TRIAXIAL TESTING OF BITUMINOUS MIXTURES AT HIGH CONFINING PRESSURES

THE OBJECT OF THIS LABORATORY RESEARCH WAS TO DEVELOP A BETTER UNDERSTANDING OF THE BASIC FACTORS THAT CONTRIBUTE TO THE DEVELOPMENT OF SHEARING STRENGTH IN BITUMINOUS-AGGREGATE MIXTURES. THE TWO AGGREGATE GRADATIONS USED WERE REFERRED TO AS OPEN-GRADED AND ONE-SIZE, AND WERE INCORPORATED WITH AN ASPHALT CEMENT INTO BITUMINOUS MIXTURES. THE OPEN-GRADED AND ONE-SIZE MIXTURES WERE CHOSEN BECAUSE THEY BOTH PERFORM SATISFACTORILY AS PAVING MIXTURES FOR MANY SERVICE CONDITIONS, BUT ONLY THE OPEN-GRADED MIXTURE POSSESSES ADEQUATE STABILITY WHEN EVALUATED BY CONVENTIONAL TESTING METHODS. IN ADDITION TO AGGREGATE GRADATION, THE OTHER VARIABLES CONSIDERED IN THIS INVESTIGATION WERE CONFINING PRESSURE (0-150 PSI), SPECIMEN HEIGHT, TYPE OF AGGREGATE, AND THE ASPHALT CONTENT. TEST SPECIMENS HAVING A HEIGHT TO DIAMETER RATIO LESS THAN TWO ALSO WERE FABRICATED TO MEASURE THE INFLUENCE OF SPECIMEN HEIGHT ON THE TRIAXIAL STABILITY AT HIGH CONFINING PRESSURES. THIS PHASE OF THE RESEARCH INVESTIGATION WAS DESIGNATED AS THE IRRATIONAL TRIAXIAL TEST. FOR BOTH THE RATIONAL AND IRRATIONAL TRIAXIAL TESTS, THE OPEN-GRADED MIXTURE SHOWED STRENGTH PROPERTIES WITH A DIRECT CORRELATION TO THE COULOMB EQUATION. THEREFORE, THE STRENGTH PROPERTIES OF THIS MIXTURE MAY BE REPRESENTED BY THE TWO CONSTANTS, COHESION AND ANGLE OF FRICTION. HOWEVER, THE SHEARING STRENGTH VALUES PRODUCED BY THE IRRATIONAL TRIAXIAL TEST WERE HIGHER THAN THE CORRESPONDENDING VALUES FOR THE RATIONAL TRIAXIAL TEST, AND DIFFERENT VALUES OF COHESION AND ANGLE IF INTERNAL FRICTION WERE OBTAINED BY THE TWO TESTING PROCEDURES. THE TRIAXIAL TESTING OF THE ONE-SIZE MIXTURE INDICATED THAT A CURVILINEAR RELATIONSHIP EXISTED BETWEEN THE CONFINING PRESSURE AND THE NORMAL STRESS. THUS, THE SHEARING STRENGTH OF THIS ONE-SIZE MIXTURE CANNOT BE ASCERTAINED WHOLLY BY SUCH CONSTANTS AS THE COHESION AND THE ANGLE OF INTERNAL FRICTION. FOR SPECIMENS MADE FROM BOTH AGGREGATE GRADATIONS, THE CRUSHED-LIMESTONE AGGREGATE PRODUCED HIGHER TRIAXIAL STABILITY VALUES THAN THE UNCRUSHED GRAVAL AND NATURAL SAND FOR THE RANGE OF CONFINING PRESSURES USED. HOWEVER, THE SELECTION OF AN ASPHALT CONTENT GIVING MAXIMUM STRENGTH FOR THESE TWO AGGREGATE TYPES IN BOTH THE OPEN-GRADED AND THE ONE-SIZE MIXTURES WAS DETERMINED TO BE INDEPENDENT OF THE DEGREE OF THE CONFINING PRESSURE. /AUTHOR/

  • Supplemental Notes:
    • Vol 37, pp 201-218, 16 FIG, 9 TAB, 18 REF, 1 APP
  • Authors:
    • Oppenlander, J C
    • Goetz, W H
  • Publication Date: 1958

Media Info

  • Monograph Title: Proceedings of the Thirty-Seventh Annual Meeting of the Highway Research Board, Washington, D.C., January 6-10, 1958
  • Serial:

Subject/Index Terms

Filing Info

  • Accession Number: 00211638
  • Record Type: Publication
  • Files: TRIS, TRB
  • Created Date: Oct 3 1971 12:00AM