Complementarity of in situ and laboratory-based concrete permeability measurements

The South African Durability Index approach is a performance-based method for specifying and assessing durability properties of reinforced concrete structures. This approach includes a laboratory-based oxygen permeability test, the results of which have been related to the prediction of carbonation rates in in situ concrete structures. The Swiss approach (after SIA 262/1) is a performance-based method that makes use of an in situ air-permeability test method (the Torrent method) for durability specifications and assessment. Based on comprehensive experimental investigations, a comparison of the two approaches is presented. Both permeability test methods were shown to be sensitive to common intrinsic and extrinsic concrete properties, including w/c ratio, cement type and curing environment. Permeability-related performance ratings developed in South Africa and Switzerland typically placed the tested concrete specimens in the same acceptance categories. This highlighted the complementarity between the two approaches and was interpreted as a confirmation of their validity. An integrated approach is suggested based on incorporating in situ and laboratory-based permeability test methods. The aim of this approach is to minimize the influence of moisture on in situ permeability measurements and at the same time limit the amount of invasive core sampling for laboratory testing.

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