pressure, P2

28. 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

29. 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

30. ACI 201
PASS
FAIL

31. 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

32. 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

33. 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

34. 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%

35. Mean Difference 0.006
Standard dev. 0.049

37. 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 (%)

38. 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.

39. www.superairmeter.com
SAMs should be available
April 2014

40. Questions???