I have done chloride diffusion test on my concrete specimens and now I want to know if there is a link between chloride diffusion results and carbonation depth of concrete, since carbonation is generally a very slow process.
From literature there is an established link between carbonation depth and Oxygen Permeability Index (OPI) and also a link between OPI and Chloride Conductivity Index (CCI). You will have to first determine the OPI for your concrete from the CCI and from there establish the carbonation depth. Both OPI and CCI are functions of the binder type. Please consult literature on durability design of concrete and the following literature: Performance-based durability testing, design and specification in
South Africa: latest developments
M.G. Alexander & H. Beushausen
University of Cape Town, Cape Town, South Africa
The carbonation depth depends critically on the CO2 buffer capacity of the concrete per volume of cement paste. This in turn depends on the amount of reactive CaO present in the binder. The calcium present in portlandite and CSH is able to bind the CO2 and this effect is dominant compared to the diffusivity of the cement paste. This means that concrete with low diffusivity (for example containing silica fume or BFS) might show higher carbonation depth than concrete with higher diffusivity but made with Portland cement (higher amount of reactive CaO). You can find more details in this recent paper by our research group, which is also on RG:
Leemann, A., Nygaard, P., Kaufmann, J. and Loser, R., 2015. Relation between carbonation resistance, mix design and exposure of mortar and concrete. Cement and Concrete Composites, 62, pp.33-43.
To sum up: if you have only results about chloride diffusion, you cannot in general predict the carbonation depth, unless perhaps only if you consider concrete with the same type of binder. Even then, the correlation will only be empirical because binding plays an important role both in carbonation (see above) and in chloride transport.
Based on explanation of Prof. Lura you can not predict carbonation depth generally and diffusion coefficient help you for more information about quality of concrete.
many thanks for your great help and specially Prof. Lura for the perfect explanation and the great paper.
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