NUCLEAR MAGNETIC RESONANCE SENSORS FOR MOISTURE MEASUREMENT IN ROADWAYS

The feasibility of practical instrumentation based on the nuclear magnetic resonance method was investigated to address the need for accurate, reliable moisture measurements in highway systems. A prototype of an implantable sensor that uses the pulsed nuclear magnetic resonance spin-echo technique was developed and subjected to laboratory verification. The sensor is 3 by 2 by 2.25 in. (7.6 by 5.1 by 5.7 cm) and weighs about 3 lb (1.35kg). It directly measures the mass of moisture present; to obtain the percentage of moisture requires that soil density be determined by an auxiliary method. Experiments with bentonite, silica flour, and topsoil indicated that the sensor operated reliably, with an accuracy of approximately plus or minus 1 percent up to 25 percent moisture, plus or minus 2 percent up to 100 percent moisture, and plus or minus 4.5 percent up to 200 percent moisture. A dependence of sensor response on soil type necessitated calibration for each soil type. Organic matter and dissolved salt did not affect the sensor readings for bentonite, but organic matter had an effect for silica flour. All of the results obtained were qualitatively accounted for in terms of a simple moisture adsorption and bonding model.

Media Info

  • Media Type: Print
  • Features: Figures; References; Tables;
  • Pagination: pp 77-86
  • Monograph Title: FROST, MOISTURE, AND EROSION
  • Serial:

Subject/Index Terms

Filing Info

  • Accession Number: 00099656
  • Record Type: Publication
  • ISBN: 0309023807
  • Files: TRIS, TRB
  • Created Date: Nov 5 1975 12:00AM