Leakage of gas through concrete cracks

This paper aims at formulating the gas leakage rate through cracks in concrete walls. Leakage tests were carried out using eighteen specimens. Five specimens with a reinforcing bar and thirteen without were tested. The kind of fine aggregate and the size of the coarse aggregate were varied. Crushed gravel was used as the coarse aggregate. In order to examine the dispersion of the experimental results, four or five specimens with the same dimensions and of the same type of concrete were tested. The experimental results were formulated accurately by an isothermal compressible-flow equation for each identified crack. The two-dimensional Poiseuille-flow equation was also applied successfully for a small leakage rate. The dispersion of the test data from the same specimens, the influence of the aggregate and the effect of the reinforcing bar are discussed. It is concluded that the influence of the aggregate can be neglected and that the reinforcing bar reduces the leakage rate. Finally, the gas leakage rate through a concrete crack is presented. (orig.)