Evaluation of Trench Backfills at Highway Cross-Drains

Trench backfilling is a routine construction procedure when conduit structures such as pipe culverts, storm drains, and sewers are used in a highway system. Since a proper compaction of the backfill materials is essential for achieving adequate strength and stiffness, contemporary regulatory specifications rely heavily on their dry densities as backfill, requiring a minimum field compaction of 95% laboratory determined maximum dry density. Because of its simplicity and potential as a quality control tool, dynamic cone penetrometer (DCP) test was used to provide a reasonable estimation of the stiffness of different backfills and subgrade soils.Field investigation indicated that pavement dips occurred at some cross drain pipe locations but not at others under the same traffic and environmental conditions. The analyses of these results indicate that a possible way to prevent pavement dip from occurring at a cross drain is to make trench backfill stiffer than adjacent subgrade. The compaction results from the full scale laboratory tests indicate that sand is not always successfully used for highway cross drains because of its poor gradation and difficulty in compaction. Alternatives such as crushed limestone and recycled asphalt pavement (RAP) materials should be considered because of their good workability and higher stiffness when compacted.

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  • Authors:
    • Zhang, Zhongjie
    • Abu-Farsakh, Murad Y
    • Tao, Mingjiang
  • Publication Date: 2005-6


  • English

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Filing Info

  • Accession Number: 01002676
  • Record Type: Publication
  • Files: TRIS
  • Created Date: Jul 28 2005 3:15PM