Transcript 57th Annual Asphalt Conference

Use of Hamburg Loaded Wheel
Track in Specifications &
Research
th
57
Annual Asphalt
Conference
Havener Center, Campus of Missouri S&T
December 9-10, 2014 – Kenneth Ray Hobson, P.E.
To the Point
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Test Parameters
Various Equipment Suppliers
Test Methods
Agency Specifications
Reducing Variability
– National Research
– Local Research
Hamburg 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 WheelTracker
Troxler PMW WheelTracker
SmartTracker
James COX & Sons
Cooper Technology
GCTS HWTT - 100
Test Methods
• AASHTO T 334
– OHD L-55
• Tex-242F
OHD 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-55
• Maximum Rut Depth
– ½ in. [12.50 mm]
• Stripping Inflection Point (SIP)
Louisiana Specifications
Oklahoma Specifications
PMW Rut Locations
PMW Mid-Point Locations
PMW Rut Sensor Locations
1
567
11
SOM TS2c Task Force
• Additional Investigation Needed
– Specimen Preparation
– SIP Analysis
NCHRP 20-07/Task 361
Revise 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
Draft Finding – NCHRP 20-07
Reducing Variability – 10-87-2B
http://onlinepubs.trb.org/onlinepubs/nchrp/docs/NCHRP10-87_FinalReport-PrecisionEstimatesofT324.pdf
Reducing Variability – 10-87-2B
• Wheel & Measurement Locations
• Manufacturer Verification
• Confinement of Molds Middle and
Ends
• Eliminate Cutting of Specimens
• Increase Specimen Length
Reducing Variability
NCHRP 10-87-2B
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Confine Joint (Plaster of Paris)
Retighten Tray Bolts (30 minutes)
Change Mold Material
Use Reference Samples
Average All Rut Measurements
NCHRP 10-87-2B
Table 4-28
Property
Rut (mm)
Repeatability
%COV
14.2
Reproducibility
%COV
26.0
Reducing Variability
ODOT Round Robin – Exp. 3
7 Wheels – Report July 11, 2012
Reducing Variability
ODOT Round Robin – Exp. 4-5
Experiment
4
5
Rut (10k)
%COVN
43.2
77.9
Rut (10k)
%COVR
25.8
31.5
Final Reducing Variability
• Prevent Segregation
– Specimen Preparation
• Mechanical Test Aging
• %Air Voids Grouping
• Specimen Orientation (top vs. bottom)
Questions?
[email protected]
(405) 522-4986