Slag is increasingly used for replacing a part of clinker.The addition of slag modifies the hydration process and so the physico-chemical properties (such as porosity, transport properties...) of cementitious materials.Indeed the evolutions of the physico-chemical properties are determined by the hydration kinetics of the anhydrous phases and the composition of the hydrated phases.The hydration process of slag blended cement is still under investigation due to the complex interactions between clinker and slag.The aim of this work is to link the evolution of slag blended cement properties (such as bound water, chemical shrinkage, mineralogy, porosity) to the hydration state.The latter was defined by the degree of hydration of the cementitious materials.