# The Influence of Steel, Glass and Basalt Fibres on Selected Parameters of Construction Mortars
## 5 Conclusions  
The test results provide a basis for the following conclusions:  
The addition of basalt fibres to the mortar increased its compressive strength by approximately 5%. The compressive strength results are quite similar, with a difference ranging from 1 to 3 MPa.  
The mortars with basalt fibres showed the greatest increase in flexural strength after 7, 28 and 56 days of curing. Comparable results were obtained for the mortars enriched with steel fibres. The reference mortar showed the worst bending strength results. A statistical analysis was performed, which allowed us to conclude that the fcm values for the SW, SZ, ST and SB samples were the same for tests carried out after 28 days (\(p\) = 0.149) and after 56 days (\(p\) = 0.370). In summary, the compressive strengths of the mortars under consideration (SW, SZ, ST and SB) tested after 28 and 56 days did not differ from each other.  
In the capillary pull-up test, it could be observed that for mortars with fibre additives, the weight gain after 28 days of curing was approximately 30% lower. The weight gain of the samples differed depending on the type of fibre used: SW, SZ, ST or SB (\(p\) = 0.018). In addition, the same weight gain 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 highest weight gain [kg/m\({}^{2}\)] was observed for the SW samples (1.59 \(\pm\) 1.02), while the lowest was observed for the SZ series (0.66 \(\pm\) 0.38).  
In the water absorption test, the mortars with fibre additives were characterised by a lower weight gain of approximately 2% compared to the mortars without fibre additives.  
The air pore characteristics have an impact on the improvement in the water absorption and capillary rise parameters of mortars. In mortars with dispersed reinforcement, there is a favourable reduction in the pore distribution index, L. The main mechanism influencing the improvement in these parameters seems to be so-called microcrack bridging by fibres. Thanks to this phenomenon, there is a lower increase in the mass of mortars.  
Linear relationships between compressive strength and flexural strength, as well as between water absorption and capillary pull-up, were developed for the mortars tested. These relationships allow only one parameter to be tested in the laboratory, while the others can be estimated on the basis of a linear relationship.  
When determining the decrease in compressive strength, the most frost-resistant mortar was found to be the steel fibre mortar, whose compressive strength decreased by 15.1% after 28 days. The greatest decrease in compressive strength was observed in the reference series. After 25 cycles, this decrease was 18.5%. After the frost resistance test, the mortars showed a comparable loss of mass after 25 freeze-thaw cycles, amounting to less than 5%.  
Steel fibre is the fibre with the highest modulus of elasticity and stiffness among commonly used fibres. Therefore, the use of steel fibres can significantly improve the mortar's compressive and flexural strength. Steel fibre-reinforced mortar is characterised by greater resistance to freezing and thawing, as it reduces the number of microcracks in the cement matrix. It also reduces weight gain when in contact with water by hindering its transport to other parts of the mortar. The addition of steel fibres strengthens structural elements by improving their load-bearing capacity and durability, but they can also be used to reinforce existing structures undergoing repairs.  
Concept: A.K.; methodology: A.K.; software: I.J.; validation: A.K. and I.J.; formal analysis: A.K.; research: A.K. and I.J.; resources: A.K.; data curation: A.K.; writing of the original draft: A.K.; writing--review and editing, A.K. and I.J.; visualisation, I.J.; supervision, A.K.; project administration, A.K.; funding acquisition, A.K. All authors have read and agreed to the published version of the manuscript.  
This research received no external funding.