The mechanisms of CO2 diffusion in concrete can explain the
phenomena described in Section 3.1 clearly. The explanation is also
supported by work reported in literature. For instance,
Garcia-Gonzalez et al. [18] analysed the effects of supercritical carbonation
(CO2 99.995%, at 20 MPa and 318 K) on the physicochemical
properties of ordinary Portland cement pastes. Their results
showed that, for a natural carbonation process, the diffusion of
CO2 into the pores of cement paste was considered as a