IS AGGREGATE BASE THE SOLUTION IN FROST AREAS?

This paper presents a review of design considerations applicable to areas where severe frost action is to be expected, citing the significant strength loss that occurres in subgrades and in some base courses during the spring thaw period. The argument used by critics against the use of graded aggregate base in frost areas is examined, design features that will counter the argument are suggested, and areas for future research are indicated. The argument considered here is that the graded aggregate base, even while helping to protect against the effects of subgrade weakening during the spring thaw, may itself be weakened during the thawing and may itself contribute to premature pavement distress. Two solutions are proposed to preclude or mitigate the adverse effect of saturation on the dynamic load response of graded aggregate base: restrict fines to not more than 10 percent passing the no. 200 sieve, and provide an open-graded, highly previous drain between the subgrade and the base course. However, neither of these solutions will be entirely effective in frost areas, to protect against the saturation and related low density that may prevail during the thaw periods; some modifications will be required. The membrane encapsulated soil layer (MESL) concept for base and subbase course (briefly described) has thus far been focussed on fine-grained soils, which when compacted below optimum moisture content, have high strength and stiffness. Areas for future research include the following: repeated-load laboratory triaxial compression tests on graded aggregate specimens after several freeze-thaw cycles; repeated load field plate bearing tests on graded aggregate base while thawing is in progress; and field evaluation of encapsulated graded aggregate base.

  • Supplemental Notes:
    • Proceedings from a conference on Utilization of Graded Aggregate Base Materials in Flexible Pavements, March 25-26, 1974, Oak Brook Hyatt House, Oak Brook, Illinois.
  • Corporate Authors:

    National Crushed Stone Association

    1415 Elliot Place, NW
    Washington, DC  USA  20007

    National Sand and Gravel Association

    900 Spring Street
    Silver Spring, MD  USA  20910

    National Slag Association

    300 South Washington Street
    Alexandria, VA  USA  22314
  • Authors:
    • Johnson, T C
  • Publication Date: 1974

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Filing Info

  • Accession Number: 00127529
  • Record Type: Publication
  • Files: TRIS
  • Created Date: Apr 7 1976 12:00AM