Early hydration of

The kinetics and mechanism of P-C2S hydration are similar to those for C3S, apart from the much slower rate of reaction (M53,T29,F11,014,F22), and, as noted earlier, the products are similar apart from the much smaller content of CH. Preparations appear to be more variable in reactivity than those of C3S this is partly attributable to differing stabilizers (F23), but could also be due to differing amounts or natures of phases in intergranular spaces or exsolution lamellae. Preparations made at low temperatures are 

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The composition of the Hquid phase during the early hydration of Portiand cements is controlled mainly by the solution of calcium, sulfate, sodium, and potassium ions. Very Httie alumina, siHca, or iron are present in solution. Calcium hydroxide, as calcium oxide, and gypsum, as calcium sulfate, alone have solubihties of about 1.1 and 2.1 g/L at 25°C, respectively. In the presence of alkaHes released in the first 7 min, the composition tends to be governed by the equiHbrium ... 

The 5° series of Ca2Si04 pastes alone furnishes extensive information about the early stages of hydration. Between 0 and 21% hydration, data are given in Table III for 11 pastes in the same hydration range there are between 0 and 2 pastes in the eight other series. Extensive work will soon be started in this laboratory on the early hydration of all three silicates at all three temperatures. 

Kndfel, D., and Wang, J.-F. (1993) Early hydration of quick cements in the system Cj2A.y.CaF2-C2S-C2(A,F). Cement Based Materials 1,77-82. 

Shi, C., and Day, R.L. (1995b) A calorimetric study of early hydration of alkali-slag cement. Cement and Concrete Research 25, 1333-1346. 

Suzuki, K. etal. (1998) Very early hydration of Li20-Ca0-Al203-Si02 glass (in Japanese). Nippon Kagaku Kaishi 1998(6), pp. 438-441 [ref. CA 129/84893]. 

The study of the early hydration of CaaSiOs by XPS has been reported by Regourd et al. (1980) after detailed study of surface transformations of C3S grains from very early ages of hydration. 

In general, retarders are effective in the very early hydration of cement. For a given percentage, Na gluconate, citric acid, or sucrose are better retarders of initial set of a normal low alkali cement than lignosul-fonate, salicylic acid, Na heptonate, or boroheptonate.1 1... 

The C/S ratio of the C-S-H product decreases by the addition of silica. It is reported that in the absence ofSi02ataw/sratio of 10, C3S yields a C-S-H product with a C/S ratio of 0.8 at 24 hours, and this ratio decreases to 0.33, and 0.36 at w/s ratios of 1 and 0.4 respectively.The acceleration of early hydration of C3S is ascribed to the fineness of the particles that would provide preferential nucleation sites. The pozzolanic particles also offer a surface for the precipitation of C-S-H from the pore solution. Thus, the removal of the Ca and silicate ions would result in a reduction in the thickness ofthe relatively impermeable C-S-H growing on the C3S grains.[ ... 

Gu, P., Ramachandran, V. S., and Beaudoin, J. J., Study of Early Hydration of High Alumina Cement Containing Phosphonic Acid by Impedance Spectroscopy, J. Mater. Sci. Lett., 14 503-505 (1995)... 

Jansen, D., E Goetz-Neunhoeffei B. Lothenbach and J. Neubauer (2012a). The early hydration of ordinary Portland cement (OPC) An approach comparing measured heat flow with calculated heat flow from QXRD . Cement and Concrete Research 42 1) 134-138. 

Bazzoni, A., M. Cantoni and K. L. Scrivener. 2014a. Impact of Annealing on the Early Hydration of Tricalcium Silicate . Journal of the American Ceramic Society 97 (2) 584-591. 

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