Complete hydration products of portland cement compounds and their mixtures with or without gypsum produced by ball mill hydration at 20°C,
W/C=80%, were investigated by X-ray diffraction analysis, infra-red absorption spectrum, differential thermal analysis, electron microscopic observation and chemical analysis. The results obtained are summerized as follows:-
(1) Complete hydrate of 3CaO⋅SiO
2 was identified as Afwillite Ca
3(SiO
3OH)
2⋅2H
2O by X-ray diffraction and differential thermal analysis, but calculated composition of this hydrate was C
1.68SH
1.26, based on the chemical composition of initial synthesized 3CaO⋅SiO
2, loss on ignition at 900°C and the quantity of liberated Ca(OH)
2.
The Ca(OH)
2 liberated from 3CaO⋅SiO
2 during the process of hydration was extracted after Lerch-Bogue method until (001) reflection of Ca(OH)
2 was not recognized by X-ray diffraction analysis, so it is considered that both amorphous and crystaline Ca(OH)
2 were measured. The authors supposed that the difference of composition of Afwillite and complete hydrate of 3CaO⋅SiO
2 was not, as Brunauer et al say, caused by missing the amorphous Ca(OH)
2, but the essential property of hydrate having various composition within suitable range. Infra-red absorption spectrum shows the existence of hydrogen bond in Afwillite structure.
X-ray diffraction pattern of complete hydrate of β-2CaO⋅SiO
2 contained diffraction lines of Tobermorite.
(2) The complete hydrate of 3CaO⋅Al
2O
3 was cubic crystal of 3CaO⋅Al
2O
3⋅6H
2O, while that of 4CaO⋅Al
2O
3⋅Fe
2O
3 was the solid solution of 3CaO⋅Al
2O
3⋅6H
2O-3CaO⋅Fe
2O
3⋅6H
2O (lattice constant
a=12.614 Å) having approximate composition of 3CaO⋅0.8Al
2O
3⋅0.2Fe
2O
3⋅6H
2O.
Infra-red absorption sprctra of complete hydrate of 3CaO⋅Al
2O
3 and 4CaO⋅Al
2O
3⋅Fe
2O
3 suggest some difference about combined water between cubic calcium aluminate hydrate, solid solution of 3CaO⋅Al
2O
3⋅6H
2O-3CaO⋅Fe
2O
3⋅6H
2O and calcium silicate hydrate.
(3) The complete hydrate of 3CaO⋅SiO
2 with gypsum and 3CaO⋅SiO
2, 3CaO⋅Al
2O
3 mixture with or without gypsum were somewhat different from the complete hydrate of 3CaO⋅SiO
2 (Afwillite).
In the complete hydrate of 3CaO⋅SiO
2 and CaSO
4⋅2H
2O mixture, CaSO
4⋅2H
2O were completely extracted by saturated lime water, while the complete hydrate of 3CaO⋅SiO
2-3CaO⋅Al
2O
3 mixture showed X-ray diffraction patterns and differential thermal analysis curves of 3CaO⋅Al
2O
3⋅6H
2O besides calcium silicate hydrate. So it is not considered that CaSO
4⋅2H
2O and 3CaO⋅Al
2O
3 made solid solution or complex compound with calcium silicate hydrate.
From these results, the authors supposed that the reason of the formation of new calcium silicate hydrate is the difference of the equilibrium of liquid phase produced during the process of hydration.
抄録全体を表示