## 2 Experimental Program
### Examination of the SCC Characteristics  
The experimental examination of the characteristics of SCC was carried out in two phases: (1) examination of the characteristics of fresh concrete mass, (2) examination of the mechanical characteristics of hardened SCC. One of the primary methods used for testing self-compacting concrete in the fresh state is the Slump-flow test, EN 206-9: 2010 [36] which tests the consistency of fresh concrete and checks one of the key properties of SCC: workability, i.e., fluidity. Based on the recommendations of EFNARC [15] and regulations EN 206-9: 2010 [36], the minimum diameter of fresh concrete mass of SCC is 550 mm, and the maximum permissible diameter is 850 mm. The lower spread time of the t\({}_{500}\) indicates better workability. For engineering practice, it has been suggested that the spread time be in the range of 3 to 7 s. The results obtained by testing fresh concrete are shown in Table 3. \begin{table}
\begin{tabular}{c c c} \hline \hline  & **Mass for 1 m\$ [3] (kg)** & \\ \hline limestone filler & 100.0 & \\ cement & 430.0 & water absorption (\%) \\ fraction 0–4 mm & 807.5 & 0.80 \\ fraction 4–8 mm & 380.0 & 0.50 \\ fraction 8–16 mm & 553.0 & 0.40 \\ water & 210.0 & \\ MC Power Flow 1102 additive & 2.2 & \\ \hline \hline \end{tabular}
\end{table} 
Table 2: Concrete composition. Figure 1: Particle size distribution of aggregates. Based on the recommendations defined in EFNARC [15] and EN 206-9:2010 [36], the designed mixture is classified as SF1. On the basis of the measured slump time of the designed mix, it is concluded that it belongs to class VS2. The following tests were performed on hardened concrete: compressive strength, tensile splitting strength and the determination of the tangent and secant modulus of elasticity was performed. To determine the characteristic of the hardened concrete twelve 150 mm cubes and nine 150 mm diameter cylinders of 300 mm length were cast simultaneously with the beams. Determination of compressive strength of concrete was carried out on cubes having sides of 150 mm, after 2, 7, 14 and 28 days in accordance with EN 206-1. The tensile splitting strength of concrete was tested on cylinders measuring 0150/300 mm, and it was determined after 28 days, in accordance with EN 12390-6. The determination of the tangent and secant modulus of elasticity was performed in accordance with the standard EC 2 [37]. The test results of compressive strength as well as tensile splitting strength are shown in Table 4. Tensile splitting strength is an important parameter of mechanical characteristics of concrete. Weak tensile properties of concrete lead to failure of structure, therefore numerous papers investigated the possibility of improving tensile strength. In [38], it is confirmed that adding fiber polymers into cement paste can improve its tensile splitting strength. In addition, fiber polymers change the way of failure of cylinder sample during the test. Namely, failure of sample without fiber polymers is due to failure of cement paste and, on the other hand, failure of sample with fiber polymers occurs due to failure of cement paste, fiber detachment and pull-out continuation [38]. During determining compressive strength on the cylinders, the stress-strain relation was recorded, as presented in Figure 2. Since strains are usually very small, we used microstrain instead, which is strain times \(10^{-6}\).