C3S is a nesosilicate phase which reacts with water to give C-S-H and CH.The precipitation of these hydration products has long hampered accurate investigations of the C3S dissolution alone and most researchers attempted to interpret data from the C3S hydration instead.This can lead to inaccurate conclusions due to the coupled nature of the dissolution and precipitation processes which comprise the hydration reaction.The continuous monitoring of ions released during dissolution of C3S in very dilute solutions, i.e.in conditions devoid of hydrates, (Nicoleau et al.2013) has recently allowed new conclusions on the dissolution phenomenon.