and consequentially underestimates the Ca/Si ratio of the phase formed (Figure ). That is because the experimental system is supersaturated before the precipitation, a state that thermodynamic modeling cannot capture. Of note, no sodium incorporation in the solid phase is observed within the duration of the experiment (Figure ), as the sodium concentration evolution perfectly matches the expected trend in the absence of precipitation or sorption. In conclusion, the small discrepancies between the experimental and modeled data highlight that a kinetically governed system cannot be easily and accurately thermodynamically modeled. In such a case, a compromise must be made between accurate modeling of (i) the kinetic of C-S-H nucleation and (ii) the C-S-H phase composition. The impact of citric acid, tartaric acid, and succinic acid on the nucleation of C-S-H is shown in Figure . As the shift of the first maximum towards a higher supersaturation with respect to C-S-H, and therefore a higher concentration of calcium in solution, is connected with the inhibition of the nucleation, it can be seen that tartaric acid (Fig 9 ) dotted line) shows the highest concentration-dependent inhibiting effect of the investigated molecules (Table ). In contrast, citric acid shows the highest concentration-dependent delaying effect on the nucleation of C-S-H to larger amounts of calcium with a much lower effect on the supersaturation (Table ). Succinic acid shows almost no observable shift within the measurement's inaccuracies (Fig 9-C and Table ). Another point worth noting is that, while the slope of the calcium curve prior to C-S-H nucleation is typically related to PNCs formation, it is observed here to be directly correlated to the expected amount of free calcium (i.e., calcium that is not complexed by citrate, tartrate, or succinate) as calculated with PHREEQC (Figure ). Consequently, as in the CH nucleation system, the additive does not seem to influence the stability of the C-S-H PNCs. In addition, the amount of calcium complexed by citric, tartaric, and succinic acid modeled with PHREEQC is equivalent within error to the excess calcium missing in the acid systems (Table ). The excess missing calcium ([Ca 2+ ] excess missing ) is defined as the difference between the missing calcium concentration of the additive-containing and reference experiment (equation 7). Therefore, it captures the removal of calcium ions from the solution caused by the presence of the additive. The equivalence of the calculated calcium complexation and the missing excess calcium concentration suggests that the additive's effect on C-S-H nucleation can mostly be attributed to the formation of calcium complexes and that there is little to no interaction between the additives and the very small amount of PNCs present in the system.