Methods of measuring the air and water permeability of concrete

Abstract

Synopsis This paper describes simple and portable apparatus for estimating the air and water permeability of concrete in situ. The methods used require a small hole 5·5 mm diameter and 30 mm deep to be drilled in the specimen. The hole is plugged with a catalysed liquid silicone rubber which sets to give a resilient seal to the small cavity in the concrete. A gas- and liquid-tight connection is obtained by inserting a hypodermic needle through the silicone ruhber. The results obtained using the apparatus on laboratory-prepared concrete show good correlation with both water/cement ratio and compressive strength; it is suggested that the proposed methods may prove useful for predicting the durability of concrete. The techniques are sensitive enough to detect differences in aggregate porosity. The moisture content of the concrete has a major injiuence on the readings; a miniaturized moisture meter is being developed so that corrections can be made for this effect.