# The Influence of Steel, Glass and Basalt Fibres on Selected Parameters of Construction Mortars
## 3 Results
Using [PERSON]'s test, we obtained differences between the compressive strength for the SW, SZ, ST and SB series between 7 and 28 days (\(p<0.001\)) and 7 and 56 days (\(p<0.001\)), while between 28 and 56 days, the same relationship occurred for the parameters of the SW (\(p=0.046\)), SZ (\(p=0.002\)), and ST (\(p=0.001\)) series. In addition, the average value of fcm [MPa] for the SW, SZ, ST and SB series increased with maturation time after 7, 28 and 56 days (Table 6). The addition of basalt fibres to mortars resulted in an increase in compressive strength over the entire period studied by an average of about 5%. The results obtained indicate that glass fibres and steel fibres did not improve the compressive strength of the mortar. The results are quite similar, and the difference ranged from 1 to 3 MPa (Table 9). The flexural strength test concerns static conditions, which means that the system is not subject to any changes over time. Some researchers have gone further, such as [PERSON], [PERSON], [PERSON], [PERSON] et al. [6], and studied materials under dynamic conditions. Dynamic loads are crucial for ensuring the safety and durability of structures, especially in situations where sudden or short-term forces occur. Dynamic changes over time show a U-shaped effect in the tested materials. Their strength depends on the material used, the depth of the impact and the forces acting at a given time. According to research conducted by [PERSON], [PERSON], [PERSON], [PERSON], [PERSON], and [PERSON]. [54], it appears that dosing steel fibres below 20 kg/m\({}^{3}\) slightly improves strength, which does not increase proportionally to the amount of fibres dosed. The best results were obtained for fibre contents of 25-50 kg/m\({}^{3}\). A fibre dosage above 50 kg/m\({}^{3}\) does not increase strength. Therefore, a dosage of 25 kg/m\({}^{3}\) was used in this study. Absorption and capillary rise tests were performed on three barrels from each series of 4 cm \(\times\) 4 cm \(\times\) 16 cm mortars after 28 days of maturation [Figure 8]. There is a statistically significantly high correlation between time and the weight gain of the SW (\(p\) < 0.001), SZ (\(p\) < 0.001), ST (\(p\) < 0.001) and SB (\(p\) < 0.001) samples. The calculated  
Figure 8: Weight gain in capillary rise test [kg/m\({}^{2}\)]. Figure 7: Average flexural strength gain of the tested series. correlation coefficient is positive and therefore the weight gain of the SW, SZ, ST and SB samples increases with time (Table 10, Figure 8). The weight gain of the samples [kg/m\({}^{2}\)] differs depending on the type of fibres used in the given SW, SZ, ST or SB series (\(p\) = 0.018). Using the Tukey test, we obtain statistically significant differences between SW and SZ (\(p\) = 0.009). In addition, an equal weight gain of samples was observed between SW and ST (\(p\) = 0.188); SW and SB (\(p\) = 0.336); SZ and ST (\(p\) = 0.576); SZ and SB (\(p\) = 0.373); and ST and SB (\(p\) = 0.986). The largest increase in the weight of samples [kg/m\({}^{2}\)] occurred for the SW samples (1.59 \(\pm\) 1.02),while the smallest occurred for the SZ series (0.66 \(\pm\) 0.38) (Table 11, Figure 9). Analysing the results for the weight gain of the samples in the capillary rise and saturation tests (Figure 10, Table 12), it can be observed that for the mortars with fibre additives, the weight gain after 28 days of maturation was significantly lower compared to the reference series. For mortars with the addition of fibres, the weight gain was lower by about 30% in the capillary rise test. The addition of fibres to the mortars reduced the water absorption capacity of the mortars tested. For mortars with the addition of fibres, there was a smaller weight gain in the absorbency test by about 2 percentage points for all the mortars with the fibres considered.