While the petrographic examination of aggregate and hardened concrete has been conducted in Ontario since the late 1940's, there have been problems in communicating the results of the examinations to engineers. This resulted in the development of the "Petrographic Number" (P.N.) as a way of expressing the quality of coarse aggregate. Four quality categories are recognized: good aggregate (factor 1), fair (factor 3), poor (factor 6), and deleterious (factor 10). The Petrographic Number is calculated by multiplying the percentages of each rock type by the appropriate factor. The products are then added up to arrive at the P.N. Petrographic examination is conducted on sand using automated equipment. The percentage of deleterious (mica, shale) or alkali-reactive components (chert, glass) is reported. Petrographic examination of concrete is also conducted. This paper was presented at the Symposium on Petrography Applied to Concrete Aggregates, sponsored by ASTM C-9, St. Louis, Missouri, June 1989. (Author/TRRL)

  • Corporate Authors:

    Ontario Ministry of Transportation

    1201 Wilson Avenue
    Downsview, Ontario  Canada  M3M 1J8
  • Authors:
    • Rogers, C A
  • Publication Date: 1989-6

Media Info

  • Features: References;
  • Pagination: 35 p.

Subject/Index Terms

Filing Info

  • Accession Number: 00619668
  • Record Type: Publication
  • Source Agency: Transportation Association of Canada (TAC)
  • Files: ITRD, TRIS
  • Created Date: Mar 31 1992 12:00AM