REVIEW OF ROAD CONSTRUCTION IN MANCOS SHALE

A brief history is presented of the methods of construction that were used or are being used in 22 projects (that varied in age from 1 to 12 years) where the presence of Mancos Shale has caused considerable damage to the roadway. Several variables were present in the projects and include such aspects as contractors, engineers, soil type, designs and treatment. The designs varied from no treatment to a combination of treatments. The treatments tried out are: pumping a brine slurry in 5 ft deep holes on 10 ft centers; membrane treatment; line treated subgrade; pounding line treatment, and other treated subgrades. Studies indicate that exposure to water and/or air is the main cause for the heaving, and attempts have been made to limit the changes of the water and air. It has been suggested that moisture density tubes be installed to check the moisture above and below the membrane and the moisture with no membrane. Moisture graphs and a summary of the road conditions are included in appendices. Four of the projects which were considered of particular interest are described in outline. The study leads to the conclusion that there is no one solution. Taking as example the membrane method, in some cases the membrane is placed immediately after the Mancos has been exposed while in some cases the Mancos was exposed for several days to both air and water before membrane placement. When subexcavating the cuts and backfilling, a granular backfill is better than weathered Mancos. The opposite is also true. However, several factors are present that could affect the treatment such as grade, area, traffic and natural moisture. The treatments to be considered should include: (1) lime treated subgrade (with membrane/without membrane); (2) membrane (full or partial/with and without untreated base course); (3) fill section (using Mancos using granular material); (4) subexcavating cuts (backfill with Mancos/backfill with granular material.

  • Corporate Authors:

    Utah Department of Public Safety

    317 State Office Building
    Salt Lake City, UT  United States  84114
  • Authors:
    • Craner, C
  • Publication Date: 1972-11

Media Info

  • Features: Appendices; Figures; Photos; References; Tables;
  • Pagination: 38 p.

Subject/Index Terms

Filing Info

  • Accession Number: 00260211
  • Record Type: Publication
  • Files: TRIS
  • Created Date: Oct 11 1974 12:00AM