OBSERVATIONS ON THE USE OF FOLIATED ROCKS FOR COARSE AGGREGATE IN PAVING CONCRETE

THE APPLICATION OF PETROGRAPHY IS ILLUSTRATED IN INTERPRETING THE MODE OF DISTRESS OF CERTAIN PLATY ROCKS IN CONCRETE PAVEMENT AND BRIDGE DECKS AND IN GUIDING THE SELECTION OF OSTENSIBLY SIMILAR STONE FOR USE AS CONCRETE AGGREGATE. AN INVESTIGATION OF FLECKING OF A CONCRETE PAVEMENT LED TO THE CONCLUSION THAT THE STONE WHICH WAS USED EXERCISED A CRITICAL CONTROL OVER THE FLECKING BY LOCALIZING STRESSES ACTING IN THE PAVEMENT ALONG THE INTERFACE OF APPROPRIATELY ORIENTED PLATY PARTICLES AND THEIR MORTAR COVER. THE STONE, NOMINALLY A GRANITE GNEISS, WAS INVESTIGATED IN PLACE AND FOUND TO BE LOCALLY STRONGLY FOLIATED AND TO GRADE INTO WHAT MAY BE CALLED PHYLLITE. THE MECHANISM OF THE FLECKING, WHICH MANIFESTS ITSELF AS AN APPARENT BOND FAILURE, IS DEPENDENT ON THE ORIENTATION AND THE ARRANGEMENT OF THE MICAS IN THE ROCK AND THE LIKELIHOOD THAT THE MICA TO MICA BOND IN THE ROCK IS WEAKER THAN THE MICA TO MORTAR BOND IN THE PAVEMENT. MECHANICAL OR FREEZE-THAW ACTION ALONG AN AGGREGATE-MORTAR INTERFACE, WHICH HAS BEEN INITIALLY SEPARATED, LEADS TO ULTIMATE FLECKING OF THE MORTAR COVER OVER THE PLATY PARTICLE. A SLATE, WHICH IS SIMILAR IN ITS GROSS MINERALOGY AND FABRIC TO THE OTHER ROCK WAS RECOMMENDED FOR TRIAL USE AS A CONCRETE AGGREGATE. THE ANTICIPATED RESISTANCE OF THE SLATE TO THE SAME MECHANISM THAT PRODUCED THE APPARENT BOND FAILURE IN THE FIRST ROCK IS BASED ON PETROGRAPHIC WORK SHOWING THAT THE FABRIC OF THE ROCK IS DIFFERENT IN IMPORTANT RESPECTS FROM THE OTHER.

  • Supplemental Notes:
    • No 63, pp 111-128, 15 FIG, 2 TAB, 3 REF
  • Corporate Authors:

    Virginia Highway Research Council

    Charlottesville, VA  USA 
  • Authors:
    • Ozol, M A
  • Publication Date: 1966-12

Subject/Index Terms

Filing Info

  • Accession Number: 00212415
  • Record Type: Publication
  • Source Agency: Bureau of Public Roads /US
  • Files: TRIS
  • Created Date: Jul 12 1994 12:00AM