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 whi