中文摘要：

采用多孔介质扩散机制推导出混凝土的气体渗透系数，并比较了CO2和O2两种气体在混凝土中扩散能力。通过加速碳化试验研究了气体渗透系数与碳化深度的关系。试验结果发现CO2气体在粉煤灰混凝土中的扩散能力较O2气体差，并且混凝土试件的28d碳化深度随着粉煤灰掺量的增加均呈现减小的趋势。采用多孔介质扩散机制推导出来的气体扩散系数不能完全表征混凝土的碳化性能。

英文摘要：

Air permeability coefficient of concrete materials was calculated based on diffusion mechanism of porous medium,and diffusion rates of CO2 and O2 were analysed.The relationship between air permeability coefficient and carbonation depth was also investigated by accel- erate experiment.Results show that the diffusion rate of CO2 is lower than that of O2.Carbonation depth decreased with increase of fly ash.Car- bonation performance of concrete can not be deduced by air permeability coefficient based on diffusion mechanism of porous medium.