Improved Test Methods for Specific Gravity and Absorption of Coarse and Fine Aggregate

Knowledge of the specific gravity and absorption of coarse and fine aggregates is essential to the development of satisfactory mix designs for both portland cement concrete (PCC) and hot mix asphalt (HMA). Most importantly, production of PCC and HMA relies on accurate measurement of aggregate specific gravity. Further, aggregate specific gravities are needed to calculate the voids in mineral aggregate (VMA), voids in total mix (VTM), and binder content of HMA mixes--which are key volumetric determinants of HMA performance. For PCC, the aggregate absorption is used for achieving the target water/cement or water/cementitious material ratio; it also affects the workability of PCC and may have a significant impact on PCC's resistance to freezing and thawing. The present American Association of State Highway & Transportation Officials (AASHTO) standard test methods for aggregate specific gravity and absorption, namely, T 84, Specific Gravity and Absorption of Fine Aggregate, and T 85, Specific Gravity and Absorption of Coarse Aggregate, share several shortcomings in terms of subjectivity of the measurements, time requirements for conditioning and testing, and repeatability. Research is needed to identify promising new methods for measuring aggregate specific gravity and absorption or revisions to the present AASHTO methods that offer improved accuracy, precision, and practicality of the measurements. The objective of this project is to develop improved test methods for determining the specific gravity and absorption of coarse and fine aggregates for consideration by the AASHTO Highway Subcommittee on Materials. Development of the test methods will aim for balanced improvements in their (1) accuracy, precision, and ruggedness; (2) ease of use; (3) time of conditioning and testing; (4) cost; and (5) ability to deal with natural, crushed, recycled, and manufactured materials, compared with present standard methods. The ramifications of changes to the test methods on HMA mix design and PCC proportioning, other aggregate characteristics, and technician training and qualification shall also be addressed.

Language

  • English

Project

  • Status: Completed
  • Funding: $350000.00
  • Contract Numbers:

    Project 4-35

  • Sponsor Organizations:

    Federal Highway Administration

    1200 New Jersey Avenue, SE
    Washington, DC  United States  20590

    American Association of State Highway and Transportation Officials (AASHTO)

    444 North Capitol Street, NW
    Washington, DC  United States  20001

    National Cooperative Highway Research Program

    Transportation Research Board
    500 Fifth Street, NW
    Washington, DC  United States  20001
  • Project Managers:

    Harrigan, Edward

  • Performing Organizations:

    Auburn University

    National Center for Asphalt Technology
    310 Sanford Hall
    Auburn, Alabama  United States  36849-5131
  • Principal Investigators:

    West, Randy

  • Start Date: 20080403
  • Expected Completion Date: 0
  • Actual Completion Date: 20141231
  • Source Data: RiP Project 16894

Subject/Index Terms

Filing Info

  • Accession Number: 01464585
  • Record Type: Research project
  • Source Agency: National Cooperative Highway Research Program
  • Contract Numbers: Project 4-35
  • Files: TRB, RiP, USDOT
  • Created Date: Jan 3 2013 2:45PM