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CONCRETE TECHNOLOGYwww.cpi-worldwide.com CPI %u2013 Concrete Plant International %u2013 6 | 2025YOUR WET CAST EXPERTSAUTOMACAD.COM 1 450.632.6323REDUCE COSTS AND INCREASEPRODUCTION PERFORMANCEWITH AUTOMATIONn Sean Alfred is a quality field engineer at Remedy Asset Protection in Australia specializing in concrete non-destructive testing. He holds an MSc. degree from the University of Cape Town and is a professional member of Engineers Australia. His research interests are in concrete durability and non-destructive testing of concrete structures. sean.alfred@remedyap.com.aun Hans Beushausen is Professor for structural engineering and materials in the Department of Civil Engineering at the University of Cape Town and co-Director of the Concrete Materials & Structural Integrity Research Unit. His research fields include concrete durability (material aspects, durability testing, design and specification), performance assessment and repair of concrete structures, and sustainable concrete technology (low carbon cementitious binders, recycled aggregates). He is an editor of the magazine Concrete Plant International, a member of fib and ACI, and Vice President of RILEM.hans.beushausen@uct.ac.zan Mark Alexander is Emeritus Professor of Civil Engineering, and a Senior Research Scholar in the University of Cape Town. He has a PhD from the University of the Witwatersrand, Johannesburg, and is a Fellow of the University of Cape Town, of RILEM, of the South African Institution of Civil Engineering, the South African Academy of Engineering, and the Indian Concrete Institute. He is a registered Professional Engineer in South Africa. His research interests are in concrete durability, service life prediction, concrete sustainability, and repair and rehabilitation of deteriorated concrete structures. mark.alexander@uct.ac.zabinder type, and age. The results reported here indicate that the two methods correlate reasonably well with existing data in dry site conditions, i.e. in the Cape Town summer months. However, further investigations are warranted to understand the influence of moisture on the correlation between the TPT and OPI in moist conditions, which is especially relevant when testing concrete in the wet season, which in Cape Town would be winter.BackgroundThe increasing importance of concrete durability testing has been influenced by a greater understanding of deterioration mechanisms in concrete, advancements in testing methods and technologies, sustainability concerns, and research and development. This has led to the rise of durability indicator approaches utilizing specialized early-age tests to investigate the transport properties in the concrete [1-3]. In particular, gas permeability methods have been developed to provide insights into the concrete%u2019s resistance to gas penetration, and by proxy, the concrete%u2019s penetrability.In South Africa, the Oxygen permeability index (OPI) approach has become a well-established standard procedure for assessing the quality of the concrete cover layer [4-7]. The approach involves a laboratory-based test to determine the coefficient of permeability on cored and cut concrete samples (Fig. 1). The samples are prepared from cores extracted from the actual structure or representative panels manufactured using the same concrete batch and the same concreting conditions as the structure. The rate at which oxygen gas flows through the concrete sample under pressure quantifies the nature of the concrete%u2019s pore structure. A higher OPI value indicates better durability.