Reactive transport modelling of long-term carbonation

Concrete specimens of sulphate resistant Portland cement (SRPC) exposed to natural carbonation in a controlled environment for 13 years revealed that the carbonation was significantly underestimated by accelerated tests and extrapolation by a linear diffusion equation. The results confirmed that carbonation as a phenomenon is too complex to be predicted by a conventional diffusion equation for periods considerably exceeding the experimentally covered period. A comprehensive approach consisting of a thermodynamic model and a statistical methodology to simulate long-term carbonation verified by versatile experimental data was presented. As an application of the method, long-term carbonation was simulated for the SRPC concretes.