Moisture transport in CO2-cured cement-based materials with sufficient carbonation

CO 2 curing has a great influence on the phase assemblages and pore structure in cement-based materials, thereby altering their moisture transport behaviors. However, the effect of CO 2 curing on the moisture transport in cement-based materials still remains unclear. In this study, the water vapor sorption isotherms (WVSIs), capillary water absorption, and drying kinetics of Ordinary Portland cement (OPC) and slag cement materials under CO 2 curing with sufficient carbonation were investigated. The variations in the pore structure caused by CO 2 curing were also examined by employing the surface fractal dimension based on MIP results. The WVSIs results indicate that the hysteresis phenomenon diminishes in CO 2 -cured materials compared to standard-cured materials, which is attributed to the fact that CO 2 curing reduces the content of C-S-H gel and the amount of “ink-bottle” pores. CO 2 curing can lead to an increase in the capillary water absorption capacity of cement-based materials and a decrease in its moisture retention capacity due to the alteration in the pore structure. In addition, the drying kinetics results demonstrate that CO 2 curing leads to greater mass loss at a given RH. The inverse calculation shows an increase in the intrinsic permeability ( K l ) of CO 2 -cured specimens, and the K l increases further with higher slag content. This trend is consistent with the observed increases in the water absorption coefficients and the reductions in the moisture retention capacity.