The results in the present study are summarized as follows;
(1) The carbonation reaction of synthetic 11Å tobermorite in aqueous solution occurs through two rate-determining steps, that is, the rate-determining step changes from the surface reaction to the internal diffusion process with the progress of carbonation. This phenomenon is considered to be due to the increase in the diffusion resistance with the formation of CaCO3 in the reaction layer of tobermorite.
(2) The rate law for the surface reaction control process is expressed as -d[CaO]/dt=k[CaO][CO2]aq, where k is 1.67M-1min-1 at 30°C and the activation energy for k is 35.3kJ/mol.
(3) The carbonation rate of synthetic 11Å tobermorite in the aqueous solution is relatively fast. Hence, it is expected that tobermorite is applicable as the material for fixation and solidification of 14CO2 by finding the optimal conditions.
