Calcium sulfate sources like gypsum or anhydrite are added during clinker grinding to act as setretarding agents . This addition not only slows down the initial C 3 A reaction, thereby preventing a flash set but also redirects the hydration pathway of C 3 A towards ettringite formation . The retardation of the early C 3 A hydration in the presence of calcium sulfate is attributed largely due to the adsorption of sulfate or calcium sulfate ion-pair complexes . The precipitation of ettringite significantly impacts the initial material characteristics, particularly the rheological properties of OPCbased pastes and mortars. Jakob et al. demonstrated the critical role of ettringite in the early-stage rheology of OPC pastes , and Gołaszewski showed that the yield value of mortars is influenced by the conversion of C 3 A to ettringite . Furthermore, the static yield stress of a model cement pastes containing C 3 A and C 3 S depends exponentially on the C 3 A phase content of the model cement .