FRICTION REDUCING MEDIUMS FOR RIGID PAVEMENT SUBBASES

INCREASED INTEREST IN THE USE OF PRESTRESSED CONCRETE PAVEMENTS HAS BEEN ACCOMPANIED BY AN AWARENESS OF THE NEED FOR FRICTION REDUCING MEDIUMS BETWEEN THE SUBBASE AND THE SLAB IN ORDER TO MINIMIZE THE REQUIRED PRESTRESSING FORCE. THE BUREAU OF PUBLIC ROADS HAS TESTED SEVERAL DIFFERENT MEDIUMS IN A WINTER-SPRING STUDY AND A SUMMER STUDY. THE FINDINGS FROM THESE STUDIES ARE DISCUSSED IN THIS ARTICLE. IN THE STUDIES, CONCRETE SLABS 6 FEET SQUARE WERE MOVED HORIZONTALLY ALTERNATELY FORWARD AND BACKWARD, SEVERAL TIMES TO SIMULATE THE MOVEMENT OF PAVEMENTS IN SERVICE. THE THRUST NECESSARY TO CAUSE HORIZONTAL MOVEMENT AND THE MAGNITUDE OF DISPLACEMENT CAUSED BY THE THRUST WERE MEASURED FROM THE FIRST DETECTABLE MOVEMENT UNTIL FREE SLIDING OF THE SLAB BEGAN. ALL THE SLABS USED IN THE TEST WERE 5 INCHES THICK BUT WEIGHTS WERE ADDED FOR TWO SETS OF TESTS SO THAT THE EFFECTS OF 8- AND 11-INCH SLABS WERE OBTAINED. RESISTANCE TO SLAB MOVEMENT WAS DETERMINED FOR THE SEVER UNDERLYING MATERIALS' A PLASTIC SUBGRADE, TWO TYPES OF GRANULAR SUBBASES, AND FOUR TYPES OF MEDIUMS ON A GRANULAR SUBBASE. MOST OF THE TESTS WERE MADE AT A VERY SLOW RATE OF LOADING, BUT FOR COMPARISON PURPOSES SOME TESTS WERE RUN AT MEDIUM AND FAST RATES. THE LEAST RESISTANCE WAS RECORDED WHEN THE MEDIUM WAS EITHER A THIN LAYER OF SAND OR A DOUBLE LAYER OF POLYETHYLENE SHEETING ON A THIN, LEVELING COURSE OF SHEET ASPHALT. BOTH OF THESE MEDIUMS WERE CONSIDERED EFFECTIVE IN REDUCING FRICTION BETWEEN THE SUBBASE AND THE SLAB. /RRL/A/

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  • Supplemental Notes:
    • Vol33, No6, PP106-111, 10FIG, 1TAB, 2PHOT, 4REF
  • Authors:
    • Timms, A G
  • Publication Date: 1965-2

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  • Accession Number: 00206547
  • Record Type: Publication
  • Source Agency: Road Research Laboratory /UK
  • Files: TRIS
  • Created Date: Feb 20 1994 12:00AM