## 4 Results and Discussion
### Mechanical Properties
#### 4.1.3 Toughness Tests via Charpy Method  
Toughness tests were carried out at 25 \({}^{\circ}\)C; five trials per composite type. The trials were conducted in order to check if upon impact there is visually unnoticeable structure delamination weakening  
Figure 14: Relation of [PERSON]’s modulus E and temperature for VE (REF) sample and VE composites reinforced with basalt powder (BP), basalt fibre (BF) and basalt textile (BT) (Table 2). the construction and de facto constituting places where further damage may develop, e.g., under moist conditions and subsequent freezing spells at negative temperatures. That is why it is becoming essential to produce composites of high impact resistance and early detection of such damage is important for safe exploitation of building constructions. Every sample experienced fracture upon impact. The failure phenomenon was dependent not only on the impact energy, but also the impactor shape. The speed of the shock wave propagation in the construction material played an important role in the process. The work needed to tear apart a construction composite depends on the length of fibres, as at the sample fracture time the fibres come out of the sample instead of breaking. Conclusions based on Figure 15 are that the composites modified with fabric (EP/BT and VE/BT) were characterised by the lowest relative toughness values. This suggests that the energy at the fracture moment was a sum of the energy used for the matrix-fibre separation, which meant the destruction of the interface adhesion, the energy used for overcoming friction and pulling the separated fibres out of the matrix and also the energy needed for the crack propagation across the polymeric matrix itself. It is deduced that if the fibres had undergone stretching, the impact energy would have been much greater because the energy used for fibre tensile deformation during impact trials typically exceeds the other energy components. The highest values of relative toughness were recorded for the chopped fibre-modified composites. However, worth underlining is the fact that in order to achieve much better impact strength of chopped fibre-reinforced composites, one would need to use fibre with a length equal to the so-called critical length of fibre with poor adhesion to the polymeric matrix. When analysing the results obtained for the resin composites strengthened with chopped fibre (EP/BF and VE/BF), it should be highlighted that impact-induced fracture for such composites was dependent mostly on the content of the fibres, their resistance to tensile deformation, the polymer-fibre interactions and the ductility of the resins. The fracture of the composites containing chopped fibres proceeded in relation to two factors: delamination and fracture of long fibres. The observations and analysis results show that in the first impact destruction phase, there must have been deformations and cracks in the resin. Nevertheless, the final results show that the textile was characterised by a much higher adhesion to the epoxy resin than to the vinylester resin. Next, cracking involved fibres, their sections were broken off and pulled out from the resin. The last stage, like in the case of the textile-modified (BT) composites, was sample destruction. The higher relative toughness values  
Figure 15: Relative toughness KZ of composite materials at 25\({}^{\circ}\)C.  
suggest, though, a better ability to absorb energy by the chopped fibres than by basalt textile, which means that the fibres must have been characterised by a lower value of the elasticity modulus than the textile. The best toughness results were obtained for the epoxy composite strengthened with basalt powder (EP/BP). It turns out that filling with fine particles to a high degree allows not only good adhesion to the polymeric matrix, but most of all better dispersion within the matrix, which was a problem in the case of long and chopped fibres.