Estimating the electrical conductivity of cement paste pore solutions from OR-, K+ and Na+ concentrations by K.A. Snyderand X. Feng Building and Fire Research Laboratory National Institute of Standardsand Technology Gaithersburg, MD 20899 USA B.D. Keen Building Research Association of New Zealand (BRANZ) Porirua City, NEW ZEALAND and T .0. Mason Department of Materials Science and Engineering Northwestern University Evanston,IL USA Reprinted from Cementand ConcreteResearch, Vol.-33,No.6, 793-798, June 2003. NOTE: This paper is a contribution of the National Institute of Standards and Technology and is not subject to copyright. National Institute of Standards and Technology Technology Administration, U.S. Deportment of Commerce