In this study, we investigate the secondary sorption in an air-entrained Portland cement mortar that is purged with different gases— $$\hbox {CO}_{2}, \hbox {CH}_{4}$$ CO 2 , CH 4 , or $$\hbox {N}_{2}$$ N 2 . By altering the gas phase present in the void space, we are able to evaluate how gas solubility influences the secondary sorption. The rate of water sorption in the presence of different gases in the entrained voids was captured using successive 30 min X-ray micro-computed tomography scans for 24 h after water-specimen contact. The results show the higher the solubility of the gas, the faster the mortar reaches saturation. The air voids in the $$\hbox {CO}_{2}$$ CO 2 -purged specimen begin to absorb water within 30 min and reach a critical degree of saturation within hours, while the air voids of $$\hbox {N}_{2}$$ N 2 and $$\hbox {CH}_{4}$$ CH 4 -purged specimens show a significantly slower water absorption over 24 h. The high solubility of $$\hbox {CO}_{2}$$ CO 2 was found to alter the X-ray mass attenuation value of the water as the water becomes $$\hbox {CO}_{2}$$ CO 2 saturated. These tests reveal the gas type present in the void space significantly influences secondary sorption of Portland cement mortars. The findings of this study have implications on predicting mass transport in cement-based materials used in below ground carbon sequestration structures.

中文翻译：

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X射线CT观察气体溶解度对硅酸盐水泥砂浆二次吸附的影响

在这项研究中，我们研究了用不同气体吹扫的加气硅酸盐水泥砂浆中的二次吸附 - $$\hbox {CO}_{2}, \hbox {CH}_{4}$$ CO 2 ， CH 4 ，或 $$\hbox {N}_{2}$$ N 2 。通过改变空隙空间中存在的气相，我们能够评估气体溶解度如何影响二次吸附。在水与样品接触后 24 小时内，使用连续 30 分钟 X 射线显微计算机断层扫描扫描捕获夹带空隙中存在不同气体时的吸水率。结果表明，气体的溶解度越高，砂浆达到饱和的速度就越快。$$\hbox {CO}_{2}$$ CO 2 净化的样品中的空隙在 30 分钟内开始吸水，并在数小时内达到临界饱和度，而$$\hbox {N}_{2}$$ N 2 和$$\hbox {CH}_{4}$$ CH 4 净化的样品的气隙在24小时内吸水率显着降低。发现 $$\hbox {CO}_{2}$$ CO 2 的高溶解度会随着水变成 $$\hbox {CO}_{2}$$ 而改变水的 X 射线质量衰减值CO 2 饱和。这些测试表明空隙空间中存在的气体类型显着影响波特兰水泥砂浆的二次吸附。这项研究的结果对预测用于地下固碳结构的水泥基材料的质量传输具有重要意义。这些测试表明空隙空间中存在的气体类型显着影响波特兰水泥砂浆的二次吸附。这项研究的结果对预测用于地下固碳结构的水泥基材料的质量传输具有重要意义。这些测试表明空隙空间中存在的气体类型显着影响波特兰水泥砂浆的二次吸附。这项研究的结果对预测用于地下固碳结构的水泥基材料的质量传输具有重要意义。