Using pore parameters to estimate permeability or conductivity of concrete

This study investigated the relationships between pore parameters and transport properties. Fourteen concrete mixtures were investigated for water permeability, conductivity for the pore solutions and bulk concrete, as well as total porosity and critical pore diameter. The measured parameters allowed comparison to the Katz-Thompson relationship as well as Archie's Law. Using a low-pressure device, measured permeability from 1 to 28 days was found to be approximately an order of magnitude higher than that calculated using the Katz-Thompson relationship for the six mixtures examined with this technique. Better agreement between measured and predicted permeability was found using apparatus capable of higher applied pressure. Comparing the data to other published data, the Katz-Thompson relationship seems to be a useful technique for the approximation of water permeability. The exponential relationship between porosity and normalized conductivity (the inverse of the Formation factor) forming the basis of Archie's Law was found to hold within each specific concrete mixture. However, no overall trend was apparent. The constants of the Archie's Law vary over a wide range.