Basalt Fibre – Ancient Mineral Fibre for Green and Sustainable Development

Basalt is a solid, compact igneous rock which is formed when volcanic lava cools adequately to solidify, covering many parts of the Globe. It is mainly used as a crushed rock in building and highway engineering. Both the staple and continuous type of fi bres can be manufactured from basalt rocks. Basalt fi bres have excellent mechanical, chemical and thermal properties. They are highly resistant to alkalis, acids, salt attack, oxidation and radiation. Basalt fi bres are most suitable for concrete reinforcement, bridge and shoreline structures. Basalt-based composites off er better performance than steel and all known reinforced plastics (1 kg of basalt reinforcement equals 9.6 kg of steel). Basalt fi bres are also fulfi lling the concept of sustainable design and green building. In various applications, basalt fi bres are replacing various high-performance fi bres, e.g. asbestos, glass, aramid and carbon fi bres. Recently, continuous basalt fi bres have become attractive for electro-technical purposes as an insulation material and a natural fl ame retardant. An attempt has been made to provide a comprehensive review covering the basalt fi bre manufacturing process, the eco-friendly building system, prime fi bre properties, products and its ubiquitous application.

1 Introduction e industry is always motivated to locate new and better materials to manufacture new or improved products.With this in mind, the environment, strength, economy, risk and sustainability are important factors when a product is changed or a new product is developed.Sustainable building,
ese days, a signi cant escalation has been observed in the production of composite materials.Intensively developed polymer composite materials (PCM) are used in di erent sectors of the industry and technology.One of the basic reinforcing elements of composite materials is the bre.e glass bre and carbon bre are among the most e ective and promising reinforcing bres for manufacturing polymer composite materials used in the conditions of high loads.In the glass bre production, a rare component, boron oxide (B 2 O 3 ), is used, while the carbon bre bears high manufacturing costs.Consequently, both bres have no prospect for mass application.Currently, a lot of work is being executed on the development of a modern continuous bre from basalt stones.With the industrial production of the basalt bre on the basis of new technologies, the cost is equal or even less than the cost required for the production of glass bres.Basalt bres and materials on their basis have the most preferable parameter, the ratio of quality and price in comparison with glass and carbon, and other types ofbres [1].Basalt originates from volcanic magma and ood volcanoes, a very hot uid or semi uid material below the Earth's crust, solidi ed in open air.Basalt is a common term used for a variety of volcanic rocks, which are dark grey in colour, formed from molten lava a er solidi cation [2].Basalt is a building material that could e ectively nd wider application, since it is abundant worldwide.Basalt bres are more advanced than other bres in terms of thermal stability, heat and sound insulation properties, vibration resistance and durability.ey are used as a bre reinforcement of resin, pipes and geocomposites.Russia has unlimited basalt reserves.e bulk of Iceland's bedrock is basalt, which is widely used as a building material in the country.Basalt rock beds with the thickness of as much as 200 m have been found in the East Asian countries.Basalt is a building material that could due to its worldwide abundance e ectively nd wider application.One suggested use would be as a bre reinforcement of resin.

Composition of basalt fi bre
A basalt bre is a material made from basalt rock which is composed of plagioclase, pyroxene and olivine minerals [2].Plagioclase is an important series of minerals within the feldspar family.e name pyroxene comes from the Greek words for re and stranger.Pyroxenes were named this way due to their presence in volcanic lavas, where they are sometimes seen as crystals embedded in volcanic glass; it was rst assumed that they were impurities in the glass, hence the name " re strangers".
e pyroxenes are a group of important rock-forming inosilicate minerals discovered in several igneous and metamorphic rocks.Inosilicates, or chain silicates, have interlocking chains of silicate tetrahedral with either SiO 3 , 1 : 3 ratio, for single chains or Si 4 O 11 , 4 : 11 ratio, for double chains.A pyrogenic rock is formed through the cooling and solidi cation of magma or lava.A metamorphic rock is a result of the transformation of an existing rock type [3].A comparison of basalt with granite is shown in Table 1.
e mineral olivine is a magnesium iron silicate with the formula (Mg, Fe) 2 SiO 4 .It is a common mineral in the Earth's subsurface but weathers quickly on the surface.
e mineral level and chemical makeup of basalt formation depends on the geographical area.Moreover, the rate of cooling when the original ow reaches the Earth's surface in uences the crystal structure.Basalt is mostly found on ocean oors, while granite represents the Earth's crust in all continents.Basalt is an extrusive, while granite is an invasive igneous rock.Basalt is darker, composed of magnesium and iron, whereas granite is lighter, and composed of feldspar and quartz.Basalt is called ma c, whereas granite is known as felsic.Basalt splits along columnar planes, while granite splits along horizontal planes [6].Despite basalt stones being easily available with di erent compositions, only certain compositions are suitable for manufacturing a continuous lament with the diameter range 9-24 micrometres.A basalt bre contains about 48.8-52.2% of silicon dioxide (SiO 2 ), about 14-17.5% of aluminium Sustainable Development Tekstilec, 2016, 59(4), 321-334 oxide (Al 2 O 3 ), the rest of the components being shown in Table 2.

Basalt fi bre production with melt blowing (Junkers technology)
Basalt bres are produced in a continuous process similar to that of glass bres.A basalt rock is crushed, washed and loaded into a bin attached to feeders which further transfer the material into the melting baths in gas-heated furnaces.is process is made simpler due to the less complex composition of basalt bres as compared to glass bre processing.A glass bre normally contains aluminium, silica, boron oxide and several other minerals that must be fed separately into the metering system before entering the furnace. is is not the case with basalt bres as it does not consists of any such secondary materials and thus the process requires a single feed line to carry the crushed basalt rock into the melt furnace.As basalt stone is procured directly from the nature, this results in its manufacturers having less direct control over the purity and consistency of the raw basalt stone.When crushed, basalt enters the furnace, thereby liquefying the material at the temperature of 1500 °C (melting point of glass is 1400-1600 °C).It becomes di cult to uniformly heat the entire basalt mix with overhead gas burners used in conventional glass furnaces.e melting basalt must be held in a reservoir for extended periods, up to seve ral hours to ensure a homogenous temperature under the overhead gas.Several strategies Basalt is solidi ed lava, like rhyolite.However, it ows much quicker as it is less viscous.Distinguishing characteristics Visible crystals of pink feldspar white or grey quartz, and black mica.ere is no horizontal banding in granite.
Red-brown to black, frothy with small visible holes where gas escaped while the lava cooled.

Composition
Feldspar, quartz, mica, hornblende Feldspar, olivine, pyroxene, amphibole have been developed by basalt producers to promote uniform heating, which includes the immersion of electrodes in the bath.Finally, a two-stage heating scheme is employed, which features separate zones, furnished with controlled heating systems.e temperature control system in the furnace outlet zone feeding the extrusion bushings requires great precision; hence, a less sophisticated control system in the initial heating zone may be used.e blowing technology with centrifugal cylinders (e.g.Junkers method) is used for manufacturing cheap bres with 60-100 mm in length and 8-20 μm in diameter, primarily used as insulating materials in the construction and automotive industries.e basalt melt is fed to a horizontal sha bre spinning machine a er coming from the 1580 °C furnace, which consists of three centrifugal heads, one accelerating and two brillating cylinders [9,10].e bres formed as a result of the centrifugal force are blown-o with high-pressure air as depicted in Figure 1.Basalt rocks are crushed (5-12 mm) for a continuous basalt bre (CBF) production, the metal and magnetic contaminations are removed with the help of magnetic separation and screening, and small inclusions like dirt and dust are removed by washing. is is followed by drying, which is carried out either at natural air circulation or in a special dryer.
e prepared raw material is periodically loaded into the hopper of the loader mounted above the smelting furnace [11].
e smelting furnace (Figure 2) represents a recuperative bath-type furnace of continuous operation with direct gas heating of the smelting zone.Basalt rocks melt at 1500 ± 50 °С as a result of the burning of air-natural gas mixture.e melt ows into the feeder due to gravity forces a er the homogenisation.At the bottom of the feeder, electrically heated feeding tubes are located, through which the melt is supplied to electrically heated platinum-rhodium bushing.From the bushing, the melt is drawn in the form of a lament yarn [12].
Figure 2: Smelting furnace: 1 -bath type furnace, 2feeding tube, 3 -bushing, 4 -gathering shoe, 5winder [13] In the process of continuous lament, their surface is coated with a sizing agent which stops the growth of micro-cracks on the lament surface to avoid the decrease in bre strength.Additionally, the sizing agent improves the adhesive properties of bres.With the help of a gathering shoe, the lament yarn is wound on a spool.e manufacturing of a high quality continuous lament requires a proper selection of the raw materi-Sustainable Development Tekstilec, 2016, 59(4), 321-334 al, in addition to the melting and drawing technological parameters and properties.e manufactures of continuous laments require materials with a low rate of crystallisation; basalt glass should have the drawing interval which is wide enough [14,15].
e CBF manufacturing process is di erent to bre glass in the following ways: Basalt is a natural raw material which is melted to the state of super uent magma, Basalt bre shows a di erent crystalline structure and chemical composition from glass bre, ermo-physical properties of the basalt melt di er from alumina silicate glass melts [12].e process of basalt melting does not include the operations that are speci c for glass melting, and clearing and cooling the glass melts, which results in the di erence between the design of basalt melting furnaces and the design of glass melting furnaces.
e basalts obtained from di erent basalt deposits di er in their properties, a ecting the parameters of the continuous basalt bre production process.
e reduction in the diameter of the mono lament results in the increase of elasticity and thus proves useful in textile processing.
e diameter of the mono lament depends on the temperature in the feeder and the speed of the lament drawing.

Mechanical and physical properties of basalt fi bre
Basalt, the density of which is between 2.8-2.9 g/cm 3 , has a maximum contribution of iron and magnesium.Being extremely hard (from 5 to 9 on Mohs scale) gives basalt a superior abrasion resistance.Casted basalt is o en used as a paving and building material.Continuous basalt bres and fabrics are labelled as safe by the US and European occupational safety guidelines [7,16].
A continuous lament of basalt with the diameter of more than 5 µm cannot split longitudinally and is thus characterised as non-respirable.e continuous basalt bres ( laments) have the diameter between 9 and 13 µm, which is a suitable replacement for asbestos.Continuous bres are highly water resistant (90.0-99.9%).e speci c tenacity of continuous basalt bres exceeds that of steel bres by many times.Basalt is by roughly 5% denser than glass.e tensile modulus (E modulus, Young modulus) of continuous basalt bres is higher than of E-glass bres, making them attractive for the reinforcement of composites.A basalt textile exhibits su cient exibility, drape ability and good fatigue resistance.Yarn made from continuous basalt bres shows low friction coe cients when compared to most reinforcement materials [7,[16][17][18][19].

Chemical properties of basalt fi bre
Continuous basalt bres have good acid, alkaline and solvent resistances, surpassing those of E-glass bres.
e main advantage of basalt bres is the resistance to an alkaline environment, as it can withstand the pH of up to 13-14.e bre has good resistance to UV-light and biological contamination in addition to its anti-corrosion properties.In its pure form, it is free of odour and has low soiling sensitivity with the absorption of humidity less than 0.1% at 65% of relative air humidity at room temperature.Continuous basalt bres show excellent wettability with natural adhesion to a broad range of binders, coating compounds and matrix materials in composite applications [20].A comparison of chemical resistance of basalt and glass bres is shown in Table 3. Figures 3 and 4 show a comparison of the damage of basalt, carbon and glass bres at alkaline conditions.Basalt materials have strong resistance against the action of fungi and microorganisms.However, a er the weaving, basalt fabrics show easy damage due to their poor bending properties. is defect may be overcome with some coating and nishing.

Thermal properties of basalt fi bre
Basalt bres have excellent thermal resistance.ey can easily withstand the temperature of 1100-1200 °C for hours without enduring any physical damage.Unstressed basalt bres can maintain their integrity even at up to 1250 °C, making them superior in comparison with E-glass and carbon bres.
e thermal properties of basalt bres for composites are shown in Table 4 [19,22].

Assessment of diff erent high-performance fi bres in comparison with basalt fi bres
Basalt bres have a higher or a comparable modulus of tensile strength and elasticity than E-glass bres.Moreover, they have great chemical and thermal stability, and good electrical and sound insulating properties.e thermal insulating properties of basalt bres are by three times higher than that of asbestos bres.ey show by 10 times better electrical insulating properties than E-glass.Table 5 describes the properties of basalt bres compared with di erent high-performance bres [23,24].Basalt bres o er the prospects of a completely new range of composite materials and products with their unique range of properties.Some basalt products are shown in Figure 5.A continuous basaltbre is mainly used in the making of roving fabrics, thin fabrics, reinforcing nets for building and road constructions, chopped bre mats and thin mats (basalt paper) [26][27][28].

Basalt scales
Basalt scales got their name due to the protective quality similarity with sh scales.Basalt scales are used exclusively for the production of protective, wear proof, anticorrosive and chemically proof coverings, reinforced composite materials, reinforced plastics, frictional materials (e.g.brake blocks and clutch plates) [29].e wear resistance and chemical stability of lacquer coatings reinforced with basalt scales increases by several times.e durability

Basalt bre bars
By utilizing basalt bres and a resin epoxy binder, basalt composite bars are prepared.ey are noncorrosive, with the tensile strength by three times higher than that of a steel bar normally used in the building construction.Nevertheless, these bars are costly and also not resistant to alkalis.e high mechanical performance/price ratio of basalt bre composite bar, combined with the corrosion resistance to alkaline attack, advocates replacing steel in concrete with basalt bre composite bars [27,28,[31][32][33][34].

Basalt roving
Roving is a natural, inert and extremely strong material, which is resistant to aggressive environments, has long service life and excellent electric insulating properties.Basalt roving is a bundle of continuous mono-directional complex basalt bres.Basalt roving is heat resistant; its long use temperature range is between 200-680 °C.Temporarily, it can withstand up to 900 °C.Its absolute hardness on the Mohs scale is graded 8-9 (for comparison, diamond equals 10).Its speci c tensile strength is by 2.5 times higher than that of alloyed steel and by 1.3 times higher than that of E-glass [29,34,35].

Basalt fabrics
Basalt fabrics are produced for structural, electrotechnical, general and specialised purposes.Basalt fabrics are useful for producing structural basaltplastics based on various thermosetting binders epoxy and phenolic polyesters (e.g. by laying out method) from which components for automobiles, aircra s, ships and household appliances can be produced.e basalt-plastics acquire the shield properties against electromagnetic radiation in the case of preliminary metallisation.Basalt fabrics can also be used as basics when producing so and rigid roo ng [35].Basalt fabrics are used for the electrotechnical purposes as a base for the production of insulation materials.ese materials are employed in the production of substances for printed circuit boards for electronics and electrical engineering.
e employment of incombustible basalt fabric inserts in industrial ventilators increases their re safety as well as the re resistance of ventilating systems.e cost of basalt fabrics is considerably lower than that of similar materials.Basalt woven materials are resistant to ames due to their non-combustible properties that make basalt tapes e ective as extra resistant insulation for electrical cables and underground ducts.Basalt fabric hoses may be useful for reinforcing cables, as well as for repairing the interior and exterior of tubes and pipelines [36][37][38].

Basalt prepregs
Prepregs are pre-impregnated composite basaltbres or fabrics into which a pre-catalysed polyester resin system has been impregnated by a machine.
e resin systems in these materials react very slow at room temperature, allowing a long shelf life.ey are cured by heating at the prescribed elevated temperature [39,40].Prepregs have a long life (at least 4 years) under storage conditions, hermetically packed at the temperature under 40 °C [41][42][43].Prepregs are used for the production of various basalt plastic composites.

Basalt bre pipes
Basalt bre pipes are obtained by winding basalt threads impregnated with a binder.ey are regarded as one of the most promising materials in the modern construction technology.
ey are much better than the materials used in the designs of piping hot water systems such as steel, asbestos and other traditional building components.ey are chemically-resistant in aggressive environments and ecologically friendly.e enormous stock of basalt raw materials and the relatively low cost make its use very tempting, particularly in laying of the heating systems.e basalt bre pipes may be useful as components for sha linings, building components, for transporting corrosive liquids and gases in constructions, industrial, agricultural and public service sectors.Other possible areas of application for basalt pipes are masts, aerial frames, various pipes in constructions, communication etc. ey can be applied in a pipeline construction with the working temperature of up to 115 °C and pressure of up to 1.5 MPa with the exploitation period of no less than 25 years.
e basalt bre insulated pipe is a new concept of energy e cient hot water and heating pipelines.
ese pipes have high corrosion resistance and do not require special electrochemical protection.ey are resistant to the e ects of fungi, groundwater and sewage, which increases the lifetime of basalt bre pipes by up to 50 years and more [40,42].Sustainable Development Tekstilec, 2016, 59(4), 321-334 Subsequently, basalt bre pipes also have a signicant maintenance and mounting advantages compared to conventional steel pipes.Due to their greater hydraulic resistance, the capacity of basalt bre pipes is much higher than that of a steel pipe.Moreover, they are by 3-4 times lighter than steel pipes.
is makes the installation of basalt bre pipes cheaper and more convenient.Another important advantage of basalt bre pipes is their higher durability.e operation time of basalt bre pipes is at least 20 years in comparison to the 5-7 years of steel pipes.Galvanised steel pipes are used to extend the operation time.However, the price of such pipes is by 75% higher than that of conventional steel.us, the operating costs (depreciation, maintenance) for basalt bre pipes are signi cantly lower than for pipes made from steel [38].

Flame retardant protection product
Flame retardant fabrics are fabrics which are dicult to ignite, easy to self-extinguish, they burn slowly, have small burned area, reducing re damage and the loss of property.Flame retardant fabrics play an important role in our daily life and production [44].
e performances of high-temperature resistantbres are: (1) no size change at high temperature; (2) high so ening and melting temperature; (3) high kindling and ignition point; (4) high thermal decomposition temperature; (5) having the general characteristics of bres, e.g.exibility, elasticity, workability, ame resistance or incombustibility; (6) general characteristics even a er exposed for a long time to high temperature.Basaltbres are characterised by all of the above.e application temperature of CBF is from -269 °C to up to about 650 °C (so ening temperature is 960 °C).Furthermore, CBF has outstanding ame-resistance performance and can be developed in a ame-resistant protection eld [44,45].Basalt bres have excellent ame retardant properties.Fibre combustion is decided according to: 1) the composition and structure of a bre, which directly a ects its thermal decomposition temperature and formed speed of OH and H; 2) the oxygen supply circumstance, as the bre combustion performance is judged by the limit oxygen index (LOI).e lower the LOI value, the easier is the bre combustion.A bre is in ammable when its LOI is less than 20%, it is ammable bre when the LOI of a bre reaches 20-26%, ame-retardant when LOI reaches 26-34% and non-combustible when the LOI of abre is above 35% [44].

Application of basalt fi bre
Geocomposites A protective cap using geocomposites in waste disposal sites, including.incorporated basalt materials, can put forward the best protection for human health and environment against radioactive waste.A lot of this waste needs to be protected for centuries in an isolated way for an ino ensive disposal [46,47].Such a capping system for a long-term use should include the ability to function in a semi-arid to subhumid climate, to limit the recharge of water table to near the zero amount, should be maintenance free, resist animals, human intrusion and limit the release of noxious gases.Waste dumping pits are constructed in several layers which include coarse material such as sands, gravels and basalt riprap [4].Basalt geo-meshes are ecologically safe and can withstand very high temperatures of molten asphalt.Basalt geo-meshes are chemically inert and lighter than metallic meshes.ey are also t for soil and embankment stabilisation, and environmental and ecological safety.Geo-polymeric concretes reinforced with basalt bres o er better fracture toughness than conventional cement structures (as shown by three-point bending tests) [48].

Civil construction
Basalt bres are also used in building constructions and facing plastics such as reinforcing plaster grids, warmed panels for the construction of prefabricated houses, oors, dropped ceilings, reproof walls, re resistant doors, building plastics etc. [49].
e bre reinforced polymer (FRP) composite bars and fabric sheets are currently used as internal or external reinforcement for concrete members in many structural systems.e use of corrosion resistant FRP reinforcement is bene cial in transportation structures particularly in those exposed to de-icing salts, and/or located in a highly corrosive environment.Glass, carbon and aramid bres are commonly used in the manufacture of reinforcing bars for concrete applications.Recent developments in the bre production technology allow the mak-ing of basalt bre reinforced polymer (BFRP) bars.Nowadays, several BFRP products are made in the form of straight rods, loops, two dimensional meshes and spirals.ey show strength, light weight, non magnetic and non corrosive properties, and good fatigue endurance properties.e high initial cost, low modulus, linear tensile stress strain behaviour until failure, and durability issues are some limitations to the adoption of BFRP materials in the transportation infrastructure [ • wrapped with basalt bres has shown an increase by about 68% over the exural strength of conventional specimens.

Automotive industry
Basalt chopped strands are good for use in friction materials.Brake pads based on basalt bre have a better and more stable friction coe cient and higher endurance than those based on glass bres.Basalt bres are also used as llers for car mu ers, showing great silencing virtue and good resistance to thermal cycling.Higher strength and elastic modulus of basalt bres (compared to conventional E-glass and carbon bres) o er car makers the opportunity for a signi cant cost-reduction of SMC/BMC parts while retaining the high strength and sti ness.Basalt bres are also used as a substitute of glass bres in radars due to the same dielectric and transparency properties [53].

Electricity and electronics industry
Basalt fabrics are used for electro-technical purposes as a base material for the production of insulation materials.A preliminary metallisation of fabrics results in the shielding properties of electromagnetic radiations.Basalt can be used over a wide temperature range from about -200 to 800 °C, compared to E-glass, which can be used from -6 °C to 450-600 °C.It can substitute asbestos in almost all applications due to its heat insulating characteristics.e tapes made from basalt bres may be used in electrical cables as the insulation material against re hazards during power transmission.Basaltbres can sustain their properties for low temperature insulations.In power industries, basalt bres are also used for re resistant cable construction components as llers, braiding and tapes [35,54].

Chemical and petrochemical industry
In the petrochemical industry, basalt bres are used as chemical and wear-proof coverings of tanks, pipelines, oil pipelines, and as non-ammable coverings of reproof composite materials.Traditionally used in oil collection systems and pumping water systems, carbon steel pipes have a very short period of lifetime due to their weak anti-corrosion resistance and a ection by aggressive components, which are in varying degrees contained in hydrocarbons, as well as hydrogen sulphide, carbon disulphide, brine and corrosion products.Increasing the lifetime of pipelines is possible by making costly repairs, cathode protection and adding anticorrosive inhibitors.e more the pipeline is aging, the more the matter of anticorrosive preventions increases.In terms of economic e ciency, one of the most acceptable options to solve these problems is to use basalt bre pipes [55].Basalt is also used in the chemical industry for the production of chemically proof materials and products: pipes, tanks for aggressive liquids, acids, alkalis, chemical fertilisers, poisonous substances etc. [56].

Municipal and home appliances services
Nowadays, the problem of enhancing the reliability of the functioning of housing and utilities infrastructure has become of great signi cance.e ground is saturated with technological communications, electrolytic mixtures and stray currents, which help in accelerating the corrosion of steel pipes.Moreover, high temperature can accelerate the chemical processes.From the point of view of economic e ciency, the most acceptable options for these problems are using basalt and glass bre pipes.High physical-mechanical performance, as well as the resistance to corrosive environments has identied the broad use of these materials in various elds of industry, e.g.materials for cleaning installation lters for air and liquid environments, big pipes for Sustainable Development Tekstilec, 2016, 59(4), 321-334 water supply and sewage, municipal drains, cleaning installations etc. [4,57].

Miscellaneous applications
Basalt bres are used as the material for thermal equipment, furnaces, recuperators and pipelines.Basalt lters are best for the ltration of metals melt during moulding, for clearing waste gases from the dust at ore mining and processing plants, for sewage treatment etc.Moreover, basalt bre products are used in port constructions, sea platforms as reinforcing and construction materials made from basalt plastics, paint, varnish proof coverings of bridges, waterproof coverings for ferro-concrete installations, it can be used as thermo-insulation of furnaces and equipment during the production of ceramic and porcelain products.e eld of agriculture is also not far from using basalt bre products as grids for strengthening soil, material for hydroponics for the cultivation of bacterial cultures, tanks for storage and transportation of liquid chemical fertilisers and pesticides.Basalt materials do not absorb the radioactive radiation, which makes them candidates for the budding material in the production and transformation of radioactive materials, e.g. in nuclear power plants [58][59][60][61].

Conclusion
Most studies focus on the positive aspects of basalt bres; nevertheless, the de ciencies or lacunas of the material before using it in any application is to be taken into consideration.A few de ciencies exist in the performance of basalt bres, e.g. the instability in the basalt bre properties, resulting from the volatile composition of the basalt material.Basaltbres also show low stretch properties.e production process of basalt bres may produce many defects in the end product, e.g. the heterogeneity of the basalt melt can a ect the characteristics of the produced bre.e basalt bre may have higher speci c gravity resulting from high iron content and it can a ect its comb performance.In consequence, the modi cation of the material is important before putting it to end use.Furthermore, the cost of a basalt bre is 3 times higher than that of an E-glassbre, which is expected to fall with the increase in the production volume.
Despite the few shortcomings, the latter can be overlooked considering the weightage of the basalt bre advantages in various applications.Basaltbres can be of great interest for the building industry, since they now represent a popular choice for the replacement of carbon bres and steel owing to their high tenacity and low elongation.Due to its non-corrosive nature and very good heat resistance power, basalt has the potential to replace E-glass.It is also an ecologically friendly material, since it has no toxic reaction with air, water and other chemicals.Basalt bres can be used as a retro tting material for concrete specimens.In conclusion, it can be stated that basalt bres can be used in a wide range of applications in the construction and concrete industry.