A STUDY OF UNIT WEIGHT, VOLUME AND CEMENT FACTOR OF FRESH CONCRETE

TESTS WERE MADE IN THE LABORATORY AND IN THE FIELD TO SHOW THE EFFECT OF VARIOUS METHODS OF COMPACTION ON UNIT WEIGHT, YIELD AND CEMENT FACTOR OF FRESH CONCRETE. THE FOLLOWING CONCLUSIONS ARE BASED ON THE FINDINGS OF TESTS USING VARIOUS CONCRETE MIXES, COMPACTION EFFORTS, AND FIELD SAMPLES: (1) LARGE INCREASES IN THE AMOUNT OF VIBRATION OF CONCRETE IN THE UNIT WEIGHT TEST PRODUCED VERY SMALL CHANGES IN THE ACTUAL UNIT WEIGHT. REVIBRATION OF JOB CONCRETE FOR 20 SECONDS WITH AN INTERNAL VIBRATOR FOLLOWING STANDARD RODDING (WHICH WOULD FAR EXCEED NORMAL JOB VIBRATION) PRODUCED AN INCREASE IN UNIT WEIGHT OF APPROXIMATELY 0.3 PERCENT. (2) THE VIBRATION IN UNIT WEIGHT AND CALCULATED CEMENT FACTOR AS DETERMINED FROM THE UNIT WEIGHT TEST TAKEN IN FRONT OF AND BEHIND A PAVING MACHINE IS VERY MINOR. ON THE TWO PROJECTS TESTED, THE UNIT WEIGHT WAS FOUND TO AVERAGE 0.5 PERCENT AND 0.4 PERCENT GREATER WHEN SAMPLED BEHIND THE PAVING MACHINE. (3) THE LONG-ESTABLISHED SYSTEM OF USING THE UNIT WEIGHT TEST TO DETERMINE YIELD AND CEMENT FACTOR OF CONCRETE DELIVERED TO THE JOB IS MORE ACCURATE THAN ANY OTHER SYSTEM. /BPR/

  • Supplemental Notes:
    • Hpr, D-3-17, M&R 635148-1
  • Corporate Authors:

    California Division of Highways

    Materials and Research Department
    Sacramento, CA  USA  95819
  • Authors:
    • Spellman, D L
    • Ames, W H
    • Woodstrom, J H
  • Publication Date: 1967-6

Subject/Index Terms

Filing Info

  • Accession Number: 00212024
  • Record Type: Publication
  • Source Agency: Bureau of Public Roads /US
  • Files: TRIS
  • Created Date: Jan 8 1994 12:00AM