DETERMINATION OF SILICA FUME IN UNHYDRATED, BLENDED, DRY-PACKAGED MIXTURE, AND HYDRATED MORTAR

The authors propose a test methodology as a quality control procedure to identify the relative amount of dry silica fume present in a prepackaged blend of dry, unhydrated, cementitious material. The method assumes availability of representative samples of each of the raw material ingredients prior to packaging, including portland cement, silica fume, fly ash, silica sand, and a representative sample of the mixed product. Known percentages of silica fume by weight of portland cement were added separately to a basic blended mixture and analyzed by combined heat treatment and x-ray diffraction (XRD) method. An estimate of the amount of silica fume in a prepackaged cement was determined via a calibration curve developed from standard laboratory mixtures. A reasonable degree of accuracy was achieved. Also, a neat portland cement and portland cement plus fly ash plus sand mixtures containing various proportions of silica fume by weight of cement were hydrated and analyzed at selected periods for up to 180 days to determine residual silica fume. The diminution of calcium hydroxide in the cement-fly ash mixture and in the combined silica fume and fly ash cement mixtures were observed during this period using thermogravimetric analysis and scanning electron microscopy.

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  • English

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  • Accession Number: 00715289
  • Record Type: Publication
  • Files: TRIS
  • Created Date: Jan 1 1996 12:00AM