EXAMINATION OF MIXING OF CONCRETE BY USING RADIOACTIVE NUCLIDES

EXPERIMENTAL METHODS FOR DETERMINING THE MIXING TIMES FOR SATISFACTORY HOMOGENEITY OF CONCRETE ARE DEVELOPED ON THE BASIS OF TRACER ANALYSIS. AS SUITABLE TRACERS, RARE EARTH ELEMENTS ARE RECOMMENDED, LANTHANUM BEING THE MOST CONVENIENT ADDITION /AS LANTHANUM OXALATE/, IN 0.5 PERCENT CONCENTRATION. SINCE THE ACTIVITY IS REDUCED AFTER SEVEN HALF-LIVES TO LESS THAN 1 PERCENT, MEASUREMENTS WITH THE GEIGER COUNTER ARE MADE AFTER 100 HOURS. PRACTICAL EXPERIMENTS ARE ILLUSTRATED TO SHOW A DISTINCT INFLUENCE OF THE GRANULOMETRIC CONCRETE COMPOSITION, I.E., THE RATIO OF THE MEASURED SURFACE/MAXIMUM GRAIN CROSS SECTION. IT IS CONCLUDED THAT THE MEASURED SURFACE MUST BE AT LEAST TWICE THE LARGEST GRAIN CROSS SECTION /15 MM. IN THE EXPERIMENTS/. CURVES SHOW, FOR DIFFERENT GRAIN SIZES, THE DEGREE OF INTERMIXING. DIAGRAMS ARE ALSO PRESENTED SHOWING THE PROGRESSIVE DEGREE OF MIXING EFFICIENCY AS A FUNCTION OF MIXING TIME, WITH THE IMPORTANT GENERAL RESULT THAT IN LARGE MIXING UNITS, 25 TO 50 SECONDS ARE SUFFICIENT FOR OPTIMAL APPROXIMATION TO IDEAL CONDITIONS. /AUTHOR/

  • Supplemental Notes:
    • Vol 12, No 1/2, PP 141-144
  • Corporate Authors:

    Wiss Z Hochschule Verkehrwesen /Ger

    ,    
  • Authors:
    • Hanke, I
  • Publication Date: 1966

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Filing Info

  • Accession Number: 00212358
  • Record Type: Publication
  • Files: TRIS
  • Created Date: Apr 20 1994 12:00AM