EFFECT OF FLY ASH ON CLASS 47C CONCRETE

ALL OF THE SAND-GRAVEL AGGREGATES PRODUCED IN NEBRASKA ARE REACTIVE WITH CEMENT WHEN USED IN CONCRETE. TO DEVELOP A MIX WHICH REDUCES THIS REACTION TO A SAFE LEVEL, PART OF THE SAND-GRAVEL AGGREGATE IS REPLACED WITH CRUSHED DOLOMITE OR LIMESTONE. HOWEVER, IN CERTAIN PARTS OF THE STATE, THE COST OF LIMESTONE OR DOLOMITE IS PROHIBITIVE. THIS INVESTIGATION WAS CONDUCTED TO DETERMINE WHETHER FLY ASH COULD BE USED TO IMPROVE THE WORKABILITY AND STRENGTH OF THE CONCRETE AND AT THE SAME TIME ASSURE THAT THE CEMENT-AGGREGATE REACTION WOULD BE HELD TO A SAFE LEVEL. FOUR BASIC CONCRETE MIXES WERE USED IN THIS INVESTIGATION. THEY WERE A 5.5-BAG MIX WITHOUT FLY ASH /THE STANDARD CLASS 47C MIX USED BY THE STATE/ AND 5.0, 5.5, AND 6.0-BAG MIXES WITH THE ADDITION OF FLY ASH. A HIGH ALKALI CEMENT WAS USED IN ALL THE MIXES. THE TESTS MADE INCLUDED WETTING AND DRYING TESTS AND FREEZING AND THAWING TESTS ON BEAMS AND COMPRESSIVE STRENGTH AT 7, 28, 180, AND 360 DAYS ON CYLINDERS. THE FOLLOWING CONCLUSIONS WERE DERIVED FROM THIS RESEARCH' /1/ THE ADDITION OF FLY ASH REDUCED THE EXPANSION IN ALL CASES, /2/ THE CONCRETES MADE WITH FLY ASH ADDITIONS WERE MORE DURABLE THAN THE CONCRETE WITHOUT FLY ASH, AND /3/ THE CONCRETES WITH ADDITIONS OF FLY ASH GAVE SLIGHTLY LOWER EARLY STRENGTHS, BUT THE LATER STRENGTHS WERE AS HIGH OR HIGHER THAN THE CONCRETE WITHOUT FLY ASH. /BPR/

  • Supplemental Notes:
    • Hpr-1 /5/, BPR-63-8, D-3
  • Corporate Authors:

    Nebraska Department of Roads

    1500 Highway 2, P.O. Box 94759
    Lincoln, NE  United States  68509
  • Publication Date: 1967-3

Subject/Index Terms

Filing Info

  • Accession Number: 00212009
  • Record Type: Publication
  • Source Agency: Bureau of Public Roads /US
  • Files: TRIS, STATEDOT
  • Created Date: Jul 21 1994 12:00AM