Depth profiles of carbonates fonned during natural carbonation

The depth profiling of carbonates formed during a natural carbonation of mortars with one face exposed directly to rain and the opposite face sheltered have been measured. The amount of carbonates formed on mortars sheltered from rain is generally higher. The depth of carbonation evaluated by the phenolphthalein test cannot be directly correlated with the carbonate profile. The CO2 diffusion coefficients calculated on the basis of the distribution of carbonates are of the same order of magnitude as those measured by a direct method. A threshold value of diffusivity appears when the sand concentration increases. This point is discussed and compared with other characteristics of mortars and concretes that exhibit similar behavior. (C) 2002 Elsevier Science Ltd. All rights reserved.