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THE RELATIONSHIP BETWEEN MIXING TIME AND TYPE OF CONCRETE MIXER

THE AIMS OF THE INVESTIGATION WERE TO DETERMINE WHETHER THE PRESENT GENERALLY APPLICABLE MINIMUM MIXING OF 1 1/2 MINUTES IS JUSTIFIED WITH RESPECT TO VARIOUS TYPES OF MIXER AND TO EVOLVE A SUITABLE METHOD FOR THE FUTURE STANDARDIZED TESTING OF CONCRETE MIXERS. THE THEORIES ON WHICH THE ORGANIZATION OF THE STUDY IS BASED ARE DISCUSSED. VARIOUS FACTORS INFLUENCE THE RELATIONSHIP BETWEEN MIXING TIME AND TYPE OF MIXER BUT ONLY THE MOST DOMINANT OF THESE FACTOR - CONCRETE MIX ANALYSIS-HAS BEEN CONSIDERED AS TEST VARIABLE. IN THE DETERMINATION OF THE THREE MIXES EMPLOYED, CONSISTENCY--CLASSIFIED AS SEMI-LIQUID, PLASTIC AND VERY STIFF--HAS BEEN SELECTED AS THE MOST SIGNIFICANT FACTOR. THREE TYPES OF MIXER WERE TESTED: A 2,500-LITER GRAVITY MIXER AND TWO HORIZONTAL MIXERS, ONE 1,500-LITER AND ONE 150-LITER MODE. THE MEASURING METHODS EMPLOYED ARE PRIMARILY INTENDED TO DETERMINE THE VARIATIONS IN THE DISTRIBUTION OF THE MIX CONSTITUENTS AND STRENGTH ON THE BASIS OF EIGHT SPECIMENS TAKEN CONTINUOUSLY DURING THE DISCHARGE OF A BATCH. THE PYCNOMETER METHOD PLUS WET SCREENING WERE EMPLOYED TO DETERMINE THE CONTENT OF CEMENT AND OF FINE AND COARSE AGGREGATE IN EACH SPECIMEN. THE STRENGTH DEVELOPMENT OF THE CONCRETE WITH INCREASED MIXING TIME AND THE DEVELOPMENT OF CONSISTENCE WERE ALSO USED AS MEASURING METHODS. OF THE RESULTS REPORTED, IT IS APPARENT THAT THE PRESENT MINIMUM MIXING TIME COULD BE REDUCED, BUT THAT MIXING TIME IS DEPENDENT ON MIXER TYPE AND MIX ANALYSIS. THE RESULTS ALSO SHOW THAT THE TEST METHOD CAN BE USED TO ASSESS THE HOMOGENIZING ABILITY OF A CONCRETE MIXER.

Media Info

  • Features: Figures; References; Tables;
  • Pagination: 92 p.
  • Serial:
    • Issue Number: 42

Subject/Index Terms

Filing Info

  • Accession Number: 00215521
  • Record Type: Publication
  • Files: TRIS
  • Created Date: Jun 28 1972 12:00AM