# Resistance of Concrete with Crystalline Hydrophilic Additives to Freeze-Thaw Cycles
## 4 Discussion  
From Figure 7a,b, it is evident that in mixture M2 containing an air-entraining agent, there is a significant reduction in mass loss due to scaling after 56 freeze/thaw cycles compared to mixture M1, while the crystalline hydrophilic additive in mixtures M3 and M4 acted contrary to expectations, increasing the mass loss due to scaling, i.e., increasing the mass loss due to exposure of samples to deionized water. The mixture with a lower proportion of crystalline hydrophilic additive (M3) records a lower mass of scaled material compared to the mixture with a higher proportion of crystalline hydrophilic additive (M4). This is contrary to the observations in [50] where the mass loss ratio due to freeze/thaw cycles is significantly lower in mixtures with the addition of CA compared to the reference mixture. The mixture with the least amounts of scaled material, and therefore the best resistance to freeze/thaw cycles according to this method, and under conditions of exposure to deionized water, is mixture M2, followed by mixtures M1, M3, and M4 in sequence. From Figure 7c,d, it is noticeable that in mixture M2 containing an air-entraining agent, there is a drastic reduction in mass loss due to scaling after 56 freeze/thaw cycles compared to mixture M1, while the crystalline hydrophilic additive in mixtures M3 and M4 acted  
Figure 10: Relative dynamic modulus of elasticity: (**a**) measured on concrete cubes; (**b**) measured on concrete prisms. Figure 9: Spacing factor. contrary to expectations, increasing the mass loss due to scaling, i.e., increasing the mass loss due to exposure of samples to a 3% sodium chloride solution. The mixture with a lower proportion of crystalline hydrophilic additive (M3) records significantly lower scaled material mass compared to the mixture with a higher proportion of crystalline hydrophilic additive (M4). The lowest scaled material mass, and thus the best resistance to freeze/thaw cycles according to this method and under conditions of exposure to a 3% sodium chloride solution, is recorded by mixture M2, followed by mixtures M1, M3, and M4 in sequence. When it comes to surface damage due to freeze/thaw cycles, the air-entraining agent is evidently the most effective additive for preventing damage, almost equally effective regardless of whether freezing/thawing occurs with or without salt presence, while the negative effect of the crystalline hydrophilic additive is significantly more pronounced during freezing/thawing in the presence of salt. Such research findings on the impact of the crystalline hydrophilic additive are even worse than the results presented in [51]. Specifically, [PERSON] et al. [51] concluded in part of their study addressing the scaling of concrete exposed to a 3% sodium chloride solution that the crystalline hydrophilic additive (in amount of 0.8% per cement weight) does not affect this type of damage caused by freeze-thaw cycles. From Figure 8a, it can be concluded that the drop in the dynamic modulus of elasticity as a measure of internal damage during exposure to freezing/thawing in the presence of deionized water is most pronounced in mixture M1. Mixture M4 has a smaller drop in the dynamic modulus of elasticity than mixture M1, while mixtures M3 and M2 recorded an increase in the dynamic modulus of elasticity. The increase in the dynamic modulus of elasticity during the freeze/thaw cycles is consistent with the increase in mass during freezing/thawing reported in [52]. The authors in [52] explain that freeze/thaw cycles promote the mobility of pore solution through osmosis. As a result, portlandite dissolved in pore water migrates, facilitating the reactions involved in the self-healing procedure. Additional ice formation in pores likely contributed to the reported mass increase, thus supporting the evolution of the self-healing process.