A STUDY OF TRANSIT MIXED CONCRETE

A RESEARCH PROJECT IS DESCRIBED IN WHICH VARIOUS ASPECTS OF TRANSIT MIXED CONCRETE WERE STUDIED. PHASE I DESCRIBES THE WORK PERFORMED IN EVALUATING THE EFFECTS OF EXTENDED RETENTION OF CONCRETE IN A TRANSIT MIX TRUCK FOR THREE HOURS. FOUR MIXES WERE EVALUATED. THESE WERE (1) SAND AND GRAVEL CONCRETE WITH NO ADMIXTURES, (2) SAND AND GRAVEL CONCRETE WITH ADMIXTURES, (3) LIGHT-WEIGHT COARSE AGGREGATE AND SAND WITH THE MOISTURE CONTENT OF THE COARSE AGGREGATE MAINTAINED AT APPROXIMATELY 15 PERCENT, AND (4) THE SAME MIX WITH THE MOISTURE CONTENT OF THE COARSE AGGREGATE MAINTAINED AT APPROXIMATELY 30 PERCENT. PHASE II DESCRIBES THE WORK PERFORMED IN THE FIELD TO DETERMINE YIELD, SLUMP LOSS, LOSS OF ENTRAINED AIR, WATER REQUIREMENTS AND A COMPARISON OF FIELD MANUFACTURED SPECIMENS TO LABORATORY MANUFACTURED SPECIMENS. THESE TESTS WERE PERFORMED ON CONCRETE AS WAS BEING USED ON CONSTRUCTION PROJECTS THROUGHOUT THE STATE. THE CONCLUSION REACHED FROM PHASE I OF THIS STUDY WAS THAT SAND AND GRAVEL CONCRETE WITHOUT ADMIXTURES IS AFFECTED MORE BY LONG RETENTION IN A TRANSIT MIXED TRUCK THAN IS SAND AND GRAVEL CONCRETE WITH ADMIXTURES. IF NECESSARY AS MUCH AS TWO HOURS RETENTION COULD BE TOLERATED WITHOUT SEVERELY DAMAGING THE PROPERTIES OF THE CONCRETE. LIGHTWEIGHT CONCRETE WITH 15 PERCENT MOISTURE IN THE COARSE AGGREGATE PERFORMED BETTER THAN LIGHTWEIGHT CONCRETE WITH 30 PERCENT MOISTURE IN THE COARSE AGGREGATE. PHASE II INDICATED THAT SLUMP LOSS, LOSS OF ENTRAINED AIR AND YIELD ARE NOT AS LARGE OF A PROBLEM AS HAS BEEN INDICATED IN THE PAST. /AUTHOR/

  • Supplemental Notes:
    • Rpt 30, 32 PP, 8 FIG, 7 TAB, APP
  • Corporate Authors:

    Louisiana Department of Highways

    Research and Development Section
    Baton Rouge, LA  United States 
  • Publication Date: 0

Subject/Index Terms

Filing Info

  • Accession Number: 00213801
  • Record Type: Publication
  • Files: TRIS, STATEDOT
  • Created Date: Oct 5 1970 12:00AM