In Switzerland as well as in the rest of Europe the cement market is changing rapidly. These changes began in the middle of the 1990’s when in Switzerland the cement CEM II/A-LL (Portland-limestone cement) was launched. This cement has increasingly replaced the ordinary Portland cement CEM I. In the last few years a series of other cement types have been brought on the market. This trend runs parallel to the rest of Europe, with some country-specific differences.

Up to now it could be assumed, that with the use of the existing cements for new constructions the carbonation of concrete did not represent a direct and relevant risk for rebar corrosion any longer, since the actual standards (codes) for concrete constructions required a far higher concrete cover than earlier. With the expected new cement types this situation might change considerably. Thus, the innovations of the cement producers might imply certain risks for the durability of concrete constructions. It has to be considered in this context that critical chloride content for corrosion decreases with a decreasing pH of the pore water and, therefore, with the advancing carbonation of the concrete cover as well as.

With this project the influence of the concrete composition (cement type and content, w/c ratio) and the curing conditions on the carbonation resistance should be investigated. For this purpose the carbonation coefficient (mass for the carbonation resistance) of a variety of concrete compositions should be determined and correlated with physical and chemical parameters of the mixes.