Coupling of carbonation and chlorides ingress mechanisms is very common in concrete under certain exposure conditions such as coastal environments. The aggravation/ mitigation of corrosion by the existence of carbonation lies on the fact that microstructural changes due to carbonation result in changes on the transport properties of the material. In this study we investigate and quantify evolving transport properties of ordinary Portland cement paste, such as porosity, tortuosity and intrinsic permeability. Dual X-ray micro computed tomography (micro CT) is used for the quantification of porosity. Furthermore Dynamic Vapour Sorption (DVS) measurements are carried out to resolve water retention and relative permeability curves. The authors expect to provide insights into the mechanisms of accelerated carbonation in both types of cement paste, as well as data for input and validation of numerical and analytical models on this degradation phenomenon.