The relationship between permeability coefficients for concrete obtained using liquid and gas

Abstract

Synopsis Tests have been carried out on four concretes to measure their permeability coeficient using both water and nitrogen. In every case the gas permeability was significantly higher than the water permeability, the dlference increasing as the permeability reduced. The theory of gas slippage, first reported in 1875 and subsequently studied in relation to oil sands in 1941, has been identified as a major reason for the recorded differences betweeri the water and gas permeability coefficients for concrete. An equation relating water and gas permeability has been derived for mature, sealed-cured concrete, which takes into account the mean absolute pressure used for gas permeability measurement. This can be used to adjust gas permeability results to give a reasonable approximation of the intrinsic permeability of the concrete.