A SYSTEM FOR CALIBRATION OF THE MARSHALL COMPACTION HAMMER. FINAL REPORT

The Marshall method is used by many State and local highway agencies for the design of hot-mix asphalt. Although the procedure is specified by several industry standards, round-robin testing programs have confirmed wide variability in Marshall results. Much of the scatter in the data is attributed to compaction hammer variables, such as variation in drop weight, drop height, friction, hammer alignment, pedestal support, and foundation. To reduce the variability in the test results, an easy-to-use and relatively inexpensive system has been developed for the calibration of mechanical Marshall compaction hammers. This system consists of a spring-mass device with force transducer, power supply, and data acquisition system. The spring-mass device replaces the standard specimen mold during calibration. Force-time histories from multiple hammer blows are recorded and analyzed to determine average peak force, energy, and cumulative impulse. Using this information, a proposed calibration procedure has been developed. The procedure involves adjusting the number of blows to achieve a standard cumulative impulse. A limited laboratory evaluation program has been completed to demonstrate the system. The variability of test results for specimens prepared in calibrated machines was reduced by as much as 60%, as measured by the reduction in standard deviation and range of data for 15 specimens. A draft calibration standard has been developed and formatted according to AASHTO standards.

  • Corporate Authors:

    National Institute of Standards and Technology

    Technical Analysis Division
    Gaithersburg, MD  United States  20760

    Federal Highway Administration

    Turner-Fairbank Highway Research Center, 6300 Georgetown Pike
    McLean, VA  United States  22101
  • Authors:
    • Shenton, H
    • Cassidy, M
    • Spellerberg, P
    • Savage, D
  • Publication Date: 1994-7

Language

  • English

Media Info

  • Features: Appendices; Figures; Photos; References; Tables;
  • Pagination: 147 p.

Subject/Index Terms

Filing Info

  • Accession Number: 00664245
  • Record Type: Publication
  • Report/Paper Numbers: FHWA-RD-94-002, NISTIR 5338, NCP 3E1b
  • Contract Numbers: DTFH61-92-Y-30052
  • Files: TRIS, USDOT
  • Created Date: Aug 2 1996 12:00AM