This Technical Report describes a method for characterising the time-dependent leaching behaviour of components from hardened concrete, for use in the natural environment.This method specifies the procedures for determining the controlling mechanism(s) for leaching of components, their effective diffusion coefficients, in the case of diffusion-control and their cumulative release behaviour over any period of time.This characterisation method consists of two leaching test procedures. A potential or availability (pulverised specimen) test and a diffusion (tank) [monolithic specimen] test.The test procedures produce leachates, the analytical procedures for which are not included in this Technical Report.This Technical Report does not comprise a compliance method.NOTE 1The information obtained from the method is quantitative. In the absence, however, of similar information for other construction materials or compliance criteria for acceptable/unacceptable performance of hardened concrete, the data obtained with neither permit a relative nor an absolute assessment of the environmental quality/compatibility of the concrete, unless, by default, in the case where leached concentrations of environmentally significant components are at, or below, their analytical limits of detection.NOTE 2In principle, this method could be used to characterise the leaching behaviour of hardened concrete, irrespective of the exposure conditions (e.g. natural environment, contact with drinking water etc.) which the concrete would experience in service. It should be noted, however, that a European standard test method for the extraction/migration of mineral micropollutants is also likely to be developed by CEN/TC 164 - Water supply.NOTE 3Analytical procedures for determining concentrations of components in leachates and which may be suitable for the purposes of this Technical Report are being developed by CEN/TC 292 - (...)