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?

khobson@odot.org

(405) 522-4986

khobson@odot.org

(405) 522-4986