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The role of calcium carbonate in cement hydration

qingpeiliang 添加于 2013-5-28 21:14 | 1820 次阅读 | 0 个评论

作者
Matschei T, Lothenbach B, Glasser FP
摘要
Limestone, mainly consisting of calcite, is a permitted additive to Portland cements often up to a 5 wt.% limit. It is shown by experiment and calculation that much, if not all, of this calcite is reactive and affects the distribution of lime, alumina and sulfate and thereby alters the mineralogy of hydrated cement pastes. Calcite affects the mineralogical variant of the AFm phase(s). Calcite additions affect the amount of free calcium hydroxide as well as the balance between AFm and AFt phases, although C–S–H is unaffected in much of the range of compositions. Generic data are shown in graphical form to quantify these mineralogical changes as functions of cement composition and amount of added calcite. Calculations of the specific volume of solids as a function of calcite addition suggest that the space-filling ability of the paste is optimised when the calcite content is adjusted to maximise the AFt content. However, before the calculated data can be used uncritically, certain kinetic constraints on reactivity also need to be assessed. Progress towards the quantification of paste mineralogy suggests that (i) elucidation of the mineralogy of pastes, particularly blended cement pastes, is facilitated by using both theoretical and experimental approaches and (ii) that the ultimate goal, of calculating paste mineralogy from the bulk chemistry, is attainable.
详细资料
- 文献种类: Journal Article
- 期刊名称: Cement and Concrete Research
- 期刊缩写: Cement and Concrete Research
- 期卷页: 2007年第37卷第4期 551-558页
- ISBN: 0008-8846
学科领域工程技术 » 材料科学
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