Modelling of chloride binding related to hydration products in slag-blended cements

•The composition of the slag is crucial to the chloride binding capacity of a paste.•The interaction between the slag and OPC components is taken into account.•The C–S–A–H phase binds approximately two thirds of the total bound chlorides.•The remaining third is attributed to AFm phases.•The results of the model are highly improved from a previous model from literature.

An improved hydration model of slag-blended cements, taking into account new insights, is used to estimate and quantify the hydration products of slag-blended cements. Individual chloride binding isotherms are used to correlate these amounts of hydration products with the amount of bound chlorides. A number of parameters are directly or indirectly taken into account when estimating the chloride binding ability of a slag-blended cement paste: cement composition, slag content, water/binder ratio, curing age, and free chloride concentration. The model allows the study of the breakdown of bound chlorides by hydration products and their source – either the OPC or the slag.