# Resistance of Concrete with Crystalline Hydrophilic Additives to Freeze-Thaw Cycles
## 2 Experimental Part
### Properties of Fresh and Hardened Concrete  
The consistency of the concrete was determined according to EN 12350-2 [41], the density of fresh concrete according to EN 12350-6 [42], and the air content according to the standard EN 12350-7, with the pressure gauge method [43]. The obtained results are shown in Table 3.  
According to Table 3, all mixtures belong to consistency class S3 (10-15 cm) according to EN 206 [44]. The addition of crystalline hydrophilic admixture had no impact on workability, which is in accordance with [45]. In terms of density, all mixtures can be considered normal weight concrete. As expected, mixture M2 has the highest air content in fresh concrete, for which the air-entraining agent in the mixture is directly responsible. Crystalline hydrophilic admixture did not affect the air content in fresh concrete for both tested doses, but [PERSON] et al. [46] tested mixtures with different concentrations of Penetron crystalline admixture (1% and 2.5% of the cement mass) and found that the mixture with 1% crystalline admixture had the highest air content of all tested concretes. From each mixture, 14 cubes of dimensions 15 cm \(\times\) 15 cm \(\times\) 15 cm and 3 prisms of dimensions 10 cm \(\times\) 10 cm \(\times\) 40 cm were prepared. After casting, the concrete specimens were stored under cover for 24 h under laboratory conditions until demolding to prevent water evaporation. After demolding, the specimens were in the mist room at 20 \(\pm\) 2 \({}^{\circ}\)C and RH \(\geq\) 95% until the age of testing. On 3 out of 14 cubes, the compressive strength of 28-day-old specimens is determined according to EN 12390-3 [47], and the results and their corresponding standard deviations are shown in Figure 2. \begin{table}
\begin{tabular}{c c c c c} \hline \hline
**Mixture** & **M1** & **M2** & **M3** & **M4** \\ \hline Consistency–slump (cm) & 12 & 14 & 11 & 11 \\ Density (kg/m\({}^{3}\)) & 2504 & 2439 & 2520 & 2489 \\ Air content (\%) & 1.5 & 5 & 1.5 & 1.6 \\ \hline \hline \end{tabular}
\end{table} 
Table 3: Properties of concrete mixtures in their fresh state. Figure 2: Compressive strength of concrete at the age of 28 days. From Figure 2, it is evident that CA present in concrete mixtures M3 and M4 did not significantly affect the compressive strength of the concrete, which is in line with the conclusions presented in [32; 48; 49]. The presence of air entraining agent in mixture M2 significantly reduced the compressive strength of the concrete which is consistent with the well-known fact that air entraining agent negatively affects concrete strength [5]. Furthermore, from each of the eight cubes, one slab of dimensions 15 cm \(\times\) 15 cm \(\times\) 5 cm (total of eight slabs) was sawn out to monitor scaling due to freeze/thaw cycles according to CEN/TS 12390-9 [34], and the relative dynamic modulus of elasticity due to freeze/thaw cycles according to Clause 8 of CEN/TR 15177 standard [35] using an ultrasonic pulse transmission time device, and one slab of dimensions 10 cm \(\times\) 15 cm \(\times\) 4 cm to measure the spacing factor according to EN 480-11 standard [36]. Half of the slabs intended for scaling and relative dynamic modulus of elasticity monitoring were subjected to freeze/thaw attack in the presence of a 3 mm deep layer of deionized water, and the other half were subjected to freeze/thaw attack in the presence of a 3% sodium chloride solution. Figure 3 shows all the slab samples in the freezing and thawing chamber (producer: Schleibinger, Buchbach, Germany), and Figure 4 shows the monitoring of the amount of scaled material and dynamic modulus of elasticity during exposure to freeze/thaw cycles. Figure 4: Measurements during exposure of panels to freeze/thaw cycles: (**a**) scaling; (**b**) monitoring of dynamic modulus of elasticity. Figure 3: Slab samples in the freezing/thawing chamber. Figure 5 shows the slab prepared for measuring the spacing factor and the measuring device for the measuring.