MOISTURE STABILIZATION BY MEMBRANES, ENCAPSULATION AND FULL DEPTH PAVING

FROM A REVIEW OF SEVERAL EXPERIMENTAL PROJECTS (AT CLIFTON, ORDWAY, ELK SPRINS, AND OTHER SITES) CONSTRUCTED ON EXPANSIVE SOILS IN VAROUS REGIONS OF COLORADO THE FOLLOWING CONCLUSIONS WERE DRAWN: (1) CATALYTICALLY BLOWN ASPHALT MEMBRANES CAN BE PLACED FOR ABOUT 50 CENTS PER SQUARE YARD AND ARE EFFECTIVE IN MAINTAINING AS-CONSTRUCTED MOISTURE IN SUBGRADE SOILS. (2) FULL DEPTH ASPHALT BASES ARE EFFECTIVE IN REDUCING MOISTURE BUILDUP IN SUBGRADE SOILS. SPECIAL PRECAUTIONS ARE NEEDED, HOWEVER, TO PREVENT MOISTURE CHANGE CYCLES AT THE SHOULDERS IN ORDER TO PREVENT LONGITUDINAL CRACKING IN THE PAVEMENT A FEW FEET IN FROM THE SHOULDER. (3) GRANULAR UNTREATED BASES, EITHER DIRECTLY OR INDIRECTLY, ARE RESPONSIBLE FOR THE HIGHER MOISTURES FOUND UNDER SUCH BASES IN COMPARISON TO FULL DEPTH ASPHALT BASES. (4) ENCAPSULATED OR ENVELOPED SUBGRADE SOILS REMAIN AT A LOWER MOISTURE CONTENT. THIS COES NOT APPEAR TO BE ECONOMICALLY PRACTICAL, HOWEVER, SINCE ON THE ELK SPRINGS PROJECT, ENOUGH ADDTIONAL SOIL SUPPORT WAS NOT GAINED OVER THAT UNDER ASPHALT BASE TO OFFSET THE EXTRA COST OF PLACING THE MEMBRANE. (5) SOIL SUPPORT VALUES UNDER ASPHALT MEMBRANES AND FULL DEPTH ASPHALT BASES ARE CONSIDERABLY HIGHER THAN UNDER GRANULAR UNTREATED BASES WHEN COMPARED FOR SIMILAR CONDITIONS. A NEW CORRELATION OF LABORATORY STABILOMETER R VALUES AND FIELD SOIL SUPPORT VALUES FOR THE DRIER CONDITIONS IS SUGGESTED. UNDER CONDITIONS SIMILAR TO ORDWAY AND ELK SPRINGS, THIS WOULD RESULT IN A DECREASED THICKNESS OF THE PAVEMENT STRUCTURE OF ABOUT 0.45 STRUCTURAL NUMBER BELOW THAT CALLED FOR BY THE CURRENT COLORADO FLEXIBLE PAVEMENT DESIGN PROCEDURE. (6) THE CURRENT COLORADO DESIGN PROCEDURE FOR FLEXIBLE PAVEMENTS IS REASONABLY ACCURATE FOR UNTREATED GRANULAR BASES AND SHOWS NO NEED FOR ADJUSTMENT. (7) IT IS NOT PRACTICAL TO REPRODUCE FIELD MOISTURE CONDITIONS WHEN MOLDING STABILOMETER SPECIMENS IN THE LABORATORY TO PREDICT ACTUAL FIELD SOIL SUPPORT VALUES.

  • Supplemental Notes:
    • Proceedings, Workshop on Expansive Clays and Shales in Highway Design and Construction, Denver, Colorado, 1972. Available in 2 volumes from NTIS, PB-225842.
  • Corporate Authors:

    University of Wyoming, Laramie

    Wyoming Survey and Analysis Center, 710 Garfield
    Laramie, WY  United States  82070
  • Authors:
    • Brakey, B A
  • Publication Date: 1973-5

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Filing Info

  • Accession Number: 00233511
  • Record Type: Publication
  • Report/Paper Numbers: Workshop Proceedings
  • Files: TRIS
  • Created Date: Jul 31 1974 12:00AM