## 4 Results of the Calculations  
Table 5 summarizes the values of material parameters for C1-C5 concretes obtained thanks to the minimization of the auxiliary objective function \(G\) (Equation (29)), i.e., the  
effective chloride diffusion coefficients (\(D_{\text{eff}}\)) (as in Equation (6)), slopes of the linear binding isotherm (\(a\)) (as in Equation (11)), and corresponding apparent chloride diffusion coefficients (\(D_{\text{app}}\)) (Equation (13)). The minimum values of the objective function (\(G_{\text{min}}\)) along with the corresponding global errors (\(e_{\text{g}}\)) of adjusting the experimental data to the results from the diffusion model (Equation (37)) are also given in Table 5. In this approach, a linear approximation of the chloride binding isotherm is used (Equation (11)). In the case of concrete C1, the authors determined \(a=0\), which means that using the proposed method, no significant and detectable chloride binding by the cement matrix was found during the 6-month diffusion period. For this reason, no further calculations were carried out for this concrete using the minimization of the objective function \(F\) defined by Equation (25). Concrete C1 is also characterized by the lowest \(D_{\text{eff}}\) coefficient in relation to concretes C2-C5. This fact means that thanks to Portland cement CEM I 42.5 R of high early strength, a layer was formed at the surface of the C1 concrete samples relatively effectively inhibiting the diffusion of chlorides, which is not related to the effect of their binding in the cement matrix. This is also consistent with the data in Table 1, where it can be read that the Portland cement used in the concrete C1 is characterized by a lower content of aluminum oxide, the compounds of which are consumed in the chloride binding process (see Introduction). In the case of other concretes, where ash Portland cement CEM II/B-V 32.5 R (concrete C2), blast furnace cement CEM III/A 42.5 N-LH/HSR/NA (concrete C3), low-alkali Portland cement of normal early strength CEM I 42.5 N-SR3/NA (concrete C4), and pozzolanic cement CEM IV/B(V) 32.5 R-LH/NA (concrete C5) were used, from one to two orders of magnitude greater effective diffusion coefficients of free chlorides were found. It indicates the formation of a cement matrix in the near-surface zones of their samples for which the diffusion of free chlorides is much easier compared to concrete C1. In each of these cases, non-zero values of the slope \(a\) of the linear binding isotherm were also found, which at the same time are not proportional to the aluminum oxide contents in the individual cements (Table 1). However, these contents are from about 1.5 to 3 higher in the case of cements used in concretes C2, C3, and C5, if compared to the Portland cement used in C1. It is also worth noting that due to the high slopes \(a\) for concretes C3 and C5, their apparent chloride diffusion coefficients are already comparable with the effective diffusion coefficient of concrete C1. On the other hand, in this case, the chloride diffusion process is already associated with intensive chloride storage in the near-surface concrete layers. Table 6 summarizes the values of material parameters for concretes C2-C5 obtained thanks to the minimization of the objective function \(F\) (Equation (25)), i.e., the effective diffusion coefficients (\(D_{\text{eff}}\)) (as in Equation (6)) and the vertices coordinates of the binding isotherm broken line: \(C_{\text{f}(1)}\), \(C_{\text{f}(2)}\), \(C_{\text{b}}\left(C_{\text{f}(1)}\right)\), \(C_{\text{b}}\left(C_{\text{f}(2)}\right)\), and \(C_{\text{b}}\left(C_{\text{f}(3)}\right)=C_{\text{b}}(C_{\text{fe}})\) (according to Equation (21) for \(n=3\)). The minimum values of the objective function (\(F_{\text{min}}\)) along with the corresponding global errors (\(e_{\text{g}}\)) of adjusting the experimental data to the results