Synopsis
This paper describes a method of measuring the relative permeability of concrete specimens to gases by passing nitrogen through them. The specimen is a 100 mm cube sealed on two opposite faces and with a central 6 mm hole running between them. Nitrogen from a sealed reservoir at a standard initial pressure is passed into the hole. The reservoir pressure is automatically recorded at suitable intervals, and the rate at which it falls is a measure of the permeability. The test has been shown to be quick and simple to carry out, and to have good repeatability provided specimens are allowed to dry suflciently before testing. The apparatus has also been used to pass CO2 through a specimen, causing its permeability to fall as a result of carbonation. Suggestions for future work to make use of the method are given.
