GAP-GRADED VERSUS CONTINUOUSLY-GRADED AIR-ENTRAINED CONCRETE FOR HIGHWAY FACILITIES /TECH RPT NO 3/

THE MOST IMPORTANT PHYSICAL PROPERTY OF PLASTIC CONCRETE WITH RESPECT TO PLACEMENT IS WORKABILITY, THE EASE WITH WHICH A STIFF MIX WITH LOW SLUMP CAN BE COMPACTED INTO A UNIFORM MASS. HERTOFORE, HOWEVER, VERY LITTLE IS KNOWN ABOUT THE WORKABILITY OF GAP-GRADED CONCRETE. IT IS, IN FACT, EVEN MORE WORKABLE THAN CONTINUOUSLY-GRADED CONCRETE OF THE SAME MAXIMUM SIZE OF COARSE AGGREGATE. THE GENERAL PREJUDICE THAT GAP-GRADED CONCRETE IS HARSHER THAN ITS CONTINUOUSLY-GRADED COUNTERPART MUST, THEREFORE, BE DISPELLED WITH EXPERIMENTAL EVIDENCES BEFORE GAP-GRADING CAN BE INTRODUCED INTO GENERAL PRACTICE. IN THE WORK PRESENTED HEREIN INVOLVING 330 MIXES, THE WORKABILITY IN THE PLASTIC STATE OF BOTH GAP-GRADED AND CONTINUOUSLY-GRADED CONCRETES OF VARIOUS MIX PROPORTIONS, HAS BEEN MEASURED CONCURRENTLY BY THE SLUMP OF A STANDARD CONE AND BY A VEBE CONSISTOMETER. THE RESULTS ARE COMPARED FOR GAP-GRADED VERSUS CONTINUOUSLY-GRADED CONCRETES ON THE BASIS OF EQUAL MAXIMUM SIZE OF COARSE AGGREGATE, WATER-CEMENT RATIO, AND AGGREGATE-CEMENT RATIO. THE COMPARISON HAS SHOWN THE RELATIVE EASE OF PLACING GAP-GRADED CONCRETE TO ATTAIN UNIFORM COMPACTION. BASED ON TEST DATA, A COMPARATIVE STUDY OF THE EFFICACY OF SLUMP TEST VERSUS VEBE TIME AS A MEASURE OF WORKABILITY HAS BEEN MADE. IT REVEALS THAT THE SLUMP TEST IS NOT FULLY INDICATIVE OF THE WORKABILITY FOR STIFFER MIXES WITH SLUMP LESS THAN ONE INCH (2.54CM) WHICH SHOULD BE NORMALLY USED FOR OBTAINING ECONOMICAL HIGH-STRENGTH CONCRETES. IT FURTHER INDICATES THAT THE VEBE CONSISTOMETER SHOULD BE USED INSTEAD IN ALL STIFF MIXES. A NEW AND PATENTABLE WORKABILITOMETER, WHICH CAN GIVE A QUANTITATIVE MEASURE OF WORKABILITY FOR BOTH CONTINUOUSLY- AND GAP-GRADED CONCRETES, IS PROPOSED./AUTHOR/

  • Supplemental Notes:
    • Tech Rpt No 3, 642(68)
  • Corporate Authors:

    South Dakota School of Mines and Technology, Rapid City

    501 East St Joseph Street
    Rapid City, SD  United States  57701

    South Dakota Department of Transportation

    700 East Broadway Avenue
    Pierre, SD  United States  57501

    Bureau of Public Roads /US

    400 7th Street, SW
    Washington, DC  United States  20590
  • Authors:
    • Li, Shengbo Eben
    • Ramakrishnan, V
    • Rangan, B V
  • Publication Date: 0

Subject/Index Terms

Filing Info

  • Accession Number: 00212073
  • Record Type: Publication
  • Source Agency: Bureau of Public Roads /US
  • Files: TRIS, STATEDOT
  • Created Date: Jul 14 1970 12:00AM