The calcium affinity of citrate, tartrate, and succinate is observed to be lower in the C-S-H nucleation system (Table ) compared to the portlandite nucleation system, where higher complexation by calcium is achieved regardless of the initial acid concentration (Table ). Here, the high initial sodium concentration in the titrated solution (≈ 172.8 mmol L -1 compared to ≈ 0 mmol L -1 for portlandite nucleation) possibly affects the complexation reaction: the strong competition between calcium and sodium affinity for citrate and tartrate may result in lower calcium complexation. This could explain why the acids show a much lower inhibiting effect on C-S-H nucleation. In addition, while the amount of PNC is minimal at pH 13, Picker et al. observed it to be more pronounced at a lower pH of 12. It can be postulated then that the acids could have a higher effect on C-S-H nucleation at lower pH where the interaction between the molecules and the PNC droplets could be promoted. In conclusion, citric and tartaric acid's capacity to partially complex calcium in this system can explain their inhibiting and retarding effect. Succinic acid, in contrast, does not influence the nucleation of C-S-H. As the succinic and tartaric acids consist of the same dicarboxylic motif but with additional hydroxyl groups for tartaric acid, those additional groups significantly influence the ability of the additive to inhibit the nucleation of C-S-H.