This part of ISO 1920 specifies a method for determining the unidirectional non-steady-state chloride penetration parameters of conditioned specimens of hardened concrete. The test method enables the determination of the chloride penetration at a specified age, e.g. for ranking of concrete quality by comparative testing. NOTE 1 The aim of the test is to assess the potential resistance to chloride ingress for a concrete mix. NOTE 2 Since resistance to chloride penetration depends on ageing, due to the effects of continual hydration of the concrete, the ranking may also change with age.