Conclusion

A simple model for estimating the pore solution conductivity can be constructed using only single parameters for each ionic species. The equation proposed here is accurate to within 8 % for K$^+$:Na$^+$ ratios ranging from 4:1 to 1:1, and for ionic strengths as high as 2 mol/L. The coefficient of variation in the predicted conductivities is relatively constant over the entire range, suggesting that minor extrapolations should not lead to excessive errors. In addition, the chemical and physical effects during a migration test can be separated using the equation, allowing one to extract a true microstructural transport coefficient.