Determinations of hydrated aluminate and silicate phases

Opinions have differed as to the possibility of determining the hydrated) aluminate phases by thermal or X-ray methods. The determination of ettringite was discussed in Section 6.2.2. Bensted (B99), who used DTAJ found that for ordinary Portland cements the ettringite content increase with time during the first 2 h to maximum values of 2.2-2.8%, and that th quantity of ettringite formed at any given time increased with the w/c ratio  

There are probably no effective direct methods at present for determining either C-S-H or AFm phases in cement pastes in both cases, this is probably attributable to the low degree of crystallinity. Odler and Abdul-Maula (015) found that determination of AFm phase by QXDA was only semiquantitative. Postulated quantitative phase compositions of cement pastes may, however, be tested by comparing observed and calculated TG curves (Section 7.3.3). 

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