Phase Composition of Cement Hydrated in Hydrothermal Conditions

3 Phase Composition of Cement Hydrated in Hydrothermal Conditions 

The hydrothermal treatment of concrete was introduced principally for the aceelera-tion of cement paste hardening process whieh allowed the curing period shortening. Then after it has been proved that this proeess gives the possibility of eement replacement by waste materials, practically inert in water at ambient temperature. 

It is convenient in practice to separate the two temperature ranges, when the phase composition of cement paste subjected to the thermal treatment is discussed up to 100 °C in water vapor under the atmospherie pressure, and at higher temperatures and pressures, corresponding to the pressure of saturated water vapor. 

The hydration of cement paste in water vapour at atmospherie pressure and temperatures up to 100 °C causes a significant acceleration of the proeess. Odler and Skalny [191] found the hydration degree of CjS after 6 h at temperature 50,75 and 100 °C as 23, 36 and 48% respectively. At 100 °C the hydration of C3S was eom-pleted after 3 days. 

The process rans according the Arrhenius equation in the temperature range from 4 to 110 °C, as it has been proved by Verbeck [192] and the apparent activation 

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