## 2 Materials and Methods
### Methods  
For each fraction of aggregates, the crushing strength, the content of irregular grains and mineral dust, as well as the bulk and specific density from which the total porosity was calculated were determined. The crushing strength of aggregates was determined using the so-called aggregate crushing value (ACV) according to the PN-B-06714-40 standard [23], similarly as in the BS 812 standard [24]. An aggregate sample in a steel cylinder with an inside diameter of 150 mm was loaded with a force of 200 kN. The test is carried out on 4 \(\div\) 8 mm, 8 \(\div\) 16 mm and 16 \(\div\) 31.5 mm fractions. The aggregate crushing value is defined as the percentage of grains crushed into grains smaller than \(\frac{1}{4}\) of the lower sieve size of a given fraction. The ACV can be used to classify the aggregate and assess its suitability for the proper concrete. The content of irregular grains, i.e., flat and elongated grains (with the proportion of the smallest to the largest grain size exceeding 1:3) was determined according to the PN-B-06714-16 standard [25]. The mineral dusts content (percentage of the aggregate of grains smaller than 0.063 mm i.e., clays, clayey particles, etc.) was determined according to the PN-B-06714-13 standard [26]. The specific density was tested using the pycnometric method, after grinding the aggregate to dimensions smaller than 0.08 mm. The air contained between the grains of powdered material was removed by inserting a pycnometer in a vacuum chamber, and reducing the pressure to 2.33 kPa. The apparent density was tested on the basis of the EN 1097-6 standard [27]. The total porosity was calculated from the value of apparent density and specific density. The air content of the fresh concrete mix has been determined for each concrete, using the pressure method based on the EN 12350-7 standard [28]. The consistency was tested according to the EN 12350-2 [29] standard. To determine the compressive strength and splitting tensile strength after 28 days of curing, 36 cubic samples with the edge length of 150 (6 for each concrete) [30; 31]. Cylindrical specimens with a diameter of 150 mm and a height of 300 mm were used to determine the elastic modulus (18 specimens, 6 for each concrete) [32]. \begin{table}
\begin{tabular}{c c c c c c c} \hline \hline
**Components** & **Unit** & **GC2/8** & **ACV 1** & **GC2/16** & **ACV 1** & **GC2/31.5** & **ACV 1** \\ \hline  & & & (\%) & & (\%) & & (\%) \\ \hline CEM 14 2.5R cement & (kg:m\({}^{-3}\)) & 364 & & 364 & & 364 & \\ Quartz sand (0 \(\div\) 2 mm) & (kg:m\({}^{-3}\)) & 708 & & 708 & & 708 & \\ Gravel (2 \(\div\) 4 mm) & (kg:m\({}^{-3}\)) & 476 & & 119 & & 60 & \\ Gravel (4 \(\div\) 8 mm) & (kg:m\({}^{-3}\)) & 714 & 7.9 & 357 & & 178 & \\ Gravel (8 \(\div\) 16 mm) & (kg:m\({}^{-3}\)) & - & - & 714 & & 238 & 11.6 \\ Gravel (16 \(\div\) 31.5 mm) & (kg:m\({}^{-3}\)) & - & - & - & - & 714 & \\ Superplasticizer & (kg:m\({}^{-3}\)) & 2.548 & & 1.49 & & 1.048 & \\ Water & (kg:m\({}^{-3}\)) & 165 & & 165 & & 165 & \\ \hline \hline \end{tabular}  
* ACV—aggregate crushing value for aggregates with grain diameters over 4 mm.  
\end{table} 
Table 4: Composition of concrete mixtures. According to the EN 12390-3 [30] standard, the compressive strength test was carried out on cubic samples with an edge length of 150 mm. The values of elastic modulus were determined on the basis of the EN 12390-13 [32] standard (Figure 1). The splitting tensile strength was determined in accordance with the EN 12390-6 [31] standard on concrete blocks with an edge length of 150 mm. The concrete brittleness (K) can be calculated from the following formula:  
\[\mathrm{K}=\frac{\mathrm{f_{ctax}}}{\mathrm{f_{c}}}, \tag{1}\]  
where: f\({}_{\mathrm{c}}\)--compressive strength (MPa), f\({}_{\mathrm{ct,ax}}\)--axial tensile strength (MPa). The splitting tensile strength was determined in the presented tests.