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Estimating the Electrical Conductivity of Cement Paste Pore Solutions From OH-,K+ and Na+ concentrations.


pdf icon Estimating the Electrical Conductivity of Cement Paste Pore Solutions From OH-,K+ and Na+ concentrations. (1316 K)
Snyder, K. A.; Feng, X.; Keen, B. D.; Mason, T. O.

Cement and Concrete Research, Vol. 33, No. 6, 793-798, June 2003.

Keywords:

cements; electrical conductivity; pore solution; transport properties; alkalis

Abstract:

A proposed method for estimating the electrical conductivity of cement paste pore solution at 25 deg C is based on the concentrations of OH-, K+ and Na+. The approach uses an equation that is a function of the solution ionic strength, and requires a single coefficient for each ionic species. To test the method, the conductivity of solutions containing mixtures of potassium hydroxide and sodium hydroxide with molar ratios of 4:1, 2:1 and 1:1, and having ionic strengths varying from 0.15 to 2.00 mol/l were measured in the laboratory and compared to predicted values. The proposed equation predicts the conductivity of the solutions to within 8% over the concentration range investigated. By comparison, the dilute electrolyte assumption that conductivity is linearly proportional to concentration is in error by 36% at 1 mol/l and in error by 55% at 2 mol/l. The significance and utility of the proposed equation is discussed in the context of predicting ionic transport in cement-based systems.