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The National Academies

NCHRP Synthesis 20-05/Topic 50-14 [Active (Synthesis)]

Practices for Fabrication Asphalt Specimens for Testing in Laboratories
[ NCHRP 20-05 (Synthesis of Information Related to Highway Practices) ]

  Project Data
Funds: $45,000
Authorization to Begin Work: 5/1/2018 -- estimated
Staff Responsibility: Jo Allen Gause
Research Agency: University of New Hampshire
Principal Investigator: Jo Sias
Effective Date: 10/30/2018
Fiscal Year: 2018

Final Scope

Performance testing of asphalt mixtures is becoming more widespread for a variety of reasons and with a variety testing devices. The tests results are sensitive to the preparation of the specimens. Guidelines exist for conducting the tests, however they do not all provide uniform or comprehensive direction for fabricating test specimens. Detailed ruggedness studies identifying critical sources of variability have rarely been conducted in this area. Therefore, individual laboratories follow their own procedures where the standards are not specific.

The objective of this synthesis is to document state departments of transportation (DOTs) procedures with respect to laboratory fabrication of asphalt performance test specimens. For the purpose of this synthesis fabrication begins with a mixture and results in a prepared test specimen.

Information about specimen fabrication to be gathered includes (but is not limited to):
• Purpose of the testing (e.g., mix design, quality assurance, research);
• Methodologies used by DOTs and targeted non-DOT asphalt testing labs;
• Tests performed and standards or procedures used (AASHTO, ASTM, in-house, etc.);
• Equipment used (splitting, charging mold, compaction, coring, cutting, etc.);
• Short and long-term aging procedures;
• Lab testing sequencing and time limitations (maximum shelf life, operational disruptions, etc.); and
• Common issues encountered and solution developed.

Information will be gathered through literature review, survey of state DOTs and targeted non-DOT entities, and interviews with selected entities for the preparation of case examples. The DOT survey should be directed to the voting member of the AASHTO Committee on Materials and Pavements (COMP). Knowledge gaps and suggestions for research that could address those gaps will be identified.

Information Sources (Partial):
• NCHRP Report 702, Precision of the Dynamic Modulus and Flow Number Tests Conducted with the Asphalt Mixture Performance Tester, National Cooperative Highway Research Program
• Relevant NCHRP synthesis reports
• NCHRP 20-07 Task 406 report (in progress)
• Effect of Specimen Fabrication Variables on the Measured Mechanical Properties of Asphalt Mixtures Tested in the Asphalt Mixture Performance Tester (AMPT), Asphalt Institute, Prepared for Cooperative Agreement DTFH61-11-H-00033.
• AASHTO R83 Preparation of Cylindrical Performance Test Specimens Using the Superpave Gyratory Compactor (SGC)
• AASHTO R30 Mixture Conditioning of Hot Mix Asphalt (HMA)
• Other relevant AASHTO and ASTM standards 

TRB Staff
Jo Allen Gause
Phone: 202-334-3826
Email: jagause@nas.edu

Meeting Dates
First Panel:  October 30, 2018, Washington, DC
Teleconference with Consultant: November 19, 2018, 10:00 a.m., EST
Second Panel: July 18,

Topic Panel
Stacey D. Diefenderfer, Virginia Transportation Research Council
Gregory D. Johnson, Minnesota DOT
Rebecca S. McDaniel, Purdue University
Ross Metcalfe, Montana DOT
Jesus A. Sandoval-Gil, Arizona DOT
Brian Welch, Maine DOT
David Mensching, Federal Highway Administration
Nelson H. Gibson, Transportation Research Board

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