Analytical Study of Pure and Extended Portland Cement Pastes: II, Fly Ash- and Slag-Cement Pastes |
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| Authors: | H F W TAYLOR K MOHAN G K MOIR |
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| Affiliation: | Department of Chemistry, University of Aberdeen, Old Aberdeen AB9 2UE, Scotland;Blue Circle Technical, Research Laboratories, Greenhithe, Kent DA9 9JQ, England |
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| Abstract: | A range of pastes of portland cement interground with low-calcium fly ash or granulated blast furnace slag was studied by X-ray diffraction, analytical electron microscopy, thermo-gravimetry, and determinations of CO2 and of unreacted fly ash or slag. Partial replacement of clinker by fly ash results in increased reaction of the alite from at least as early as 3 d. The amount of Ca(OH)2 formed from a given weight of clinker increases at 3 d due to the enhanced reaction, but from 28 d onward, it decreases due to the pozzolanic reaction. The mean Ca/SI ratio of the C-S-H decreases with time or fly ash content, toward a lower limit of ～1.4. Partial replacement of clinker by slag also decreases both the amount of Ca(OH)2 formed from a given weight of clinker and the mean Ca/Si ratio of the C-S-H, but to a lesser extent. Using the methods described in Part I of this paper, the results of the experimental methods were tested for mutual consistency, and volume percents of phases, porosities, and related quantities were calculated. |
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