EFFECTS OF TYPE OF MATERIAL ON NUCLEAR DENSITY MEASUREMENTS

THE PAPER DESCRIBES LABORATORY AND FIELD INVESTIGATIONS CARRIED OUT TO IMPROVE THE PRACTICAL APPLICATION OF THE NUCLEAR METHOD IN HIGHWAY CONSTRUCTION. VARIOUS FACTORS HAVE BEEN STUDIED, INCLUDING THE EFFECTS OF DENSITY GRADIENT, SOURCE ENERGY, AND PARTICULARLY SOIL TYPE, ON DENSITY MEASUREMENTS. TWO METHODS ARE DESCRIBED FOR THE POSSIBLE ELIMINATION OF THE EFFECT OF SOIL TYPE IN PRACTICAL DENSITY MEASUREMENTS. IN THE FIRST, DIRECT TRANSMISSION IS USED AS AN AUXILIARY TEST WITH BACKSCATTER MEASUREMENTS. RESULTS ARE GIVEN TO ILLUSTRATE THE ADVANTAGES OF THIS METHOD FOR DETERMINING THE CORRECT CALIBRATION CURVE FOR THE BACKSCATTER METHOD AND ALSO FOR THE EVALUATION OF ANY DENSITY GRADIENT IN THE SOIL LAYER. IN THE SECOND METHOD INTRODUCTION OF A CERTAIN AIR GAP BETWEEN THE SURFACE PROBE AND THE SOIL SURFACE IS USED TO OBTAIN A COUNT RATIO WHICH, WHEN PLOTTED AGAINST DENSITY, GIVES A POSITIVE SLOPE RELATIONSHIP INDEPENDENT OF SOIL TYPE FOR DENSITIES UP TO 400 PCF. THIS METHOD ONLY EMPLOYS THE BACKSCATTER TECHNIQUE AND IS THEREFORE COMPLETELY NONDESTRUCTIVE. IT IS SHOWN FURTHER HOW THE AIR-GAP METHOD CAN BE USED FOR EFFECTIVE DENSITY MEASUREMENTS ON SOIL LAYERS. MEASUREMENTS AT PREDETERMINED AIR GAPS FURTHER PERMIT CONTINUOUS RECORDS OF DENSITY TO BE OBTAINED BY USING A SUITABLE RATEMETER. /AUTHOR/

Media Info

  • Media Type: Print
  • Features: Figures; References; Tables;
  • Pagination: pp 1-14
  • Monograph Title: Nuclear Measurements 1963
  • Serial:

Subject/Index Terms

Filing Info

  • Accession Number: 00215786
  • Record Type: Publication
  • Files: TRIS, TRB
  • Created Date: Dec 12 1994 12:00AM