Modern concrete relies on chemical admixtures to adjust performance objectives for properties such as slump flow and setting time. Set retarders, for example, are an admixture class specifically designed to delay the setting of concrete. Commonly employed set retarders are organic phosphonates, sugars (such as sucrose), and hydroxy-carboxylic acids like citric, tartaric or gluconic acid . Despite their widespread use, the detailed mechanism by which set retarders influence the hydration kinetics of cement remains unresolved in all details . Cement hydration is a coupled process of clinker phase dissolution on one side and nucleation and crystal growth of hydrate phases such as calcium silicate hydrate (C-S-H), portlandite (CH), and ettringite on the other. Various interaction mechanisms between set retarders and cement have been proposed , including the inhibition of clinker phases dissolution through surface adsorption and the suppression of hydrate phases nucleation ]. Yet, because dissolution and nucleation always coincide during cement hydration, mechanistic studies must decouple the set retarder's interaction with the clinker phases from its interaction with the hydrated phases. The challenge is understanding the intricate relationship between the chemical structure of the admixtures and their effects on cementitious materials. This understanding is of paramount importance for the rational optimization of concrete mix-designs .