Cement Chemistry
CARBONATION KINETICS─WHAT IS THE DIFFERENCE IN KINETICS BETWEEN ACCELERATED CONDITION AND NATURAL CONDITION─
2019 Volume 73 Issue 1 Pages 38-43
Details
2019 Volume 73 Issue 1 Pages 38-43
The carbonation process of concretes had been discussed by taking accounts of mass, reactivities with CO32－ and particle sizes of CH and C-S-H. It was assumed that the reactivity of CH with CO32－ is only a little higher than that of C-S-H, and the particle diameters are 30μm for CH and 30nm for C-S-H. And also, it is assumed that the rate of carbonation of particle system obey Jander’s rule when they are in the liquid with constant concentration. When the rate of supply of CO32－ is lower than the rate of carbonation obeyed Jander’s rule, the amounts of carbonation should be equal to that of CO32－ supplied. When the amounts of CO32－ supplied becomes more than that obeyed Jander’s equation, the process may move to next step. Owing to these ideas how the accelerating condition affects to the rate of carbonation had been discussed. As a result, following results were obtained；1. the reaction ratio of CH at the carbonation front will differ with the accelerating condition. 2. The color of the carbonation zone will be pink due to the accelerating condition. 3. The coefficient of carbonation will depend on the amounts of C-S-H and CH with a weight.
