STABILITY AND DURABILITY OF PLANT-MIX MACADAM

ENGINEERS HAVE HAD LITTLE DIFFICULTY IN DESIGNING BITUMINOUS PAVING MIXES OF ADEQUATE STABILITY. IT HAS BEEN MORE DIFFICULT TO PROVIDE PROTECTION AGAINST "STRIPPING" OF THE ASPHALT FILM WITHOUT SACRIFICING STABILITY THROUGH THE USE OF EXCESSIVE AMOUNTS OF ASPHALT. THIS HAZARD CAN BE LARGELY ELIMINATED BY USING A MACADAM-TYPE AGGREGATE WITH A SAND-ASPHALT FILLER; IT CAN BE IMPREGNATED WITH ENOUGH ASPHALT TO PROVIDE PROTECTION AGAINST STRIPPING. FOUR TEST SPECIMENS WERE PREPARED FROM EACH SAMPLE BATCH. ONE SPECIMEN WAS A CYLINDER OF 4-IN. DIAMETER AND 8 IN. HIGH, COMPACTED BY PLUNGER UNDER A STEADY LOAD OF 31,400 LB. FOR ONE MINUTE. THE REMAINING THREE SPECIMENS WERE 2-2-12-IN. SQUARE BARS COMPACTED IN TWO LAYERS BY A SPECIALLY DESIGNED ROLLER. THE CYLINDERS WERE PREPARED TO BE USED IN THE CLOSED SYSTEM TRIAXIAL TEST, AND THE BARS WERE PREPARED TO BE USED IN THE FREEZING-AND-THAWING TESTS. THE STABILITY OF EACH MIXTURE WAS DETERMINED BY THE STANDARD CLOSED-SYSTEM TRIAXIAL COMPRESSION TEST. THE FREEZING AND THAWING TESTS WERE CONDUCTED BY FREEZING THE BARS AT -16 F., WITH ONE GROUP FROZEN IN AIR AND ANOTHER DUPLICATE GROUP FROZEN UNDER WATER, AND THEN THAWING THEM AT ROOM TEMPERATURE (72 F.). THE SPECIMENS WERE MAINTAINED AT THE -16 F. TEMPERATURE OVERNIGHT, AND WERE TAKEN OUT IN THE MORNING, THAWED AT ROOM TEMPERATURE FOR 2 1/2 HR., AND LEFT TO DRY FOR ANOTHER 2 HR. THE DRY SPECIMENS WERE WEIGHED, MEASURED, AND THEN SUBJECTED TO THE SONIC TEST. /AUTHOR/

  • Supplemental Notes:
    • Vol 31, pp 246-253, 4 FIG, 9 TAB, 6 PHOT
  • Authors:
    • Clanton, J R
    • Hennes, R G
  • Publication Date: 1952

Media Info

  • Monograph Title: Proceedings of the Thirty-First Annual Meeting of the Highway Research Board, Washington, D.C., January 15-18, 1952
  • Serial:

Subject/Index Terms

Filing Info

  • Accession Number: 00211622
  • Record Type: Publication
  • Files: TRIS, TRB
  • Created Date: Aug 1 1971 12:00AM