2019 Volume 73 Issue 1 Pages 79-86
The present study experimentally examined the relationship between the property of oxygen transport in hardened cement paste after sodium sulfate solution immersion and the change of hydration products. Oxygen diffusion coefficient, pore volume, pore distribution and phase composition of cement paste specimens exposed to sodium sulfate solution and ion exchanged water were acquired. As the result, the oxygen diffusion coefficient of the specimens after sodium sulfate immersion decreased compared to that of the specimens after ion exchanged water immersion. This decrease in the oxygen diffusion coefficient was considered to be caused by the complication of the pore structure of the hardened cement paste due to the decrease of pore volume （diameter ＞ 20nm） when the specimens are immersed in sodium sulfate solution. And there was a certain correlation between the volume of C-S-H and ettringite and the pore volume （diameter ＞ 20nm）. It is one of the evident that the formation of ettringite reduced the pore volume （diameter ＞ 20nm） and reduced the oxygen diffusion coefficient.
