ABNORMAL STIFFENING OF CONCRETE CONTAINING CHEMICAL WATER-REDUCING AND RETARDING ADMIXTURES

THIS WORK INVESTIGATES AN ABBREVIATED TEST FOR PREDICTING JOB SETTING PERFORMANCE OF ADMIXTURES. THE SETTING TIMES OF PASTES WERE DETERMINED SIMULTANEOUSLY WITH THE HEAT GENERATION STUDIES USING TWO TECHNIQUES, NAMELY, VICAT PENETRATION, AND A NEW CONE PENETRATION TEST PROPOSED BY KUNTZE AND HAWKINS. DETAILS OF THE TECHNIQUES ARE GIVEN. EXTENSIVE CONSIDERATION WAS GIVEN IN PLANNING THIS RESEARCH TO THE BEHAVIOR OF CEMENT-WATER PASTES RELATIVE TO THE STIFFENING OF CONCRETE ITSELF. THE TEST PROCEDURE INVOLVES AUTOMATIC RECORDING OF CEMENT PASTE-ADMIXTURE TEMPERATURES WHEN THE PASTES ARE STORED IN VACUUM THERMOS FLASKS TO CONSERVE THE HEAT. THE TIME-TEMPERATURE "SIGNATURE" GENERATED BY THE PASTE IS QUITE SUCCESSFUL IN DETECTING UNUSUAL SETTING OF THE CEMENT-ADMIXTURE COMBINATION. ALTHOUGH JOB CEMENT AND ADMIXTURE ARE NEEDED TO PERFORM THE EVALUATION, LESS THAN 2 LB OF CEMENT IS NEEDED FOR EACH BATCH, AND ONLY ABOUT 1 LB PER BATCH WOULD BE REQUIRED IF EXPERIENCES PROVES THAT THE SETTING TIME TESTS CAN BE FOREGONE. CRITERIA ARE PROPOSED WHICH WILL IDENTIFY THE DOSAGES AND MIXING TEMPERATURES FOR THE PARTICULAR CEMENT AND ADMIXTURE COMBINATION. THE UNUSUAL SETTING OF CONCRETE, MANIFESTED BY VERY RAPID LOSS OF SLUMP, RAPID ATTAINMENT OF 60 PSI PENETRATION RESISTANCE OF WET-SCREENED MOTOR, OR EXCESSIVELY LONG TIME OF SETTING (10-12 HR OR MORE), IS DISCUSSED.

  • Supplemental Notes:
    • Rept No 320116-1-F 4 APP
  • Corporate Authors:

    University of Michigan, Ann Arbor

    Ann Arbor, MI  USA  48109
  • Authors:
    • Legg, F E
  • Publication Date: 1972-11

Media Info

  • Features: Figures; References; Tables;
  • Pagination: 41 p.

Subject/Index Terms

Filing Info

  • Accession Number: 00214270
  • Record Type: Publication
  • Report/Paper Numbers: Final Rept
  • Files: TRIS
  • Created Date: Mar 15 1974 12:00AM