TIME DEFORMATION STUDIES ON TWO EXPANDED SHALE CONCRETES

THIS REPORT DESCRIBES AND PRESENTS RESULTS OF TESTS ON CONCRETES PRODUCED WITH LIGHTWEIGHT AGGREGATES THAT ARE AVAILABLE IN QUANTITY IN OREGON. THE PRINCIPAL AGGREGATES DISCUSSED ARE EXPANDED SHALES PRODUCED BY TWO LOCAL FIRMS. THE STUDIES CONSISTED OF THE DEVELOPMENT OF LIGHTWEIGHT CONCRETE MIXES HAVING SUITABLE WORKABILITY AND STRENGTH FOR USE IN PRESTRESSED MEMBERS AND THE MEASUREMENT OF CREEP AND SHRINKAGE IN CONCRETE PRISMS CAST FROM SELECTED MIXES. THE TIME DEFORMATION STUDIES WERE CONDUCTED ON PRISMS 5 IN. BY 6 IN. BY 107 IN., WITH GAGE POINTS 100 IN. CENTER TO CENTER. A STRESS OF 2,000 PSI, APPLIED AT AN AGE OF 28 DAYS, WAS MAINTAINED AT A RELATIVELY CONSTANT VALUE BY PERIODIC RETENSIONING OF STRESSING BARS. PREVIOUS STUDIES ON CREEP AND SHRINKAGE CHARACTERISTICS OF COMMON CONCRETES AND OTHER LIGHTWEIGHT CONCRETES ARE REVIEWED FOR PURPOSE OF COMPARISON. VALUES ARE PRESENTED FOR ESTIMATING THE STRESS LOSS IN PRESTRESSING STEEL USED IN CONJUNCTION WITH THE EXPANDED SHALE AGGREGATES IN PRESTRESSED MEMBERS. BY COMPARISON WITH OTHER TEST RESULTS, IT APPEARS THAT THE TIME DEFORMATIONS OF THE EXPANDED SHALE PRISMS ARE NOT APPRECIABLY HIGHER THAN MIGHT BE FOUND IN SAND AND GRAVEL CONCRETE OF EQUAL STRENGTH; HOWEVER, THE MEASURED DEFORMATIONS GREATLY EXCEED THOSE PROVIDED FOR IN TYPICAL RECOMMENDATIONS FOR ESTIMATING STRESS LOSSES IN PRESTRESSING STEEL. /AUTHOR/

  • Supplemental Notes:
    • Vol 37, pp 90-105, 6 FIG, 2 TAB, 8 REF
  • Authors:
    • Beecroft, G W
  • Publication Date: 1958

Media Info

  • Monograph Title: Proceedings of the Thirty-Seventh Annual Meeting of the Highway Research Board, Washington, D.C., January 6-10, 1958
  • Serial:

Subject/Index Terms

Filing Info

  • Accession Number: 00213978
  • Record Type: Publication
  • Files: TRIS, TRB
  • Created Date: Oct 3 1971 12:00AM