SOME APPLICATIONS OF BORON TRACER TECHNIQUE (PART 1)

BECAUSE OF RADIATION HAZARDS THE USE OF RADIOISOTOPE TRACERS HAS BEEN RESTRICTED IN DENSELY POPULATED AREAS. A NEW TECHNIQUE USING BORON AS TRACER AND NEUTRON MOISTURE METER AS DETECTOR HAS BEEN DEVELOPED. BORON ABSORBS THERMAL NEUTRON, AND IS A RARE SOIL CONSTITUENT. WHEN BORON IS FOUND IN SOIL AS TRACER, IT REDUCES THE COUNTING RATE OF THE NEUTRON MOISTURE METER. IN ORDER TO USE THE NEUTRON MOISTURE METER AS A BORON METER, EXPERIMENTS WERE CARRIED OUT TO INVESTIGATE THE RELATION BETWEEN CHANGES IN THE CONCENTRATION OF BORON AND THE COUNTING RATE OF THE NEUTRON MOISTURE METER. THE RESULTS SHOWED THAT THE COUNTING RATE CHANGES INTO AN EXPONENTIAL FUNCTION WITH THE BORON CONCENTRATION. THE SAME RESULT WAS OBTAINED BY CALCULATION WITH FERMI'S AGE EQUATION. THE AUTHORS DESCRIBE SOME EXAMPLES OF IN-SITU APPLICATIONS OF THIS TRACER TECHNIQUE. BORON IS USED IN THE FORM OF A SOLUTION. IT CAN BE USED FOR THREE PURPOSES: (1) IN-SITU DETERMINATION OF THE EXTENT OF GROUTED ZONES. THERE ARE NO NON-DESTRUCTIVE METHODS OF INVESTIGATING THE EXTENT OF AREAS. BY USING THE BORON TRACER TECHNIQUE, THE EXTENT OF GROUTED AREAS CAN BE DETERMINED FROM THE COUNTING RATE OF THE NEUTRON MOISTURE METER BY MEANS OF THE DILUTION METHOD. TUBES ARE INSERTED AT GIVEN DISTANCES INTO THE GROUND IN WHICH THE MOISTURE CONTENT IS MEASURED BY MEANS OF NEUTRONS. AFTER A CHEMICAL GROUT CONTAINING A PREDETERMINED AMOUNT OF BORON HAS BEEN INJECTED INTO THE GROUND, THE MOISTURE CONTENT IS MEASURED AGAIN. THE AREA OF GROUTING CAN BE ESTIMATED BY COMPARING THE COUNTING RATE OF NEUTRON MOISTURE METER BEFORE AND AFTER GROUTING. (2) MEASURING SOIL SETTLEMENT. THE CONVENTIONAL DOUBLE TUBE SETTLEMENT METERS DO NOT GIVE ACCURATE MEASUREMENTS IN POOR GROUND, ESPECIALLY IN LONG-TERM MEASUREMENTS. BY BURYING A RING-SHAPED PLASTIC TUBE FILLED WITH BORAX AND LOCATING IT PRECISELY BY NEUTRON MOISTURE METER. THE SETTLEMENT BEHAVIOR OF SOIL CAN BE EASILY MEASURED. (3) MEASURING THE DISTRIBUTION OF EACH BATCH OF CONCRETE DURING THE CONSTRUCTION OF UNDER-WATER CONCRETE WALLS. IF BORON IS MIXED WITH THE FRESH CONCRETE AND MEASURED WITH A NEUTRON MOISTURE METER THROUGH THE ACCESS TUBE PREVIOUSLY INSERTED INTO THE SPACE TO BE FILLED WITH CONCRETE, THE FLOW PATTERN OF THE CONCRETE CONTAINING BORON CAN BE EASILY IDENTIFIED.

  • Corporate Authors:

    Kajima Inst Constr Tech /Japan

    ,    
  • Authors:
    • Ariizumi, A
    • Yamamoto, T
  • Publication Date: 1969

Language

  • English

Media Info

  • Features: Figures; References; Tables;
  • Pagination: p. 115-24

Subject/Index Terms

Filing Info

  • Accession Number: 00230392
  • Record Type: Publication
  • Source Agency: Transport and Road Research Laboratory (TRRL)
  • Files: TRIS
  • Created Date: Sep 25 1972 12:00AM