NUCLEAR MEASUREMENT OF SUBGRADE MOISTURE

In this investigation it was proposed to establish a technique for measuring subgrade moisture under pavements with sufficient accuracy, and minimal effort, interference with traffic, and recalibrations. Both electrical resistance and nuclear methods were investigated. The following conclusions were reached: (1) the nuclear depth probe method of measuring subgrade moisture is more reliable and easier to use than is the electric resistance method, it does not require precalibration and a general calibration curve for a given probe design could be developed for Virginia; (2) the use of a split sampler for a 2 inch (50 mm) diameter access tube gives a snug fit between the outside wall of the access tube and the surrounding soil, and thus eliminates possible errors in measurement due to an air gap, and it also gives a semi- undisturbed sample of the subgrade soil which is needed for calibration; (3) the access tube could be driven in all types of soils through which the split sampler could pass, without becoming bent; (4) this investigation satisfactorily resolved the methods of sealing the access tube from the top and bottom and removing moisture from the access tube before testing; and (5) the standard error of estimate in the use of a nuclear calibration curve for moisture content could be reduced by using the dry density and soil sieve analysis data.

  • Record URL:
  • Supplemental Notes:
    • Originally printed in the Proceedings of the Specialty Conference on In Situ Measurement of Soil Properties, ASCE, Raleigh, N.C., June 1-4, 1975.
  • Corporate Authors:

    University of Virginia, Charlottesville

    Center for Transportation Studies, P.O. Box 400742
    Charlottesville, VA  United States  22904-4742
  • Authors:
    • Vaswani, N K
  • Publication Date: 1975-6

Media Info

  • Features: Figures; References; Tables;
  • Pagination: 103 p.

Subject/Index Terms

Filing Info

  • Accession Number: 00126840
  • Record Type: Publication
  • Report/Paper Numbers: #97 Reprint
  • Files: NTL, TRIS
  • Created Date: Nov 5 1975 12:00AM