MICHIGAN'S EXPERIENCE WITH DIFFERENT MATERIALS AND DESIGNS FOR SKID RESISTANCE OF BITUMINOUS PAVEMENTS

ONLY FINE-TEXTURED, BITUMINOUS, SKID-RESISTANT SURFACES ARE CONSIDERED. ALL EXPERIMENTAL SURFACES START OUT WITH AN INITIAL AVERAGE SKID-RESISTANCE COEFFICIENT OF FRICTION OF MORE THAN 0.45. THE SANDSTONE SURFACE HAD AN INITIAL COEFFICIENT OF 0.74, THE QUARTZITE SURFACE OF 0.71, THE CRUSHED BEACH PEBBLES OF 0.63, ETC. A DIP OCCURS IN ALL THE CURVES AFTER ONE YEAR OF SERVICE FOLLOWED BY AN INCREASE AND LEVELING OFF OF THE COEFFICIENTS. AFTER 4 YEARS OF SERVICE, THE SANDSTONE AND QUARTZITE SURFACES WITH COEFFICIENTS OF 0.57 AND 0.58 ARE HIGHER THAN THE REST OF THE MATERIALS USED. A SATISFACTORY COEFFICIENT OF FRICTION SHOULD BE MORE THAN 0.35 OR 0.40, SO THAT EXCELLENT SKID RESISTANCE CAN BE OBTAINED BY USING SPECIAL HARD AGGREGATES IN THE BITUMINOUS SURFACES. HOWEVER, THE UNIFORMLY GRADED SAND-ASPHALT MIXTURES OFFER A STAISFACTORY SKID RESISTANCE AND HAVE PROVED TO BE DURABLE. HENCE, CURRENTLY MANY CRITICAL AREAS ON MICHIGAN TRUNK LINES ARE BEING RESURFACED WITH THE MORE ECONOMICAL SAND-ASPHALT MIXTURES. THE FOLLOWING CONCLUSINS ARE GIVEN: (1) SOFT COARSE AGGREGATES SUCH AS THE CARBONATE TYPES MAY POLISH FASTER THAN THE HARDER AGGREGATES. (2) FINE AGGREGATES WEAR AWAY EXPOSING NEW ONES BEFORE BECOMING POLISHED, THUS OFFERING SKID RESISTANCE AT LOWER SPEEDS (BELOW 40 MPH). (3) UNIFORMLY GRADED FINE AGGREGATES RESIST WEAR BETTER THAN NONUNIFORMLY GRADED ONES AND ARE NOT PRONE TO SURFACE DELAMINATION. (4) ANGULAR FINE-AGGREGATE PARTICLES OFFER SLIGHTLY BETTER SKID RESISTANCE THAN ROUNDED SANDS. (5) NATURAL SAND, WELL-GRADED AND CONTAINING PREDOMINANTLY HARD PARTICLES OFFERS SATISFACTORY SKID COEFFICIENT (0.40 TO 0.50) AND MAY BE CONSIDERED OVER THE SPECIAL AGGREGATES FOR ECONOMIC REASONS. (6) FRESH BITUMINOUS SURFACES ARE OILY, NONWETTING AND ARE INITIALLY SLIPPERY WHEN WET. THIS MAY BE CORRECTED BY APPLYING SAND, PRECOATED WITH ONE PERCENT ASPHALT, TO A MAT BEFORE ROLLING. (7) MATS OF 80 LB/SQ YD APPEAR TO BE THE DESIRED APPLICATION RATE FOR SKID-PROOFING PURPOSES. A LESSER THICKNESS MAY WEAR PREMATURELY AND PEAL OFF; A GREATER THICKNESS MAY RUT OR SHOVE. (8) ADDITION OF MINERAL FILLER AND ASPHALT SHOULD BE KEPT SLIGHTLY BELOW OPTIMUM TO OBTAIN SATISFACTORY SKID RESISTANCE. (9) THIN MATS ARE BEST APPLIED AT 60+ F AIR TEMPERATURES TO OBTAIN SATISFACTORY COMPACTION BEFORE CHILLING. (10) EXISTING SURFACES MUST BE THOROUGHLY CLEANED AND HAAVE A LIGHT APPLICATION OF TACK COAT BEFORE THIN BITUMINOUS SKID-RESISTANT MATS ARE PLACED. /AUTHOR/

Media Info

  • Media Type: Print
  • Features: Figures;
  • Pagination: pp 22-32
  • Monograph Title: Aggregates and skid resistance of bituminous pavements
  • Serial:

Subject/Index Terms

Filing Info

  • Accession Number: 00211612
  • Record Type: Publication
  • Files: TRIS, TRB
  • Created Date: Aug 8 1971 12:00AM