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CONCRETE TECHNOLOGY26 CPI %u2013 Concrete Plant International %u2013 6 | 2025 www.cpi-worldwide.comThe South African Oxygen Permeability Index test (OPI) and Swiss Torrent air permeability test (TPT) are well-established methods used for gas permeability evaluations of concrete infrastructure. The methods relate to the durability of concrete and are used for concrete mix design, quality control and conformity assessment. The recently published fib Model Code 2020 recognizes both methods for service life design and quality control of concrete structures. The main difference between the methods is that the OPI test is typically done on core samples removed from the actual structure or precast element, or a test panel representing the structure / element, and the TPT test is performed directly on the structure. As such, the TPT test is more practical in terms of testing procedures, while the OPI test is able to measure permeability properties independent of environmental influences on site. Comprehensive laboratory experiments have shown the compatibility of the two methods as a combined approach for enhancing the durability assessment of the concrete cover. The synergy between these two methods has so far only been reported for samples manufactured and tested under laboratory conditions. This paper explores the practicality of an integrated method using the OPI and TPT methods together, based on measuring permeability on precast concrete elements exposed on site. Concrete members were manufactured by a local precast company in Cape Town and exposed to ambient conditions. Gas permeability tests were carried out at 28 and 56 days to observe the responsiveness of the OPI and TPT to variables such as water/binder ratio (w/b), Complementarity of the Oxygen Permeability Index test and Torrent air Permeability testResearch on precast concrete elementsn Sean Alfred, Remedy Asset Protection, Australia / UCT, South AfricaHans Beushausen, Mark Alexander, Department of Civil Engineering, University of Cape Town (UCT), South AfricaFig. 1: In the Oxygen Permeability Index (OPI) test, concrete discs are installed in a pressure chamber and exposed to a pressure difference of 10 bar. The pressure decay over time is measured and used to calculate the concrete%u2019s permeability.