Estimating the permeability of cement pastes and mortars using image analysis and effective medium theory
Estimating the permeability of cement pastes and mortars using image analysis and effective medium theory
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DOI：
10.1016/j.cemconres.2011.11.018
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发表时间：
2012-02
影响因子：
11.4
通讯作者：
H. Wong;R. Zimmerman;N. Buenfeld
中科院分区：
文献类型：
--
作者：
H. Wong;R. Zimmerman;N. Buenfeld
提出了一种利用SEM图像中的孔隙面积和周长来估算水泥基材料渗透率的方法。孔结构被理想化为具有任意尺寸的孔的立方晶格。每个孔隙的水力传导率使用水力半径近似计算，并施加一个体视学因子来解释图像平面的随机取向。应用“收缩因子”来解释孔半径沿着孔轴的变化。然后利用柯克帕特里克的有效介质方程求出有效孔隙电导率，并由此导出宏观渗透率。对46种不同水灰比、水泥、龄期和含砂量的浆体和砂浆进行了试验。渗透率范围为3×10− 18 m2至5.8×10− 16 m2。据发现，76%的渗透率预测在±2倍内，98%在±5倍内从测量值。
A method to estimate permeability of cement-based materials using pore areas and perimeters from SEM images is presented. The pore structure is idealised as a cubic lattice having pores of arbitrary size. The hydraulic conductance of each pore is calculated using the hydraulic radius approximation, and a stereological factor is applied to account for the random orientation of the image plane. A ‘constriction factor’ is applied to account for variations in pore radius along the pore axis. Kirkpatrick's effective medium equation is then used to obtain an effective pore conductance, from which the macroscopic permeability is derived. The method was tested on forty-six pastes and mortars with different w/c ratio, cement, age and sand content. The permeabilities ranged from 3×10−18m2to 5.8×10−16m2. It was found that 76% of the permeabilities were predicted to within a factor of ±2, and 98% within a factor of ±5 from measured values.