EFFECT OF STUDDED TIRES ON AGGREGATE AND RELATED EFFECTS ON SKID RESISTANCE

FIELD OBSERVATIONS MADE DURING THE WINTERS OF 1966-1970 IN MINNESOTA WHEN STUDS WERE USED REVEALED THE FOLLOWING: (1) PAVEMENT WEAR WAS MINOR IN THE FIRST TWO WINTERS DUE TO THE SMALL NUMBER OF CARS (9%) EQUIPPED WITH STUDS. AS THE PROPORTION INCREASED TO 40% IN THE FOURTH WINTER, THE WEAR BECAME SO PRONOUNCED THAT A DEPTH OF 1/4 IN. WAS REACHED IN THE WHEELPATHS ON BOTH BITUMINOUS AND PORTLAND CEMENT CONCRETE. (2) THE MOST SEVERE WEAR WAS DEVELOPED ON HIGH SPEED, HIGH VOLUME ROADS SUCH AS THE INTERSTATE, FREEWAYS AND EXPRESSWAY WITHIN AND AROUND THE METROPOLITAN AREA, SHOWING THAT THE RATE OF PAVEMENT WEAR IS RELATED TO SPEED AND STUD APPLICATIONS. WHERE THE WEAR DEPRESSION WAS ABOUT 1/4 IN., AN ESTIMATE OF 1.6 MILLION STUD APPLICATIONS WAS MADE. (3) THE WEAR RATE IS SLOW FOR (A) RURAL ROADS WITH LOW TRAFFIC VOLUMES THOUGH TRAVEL SPEEDS ARE HIGH, (B) URBAN STREETS WITH SLOW TRAFFIC SPEEDS ALTHOUGH TRAFFIC DENSITY IS HIGH. HOWEVER, WHERE THERE IS A CONCENTRATION OF FAST ACCELERATION OR HEAVY BRAKING, SUCH AS ON ENTRANCE OR EXIT RAMPS TO OR FROM FREEWAYS, THE WEAR IS PRONOUNCED. (4) WHEN THE SURFACE FILM OR COATING OF ASPHALT OR CEMENT MORTAR IS WORN AWAY, THE COARSE AGGREGATE PARTICLES ARE EXPOSED, SHOWING A MOSAIC-LIKE SURFACE APPEARANCE. FOR PROGRESSING WEAR, THE MATRIX ERODES FROM BETWEEN THE HARDER COARSE AGGREGATE PARTICLES. FOR COARSE AGGREGATES OF CRUSHED ROCK OR GRAVEL CONSISTING OF IGNEOUS PARTICLES AND PEBBLES, THE HARD PARTICLES PROTRUDE ABOVE THE SURROUNDING MATRIX, PRODUCING A KNOBBY ROUGH TEXTURED SURFACE, DISCERNIBLE VISUALLY AND BY SOUND AND FEEL WHEN A CAR TRAVELS OVER IT. THE AFFECTED AREA IS APPROXIMATELY 2 1/2 FT. WIDE FOR EACH WHEELPATH. (5) LIMESTONE COARSE AGGREGATES (A) TEND TO WEAR DOWN WITH THE MATRIX REMOVAL, AND THE WHEELPATH SURFACE IS NOT AS ROUGH OR BADLY ABRADED AS THE HARD ROCK OR GRAVEL AGGREGATES; (B) MAY WEAR MORE RAPIDLY THAN THE MATRIX SO THAT THE SURFACES ARE ACTUALLY BELOW THE MATRIX. THUS, THE TYPE OF AGGREGATES USED SIGNIFICANTLY INFLUENCES THE WEAR RATE OF PAVEMENTS. WHEELPATH WEAR PRODUCES SHALLOW SURFACE RUTS THAT MAY AFFECT THE PAVEMENT'S SKID CHARACTERISTICS. READINGS WERE TAKEN WITHIN AND OUTSIDE THE WORN AREA OF THE WHEELPATH. THE SKID NUMBERS OBTAINED WERE WITHIN 2 OR 3 POINTS OF ONE ANOTHER FOR COMPANION READINGS INSIDE AND OUTSIDE THE WHEELPATH.

Media Info

  • Media Type: Print
  • Pagination: pp 46-48
  • Monograph Title: Aggregates and skid resistance of bituminous pavements
  • Serial:

Subject/Index Terms

Filing Info

  • Accession Number: 00211614
  • Record Type: Publication
  • Files: TRIS, TRB
  • Created Date: Aug 8 1971 12:00AM