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Use of Hamburg Loaded Wheel Track in Specifications &
Research
Use of Hamburg Loaded Wheel Track in Specifications &
Research
December 9-10, 2014 – Kenneth Ray Hobson, P.E.December 9-10, 2014 – Kenneth Ray Hobson, P.E.
Havener Center, Campus of Missouri S&THavener Center, Campus of Missouri S&T
57th Annual Asphalt Conference57th Annual Asphalt Conference
To the PointTo the Point
• Test Parameters
• Various Equipment Suppliers
• Test Methods
• Agency Specifications
• Reducing Variability– National Research
– Local Research
Hamburg Test ParametersHamburg Test Parameters
• Reciprocating Rolling-Wheel Device– 8” Diameter x 1.85” [203 x 47 mm]
– 158 ± 1.0 lbs. [705 ± 4.5N]
– 52 ± 2 passes / minute
• Measures– Rut Depth (mm)
– Number of Passes
PMW WheelTrackerPMW WheelTracker
Troxler PMW WheelTrackerTroxler PMW WheelTracker
SmartTrackerSmartTracker
James COX & SonsJames COX & Sons
Cooper TechnologyCooper Technology
GCTS HWTT - 100GCTS HWTT - 100
Test MethodsTest Methods
• AASHTO T 334– OHD L-55
• Tex-242F
OHD L-55OHD L-55
• Water Temperature– 122 ± 2°F [50 ± 1°C]
• Number of Passes– Equivalent Single Axle Loads (ESALs)
• 18,000 lbs. / axle
– Binder Type
• Rut Depth Measurement Location(s)
OHD L-55OHD L-55
• Maximum Rut Depth – ½ in. [12.50 mm]
• Stripping Inflection Point (SIP)
Louisiana SpecificationsLouisiana Specifications
Oklahoma SpecificationsOklahoma Specifications
PMW Rut LocationsPMW Rut Locations
PMW Mid-Point LocationsPMW Mid-Point Locations
PMW Rut Sensor LocationsPMW Rut Sensor Locations
5 6 71 11
SOM TS2c Task ForceSOM TS2c Task Force
• Additional Investigation Needed– Specimen Preparation
– SIP Analysis
NCHRP 20-07/Task 361Revise AASHTO T 324NCHRP 20-07/Task 361Revise AASHTO T 324
http://apps.trb.org/cmsfeed/TRBNetProjectDisplay.asp?ProjectID=3741
Reducing Variability NCHRP 20-07
Rut Depth Calibration
Reducing Variability NCHRP 20-07
Rut Depth Calibration
Reducing Variability NCHRP 20-07 Rut Depth Calibration
Reducing Variability NCHRP 20-07 Rut Depth Calibration
Draft Finding – NCHRP 20-07Draft Finding – NCHRP 20-07
Reducing Variability – 10-87-2BReducing Variability – 10-87-2B
http://onlinepubs.trb.org/onlinepubs/nchrp/docs/NCHRP10-87_FinalReport-PrecisionEstimatesofT324.pdf
Reducing Variability – 10-87-2BReducing Variability – 10-87-2B
• Wheel & Measurement Locations
• Manufacturer Verification
• Confinement of Molds Middle and Ends
• Eliminate Cutting of Specimens
• Increase Specimen Length
Reducing VariabilityNCHRP 10-87-2B
Reducing VariabilityNCHRP 10-87-2B
• Confine Joint (Plaster of Paris)
• Retighten Tray Bolts (30 minutes)
• Change Mold Material
• Use Reference Samples
• Average All Rut Measurements
NCHRP 10-87-2BTable 4-28
NCHRP 10-87-2BTable 4-28
Property Repeatability%COV
Reproducibility %COV
Rut (mm) 14.2 26.0
Reducing VariabilityODOT Round Robin – Exp. 3
Reducing VariabilityODOT Round Robin – Exp. 3
7 Wheels – Report July 11, 20127 Wheels – Report July 11, 2012
Reducing VariabilityODOT Round Robin – Exp. 4-5
Reducing VariabilityODOT Round Robin – Exp. 4-5
Experiment Rut (10k) %COVN
Rut (10k) %COVR
4 43.2 25.8
5 77.9 31.5
Final Reducing VariabilityFinal Reducing Variability
• Prevent Segregation– Specimen Preparation
• Mechanical Test Aging
• %Air Voids Grouping
• Specimen Orientation (top vs. bottom)
Questions?Questions?
(405) 522-4986
(405) 522-4986
