EFFECTS OF AGGREGATE FACTORS ON PAVEMENT FRICTION

EVEN THOUGH THE SKIDDING RESISTANCE OF PAVEMENTS HAS BEEN STUDIED FOR MANY YEARS, MANY QUESTIONS CONCERNING THE TRUE NATURE OF THE INTERACTION OF RUBBER AND PAVEMENT SURFACE REMAIN UNANSWERED. FOR THIS REASON CERTAIN TESTS WERE CARRIED OUT BY THE AUTHORS ON LABORATORY SPECIMENS WHICH, WHILE NOT GREATLY RESEMBLING PAVEMENTS, WERE PLANNED TO ELIMINATE MANY VARIABLES AND THUS AID IN EVALUATING THOSE WHICH REMAIN. ACTUAL SURFACE RESISTANCE MEASUREMENTS WERE MADE IN A LABORATORY MACHINE. TESTS WERE CONDUCTED ON SURFACES PLANNED IN A MANNER TO MAINTAIN A CONSTANT AREA OF AGGREGATE WHILE VARYING THE NUMBER AND SHAPE OF EDGES. ALTHOUGH NOT EXHAUSTIVE, SEVERAL RADICALLY DIFFERENT SHAPES WERE INCLUDED. FOR SOME OF THE SPECIMENS, THE AGGREGATE SHAPES USED PERMITTED CONTROLLED VARIATION IN THE SHARPNESS OF AGGREGATE EDGES. A SERIES OF TESTS WAS PERFORMED IN WHICH THE NORMAL LOAD WAS MADE THE MAJOR VARIABLE. FOR ANY ONE SPECIMEN THE AGGREGATE AREA WAS CONSTANT. ADDITIONAL SPECIMENS WERE TESTED IN WHICH THE AREA OF AGGREGATE IN CONTACT WITH THE TEST SHOE WAS VARIED WHILE THE EDGES AND TEST LOAD WERE HELD CONSTANT. THE ROCK CORES USED WERE A SOFT LIMESTONE AND A DURABLE SANDSTONE. THE POLISHING RATES OF SEVERAL DIFFERENT ROCKS WERE INVESTIGATED. SKID- RESISTANCE TESTS WERE MADE ON CORES AFTER SUCCESSIVE POLISH CYCLES USING CRUSHED QUARTZ AS A POLISHING MEDIUM. THE SAME CORES ALSO WERE TESTED AFTER POLISHING WITH ABRASIVE DUST MADE FROM THE CORE MATERIAL. TESTS ON ROCK CORES, AS POLISHED BY DIFFERENT SIZES OF ABRASIVES, INDICATED THAT FOR A GIVEN RUBBER AN OPTIMUM SIZE OF ROUGHNESS EXISTED. GRADED SILICA SAND WAS USED TO MAKE SURFACES OF DIFFERENT DEGREES OF ROUGHNESS IN ORDER TO FIND THIS OPTIMUM SIZE OF ROUGHNESS OR TEXTURE FOR THE RUBBER TEST SHOES USED. /AUTHOR/

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  • Accession Number: 00206916
  • Record Type: Publication
  • Files: TRIS, TRB
  • Created Date: Sep 12 1994 12:00AM