Seminario Internacional: Dosificación y especificación de hormigón por desempeño "Buenas Prácticas y Mejoramiento del Desempeño de Hormigones para Pavimentos"

3. New Era Testing
Dr Peter Taylor, PE (IL)

4. Who Needs More Testing?
4

5. You do
• Environments are more severe
• Loading is sooner
• Mixtures are more complicated
• Money is tighter
• Expectations are higher
• Existing tests don’t
measure the
important
properties
5

6. You do
6

7. But wait
• Lets measure the things that matter
(and no more):
• Transport properties
• Aggregate stability
• Strength
• Cold weather resistance
• Shrinkage
• Workability
• Measure them at the right time
7

8. Acceptance Testing
• Fast
• Reliable
• Meaningful
• Affordable
8

9. Transport
(Resistance to fluids)
• Resistivity
• Then calculate Formation Factor based on
• Moisture
• Temperature
• Geometry
• Curing conditions
• Ionic concentration of the pore solution
• F = Resistivity (bulk)
Resistivity (solution)
9

10. Transport
(Resistance to fluids)
• Drop Test
• Quick and dirty
• Small footprint
• Time for 20 µL to absorb into paste
10

11. Transport
(Resistance to fluids)
• Drop Test
11

12. Aggregate Stability
• AAR
• Follow AASHTO PP 65 / ASTM C 1778
• D-Cracking
• Follow local practice (i.e. IPA in Iowa)
12

13. Strength
• Compressive or flexural
13

14. Cold Weather Resistance
• Freeze Thaw (air void system)
• Super Air Meter (SAM) AASHTO TP 118
14 Ley

15. Cold Weather Resistance
• Freeze Thaw (Time to Saturation)
15 Weiss

16. Cold Weather Resistance
• Resistance to Salts
• Expansive calcium oxychloride formation
• From MgCl2 and CaCl2
• Measure with – Low temperature differential scanning calorimetry (LT-DSC)
16Sutter

17. Cold Weather Resistance
• Resistance to Salts
• Soak tests
• Soak in MgCl2 at 40°F
17

18. Shrinkage
• Cracking risk
• Warping
18

19. Ring Test
• Assesses cracking risk
• Starts immediately
19

20. Dual Ring Test
Plan View
Concrete
Invar ring
Strain
gauge
This ring can measure both
expansion and contraction.
As the concrete shrinks the ring
can measure the strains that occur.
We force a temperature gradient
in the concrete and make it crack
and compare that to 60% of the
split tension capacity after 7 days.
Weiss 20

21. Workability
• Owner should not really care, but
• Too wet = edge slump
• Too dry =
• Poor consolidation
• Vibrator trails
• Good indicator
of uniformity
• Need a measure of the
response to vibration
21

22. Workability
• Kelly ball test
• Developed in the 1950s in US
• Standardized in California DOT test
• Comparable to slump test
22

23. VKelly
• Measure initial slump (initial penetration)
• Start vibrator for 36 seconds at 8000 vpm
• Record depth every 6 seconds
• Repeat
• Plot on root time
• Calculate slope = VKelly Index
23

24. VKelly Index
0.80 1.1 in/√s
24

25. VKelly
• Effect of the aggregate system…
25

26. Box Test
• A test that examines:
• Response to vibration
• Filling ability of the grout (avoid internal voids)
• Ability of the
concrete to hold
an edge 12”
12”
12”
Ley26

27. Box Test
• Add 9.5” of unconsolidated concrete to the box
• Insert 1” diameter stinger vibrator (8000 vpm) into the center of the
box over a three count and then remove over a three count
Ley27

28. Box Test
• The edges of the box are then removed and inspected for honey
combing and edge slump
Ley28

29. 29
QC
• QC reassures contractor that the mix will get there:
• Unit weight
• Calorimetry
• Maturity
• Strength development
• Air void stability
137.0
138.0
139.0
140.0
141.0
142.0
143.0
144.0
145.0
146.0
1.1 1.2 1.3 1.4 1.5 2.1 2.2 2.3 2.4 2.5 2.6 3.1 3.2 3.3 3.4 3.5 3.6 4.1 4.2 4.3 4.4 4.5 5.1 5.2 5.3 5.4 5.5
UnitWeight(lb/ft3)
Sample ID
Unit Weight Control Chart
Unit Weight
Target
Average
Upper Control Limit (3s)
Lower Control Limit (-3s)

30. 30
Unit weight
• Uniformity
• Affected by air and water

31. 31
Calorimetry
• Calorimetry tells us about the chemistry of the system (Uniformity)

32. Maturity
• Maturity readings
• Sensors in the pavement determine in-place maturity and
thereby strength for opening
30
40
50
60
70
80
90
100
110
0
100
200
300
400
500
600
700
800
900
1000
0 12 24 36 48 60
SlabTemperature,F
Maturity(°C-Hrs)
Time(hrs)
Field Maturity (10/2/12)
Slab Temperature

33. 33
Foam Drainage
• Air void systems can change with working / pumping
• Depends on system chemistry

34. 34
What Else?
• Intelligent Compaction
• What about the ride?
• When should I saw?
• Finding the flaws

35. Construction
• Foundations – Intelligent Compaction
White 35

36. Construction
• Real Time Smoothness
• Allows contractor to learn and control critical activities
Increased Smoothness
Reduced dynamic loading
Extended pavement life
36

37. Field Investigation
• Based on time-of-flight of light (LIDAR)
37

38. LIDAR Output
38
-40
-35
-20
-40
-18
-20
-45
-16
Transverse Direction (ft)
Longitudinal Direction (ft)
-14-50
-12
0
-55
-10
-60
-8
20
-6-65
Linn County STA162 Slab 2 AM (44.1F)
RelativeDeflection(mils)
40
60
80
100
-40
-35
-
-20-40
-20
-18
-45
-16
Longitudinal Direction (ft)
Transverse Direction (ft)
-50 -14
0
-12-55
-10
-60
-8
20
-65 -6
Relativeelevation(mils)
Linn County STA162 Slab 2 PM (52.4F)
40
60
80
100
Morning
Afternoon

39. Ultrasonic P-wave velocity
• Measure speed of a compression wave through a sample
• Governed by dynamic modulus of elasticity, Poisson’s ratio,
and density (Biot’s theory)

40. Ultrasonic P-wave velocity

41. Lab Data

42. Field Work

43. Field Work

44. Finding the Steel
• Sensors
• MIT Scan-2
• MIT Scan-T2

45. Finding Flaws
• Sensors
• MIRA
• GPR

46. Finding Flaws
• MIRA – to find cracked joints
No Crack Crack

47. 47
Whew
• Use the right test for the right purpose at the right time
• It can keep us out of trouble