## 2 Experimental Results
The denotations used in the table: CEM I—Portland cement; CEM II—multi-component Portland cement; CEM III—blast furnace cement; CEM IV—pozzolanic cement; for CEM II/B, CEM III/A, and CEM IV/B, maximum contents of non-clinker principal components are in mass percentages: 35, 65, and 55, respectively; R—high early strength cement; L—low early strength cement; N—normal early strength cement; NA—low-alkali cement; HSR—sulphate-resistant cement, SR3—sulphate-resistant cement with a tricalcium silicate content of not more than 3 mass percentages; LH—cement with low heat of hydration (data also partially published in [21]). \begin{table}
\begin{tabular}{c c c c c c} \hline \hline
**Concrete** & **Type of Cement** & **Cement** & **Sand** & **Gravel** & **Water to Cement** \\  & & **(kg/m\({}^{3}\))** & **(kg/m\({}^{3}\))** & **(kg/m\({}^{3}\))** & **Ratio** \\ \hline C1 & CEM I 42.5 R & & & & \\ C2 & CEM II/B-V 32.5 R & & & & \\ C3 & CEM III/A 42.5 & 324 & 738 & 1193 & 0.5 \\  & N-LH/HSR/NA & & & & \\ C4 & CEM I 42.5 N-SR3/NA & & & & \\ C5 & CEM IV/B (V) 32.5 & & & & \\ R-LH/NA & & & & & \\ \hline \hline \end{tabular}
\end{table} 
Table 2: The composition of concrete mixtures (data also partially published in [21]). of maturation under water, was placed in an oven at 60 \({}^{\circ}\)C, and its mass was measured daily. When the mass of the sample differed on two consecutive days less than 0.1%, it was regarded as being in a dry state. Then the sample was saturated with water again by immersion to the moment its mass on two consecutive days was the same. Next, the floating weight of the sample was measured with the use of hydrostatic laboratory balance. Finally, the open porosity of the samples, \(\varepsilon\) (m\({}^{3}\)/m\({}^{3}\)), was calculated according to the following equation:  
\[\varepsilon=\frac{m_{\text{S}}-m_{\text{D}}}{m_{\text{S}}-m_{\text{FS}}} \tag{1}\]  
where: \(m_{\text{S}}\)--mass of the sample (kg) after the water re-saturation, \(m_{\text{D}}\)--mass of the sample (kg) in the dry state, \(m_{\text{FS}}\)--floating weight of the sample (kg) after the water re-saturation. The average compressive strength, apparent density, and porosity of the tested concretes are presented in Table 3.  
The chloride ion diffusion tests were also carried out at the Laboratory of Civil Engineering of the Silesian University of Technology. They were performed for every type of concrete on three cylinder-shaped samples with a diameter of 100 mm and a height of 50 mm. The concrete samples were poured into the cutouts of plastic pipes that provided them with the aforementioned dimensions. The visible surfaces of samples were untreated after setting so as to obtain a typical surface of concrete exposed to chlorides under practical conditions from the top of a concrete member and to be able to assess the chloride diffusion \"skin effect\" in this case. After they had matured for 28 days under water, they were stored at the room conditions. Prior the diffusion tests, they were re-saturated again with distilled water by immersion until they reached constant mass. The initial preparation of the samples was carried out so that the diffusion tests could begin 90 days after the concrete had set. In order to force unidirectional diffusion transport of chloride ions in the samples, 3% solution of NaCl was placed in the containers attached with waterproof glue to the top surface of the plastic pipes confining the concrete samples, and the bottom surfaces of samples were placed in distilled water. The photo of the diffusion test stand and its diagram are presented in Figure 1. The test was carried out at the temperature about 20 \({}^{\circ}\)C. It was carried out during 180 days from the beginning of the chloride diffusion process. As a result, curves describing the mean total (i.e., free and bound) chloride ions concentration in 2 mm sampling sections to a 2 cm depth of concrete samples were obtained (Table 4).