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

CHROMIUM IN CEMENT

THE OBJECT OF THE INVESTIGATIONS REPORTED WAS TO ASCERTAIN THE ORIGIN OF THE CHROMIUM WHOSE PRESENCE CAN BE DETECTED IN CEMENT AND HOW IT BEHAVES IN THE MANUFACTURE AND IN THE HARDENING OF THE CEMENT. FOR THIS PURPOSE ABOUT THREE HUNDRED PORTLAND CEMENTS AND PORTLAND BLASTFURNACE CEMENTS (OR THE VARIETIES KNOWN AS EISEN PORTLAND CEMENT AND HOCHOFEN CEMENT) MANUFACTURED IN THE FEDERAL REPUBLIC OF GERMANY WERE EXAMINED WITH REGARD TO THEIR TOTAL CHROMIUM CONTENT AND THEIR CONTENT OF WATER-SOLUBLE HEXAVALENT CHROMIUM. THE TOTAL CHROMIUM CONTENT IS BETWEEN 20 AND 100 P.P.M CR, I.E., BETWEEN 0.002 AND 0.01% CR. THE CONTENT OF CHROMATE WHICH DISSOLVES DURING THE SHORT-TERM ACTION OF WATER UPON CEMENT IS SIGNIFICANTLY LOWER AND IS SITUATED BETWEEN 1 AND 30 P.P.M. CR, I.E., BETWEEN 0.0001 AND 0.003% CR. OF THE TOTAL CHROMIUM CONTENT OF THE CEMENTS, THEREFORE, 200% IS, ON AN AVERAGE, SOLUBLE AS CHROMATE. IN THE INVESTIGATIONS CONCERNING THE BEHAVIOR OF CHROMIUM IN THE HYDRATION OF CEMENT, IT WAS ESTABLISHED THAT THERE IS PRACTICALLY NO MORE DISSOLVED CHROMATE IN A CEMENT SUSPENSION AT THE END OF 24 HOURS. THIS DISAPPEARANCE OF THE CHROMATE OUT OF THE SOLUTION CAN BE EXPLAINED EITHER BY ADSORPTION TO THE HYDRATION PRODUCTS OR BY INCORPORATION INTO THE ETTRINGITE. BY EXTRACTION OF THE HYDRATING CEMENT WITH SALT SOLUTIONS WHICH PREVENT SUCH ADSORPTION OR INCORPORATION INTO THE ETTRINGITE IT WAS FOUND THAT NEARLY ALL THE CHROMIMUM IN THE PORTLAND CEMENT CLINKER IS PRESENT IN THE FORM OF HEXAVALEN CHROMATE. THE BEHAVIOR OF CHROMIUM IN THE MANUFACTURE OF CEMENT WAS INVESTIGATED IN SPECIMENS OF RAW MEAL, CLINKER, AND CEMENT. IT WAS FOUND THAT, BY FAR, THE GREATER PART OF THE CHROMIUM IN CEMENT COMES FROM THE RAW MATERIALS. THERE IS NO MEASURABLE INCREASE IN THE CHROMIUM CONTENT CAUSED BY KILN LININGS CONTAINING CHROMIUM OR BY CHROMIUM ALLOY STEELS USED IN THE GRINDING MILLS. FOR THESE REASONS, IT IS NOT POSSIBLE TO REDUCE THE CHROMIUM CONTENT OF CEMENTS BY USING CHROMIUM-FREE MATERIALS IN KILNS AND MILLS. /AUTHOR/

  • Supplemental Notes:
    • Col 19, No 10, PP 467-472
  • Authors:
    • Pisters, H
  • Publication Date: 1966-10

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  • Accession Number: 00212505
  • Record Type: Publication
  • Files: TRIS
  • Created Date: Sep 1 1970 12:00AM