This study focuses on an evaluation of techniques for automatic gradation applicable to mineral aggregate used in highway construction. The impetus for this study was the need for improved, rapid information on aggregate gradation for process control and to facilitate producer certification of highway aggregate. Potential techniques were identified after an extensive search of methods and concepts for automatic particle sizing spanning a wide spectrum of industrial activity where such information is needed for quality or process control. An elimination process narrowed the field of potential sizing techniques to six which were subjected to rigorous study. Two of these six techniques were identified for development of a conceptual system design which included technique modification, system component identification, structural considerations, compatibility with existing plant equipment, system reliability analysis, cost estimates and analysis of technique limitations. Conclusions from this study are that while no commercially available technique meets all the industry specified criteria for automatic gradation, the two systems identified (the vidicon and the optical shadow technique) show promise of being viable in the long run. It is recommended that further work, including engineering model development and field testing be undertaken to improve the performance capability of these techniques, and that alternate gradation specifications based on other measures of particle size be developed to facilitate the inclusion of these techniques in the industry mainstream. (FHWA)

  • Corporate Authors:

    JACA Corporation

    550 Pinetown Road
    Fort Washington, PA  United States  19034

    Federal Highway Administration

    1200 New Jersey Avenue, SE
    Washington, DC  United States  20590
  • Authors:
    • Bedick, R C
    • Patankar, U
    • Commins, J A
  • Publication Date: 1980-2

Media Info

  • Pagination: 144 p.

Subject/Index Terms

Filing Info

  • Accession Number: 00311764
  • Record Type: Publication
  • Source Agency: National Technical Information Service
  • Report/Paper Numbers: FHWA-RD-79-118 Final Rpt., FCP 34F7-033
  • Contract Numbers: DOT-FH-11-9308
  • Files: TRIS, USDOT
  • Created Date: Jun 26 1980 12:00AM