A CALIBRATION MODEL FOR OPTIMIZING THE AIR-GAP METHOD OF COMPENSATING NUCLEAR DENSITY GAGES FOR SOIL COMPOSITION VARIATIONS

A MAJOR DETERRENT TO THE MORE WIDESPREAD USE OF SURFACE GAMMA-RAY SCATTER GAGES FOR MEASURING SOIL DENSITY HAS BEEN THE BIAS INTRODUCED BY THE EFFECT OF SOIL COMPOSITION. ONE PROMISING METHOD OF MINIMIZING THIS EFFECT IS THE AIR-GAP TECHNIQUE IN WHICH A RESPONSE IS TAKEN AT A FIXED DISTANCE ABOVE THE SOIL SURFACE AS WELL AS THE CONVENTIONAL RESPONSE. EXISTING METHODS OF USING THESE RESPONSES FOR MEASURING DENSITY HAVE BEEN ARRIVED AT BY TRIAL-AND-ERROR STUDIES. A MODEL OF THE GAGE RESPONSE IS USED HERE TO EXPLAIN AND OPTIMIZE THE AIR-GAP METHOD. THE STANDARD ERROR OF THE DENSITY MEASUREMENT FOR A SAMPLE GAGE ON KNOWN STANDARDS WAS REDUCED BY A FACTOR OF TWO BY USING AN EXACT SOLUTION TO THIS MODEL AS COMPARED TO THE EXISTING METHODS OF USE. IN ADDITION A METHOD OF DETERMINING THE OPTIMUM AIR-GAP DISTANCE FOR ANY COMMERCIAL GAGE AND A NOMOGRAPH SOLUTION FOR DENSITY IN TERMS OF THE TWO GAGE RESPONSES HAS BEEN DEVELOPED ON THE BASIS OF THE MODEL. /JM/

• Supplemental Notes:
  • Vol 2, No 1, PP 3-19, 7 FIG, 5 TAB, 9 REF
• Authors:
  • Gardner, R P
  • Roberts, K F
  • Hughes, C S
  • Anday, M C
• Publication Date: 1967-3

Media Info

• Serial:
  • Journal of Materials
  • Publisher: American Society for Testing and Materials (ASTM)

Subject/Index Terms

• TRT Terms: Alternatives analysis; Calibration; Density; Gamma rays; Mathematical models; Measurement; Measuring instruments; Methodology; Nomographs; Nuclear tests; Properties of materials; Soil densification; Soils
• Uncontrolled Terms: Models
• Old TRIS Terms: Air gaps; Density measurement; Soil composition
• Subject Areas: Geotechnology; Highways; Materials;

Filing Info

• Accession Number: 00216657
• Record Type: Publication
• Files: TRIS
• Created Date: Sep 9 1994 12:00AM