INVESTIGATION OF ROCK SLOPE PROTECTION MATERIAL

THE USE OF ROCK SLOPE PROTECTION MATERIAL ON HIGHWAY CONSTRUCTION PROJECTS IN CALIFORNIA HAS INCREASED MARKEDLY IN THE LAST DECADE. THE WEATHERING PROCESSES AND THEIR EFFECTS ON ROCK SLOPE INSTALLATIONS ARE EVALUATED, AND THE CONCLUSION IS DRAWN THAT INITIALLY SOUND ROCK WILL BE LITTLE AFFECTED BY WEATHERING DURING THE DESIGN LIFE OF AN INSTALLATION. TEST RECORDS COMPILED SINCE 1957 SHOW WIDE DISCREPANCIES IN CORRELATION BETWEEN THE SPECIFICATION TEST RESULTS AND PERFORMANCE. AN ANALYSIS OF DATA FROM THESE RECORDS: (1) SHOW THAT THE LOS ANGELES RATTLER TEST COULD BE DISCONTINUED AS A SPECIFICATION TEST SINCE 97.6 PERCENT OF THE SAMPLES THAT FAIL THIS TEST ARE REJECTED BY AT LEAST ONE OTHER TEST, (2) ARE THE BASIS FOR RECOMMENDING THAT THE SODIUM SULFATE SOUNDNESS TEST SPECIFICATION BE RAISED FROM FIVE PERCENT TO TEN PERCENT MAXIMUM LOSS, (3) INDICATE THAT THE PRESENTLY USED 2.5 MINIMUM SPECIFIC GRAVITY AND 2.0 PERCENT MAXIMUM ABSORPTION SPECIFICATIONS ARE REASONABLE VALUES. THE STANDARD SPECIFICATIONS DO REJECT OBVIOUSLY POOR ROCK, BUT THEY ALSO REJECT MUCH SATISFACTORY MATERIAL. A RANGE OF TEST VALUES WAS SET UP AND PERFORMANCE CATEGORIES ESTABLISHED SO THAT CORRELATIONS COULD BE MADE BETWEEN TEST RESULTS AND PERFORMANCE. A STUDY OF THE ABSORPTION TEST METHOD SHOWS THAT PARTICLE SIZE INFLUENCES THE VALUES OBTAINED. IT IS RECOMMENDED THAT A STANDARDIZED PROCEDURE FOR GRADING ABSORPTION TEST RESULTS BE CLOSELY FOLLOWED. THE WET-DRY AND FREEZE-THAW METHODS WERE EVALUATED BY TESTING BLOCKS, VARIOUS PARTICLE SIZES, AND VARYING THE TEST PROCEDURE. SEA WATER WAS FOUND TO BE LESS SEVERE THAN FRESH WATER IN THE WET-DRY TEST. THE DURABILITY TEST AS NOW PERFORMED ON COARSE AGGREGATE APPEARS TO BE A USEFUL PERFORMANCE INDICATOR. A MINIMUM DC VALUE OF 60 IS SUGGESTED BY THE AVAILABLE DATA BUT MORE TESTING IS REQUIRED BEFORE A SPECIFICATION CAN BE RECOMMENDED. CONSIDERABLE EXPERIMENTAL TESTING WAS DONE TO DEVELOP A SIMPLE AND PRACTICAL RAPID ABRASION TEST. THE RESULTS CORRELATE WITH PERFORMANCE AND THE METHOD SHOWS PROMISE AS A SPECIFICATION TEST. TWO INDEX FORMULAS WERE DEVISED THAT YIELD INDEX NUMBERS WHICH ARE RELATED TO PERFORMANCE. BOTH FORMULAS ARE SIGNIFICANTLY BETTER PERFORMANCE PREDICTORS THAN THE PRESENT SPECIFICATIONS.

  • Supplemental Notes:
    • No M & R 632561, 117 PP, 35 FIG, 15 TAB, 6 REF, 10 APP
  • Corporate Authors:

    California Division of Highways

    Materials and Research Department
    Sacramento, CA  USA  95819

    California Department of Public Works

    1120 N Street
    Sacramento, CA  USA  95814

    California Department of Transportation

    1120 N Street
    Sacramento, CA  USA  95814
  • Authors:
    • Smith, T
    • Gamble, J
    • Mearns, R
  • Publication Date: 1967-4

Subject/Index Terms

Filing Info

  • Accession Number: 00217565
  • Record Type: Publication
  • Files: TRIS, STATEDOT
  • Created Date: Jan 24 1994 12:00AM