Use Of Gyratory Testing Machine In Evaluating Bituminous Mixtures

A STUDY WAS MADE OF SELECTED LABORATORY TEST PROPERTIES OF BITUMINOUS MIXTURES COMPACTED BY THE GYRATORY TESTING MACHINE. COMPACTION IN THE GYRATORY TESTING MACHINE WAS IMPOSED ON THE BITUMINOUS MIXTURES IN AN ATTEMPT TO SIMULATE COMPACTION THAT WOULD BE IMPOSED BY CONSTRUCTION EQUIPMENT AND TRAFFIC. THE STUDY CONSISTED, IN PART, OF STABILITY AND UNIT WEIGHT MEASUREMENT OF SPECIMENS COMPACTED UNDER VARYING LEVELS OF SIMULATED CONSTRUCTION AND TRAFFIC COMPACTION. STABILITY MEASUREMENTS WERE MADE WITH THE HVEEM STABILOMETER. TWO AGGREGATE GRADATIONS WERE USED TO STUDY THE EFFECTS OF COMPACTION ON DENSE-AND OPEN-GRADED MIXTURES. COMPACTIVE EFFORT WAS VARIED BY CHANGING RAM PRESSURE AND NUMBER OF REVOLUTIONS, AS WELL AS TYPE OF OPERATION IN THE GYRATORY TESTING MACHINE. STATISTICAL ANALYSES WERE USED TO EVALUATE THE EFFECT OF THE MACHINE VARIABLES ON SPECIMEN STABILITY. THE STABILITIES OF SPECIMENS COMPACTED IN THE GYRATORY TESTING MACHINE WERE COMPARED TO THOSE COMPACTED IN THE KNEADING COMPACTOR ACCORDING TO THE HVEEM DESIGN PROCEDURE. STABILITIES AT THE SAME PERCENT VOIDS WERE ANALYZED FOR BOTH KNEADING AND GYRATORY-COMPACTED SPECIMENS. SPECIMENS COMPACTED IN THE MACHINES WERE CUT IN HALF AND UNIT WEIGHT DETERMINATIONS WERE MADE FOR SPECIMEN TOPS AND BOTTOMS. STATISTICAL TESTS WERE PERFORMED TO DETERMINE WHETHER UNIT WEIGHT GRADIENTS EXISTED IN COMPACTED SPECIMENS . PARTICLE ORIENTATION WAS STUDIED BY DISPERSING LONG SLENDER AGGREGATE PIECES IN A PLASTIC CLAY MEDIA. THE RESULTS OF THE STUDY INDICATED THAT THE LOAD IMPOSED ON SPECIMENS DURING THE COURSE OF THE STABILOMETER TEST INCREASED DENSITY AND DECREASED VOIDS IN SOME COMPACTED SPECIMENS. /AUTHOR/