PORTLAND CEMENT: PSEUDOMORPHS OF ORIGINAL CEMENT GRAINS OBSERVED IN HARDENED PASTES

A MODEL WAS FORMULATED BY TAPLIN TO REPRESENT THE HYDRATION OF PORTLAND CEMENT. THE MODEL CONSISTS OF AN INNER AND AN OUTER PRODUCT TO DERIVE EQUATIONS TO REPRESENT THIS PROCESS. INVESTIGATIONS OF HARDENED CEMENT PASTES CONFIRM TAPLIN'S MODEL. ELECTRON OPTICAL STUDIES REVEAL PRIMARILY THE FORMATION AND GROWTH OF THE OUTER PRODUCTS, AND THE NATURE AND ORIGIN OF THE INNER PRODUCT IS NOT KNOWN. THE EXISTENCE OF INNER PRODUCTS AND FORMATION OF PSEUDOMORPHS, SUGGESTED BY LIGHT MICROSCOPE STUDIES, HAVE NOT BEEN REGARDED AS FUNDAMENTAL PROCESSES IN THE HARDENING OF PORTLAND CEMENT. THE NAME PSEUDOMORPHOUS HYDRATION HAS BEEN SUGGESTED FOR THE GROWTH OF THE INNER PRODUCT. THIS PSEUDOMORPHOUS HYDRATION TAKES PLACE WITHOUT SIGNIFICANT CHANGES IN THE IMPOSED EXTERNAL DIMENSIONS. IT IS POSTULATED THAT IF THE CEMENT PARTICLES IN THE MIX EVER LOST SIGNIFICANTLY THEIR MECHANICAL RESISTANCE OR RIGIDITY, THE EXTERNAL BOUNDARIES OF THE MASS COULD NOT BE EXPECTED TO REMAIN FIXED. SCANNING ELECTRON MICROGRAPHS SHOW THAT A HYDRATION PRODUCT FORMS INSIDE THE ANHYDROUS CEMENT GRAINS AND FORMS A PSEUDOMORPH OF THE ORIGINAL CEMENT GRAINS. THE ORIGINALLY WATER-FILLED SPACE BETWEEN THE GRAINS IS PARTIALLY FILLED WITH CALCIUM HYDROXIDE CRYSTALS THAT APPEAR TO BE RESPONSIBLE FOR THE STRENGTH OF THE CEMENT PASTE.

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  • Supplemental Notes:
    • pp 549-551, 2 FIG
  • Authors:
    • Williamson, R B
  • Publication Date: 1969-5-2

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  • Accession Number: 00213380
  • Record Type: Publication
  • Files: TRIS
  • Created Date: Sep 2 1994 12:00AM