PAVEMENT RESEARCH AT THE WASHINGTON STATE UNIVERSITY TEST TRACK; VOL 3: A STUDY OF UNTREATED, EMULSION TREATED, AND ASPHALTIC-CEMENT TREATED BASES

THREE DIFFERENT KINDS OF BASE MATERIAL OF VARYING BASE THICKNESSES WERE TESTED AT THE WASHINGTON STATE UNIVERSITY TEST TRACK ON RING #3 DURING THE FALL OF 1967 AND THE SPRING OF 1968. TWELVE 18-FOOT TEST SECTIONS CONSISTING OF 4.5, 7.0, 9.5 AND 12 INCHES OF UNTREATED CRUSHED ROCK SURFACING TOP COURSE BASE; 3.0,5.0, 7.0 AND 9.0 INCHES OF EMULSION TREATED CRUSHED SURFACING TOP COURSE BASE; AND 0.0, 2.0, 3.5 AND 5.0 INCHES OF SPECIAL NON-FRACTURED SCREENED AGGREGATE ASPHALT TREATED BASE, COVERED BY A UNIFORM 3.0-INCH THICK CLASS "B" ASPHALT CONCRETE WEARING COURSE WERE TESTED DURING THIS PERIOD. THE PAVEMENT STRUCTURE WAS BUILT ON A CLAY-SILT SUBGRADE SOIL. INSTRUMENTATION CONSISTED OF MOISTURE TENSIOMETERS, STRAIN GAGES PRESSURE CELLS, LVDT GAGES AND THERMOCOUPLES FOR MEASURING MOISTURE, STRAIN, STRESS, DYNAMIC DEFLECTIONS AND TEMPERATURES. BENKELMAN BEAM READINGS WERE TAKEN. THE TESTING PERIOD REVEALED THAT THE FALL FAILURE MODES WERE DIFFERENT FROM THE SPRING FAILURES. THE FALL FAILURE PATTERN STARTED FROM TRANSVERSE CRACKS IN THE THIN SECTIONS WHICH DEVELOPED INTO ALLIGATOR CRACKING PATTERNS. THESE CRACKS APPEARED AFTER A PERIOD OF COLD WEATHER AND HEAVY RAINS FOLLOWED BY A WARMING TREND. IT SEEMS THAT THERMAL AND MECHANICAL LOADS WERE RESPONSIBLE FOR THE FALL FAILURES ON THE THIN SECTIONS. THE SPRING FAILURES WERE VERY RAPID AND SUDDEN AND WERE DUE TO ENVIRONMENTAL FACTORS WHICH LED TO SATURATED SUBGRADE, THUS RESULTING IN POOR BEARING CAPACITY. PUNCHING SHEAR WAS THE FAILURE MODE. THE THICKEST SECTIONS SURVIVED WITHOUT CRACKS BUT DEVELOPED SEVERE RUTTING. EXAMINATION REVEALED THAT THESE RUTS EXTENDED INTO THE SUBGRADE AND THAT FATIGUE CRACKING WAS DEVELOPING ON THE BOTTOM OF THE BASES. EQUIVALENCIES WERE DEVELOPED FOR THE DIFFERENT MATERIALS. ON THIS BASIS THE SPECIAL AGGREGATE ASPHALT TREATED BASE WAS SUPERIOR TO THE EMULSION TREATED AND UNTREATED CRUSHED ROCK BASES IN THAT ORDER. MAXIMUM VALUES FOR STATIC AND DYNAMIC DEFLECTIONS, STRAINS AND STRESSES FOR DIFFERENT TIMES AND TEMPERATURES WERE DEVELOPED. THE LATERAL POSITION OF THE DUAL TIRES WITH RESPECT TO THE GAGE SEVERELY AFFECTED THE STRAIN, STRESS AND DEFLECTION VALUES. TEMPERATURE ALSO CAUSED VARIATIONS IN THE MEASUREMENTS. SPRING INSTRUMENT READINGS FOR STATIC AND DYNAMIC DEFLECTIONS, STRAIN AND STRESS SHOW INCREASED VALUES BY AS MUCH AS 2 TO 4 TIMES OF THOSE OBTAINED IN THE FALL. SPRING SUBGRADE CONDITIONS PROBABLY ARE RESPONSIBLE FOR THESE DIFFERENCES. /AUTHOR/

• Record URL:
  http://www.wsdot.wa.gov/research/reports/fullreports/015.3.pdf
• 
• Supplemental Notes:
  • Vol 3, 142 PP, 105 FIG, 29 TAB, 36 REF, 1 APP
• Corporate Authors:

  Washington State University, Pullman

  Department of Civil and Environmental Engineering
  P.O. Box 642910
  Pullman, WA  United States  99164-2910
• Authors:
  • KRUKAR, M
  • Cook, J C
• Publication Date: 1969

Subject/Index Terms

• TRT Terms: Alligator cracking; Asphalt concrete; Bearing capacity; Benkelman beam; Emulsions; Foundations; Gravel; Load cells; Pavement performance; Seasons; Shear stress; Strain gages; Tensiometers; Transverse cracking; Wearing course (Pavements)
• Uncontrolled Terms: Crushed gravel; Seasonal variations; Shearing
• Old TRIS Terms: Alligatoring
• Subject Areas: Highways; Pavements;

Filing Info

• Accession Number: 00207376
• Record Type: Publication
• Files: TRIS
• Created Date: Oct 18 1971 12:00AM