An inter lab comparison of gas transport testing procedures: Oxygen permeability and oxygen diffusivity

The transport properties of concrete are useful measurements as they can provide a potential indication of durability and can be used in the prediction of the service life of concrete elements. Gas permeability and diffusivity test methods are attractive due to the ease of testing, their non-destructive nature and their potential to correlate to in-field carbonation of reinforced concrete structures. Unfortunately, limited information is available on the variability and inter-laboratory variability of the test methods that assess gas transport. This paper presents results of a recent investigation on the repeatability/variability of an oxygen permeameter and of an oxygen diffusivity instrument in two testing laboratories. Generally, a lower variability was seen for the oxygen diffusivity measurements compared to oxygen permeability. Moreover, the results confirm the importance of several parameters such as the flow and pressure used in the test and the samples conditioning method (degree of saturation and percentage of mass variation). In order to obtain repeatable results from gas transport testing between labs, the same boundary conditions (pressure and flow) and the same sample conditioning procedures should be used.