CEMENT PROPERTIES RELATED TO PERFORMANCE

A STATISTICAL STUDY WAS CONDUCTED AT THE NBS INSTITUTE FOR APPLIED TECHNOLOGY RELATING CEMENT CHARACTERISTICS TO COMPRESSIVE STRENGTHS. THE EFFECTS OF VARIABLES SUCH AS CEMENT COMPOSITION AND FINENESS ON THE COMPRESSIVE STRENGTH OF MORTARS WERE DETERMINED FOR SPECIMENS CURED UNDER VARIOUS CONDITIONS AND FOR DIFFERENT PERIODS OF TIME. NBS TESTED 100 PORTLAND CEMENTS FROM DIFFERENT AREAS OF THE COUNTRY BY COMPLETE CHEMICAL ANALYSES, INCLUDING SPECTROCHEMICAL DETERMINATIONS FOR TRACE ELEMENTS. THE COMPRESSIVE STRENGTHS OF THE TEST MORTARS WERE DETERMINTED AT 1, 3, 7, AND 28 DAYS, AND 1, 5, AND 10 YEARS AFTER STORAGE IN WATER. TESTS WERE MADE OF COMPRESSIVE STRENGTHS AFTER CURING IN MOIST AIR AND IN LABORATORY AIR FOR ONE YEAR. A SECOND SERIES OF TESTS WERE MADE IN WHICH MORTAR SPECIMENS WERE CURED WITH STEAM AT PRESSURES OF 1 AND 10 ATMOSPHERES AFTER 5 AND 24 HOURS OF INITIAL CURING. TEST RESULTS WERE ANALYZED WITH THE AID OF A DIGITAL COMPUTER AND THE USE OF A LEAST-SQUARES METHOD TO DETERMINE AND EVALUATE THE DIFFERENT VARIABLES. TEST RESULTS INDICATED THAT (1) MUCH OF THE BROAD RANGE OF COMPRESSIVE- STRENGTH VALUES UNDER BOTH NORMAL AND ACCELERATED CURING COULD BE EXPLAINED BY THE DIFFERENCES IN CHEMICAL COMPOSITION OF THE CEMENTS, (2) THE CEMENT COMPOSITION RESULTING IN THE GREATEST COMPRESSIVE STRENGTH WITH ACCELERATED CURING MAY DIFFER FROM THE OPTIMUM COMPOSITION FOR NORMAL CURING, (3) A HIGHER PERCENTAGE OF TRICALCIUM ALUMINATE WAS ASSOCIATED WITH HIGHER STRENGTHS AT THE EARLY TEST AGES, BUT WITH LOWER STRENGTHS AT 1, 5, AND 10 YEARS, (4) A HIGHER QUANTITY OF POTASH WAS ASSOCIATED WITH HIGHER STRENGTHS AT THE VERY EARLY AGES AND A HIGHER PERCENTAGE OF SODA WITH LOWER STRENGTHS AT THE LATER AGES, (5) THE EFFECTS OF DICALCIUM SILICATE AND TRICALCIUM SILICATE WERE APPARENTLY DIFFERENT AT DIFFERENT TEST AGES AND CURING CONDITIONS, AND (6) THE FINENESS OF THE CEMENT AS WELL AS THE AIR-ENTRAINING CHARACTERISTICS WERE ALSO FOUND TO BE IMPORTANT VARIABLES. WITH THIS KNOWLEDGE IT IS NOW POSSIBLE TO PREDICT MORE ACCURATELY THE POTENTIAL CONCRETE STRENGTH DEVELOPMENT AT LATER AGES AND THE EFFECTS OF ACCELERATED CURING.

  • Supplemental Notes:
    • Vol 52, No 12, P 271
  • Publication Date: 1968-12

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  • Accession Number: 00213340
  • Record Type: Publication
  • Files: TRIS
  • Created Date: Apr 28 1994 12:00AM