Study of quarry rocks, core, weathered rock, and road base aggregates from 12 sources in western Oregon reveals that degree and type of alteration and textural distribution of glass are the chief causes of degradation in basaltic aggregate used in road construction. Smectitic clays are the alteration products most responsible for breakdown. Sampling for testing should include weathered rock. Some standard tests for durability show a higher correlation than others with type and degree of alteration and with actual service records of basaltic rock. A standard petrographic microscopic test must preceed other testing. A strain test using benzidine to reveal the presence and textural distribution of montmorillonite and nontronite clays shows promise as a supplement to standard AASHTO tests. In very doubtful cases, tests using activation by thermal neutron irradiation may be used to detect sodium distribution in rocks. Scanning electron microscopy is of value to detect micro-fracturing.

  • Supplemental Notes:
    • This article is an excerpt from the Proceedings of the Fourteenth Annual Engineering Geology and Soils Engineering Symposium that was sponsored by Idaho Transportation Department, Division of Highways; University of Idaho, Department of Geology and Department of Civil Engineering; Idaho State University, Department of Geology and Department of Engineering; and Boise State University, Department of Geology, and Department of Physical Science and Engineering. This symposium was held at the Rodeway Inn, Boise, Idaho, and was hosted by Boise State University.
  • Corporate Authors:

    Idaho Department of Highways

    P.O. Box 7129
    Boise, ID  United States  83707
  • Authors:
    • Van Atta, R O
    • Ludowise, H
  • Publication Date: 1976-4-9

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Filing Info

  • Accession Number: 00142684
  • Record Type: Publication
  • Created Date: Feb 1 1977 12:00AM