# The Influence of Steel, Glass and Basalt Fibres on Selected Parameters of Construction Mortars
###### Abstract
The tensile strength of structural steels ranges from 0.2 to 0.7 GPa, while the strength of thin steel fibres reaches approximately 4 GPa [13; 14]. This difference is probably due to the fact that the crystal structure of the fibres themselves is more developed, and the iron crystals are only oriented along the axis of the fibre. The number of defects in the fibres themselves, which are small in volume, is significantly lower than in the same material with a larger volume. The fibres produced are characterised by diameters often not exceeding 15 \(\upmu\)m. This is due to the fact that fibres with smaller diameters are generally much more resistant in terms of bending strength. Studies conducted by scientists [15; 16] show that tensile strength increases rapidly when the diameter of the tested fibre is less than 15 \(\upmu\)m. With smaller diameters, there is less risk of defects on the fibre surface, such as microcracks or faults. In other words, the smaller the fibre diameter, the less likely it is to have defects, which translates into its strength parameters [17; 18; 19; 20]. Concrete with dispersed steel fibres is used for industrial floors exposed to high loads and abrasion. Glass fibres improve the watertightness and fire resistance of concrete. They are used in the construction of concrete elements exposed to water and moisture from the air. Concrete with the addition of basalt fibres is characterised by good mechanical properties and high resistance to abrasion. It is also a good thermal and electrical insulator. It is resistant to corrosion and high and low temperatures [21; 22; 23; 24]. Currently, concrete or mortars with dispersed reinforcement are increasingly used in single-family housing construction [25; 26; 27; 28]. Solutions and applications for reinforced concrete are constantly evolving. Concrete elements made using this technology are significantly more durable, waterproof, long-lasting, malleable and easier to shape into any form [29; 30; 31]. Concrete products and architectural elements blend in perfectly with the surrounding space, creating an aesthetic whole. In addition, they are characterised by above-average resistance to particularly adverse external factors, including low temperatures, sunlight, and all types of concrete corrosion. Fibre-reinforced concrete products are ideal for use in modern, industrialised and aggressive urban and industrial environments [32; 33; 34]. Examples of such structures include the metro in the Qatari capital, Doha, and the expansion of the Crossrail metro network in London. These structures are examples of the most spectacular and large-scale tunnel infrastructure projects in recent years on a global scale. The consumption of concrete and steel during the implementation of such huge investments would be very high. However, it could be reduced by using steel fibres as the only reinforcement for the tunnel lining segments [35; 36; 37]. Innovation in fibres is a rapidly growing field that encompasses new technologies, materials and production methods aimed at improving the properties and functionality of fibres. These innovations are crucial for many industries, improving the functionality, durability and sustainability of products. The development of these technologies is driven by the growing demand for advanced construction materials. Steel, basalt and glass fibres are the most common alternatives to traditional reinforcement. These fibres increase bending resistance, making them an excellent choice for more demanding construction projects. Above all, the selection of the right fibres is extremely important. It is worth noting that investing in selected fibres can lead to significant savings in the long term. Thanks to the increased durability of the structure, you can save on maintenance and repair costs. The innovative aspect of this research lies in comparing selected rheological properties and hardened mortar parameters between steel, glass and basalt fibres. Fibres added to mortars are currently widely available on the construction market.