Measuring gas permeability
Gas permeability tests measure the flow of a gas into the concrete under the action of a pressure gradient. It overcomes some of the disadvantages of measuring water absorption that include:
- In concretes that are not fully hydrated, water alters the permeability to be measured
- A measurement cannot be repeated in the same location
- The viscosity of water is approximately 100 times greater than that of air, with volume flows
being far smaller
- With water, only overpressure can be measured
Tests include the Schonlin air test, Surface Airflow Test (SAT), Vacuum test, Torrent test, Hong-Parrott, Figg air test, and Autoclam.