The electrical resistivity of concrete is increasingly measured as an indicator of its fluid transport properties, for use in quality control or for service life prediction. While electrical tests have the advantage of being easy and rapid to perform, there are several key factors that can influence the results including: 1) specimen geometry, 2) specimen temperature and 3) sample storage and conditioning. This paper addresses these issues and compares the measurements from several commercially available testing devices. First, the role of sample geometry is explained using three common geometries: surface, uniaxial and embedded electrodes. If the geometry is properly accounted for, measurements from different test geometries result in electrical resistivity values that are similar. Second, the role of sample temperature is discussed for both pore solution and bulk tests on cylinders. Third, the paper examines the importance of sample curing, storage and conditioning. Sample storage and conditioning influences both the degree of hydration and the degree of saturation. The role of sample volume to solution volume is discussed as this may influence alkali leaching. This paper is intended to identify factors that influence the results of the rapid electrical test measurements and to help identify areas of future research that are needed so that robust specifications and standard test methods can be developed. This will enable electrical tests to be used to provide rapid, accurate, repeatable measurements of concretes electrical properties.
Citation: Journal of the Transportation Research Board
Pub Type: Journals
Concrete, electrical resistivity, geometry, saturation, temperature, test method.