The phase constitution of alite in portland cement clinker highly depends not only on the chemical composition of a raw mix but also on the kinetics of crystallization from the interstitial melt. From the melt of high supersaturation alite can be crystallized so quickly as to take up foreign ions i
Phase identification of alite in portland cement clinker
โ Scribed by I. Maki; K. Kato
- Publisher
- Elsevier Science
- Year
- 1982
- Tongue
- English
- Weight
- 428 KB
- Volume
- 12
- Category
- Article
- ISSN
- 0008-8846
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โฆ Synopsis
Unequivocal phase identification of alite in portland cement clinker has been made by combined use of microscopy during heating, X-ray powder diffraction, and differential thermal analysis.
Alite thus far assigned to Mlb by X-ray powder diffractometry, in reality, gives every indication of being M 3. Only Mla should therefore be denoted simply as M I. The M 1 form of alite in clinker has long been mistaken for R because of an apparent trigonal character of its cell.
It is M 3 that gives the monoclinic cell as first described by Jeffery.
๐ SIMILAR VOLUMES
In the examination of alite in Portland cement clinker by transmission electron microscopy, the dominant structure found was that described by Jeffery (I). Twinning on the pseudomirror plane of the monoclinic structure has been found. This provides an explanation for some weak extra X-ray reflection
Crystallization of a liquid similar to that present in Portland cement at clinkering temperatures has been studied. Its composition (in wt %) is CaO = 54.8, A~203 = 22.7, Fez03 = 16.5, Si02 = 6.0. Prolonged crystallization or slow cooling yields the equilibrium phases: C3A, ferrite close to C,AF, an
In the system C3A-C~AF-SiO2-MgO, the glass formation region that is closely similar in composition to the interstitial material of portland cement clinker has been determined. The interstitial melt that exists in equilibrium with the silicates at the clinkering temperature contains a little silica.