Basalt fiber

Basalt fibers are produced from basalt rocks by melting them and converting the melt into fibers. Basalts are rocks of igneous origin. Basalt fibers are classified into 3 types:
The technology of production of basalt continuous fiber (BCF) is a one-stage process: melting, homogenization of basalt and extraction of fibers. Basalt is heated only once. Further processing of BCF into materials is carried out using "cold technologies" with low energy costs.
Basalt fiber is made from a single material, crushed basalt, from a carefully chosen quarry source. Basalt of high acidity (over 46% silica content) and low iron content is considered desirable for fiber production. Unlike with other composites, such as glass fiber, essentially no materials are added during its production. The basalt is simply washed and then melted.
The manufacture of basalt fiber requires the melting of the crushed and washed basalt rock at about 1,500 °C (2,730 °F). The molten rock is then extruded through small nozzles to produce continuous filaments of basalt fiber.
The basalt fibers typically have a filament diameter of between 10 and 20 μm which is far enough above the respiratory limit of 5 μm to make basalt fiber a suitable replacement for asbestos. They also have a high elastic modulus, resulting in high specific strength—three times that of steel. Thin fiber is usually used for textile applications mainly for production of woven fabric. Thicker fiber is used in filament winding, for example, for production of compressed natural gas (CNG) cylinders or pipes. The thickest fiber is used for pultrusion, geogrid, unidirectional fabric, multiaxial fabric production and in form of chopped strand for concrete reinforcement. One of the most prospective applications for continuous basalt fiber and the most modern trend at the moment is production of basalt rebar that more and more substitutes traditional steel rebar on construction market.
The table refers to the continuous basalt fiber specific producer. Data from all the manufacturers are different, the difference is sometimes very large values.
Comparison:
The first attempts to produce basalt fiber were made in the United States in 1923 by Paul Dhe who was granted U.S. patent 1,462,446. These were further developed after World War II by researchers in the US, Europe and the Soviet Union especially for military and aerospace applications. Since declassification in 1995 basalt fibers have been used in a wider range of civilian applications.
Since October 18, 2017, JV 297.1325800.2017 "Fibreconcrete constructions with nonmetallic fiber has been put into operation. Design rules, "which eliminated the legal vacuum in the design of basalt reinforced fiber reinforced concrete. According to paragraph 1.1. the standard extends to all types of non-metallic fibers (polymers, polypropylene, glass, basalt and carbon). When comparing different fibers, it can be noted that polymer fibers are inferior to mineral strengths, but their use makes it possible to improve the characteristics of building composites.
• Osnos S, Osnos M, «BCF: developing industrial production for reinforcement materials and composites». JEC Composites magazine / N° 139 March - April 2021, p.19 – 24.
• Osnos S., Rozhkov I. «Application of basalt rock-based materials in the automotive industry». JEC Composites magazine / N° 147, 2022, p. 33 – 36.