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https://nap.nationalacademies.org/catalog/27432/critical-issues-in-transportation-for-2024-and-beyond

CORRELATION OF CONCRETE PROPERTIES WITH TESTS FOR CLAY CONTENT OF AGGREGATE

THE PRESENCE OF CLAYS IN THE FINE AGGREGATE USED TO MAKE CONCRETE IS DETRIMENTAL TO THE STRUCTURAL PROPERTIES OF THE CONCRETE. THE TEXAS HIGHWAY DEPARTMENT CURRENTLY USES THE RESULTS OF SAND EQUIVALENT AND LOSS BY DECANTATION TESTS AS A MEANS OF DETECTING SUCH CLAY AND CONTROLLING THE QUALITY OF FINE AGGREGATE USED IN PORTLAND CONCRETE CEMENT. AS AN ALTERNATIVE TO THIS, THE SAND EQUIVALENT TEST WHICH SEPARATES THE FINER CLAY PARTICLES FROM THE COARSER PARTICLES AND COMPARES THEM ON A VOLUME BASIS MAY BE USED. THESE QUALITY CONTROL TESTS WERE DEVELOPED INDEPENDENTLY AND THE RELATIONSHIP BETWEEN THE NUMERICAL RESULTS OF EACH TEST WAS NOT KNOWN. SINCE THESE TWO TESTS FORM INDEPENDENT BASES FOR ACCEPTING OR REJECTING A MATERIAL, THE RELATIONSHIP BETWEEN THEM IS VERY IMPORTANT. THIS RELATIONSHIP WAS STUDIED AND CONCRETE PROPERTIES WERE CORRELATED WITH THESE TESTS FOR CLAY CONTENT. THE STUDY CONCLUDES' /1/ THE STRENGTH OF CONCRETE IS REDUCED AS THE QUANTITY OF CONTAMINANT IN THE AGGREGATE IS INCREASED, /2/ THE STRENGTH OF CONCRETE IS DECREASED AS THE LIQUID LIMIT OF THE CONTAMINANT INCREASES, /3/ SHRINKAGE OF THE SILICEOUS AGGREGATE CONCRETE IS INCREASED AS THE CONTAMINANT QUANTITY INCREASES, /4/ SHRINKAGE OF THE SILICEOUS AGGREGATE CONCRETE IS INCREASED AS THE LIQUID LIMIT OF THE CONTAMINANT INCREASES, /5/ THE DYNAMIC MODULUS OF ELASTICITY OF THE CONCRETE CONTAINING SILICEOUS AGGREGATE IS DECREASED AS THE LIQUID LIMIT OF THE CONTAMINANT INCREASES, /6/ THE DYNAMIC MODULUS OF ELASTICITY OF CONCRETE DOES NOT CHANGE SIGNIFICANTLY AS THE QUANTITY OF CONTAMINANT INCREASES, /7/ PRESENT TEXAS HIGHWAY DEPARTMENT SPECIFICATIONS FOR CONCRETE AGGREGATE INDIRECTLY ALLOW A 15 PERCENT REDUCTION IN 28-DAY COMPRESSIVE STRENGTH AND A 25 PERCENT REDUCTION IN 7-DAY MODULUS OF RUPTURE VALUES, /8/ SOME AGGREGATES MEET PRESENT TEXAS HIGHWAY DEPARTMENT SPECIFICATIONS BY THE LOSS BY DECANTATION TEST WHILE FAILING THE REQUIREMENTS OF THE SAND EQUIVALENT TEST, /9/ A RELATIONSHIP EXISTS BETWEEN LOSS BY DECANTATION RESULTS, LIQUID LIMIT OF THE MINUS 200 MESH FRACTION, AND SAND EQUIVALENT VALUE, AND /10/ CLAY ACTIVITY, AS INDICATED BY LIQUID LIMIT, AS WELL AS THE AMOUNT OF THE CLAY PRESENT IN THE AGGREGATE, INFLUENCE CONCRETE STRENGTH. THE SAND EQUIVALENT TEST IS A BETTER INDICATOR OF A COMBINATION OF ACTIVITY AND AMOUNT OF CONTAMINANT, WHEREAS THE LOSS BY DECANTATION TEST INDICATES ONLY THE AMOUNT. FOR THIS REASON THE SAND EQUIVALENT TEST IS A BETTER INDICATOR OF THE QUALITY OF FINE AGGREGATE FOR USE IN CONCRETE. LOSS BY DECANTATION RESULTS SHOULD BE COMBINED WITH LIQUID LIMIT DETERMINATIONS TO EVALUATE COARSE AGGREGATE.

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  • Supplemental Notes:
    • Paper sponsored by Committee on Durability of Concrete--Physical Aspects and presented at the 45th Annual Meeting. Distribution, posting, or copying of this PDF is strictly prohibited without written permission of the Transportation Research Board of the National Academy of Sciences. Unless otherwise indicated, all materials in this PDF are copyrighted by the National Academy of Sciences. Copyright © National Academy of Sciences. All rights reserved.
  • Authors:
    • Buth, Eugene
    • Ivey, Don L
    • Hirsch, Teddy J
  • Publication Date: 1966

Media Info

  • Media Type: Digital/other
  • Features: Figures; References; Tables;
  • Pagination: pp 1-17
  • Monograph Title: Aggregates for concrete
  • Serial:

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Filing Info

  • Accession Number: 00211959
  • Record Type: Publication
  • Files: TRIS, TRB
  • Created Date: Nov 18 1994 12:00AM