Use of Hamburg Loaded Wheel Track in Specifications & Research December 9-10, 2014 – Kenneth Ray Hobson, P.E. Havener Center, Campus of Missouri S&T 57 th Annual Asphalt Conference

To the Point 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

SOM TS2c Task Force Additional Investigation Needed –Specimen Preparation –SIP Analysis

NCHRP 20-07/Task 361 Revise AASHTO T 324

Reducing Variability NCHRP Rut Depth Calibration

Draft Finding – NCHRP 20-07

Reducing Variability – B

Reducing Variability – B Wheel & Measurement Locations Manufacturer Verification Confinement of Molds Middle and Ends Eliminate Cutting of Specimens Increase Specimen Length

Reducing Variability NCHRP B Confine Joint (Plaster of Paris) Retighten Tray Bolts (30 minutes) Change Mold Material Use Reference Samples Average All Rut Measurements

NCHRP B Table 4-28 PropertyRepeatability %COV Reproducibility %COV Rut (mm)

Reducing Variability ODOT Round Robin – Exp. 3 7 Wheels – Report July 11, 2012

Reducing Variability ODOT Round Robin – Exp. 4-5 ExperimentRut (10k) %COVN Rut (10k) %COVR

Final Reducing Variability Prevent Segregation –Specimen Preparation Mechanical Test Aging %Air Voids Grouping Specimen Orientation (top vs. bottom)

Questions? (405) (405)