Reference: K.A. Snyder, X. Feng, B.D. Keen and T.O. Mason, Cement and Concrete Research, 33 (6), 793-798 (2003).
(PDF Version of Original Paper)

Reply to the discussion by C. Shi of the paper "Estimating the electrical conductivity of cement paste pore solution from OH, K⁺, and NA⁺ concentrations", Cement and Concrete Research, 35 (2), 421-422 (2005). (PDF Version)

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Estimating the electrical conductivity of cement paste pore solutions from OH$^-$, K$^+$, and Na$^+$ concentrations

K.A. Snyder$^{*,a}$ X. Feng$^{a,b}$ B.D. Keen$^{c}$ T.O. Mason$^b$

$^a$Materials and Construction Research Division, BFRL, NIST
$^b$Department of Materials Science, Northwestern University
$^c$Building Research Association of New Zealand (BRANZ)

Abstract

A proposed method for estimating the electrical conductivity of cement paste pore solution at 25 ºC 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.

Keywords: B-Pore Solution; C-Electrical Properties; C-Transport Properties; D-Alkalis; E-Modeling.

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