CLIFTON-HIGHLINE CANAL EXPERIMENTAL PROJECT I 70-1(14)33

IN THE SPRING OF 1965 CONSTRUCTION WAS COMPLETED ON A SECTION OF I-25 NORTH OF GRAND JUNCTION. MANCOS CLAY FORMATIONS EXIST QUITE GENERALLY IN THIS AREA AND GREATLY AFFECT HIGHWAY PAVEMENT PERFORMANCE. THIRTY-THREE TEST SECTIONS WERE LAID OUT ON THIS PROJECT USING DIFFERENT TYPES OF SUBGRADE TREATMENTS. PAVEMENT PERFORMANCE TESTS HAVE BEEN MADE QUARTERLY BY THE RESEARCH UNIT WITH SOIL TESTS BEING MADE BY THE DISTRICT AND CENTRAL LABORATORY PERSONNEL. AVERAGE PSI VALUES RANGED FROM NEAR 4.0 IN 1965 TO 3.25 IN THE FALL OF 1967. SOME SECTIONS HAVING THICK, OPEN-GRADED, GRANULAR SUBBASES SHOW A PSI LOWER THAN 2.9. THE DECREASE IN THE PSI HAS NOT BEEN ATTRIBUTED TO DISTRESS IN THE BASE OR SUBBASE. AT THIS TIME, THE LOSS IN PSI APPEARS TO COME FROM A SWELLING IN THE SUBGRADE AND A SMALL AMOUNT OF RAVELING ON THE SURFACE. VERY LITTLE CHANGE HAS BEEN EXPERIENCED IN PAVEMENT DEFLECTIONS SINCE CONSTRUCTION. DEFLECTION MEASUREMENTS ARE .20 IN. IN THE SUMMER AND .01 IN. IN THE WINTER. AS YET, NO TREND HAS BEEN ESTABLISHED BETWEEN DEFLECTION AND DESIGN. FREE WATER HAS ACCUMULATED IN THE GRANULAR MATERIALS UNDER THE PAVEMENT, EVEN IN AREAS WITH NO WATER TABLE. SINCE THE MOISTURE IS PRESENT ABOVE THE ASPHALT MEMBRANE (IN THE SECTIONS WHERE A MEMBRANE HAS BEEN PROVIDED) AND NOT BELOW IT, MOISTURE MAY BE COMING FROM VAPOR MOVEMENT. AIR PERMEABLE GRANULAR SUBBASE AND BASES ARE APPARENTLY RESPONSIBLE FOR HYDROGENESIS. THERE IS A POSSIBILITY THAT DENSE GRADED BITUMINOUS BASES MAY ACT AS VAPOR BARRIERS WHEN PLACED DIRECTLY ON THE SUBGRADE. ASPHALT MEMBRANES CONSTRUCTED FROM CATALYTICALLY BLOWN ASPHALTS CAN BE EFFECTIVE IN PREVENTING MOISTURE FROM INTRUDING INTO SUBGRADE SOILS. IN MANCOS SHALE CUTS, ONLY THE TOP AND SIDE SLOPES OF THE SUBGRADE NEED TO BE PROTECTED SINCE THE MOISTURE IS APPARENTLY COMMING FROM ABOVE GROUND SOURCES. /AUTHOR/

  • Supplemental Notes:
    • Hpr, Bpr-1471
  • Corporate Authors:

    Colorado Department of Highways

    4201 East Arkansas Avenue
    Denver, CO  United States  80222

    Bureau of Public Roads /US

    400 7th Street, SW
    Washington, DC  United States  20590
  • Authors:
    • Brakey, B A
  • Publication Date: 1968-1

Subject/Index Terms

Filing Info

  • Accession Number: 00206325
  • Record Type: Publication
  • Source Agency: Bureau of Public Roads /US
  • Files: TRIS, STATEDOT
  • Created Date: Apr 2 1994 12:00AM