Carbonation of cement at a constant CO2 pressure and relative humidity

[chliu8219]

Hi everyone, my recent work is about the carbonation of cement. In short, my goal is to complete a solid-gas reaction, and calculate the phase evolution of cement under fixed relative humidity and CO2 partial pressure conditions. Although I understand that phreeqc is based on ion interaction parameters, I currently have no better way to solve it.
If anyone knows how to use phreeqc to achieve my goal, I would be grateful. Thank you.