1. Stiffness-Based QC/QA
Humboldt Mfg. Co.
GeoGauge
Compaction Evaluation Today
Stiffness-Based QC/QA
GeoGauge : Material Evaluation Today

2. Humboldt Mfg. Co. Norridge, Illinois U.S.A.
Mr. Scott Fiedler
Product Manager
Humboldt Mfg. Co. Norridge, Illinois U.S.A.
Manufacturer & Distributor since 1909
Testing Equipment For Road Building Materials:
Asphalt
Concrete
Soil
Laboratory Apparatus
GeoGauge : Material Evaluation Today

3. In-place stiffness & modulus
Humboldt Mfg. Co.
In-place stiffness & modulus
Young’s Modulus
Elastic Modulus
Resilient Modulus
resistance to change in shape in direction of stress
Layer Stiffness
resistance to deflection
GeoGauge : Material Evaluation Today

4. Why Stiffness Based Compaction? (Why Measure Stiffness?)
Humboldt Mfg. Co.
Why Stiffness Based Compaction? (Why Measure Stiffness?)
Objective To Improve Load Bearing Capability
Reduce Variability
Enable Effective Load Transfer & Distribution, Pavement To Subgrade
Material Moduli
New Benefits
Minimized Pavement (Surface) Damage
Double Surface Life
Stiffness Makes Engineering Sense
GeoGauge : Material Evaluation Today

5. Improvements With Stiffness Measurements
Humboldt Mfg. Co.
Improvements With Stiffness Measurements
Optimum Compaction Effort
Reduce Over-Compaction
Reduce Variations
Reduce Maintenance & Repair Costs
Longer Lasting Smooth Surface
Verify Supporting Base Properties
Increase Surface Performance and Life
GeoGauge : Material Evaluation Today

6. Benefits Of Stiffness Based QC Compaction
Humboldt Mfg. Co.
Benefits Of Stiffness Based QC Compaction
Minimized Pavement Surface Damage
> 50% Increase In Roadway Life
> 50% Decrease In Roadway Maintenance Cost
Directly Links Construction With Design
Design & Construction Parameters Are The Same
Enables Performance Specifications And Contractor Warranties
Enables Use Of Reasonable Design Margins
No Over Specification
No Over Construction
GeoGauge : Material Evaluation Today

7. Humboldt Mfg. Co.
Variability
Control Of Compaction Process Enable Control Of Variability
Increase Life & Load Capacity.
GeoGauge : Material Evaluation Today

8. Stiffness Variability Is Important
Humboldt Mfg. Co.
Stiffness Variability Is Important
“ By reducing the variability of layer stiffness to +/- 25% of the mean, the life of the pavement surface will double over current practice.” (FHWA)
Easily Achieved !
GeoGauge : Material Evaluation Today

9. What GeoGauge Measures
Humboldt Mfg. Co.
What GeoGauge Measures
In-Place (In-Situ), 230 to 310mm Layer From Surface
During The Compaction Process For Effective QC/QA
Effective Young’s Modulus (elastic,resilient)
Influenced By Normal Construction Boundaries
Influenced By Construction/Contractor Operation
Modulus Of A Layered Composite Material
Modulus Of A Composite Material
Lower Than The Sum Of The Moduli Of The Constituent Materials
Effective Stiffness Of Composite Or Layered Structure
Influenced By Material Modulus, Layer Dimensions And Layer Boundaries
230 to 310 mm from surface
GeoGauge : Material Evaluation Today

10. GeoGauge Vibrates Ground & Measures the Deflection
Humboldt Mfg. Co.
GeoGauge Vibrates Ground & Measures the Deflection
Superior Steady-State Sinusoidal Loading Technology
7,400 cycles !
GeoGauge : Material Evaluation Today

11. Basic GeoGauge Specifications
Humboldt Mfg. Co.
Basic GeoGauge Specifications
280 x 270 mm, 10 kg
Effective Young’s Modulus: 610 MPa
Effective Layer Stiffness: 70 MN/m
Depth: 230 to 310 mm From Surface
Battery Power
Measurement Duration: 75 Seconds
No License Required
GeoGauge : Material Evaluation Today

12. GeoGauge Schematic Humboldt Mfg. Co.
GeoGauge : Material Evaluation Today

13. GeoGauge Features Does Not Interfere Or Delay Construction
Humboldt Mfg. Co.
GeoGauge Features
Does Not Interfere Or Delay Construction
Detects Small Differences
Self-Contained & Hand-Portable
Quick
Not Affected By Construction Vibration, Wind or Slope
Robust, Reliable, Low Cost & Easy To Use
Established Bias, < 1% COV
Established Precision, Typically < 7% COV
Meets ASTM D6758
GeoGauge : Material Evaluation Today

14. GeoGauge Procedure Is Simple
Humboldt Mfg. Co.
GeoGauge Procedure Is Simple
Inspect GeoGauge & Power On
Select Mode & Poisson’s Ratio
Prepare & Smooth Ground
Seat Foot
Place & 1/2 turn on soft materials
Place & 1/4 turn with wet sand over hard materials or rough surfaces
Take Measurement: 75 sec.
Record Data
GeoGauge : Material Evaluation Today

15. Simple, Quick & Safe ! Remove Lose Material Smooth Surface
Humboldt Mfg. Co.
Simple, Quick & Safe !
Remove Lose Material
Smooth Surface
Moist Sand Fill Voids
Pat Firmly Sand Pad
Place GeoGauge
Press Measure Button
Result In 75 Seconds
GeoGauge : Material Evaluation Today

16. Seating On Hard or Rough Surfaces
Humboldt Mfg. Co.
Seating On Hard or Rough Surfaces
Use Wet Sand To Ensure Maximum Contact
GeoGauge : Material Evaluation Today

17. GeoGauge Applications
Humboldt Mfg. Co.
GeoGauge Applications
Compaction QC/QA
Unbound & Bound Materials
Soil, Soil-Aggregates & Aggregates
Cement Treated Materials
Minimize Asphalt Surface Reflective Cracks
Subgrade & Base Stabilization
Ensure Required Strength & Minimize Construction Down Time
Trench / Utility Cut Backfill
Ensure Duplication Of Original Properties
Hot & Cold Mix Asphalt QC/QA
Compaction & Strength Evaluation
Forensic Investigations
GeoGauge : Material Evaluation Today

18. Stiffness-Based Specifications
Humboldt Mfg. Co.
Stiffness-Based Specifications
FHWA / 25 State DOTs Development Of AASHTO Standard
Specifications Underway For 2006 Construction Season
GeoGauge : Material Evaluation Today

19. Specified For QC/QA of Roadway Layers & Cement-Treated Bases
Humboldt Mfg. Co.
Specified For QC/QA of Roadway Layers & Cement-Treated Bases
GeoGauge : Material Evaluation Today

20. Specified To Implement Mechanistic-Empirical Design
Humboldt Mfg. Co.
Measure Material’s In-Place Modulus
Level 1 Input (AASHTO 2002 Guidelines)
GeoGauge : Material Evaluation Today

21. QC/QA of Granular Materials
Humboldt Mfg. Co.
QC/QA of Granular Materials
Measurements Yield Dry Density
GeoGauge : Material Evaluation Today

22. Density Relationship Humboldt Mfg. Co.
GeoGauge : Material Evaluation Today

23. Density Relationship Humboldt Mfg. Co.
GeoGauge : Material Evaluation Today

24. Possible QC/QA Criteria!
Humboldt Mfg. Co.
Possible QC/QA Criteria!
400
Field Tests
Lab Tests
300
Log(E-Ge) = 0.54 * log(E-PLT) R 2
= 0.725
GeoGauge (MPa)
200
100
100
200
300
400
500
Plate Load Test (MPa)
GeoGauge : Material Evaluation Today

25. Humboldt Mfg. Co.
Geogauge - FWD
FWD = Geogauge – 39.8 R2 = 0.81 at 95% level confidence N=29
FWD (MPa)
GeoGauge (MPa)
GeoGauge : Material Evaluation Today

26. Correlation to Other Moduli
Humboldt Mfg. Co.
Correlation to Other Moduli
300
600
900
1200
1500 50
100
150
200
250
350
400
500
1000
2000
2500
-50 1 2 3 4 5 6 95
105
110
115
120
PFWD (small plate)
PFWD (large plate)
DCP (6" avg.)
DCP (3" avg.)
GeoGauge
sc compaction
ng compaction
Section 17, Mn/ROAD
13 Pavement Sections
at 5 MnDOT Sites
Modulus
(MPa)
Compaction
(%)
Subgrade & Base Materials
In 6 TXDOT Districts
GeoGauge, E G
, (MPa) E F
= 4.08E
Correlation Coefficient: .80
FWD vs. GeoGauge Modulus
FWD, E
Seismic vs. GeoGauge Modulus S
= 6.27E
Correlation Coefficient: .79
Seismic, E
GeoGauge : Material Evaluation Today

27. GeoGauge Operation Principle
Humboldt Mfg. Co.
GeoGauge Operation Principle
Cyclic Vertical Loading X
25 Discrete Frequencies
100 To 196 Hz, 4 Hz Increment, 2 Seconds Each
Each Frequency = 1 Test, Result is Average of 25
Self-Filtering
Ground Anomaly / Infinitely Variable
2 Geophone Sensors & 1 Driver
1 Force
1 Displacement
GeoGauge : Material Evaluation Today

28. Operation Principles cont.
Humboldt Mfg. Co.
Operation Principles cont.
Stiffness = Force over Displacement.
At Low Frequencies, ground-input impedance is dominantly stiffness controlled.
GeoGauge : Material Evaluation Today

29. Operation Principles cont.
Humboldt Mfg. Co.
Operation Principles cont.
Internal Flexible Plate is Reference Stiffness.
GeoGauge : Material Evaluation Today

30. Operation Principles cont.
Humboldt Mfg. Co.
Operation Principles cont.
Relationship Of Stiffness To Young’s & Shear Modulus .
(Poulos & Davis)
GeoGauge : Material Evaluation Today

31. Operation Principles cont.
Humboldt Mfg. Co.
Operation Principles cont.
Averaging Over Operating Frequencies & Substituting Velocity, V, for Displacement, X, Ground Stiffness Is As Follows.
Avoids the need for non-moving reference for displacement & permits accurate measurement of small displacements
GeoGauge : Material Evaluation Today

32. Calibration Principles
Humboldt Mfg. Co.
Calibration Principles
GeoGauge : Material Evaluation Today

33. Review Stiffness Based Compaction QC/QA Makes Sense
Humboldt Mfg. Co.
Review
Stiffness Based Compaction QC/QA Makes Sense
Minimized Pavement Damage
Directly Links Construction With Design
Enables Use Of Reasonable Design Margins
GeoGauge Measures Stiffness
In-Place Layer Stiffness & Modulus Of Composite Materials
GeoGauge Is Practical For QC/QA
Small, Light, Quick, Simple & Non-Invasive
Many Applications
Roadway & General Compaction
Subgrade, Base & Pavement
Soil, Aggregate & Asphalt
GeoGauge : Material Evaluation Today

34. Verifier Mass Ensures Operation
Humboldt Mfg. Co.
Verifier Mass Ensures Operation
Measures ‘stiffness’ value of compliant-mounted mass. (10.0 kg)
Average of 3 to 5 measurements, remove & rotate 45 to 90 degrees between measurements. Should be /- 5%. (Between -8.8 & -9.8)
Negative sign represents mass.
GeoGauge : Material Evaluation Today

35. Verify Operation Daily
Humboldt Mfg. Co.
Verify Operation Daily
To be made at the beginning of every test day.
Ensures operation is correct.
Deviations can be easily corrected by calibration on same Verifier Mass.
GeoGauge : Material Evaluation Today

36. GeoGauge™ Use & Seating Procedure
Humboldt Mfg. Co.
GeoGauge™ Use & Seating Procedure
Seating & Measurement Procedures For Proper GeoGauge Measurements
GeoGauge : Material Evaluation Today

37. GeoGauge Seating Procedure
Humboldt Mfg. Co.
GeoGauge Seating Procedure
Established Jointly with State DOTs, FHWA & Humboldt
Procedure Standardized
ASTM D6758
Operator Bias Minimized or Eliminated
GeoGauge : Material Evaluation Today

38. Firmly Hand-Pack Wet Sand
Humboldt Mfg. Co.
Firmly Hand-Pack Wet Sand
One small handful
Fills cavities
Hand-packing does not change material properties
Make Sand Pad approximately 150mm dia. x 3 to 6mm thick
Placing and quarter-twist of GeoGauge further reduces amount of sand between ring foot and material surface
GeoGauge : Material Evaluation Today

39. Practice, Practice, Practice
Humboldt Mfg. Co.
Practice, Practice, Practice
A must for new technicians or users
Becomes proficient & confident
Ensures reliable measurements on projects
Practice on ‘real’ compacted surfaces
Recommended for experienced users
Profiles & Identifies Deviations Faster
Quickly addresses problems while equipment still on-site
Primary QC benefit
GeoGauge : Material Evaluation Today

40. Confirm Measurement Precision
Humboldt Mfg. Co.
Confirm Measurement Precision
Minimum of three (3) measurements on representative site and material.
At the beginning of each test day and each site.
Confirm precision.
About 8% COV or less is good.
Practice & experience improves COV.
GeoGauge : Material Evaluation Today

41. Suggested Supplies Brush to remove loose materials Gloves & knee-pads
Humboldt Mfg. Co.
Suggested Supplies
Brush to remove loose materials
Gloves & knee-pads
Helps to prepare surfaces more quickly
All supplied by technician or user.
Not shown: paper & pen to document measurement data, material type & water content, layer thickness and other conditions for database purposes.
GeoGauge : Material Evaluation Today

42. Humboldt Mfg. Co.
Prepare Surface
Use a solid scraper to remove any loose, dry, hard top materials and to make surface flat.
Use brush to help remove readily loose materials.
Surface must be moist and free of loose materials before wet sand is applied.
Any user supplied flat scraper or stiff brush can be used.
GeoGauge : Material Evaluation Today

43. Brush Away Loose Material
Humboldt Mfg. Co.
Brush Away Loose Material
Can be used instead of scraper plate.
Use brush to quickly remove loose material.
Do not ‘pick’ or remove protruding attached stones or disturb material.
GeoGauge : Material Evaluation Today

44. Humboldt Mfg. Co.
Container of Wet Sand
Use fine, well-graded & clean manufactured sand that has good adhesion when wet.
Often called masonry or mortar sand.
10 to 15% moisture is ideal.
GeoGauge : Material Evaluation Today

45. Humboldt Mfg. Co.
Place Wet Sand
A small handful is generally all that is required for freshly compacted material.
Drop onto the surface.
Sand may not be required if ring-foot pattern is clearly visible without sand, which indicates soil is soft enough to conform to ring-foot for complete contact.
GeoGauge : Material Evaluation Today

46. Small Handful of Wet Sand
Humboldt Mfg. Co.
Small Handful of Wet Sand
GeoGauge : Material Evaluation Today

47. Firmly Hand-Pack Wet Sand
Humboldt Mfg. Co.
Firmly Hand-Pack Wet Sand
Spread the sand to a pad shape about 150mm dia. & no more than 6mm thick.
Use more sand for a thicker pad when required where surface is rough.
Pack firmly, equal & smooth.
GeoGauge : Material Evaluation Today

48. Always Use Wet Sand Ensures Full & Equal Annular Contact
Humboldt Mfg. Co.
Always Use Wet Sand
Ensures Full & Equal Annular Contact
Repeatability
Thin layer of sand has no influence
Well-Graded, Fine Mortar or Masonry Sand
Provides good adhesion
10 to 20% moisture
Sand may not be required if, without sand, a complete 360 degree ring-foot pattern is clearly visible, which indicates soil is soft enough to conform to ring-foot for complete contact.
GeoGauge : Material Evaluation Today

49. Place GeoGauge Rest GeoGauge ring-foot on center of sand pad.
Humboldt Mfg. Co.
Place GeoGauge
Rest GeoGauge ring-foot on center of sand pad.
No addition downward force.
GeoGauge : Material Evaluation Today

50. Twist One/Quarter Turn
Humboldt Mfg. Co.
Twist One/Quarter Turn
With both hands on side of GeoGauge, apply a one-quarter turn or twist only, to complete the seating.
Do not apply additional downward force.
Most critical step in seating the GeoGauge.
GeoGauge : Material Evaluation Today

51. Humboldt Mfg. Co.
Press ‘MEAS’ Button
Gently Press the ‘MEAS’ button, without shaking the GeoGauge
Take one-step back to avoid influence of body-weight
Measures the surface noise before actual stiffness measurements.
GeoGauge : Material Evaluation Today

52. Humboldt Mfg. Co.
Results in 75 Seconds
Displays the lowest signal-to-noise ratio of the 25 discrete frequency.
Displays the standard deviation of the 25 discrete frequency.
Finally displays the stiffness or modulus values.
Record data.
GeoGauge : Material Evaluation Today

53. Acceptable ‘Foot-print’
Humboldt Mfg. Co.
Acceptable ‘Foot-print’
Good, equal annular print is acceptable. Try to twist one-quarter turn on its axis as good as practical.
Acceptable foot-print pattern can only be determine after measurement
Practice will improve acceptance
GeoGauge : Material Evaluation Today

54. Humboldt Mfg. Co.
Questions ?
GeoGauge : Material Evaluation Today