THE MOBILE GAMMADENSITOMETER 45 - STUDY AND TESTS

LE GAMMADENSIMETRE MOBILE 45 - ETUDE ET EXPERIMENTATION.

THE PORTABLE GAMMADENSITOMETER 45 IS A PROTOTYPE FOR THE CONTINUOUS MEASUREMENT OF THE OVERALL VALUE OF THE BULK DENSITY OF ROADBASES. ITS OPERATING PRINCIPLE IS BASED ON GAMMARAY DIFFUSION. THE SOURCE/SENSOR DISTANCE IS AT A DISTANCE OF 45 CM FROM A COBALT 60 RADIATION SOURCE OF A 620 MILLICURIE ACTIVITY. THE DETECTION SYSTEM CONSISTS OF TWO SENSORS, A SCINTILLATION COUNTER AND A GEIGER MULLER COUNTER PLACED AT THE BASE OF THE LEAD SHIELD, THE ROLE OF WHICH IS TO PICK UP THE PHOTON IN THE FILM OF AIR. SUCH A SYSTEM IS OF GREAT INTEREST AS IT IS POSSIBLE, WITHIN LIMITS, TO IGNORE THE VARIATIONS IN THE THIN LAYER OF AIR AND THEREFORE TO TAKE NO ACCOUNT OF THE INFLUENCE OF THE SURFACE CONDITIONS. THE SCINTILLATION DETECTOR COUNTS CAN BE CORRECTED AS A FUNCTION OF THE COUNTS FROM THE GEIGER-MULLER COUNTER, AND IT IS THEN POSSIBLE TO OBTAIN AN ACCURATE MEASUREMENT OF THE BULK DENSITY. THE MEASUREMENTS ARE INDEPENDENT OF THE CHEMICAL COMPOSITION OF THE MATERIALS THANKS TO THE ADDITION OF A FILTER TO THE SCINTILLATION DETECTOR. THE GDM45 WAS TESTED BY COMPARING ITS MEASUREMENTS WITH THOSE OF THE GAMMADENSITOMETERS R18 AND R10. THE CLOSEST AGREEMENT WAS OBTAINED BETWEEN THE RESULTS FROM THE GDM45 AND THOSE OF THE R18. COMPARATIVE MEASUREMENTS WERE THEN MADE ON VARIOUS MATERIALS DIFFERING IN CHEMICAL NATURE SUCH AS SAND-SLAG, GRAVEL-SLAG (WITH SILICEOUS LIMESTONE AGGREGATES, AND PORPHYRY AGGREGATES) AND A GRAVEL-BITUMEN MIXTURE. IN ALL THOSE TESTS NO INFLUENCE OF THE CHEMICAL NATURE OF THE MATERIALS WAS DETECTED AND THE AGREEMENT WAS BEST BETWEEN RESULTS OBTAINED WITH THE GDM45 AND THE R18 GAMMA DENSITOMETER (0,97 OVERALL CORRELATION FOR ALL TESTS). THIS STUDY SHOWS THE DISPERSION OF DENSITIES AND DEMONSTRATES THAT LOCALIZED CONTROLS WITH THE GAMMADENSITOMETER COULD NOT ALWAYS BE REPRESENTATIVE OF THE STATE OF COMPACTION. WITH THE GDM45, IT IS POSSIBLE TO SEE THE PATTERN OF DENSITY DISTRIBUTION IN ONE SITE BY MEANS OF DYNAMIC MEASUREMENTS.

• Availability:
  • Find a library where document is available. Order URL: http://worldcat.org/issn/04585860
• Authors:
  • BELIN, J P
  • MENARD, J
  • PEYBERNARD, J
• Publication Date: 1975-5

Language

• French

Media Info

• Pagination: 105-16
• Serial:
  • BULL LIAISON LAB PONTS CHAUSS
  • Issue Number: 77
  • ISSN: 0458-5860

Subject/Index Terms

• TRT Terms: Backscattering; Base course (Pavements); Continuous structures; Density; Diffusion (Optics); Dispersion (Statistics); Gamma rays; Measurement; Tests
• ITRD Terms: 6160: Back scattering apparatus; 9006: Continuous; 5908: Density; 6769: Diffusion; 6512: Dispersion (stat); 6706: Gamma ray; 6136: Measurement; 2961: Roadbase; 6255: Test
• Subject Areas: Bridges and other structures; Data and Information Technology; Highways; I33: Other Materials used in Pavement Layers; I52: Construction of Pavements and Surfacings;

Filing Info

• Accession Number: 01307068
• Record Type: Publication
• Source Agency: Institut Francais des Sciences et Technologies des Transports, de l'Aménagement et des Réseaux (IFSTTAR)
• Files: ITRD
• Created Date: Nov 21 2010 11:05AM