Presentation delivered at the CalAPA Spring Asphalt Pavement Conference April 9-10, 2014 in Ontario. Topic: Non-destructive testing, including the use of both FWD and GPR testing, how they are done, results from the testing and how they are used in pavement management / preservation decision-making.

1. REMAIN CALM, ALL IS WELL
What,Why andWhere
By
Steve Marvin, P.E.

2. Goldilocks and the Three
Bears
 First documented testing technician
 Original Goldilocks was
 course,
 ugly,
 smelly
 old woman

3. Goldilocks and the Three
Bears
 First documented testing technician
 Morphed to
 politically correct
 cute
 little girl

4. Initial observations
House Unlocked
 Nice house
 Plenty of food
 Places to sleep

5. Tested Observations
Porridge
Too hot
Too cold
Just right
Chairs
Too small
Too big
Just right
Beds
To hard
To soft
Just right

6. Things We Know
 All pavements when constructed are the
same
 Materials
 Gradation
 Binder content
 Aggregate shape
 Aggregate Size

7. Things We Know
 All pavements when constructed with the
same
 Relative compaction

8. Things We Know
 All pavements when constructed with the
same
 Thickness
 Smoothness
 Surface texture
 Skid resistance

9. Things We Know
 All pavements are exposed to the same
 Weather cycles
 Rainfall
 Landscape irrigation runoff
 Temperatures
 Heat
 Cold
 Freezing

10. Things We Know
 All Pavements have the same
 Crown
 Cross slope
 Longitudinal slope
 Frontage Improvements

11. Things We Know
 All Pavements are constructed over the same
soil subgrade with
 Identical wet and dry strengths
 Identical moisture contents
 Identical drainage characteristics

12. Things We Know
They are subjected to the same
 Axle weights
 Tire pressures
 Numbers of axle loads
 Travel speed

13. Things We Know
They are subjected to the same
 Vehicle operation
 Speed
 Stopping
 Starting
 Standing
 Acceleration
 Turning movements

14. Things We Know
 All Pavements are maintained with
 Same pavement seals
 Same crack filling
 Same interval of maintenance
 Same pavement rehabilitation, maintenance and
resurfacing

15. Things We Know
 All pavements require
 Arbitrary 2” thick asphalt concrete overlays every
10 or 20 years
 Identical Crack preparation
 Identical Local reconstruction
 Identical Edge milling and surface preparation

16. Things We Know
 No additional information is required

17. Things We Ignore
 Axle weights increased from 18,000 to 20,000
pounds on trucks
 Axle weights increased from 18,000 to 28,000
pounds on buses
 Tire pressures for trucks and buses have increased
to >120psi

18. Things We Ignore
 Traffic volumes have increased
 Asphalt binder characteristics are changing
 Recycling is increasing
 Waste reduction legislation

19. Things We Need to Know
 Pavement construction variations
 What
 Why
 Where
 Impact

20. Things We Need to Know
 Pavement use variations
 Pavement maintenance differences
 Environmental differences

21. How Do We Find Out?
 We use pavement management to define
similarities
 We use engineering properties to define
differences

22. What Sources Do We Have?
 Historical plans
 As-built drawings
 Visual observations
 Pavement coring and potholing
 Ground Penetrating Radar

23. The Evolution of Subsurface
Exploration
1970’s GPR
 1970’s
 Oil and Mineral Deposits
 Archaeologists
 Military
 Big Money $$$$$$
 Availability?
 Equipment and Power
 DataCapacity
 Mobility
 Trained Personnel
TODAY’S GPR
 Availability 
 Smaller Equipment
 Mobility
 Power needs
 Analysis time
 Trained Personnel
 DataCapacity
 GPSCompatibility
 MultipleTypes

24. GPR: Definition
 Electromagnetic Radiation
 Microwave band (UHF/VHF
Frequency)
 Radio waves transmitted into the
Ground
 Conductivity Increases Depth
Increases
 Higher Frequencies=
Low Penetration
 Low
Frequencies=Deep
Penetration
 How itWorks
 Changes inVelocity
 Change in Dielectrics
 Typically change in Material or
Density
 Components
 Antenna
 Operating System
 Large Data Storage Capacity
 Spatial Control
 GPS
 DMI

25. GPR Types
Low Frequency Applications
 Less than 16 - 200 MHz
 LongWave Length
 Deep Penetration
 Range 30 Ft to 150 Ft
 Poor Resolution
 Cart Mounted or Sled
 Geotechnical
 Mining
 Archeological Investigation
 Ice, Snow Pack

26. GPR Types
Mid Frequency
Applications
 270 MHz to 900 MHz
 LongWave Length
 Not as Deep Penetration
 Range 50 ft to 12 ft
 Better Resolution
 Cart Mounted or Sled
 Geotechnical
 Archaeological Investigations
 Utility
 Large SubsurfaceVoids
 Ice, Snow Pack

27. GPR Types
High Frequency Applications
 1600 MHz to 2600 MHz
 ShortWave Length
 Shallow Penetration
 Range 0 Ft to 1.5 Ft
 Good Resolution
 Hand Held Device
 Concrete Structures
 Bridge Deck (PCC)
 Rebar
 PostTension Cables
 Corrosion

28. GPR Types
High Frequency Applications
 1 GHz to 2 GHz
 ShortWave Length
 Shallow Penetration
 Range 0 Ft to 2.5 Ft
 Good Resolution
 HornAntenna
 RoadwayThickness
 ShallowUtility
 ShallowVoids

29. Document Pavement History

30. Rapid Data Acquisition

31. 9” AC over 20” AB
(Example A)

32. 3.5” AC over 10” PCC
(Example B)

33. PCC

34. 4” AC over 6” AB
(Example – New Pavement)

35. Anaheim Street (Port of Long Beach)
9th Street to LA River Bridge

36. Carson Street
(Intersection Testing)

37. Buried PCC

38. Buried PCC

39. Long Term/Historical Changes

40. Historical Changes

41. Historical Parking Lot
Improvements

42. New Parking Lot Construction

43. Network level documentation

44. How is it behaving?
 How strong is the roadway?
 Areas of strength and weakness
 How does that compare with past use?
 Explain current behavior
 How will it support projected future use?
 Magnitude of reinforcement required

45. Impacts on performance
 Indirect estimates
 Estimates from component analysis based on
 Thickness information
 Visible conditions
 In-situ moisture conditions
 Subgrade strengths

46. Impacts on performance
 Direct measurement
 In-place strength testing
 Multiple locations
 Magnitude of deflection
 Shape of deflection basin
 Load/stress distribution

47. In place strength testing

48. In place strength testing

49. In place strength testing

50. In place strength testing

51. In place strength testing

52. Specific Strength
Measurements

53. Comparative Analysis

54. Combined Analysis

55. Cost Effective Rehabilitation
Strategies

56. Real Information
 Pavement Coring
 Defines layer types and history
 Ground Penetration Radar
 Provides continuous documentation of
thicknesses
 Estimating/Guessing
 Based on past observable damage
 In Place StrengthTesting
 Permits modeling of future use and needs

57. Rational Engineering
Judgment
 Information Based
 Subjective v. Objective Analysis
 Empirical v. Mechanistic Analysis
 SEARCHING FORTHE SIMPLE ANSWER

58. The Pavement Tree