03/09/2016 14:00 | Category:

The construction industry is constantly developing, new sites are opening, various facilities are being built.

Composite materials have become an integral part of this area; it is now difficult to imagine large-scale construction work without the use of composites.

Resistant, lightweight and durable, it has significant advantages over natural materials, which are heavy and do not have significant ability to change shape.

Composite materials in construction

Exist different types composite materials, they differ in their composition and properties. The most common and in demand in construction are, for example, types such as sandwich panels, carbon fiber panels, layered materials, textolites, fiberglass. All of them have high performance characteristics and a decorative effect.

The composite is used not only in the construction of residential buildings. It is difficult to imagine a bridge or dam that would not use carbon fiber panels. Various architectural elements, such as arches or domes, are also often created using composite materials. This is beneficial for developers, since it provides them with significant savings on the construction of structures, installation, storage and transportation of material, and at the same time reliability, quality, etc. performance characteristics the future building does not suffer in any way.

Designers use composites in modeling. Original colors, the ability to create unusual fancy shapes - all this can be seen if you consider all kinds of composite materials at www.hccomposite.com. With such resources, you can create truly unusual architectural structures that will also be reliable and durable.

Types, characteristics and properties

All composite materials are made using a similar structure - they have a reinforcing substance and a matrix. Reinforcement is what transfers physical and Chemical properties, is its basis. And the matrix gives the product its shape, fixing the reinforcement in a certain way.

We can highlight some examples of the most common composites in construction:

• Concrete. Their matrix can be either traditional, cement, or created on the basis of new technologies - polymer. There are a huge number of types of concrete, they differ in their properties and scope of application - from ordinary to decorative. Modern concretes Their strength is close to that of metal structures.
• Organoplastic composites. Their main filler is synthetic fibers; occasionally they are also used. natural materials. The matrix is ​​usually various resins. Organoplastics are quite light, withstand impacts well, resist dynamic loads, but at the same time they do not withstand stretching and bending well. Wood composite materials are also classified as organoplastic materials.
• Fiberglass plastics are reinforced with glass fibers, and special synthetic resins or thermoplastic types of polymers are used as a forming matrix for their production. The material is stable, durable, has low thermal conductivity, but at the same time freely transmits radio signals.
• Carbon fiber reinforced plastics are a combination of hydrocarbon fibers and various polymers. They have higher elasticity than fiberglass, are lightweight and quite durable.
• Textolites are layered materials reinforced with fabrics based on various fibers. The canvas blanks are pre-impregnated with resin and then pressed using high temperature mode, obtaining a sheet ready for use. Since fillers can be very different, the properties also vary significantly.

Advantages, disadvantages and applications

Since composites are quite effective, their use in construction is quite common due to the number of advantages of these materials.

• The products are very durable; some types of composite materials, for example, fiberglass, can compete with metal in their strength. At the same time, they are flexible and tolerate various impacts well.
• Composites are distinguished by their lightness compared to their analogues. Lightweight beams made from fiberglass are much better suited for creating floors in large spaces than metal beams. The resulting structure will not lose in strength and quality, but at the same time requires much less effort during installation work.
• The materials are highly resistant to aggressive environments, so they can be used to create not only internal structures, but also used for external, exposed to sunlight, precipitation and sudden changes in temperature.
• Chemical reagents are not harmful to composite materials, so they can be used, for example, to build warehouses where chemicals will be stored.
• Thanks to new technologies, modern composites are no longer a fire hazard; they do not allow flames to spread, practically do not smoke and do not emit dangerous toxic substances.

Composites have not only advantages, but also disadvantages that hinder their spread in the construction market.

• High cost is the main problem of composite materials. Their production requires special raw materials and modern equipment, which is why the finished products are quite expensive.
• The materials are hygroscopic, that is, they easily absorb moisture, which leads to further destruction. Therefore, they must be additionally strengthened during production with moisture-resistant protective agents.
• Some composite materials have low repairability, which increases the cost of their operation.

Composite materials, like any other, have their advantages and disadvantages.

How justified is the use of composites? Depends on specific goals, conditions, and overall budget. However, modern technologies allow us to invent new forms and types of such materials, so perhaps in the future they will become less expensive and more common, and will also have improved characteristics.

A number of areas of application of PCM in the construction industry in Russia and abroad, the advantages and disadvantages of PCM in comparison with traditional materials are considered. The trends in the development of technologies for the manufacture and use of such products as composite reinforcement and composite bridge decks are presented. The main limiting factors for the development of the PCM market for construction purposes in Russia have been identified.

Currently, the global market is witnessing an increase in the use of PCM in the construction industry. Thus, in 2010, the volume of the polymer composite materials (PCM) market in the “construction” segment amounted to ~3.1 million dollars (~17% of the total volume). According to experts, the volume of this segment will increase by 2015 to $4.4 million. The use of PCM in construction makes it possible to reduce the weight of building structures, increase corrosion resistance and resistance to adverse climatic factors, extend the time between repairs, and carry out repairs and strengthening of structures with minimal expenditure of resources and time. However, it should be noted that the development of the domestic PCM market for construction purposes, as well as the entire PCM market as a whole, is significantly inferior to the global one. In recent years, a number of measures have been taken aimed at developing technologies and production of PCM, including the formation in 2010 of the technological platform “Polymer Composite Materials and Technologies”. One of the initiators of the creation of a technological platform is VIAM, which takes an active part in the development of the composite industry and the formation of a market for composite materials and related technologies in Russian Federation not only in the aviation industry segment, but also in other segments, including the construction industry.

As noted above, the “construction” segment occupies a significant part of the PCM market. The main areas of application of PCM are: reinforcement and flexible connections; sheet piles and fencing; sandwich panels, window and door profiles; elements of bridge structures (pedestrian bridges, crossings, load-bearing elements, fencing elements, decking, cable-stayed cables); external reinforcement systems.

Taking into account the urgent need for large-scale construction of new and reconstruction of existing transport infrastructure facilities, the main attention in this article will be paid to such areas of application of PCM as composite reinforcement and elements of bridge structures.

Abroad, the widespread introduction of composite reinforcement as a reinforcing material for building concrete structures began in the 80s of the last century, primarily in the construction of bridges and roads. In the Soviet Union, research and development work on the development and use of composite reinforcement began in the 50s of the last century. In 1963, a workshop for the pilot production of fiberglass reinforcement was put into operation in Polotsk, and in 1976, “Recommendations for the calculation of structures with fiberglass reinforcement” were developed at NIIZHB and ISiA. Thus, the scientific and technical basis for the production of composite reinforcement was created back in the Soviet Union. Composite reinforcement based on a continuous fiber filler and a polymer matrix has a number of significant advantages compared to steel reinforcement (including those with anti-corrosion coating), including low density (4 times lighter than steel), high corrosion resistance, low thermal conductivity, dielectric properties , higher strength. Low density and high corrosion and chemical resistance are especially important in the construction of transport infrastructure (roads, bridges, overpasses), coastal and port structures.

In recent years, in Russia there has been a sharp increase in interest in the production of composite reinforcement intended for reinforcing concrete building structures. Glass fiber, continuous basalt fiber, and carbon fiber can be used as a reinforcing filler in reinforcement. The most common method of manufacturing composite glass or basalt plastic reinforcement is non-filler pultrusion (needletrusion, plaintrusion). Among the domestic manufacturers of glass and basalt plastic reinforcement are Biysk Fiberglass Plant LLC, Galen LLC, Moscow Composite Materials Plant LLC and many others. Carbon fiber reinforcement is produced by Composite Holding Company. In table 1 and 2 show the characteristics of domestic and foreign composite reinforcement.

Table 1

Characteristics of Russian composite reinforcement

Characteristic
	fiberglass			carbon fiber
	TU 2296-001-20994511-2006 (Biysk Fiberglass Plant LLC)	TU 5714-007-13101102-2009 (Galen LLC)	TU 5769-001-09102892-2012 (Moscow Composite Materials Plant LLC)	TU 1916-001-60513556-2010 (HC "Composite")
Tensile strength, MPa

table 2

Characteristics of foreign composite reinforcement

Characteristic	Characteristic values ​​for composite reinforcement
	fiberglass		carbon fiber
	Glass V-rod HM (Pultrall)	Aslan 100 (Hughes	Aslan 200 (Hughes
Tensile strength at tensile strength, MPa
Tensile modulus of elasticity, GPa
Elongation at break, %

It can be seen that Russian samples of composite reinforcement are not inferior in characteristics to their foreign counterparts. However, composite reinforcement is not yet widely used in construction practice in the Russian Federation. One of the reasons for this, according to the authors, is the insufficient regulatory and technical framework regulating the production and use of composite reinforcement. Although reinforcement manufacturers have carried out significant work to facilitate the speedy creation of GOST for composite reinforcement, the development of a number of standards and recommendations for designers and builders is required. For comparison, in the United States, the Concrete Institute (ACI) in 2012 released the third edition of a design manual first issued in 1999, while domestic recommendations for the design of structures with fiberglass reinforcement were developed in 1976. In addition, a more active use of composite reinforcement is hampered by the limited experience of working with it by both builders, designers and architects.

Currently, two main trends in the development of technology for the manufacture of composite reinforcement can be identified abroad: the use of two-layer reinforcement with a composite core reinforced with continuous fibers and an outer shell reinforced with chopped fiber filler, and the development of technologies for the manufacture of reinforcement using a thermoplastic polymer matrix. As an example, consider the developments of Composite rebar technologies Inc. and Plasticomp LLC. The first development of the University of Oregon is a hollow composite reinforcement and a method for its manufacture. Composite reinforcement includes a hollow core consisting of a thermosetting resin reinforced with continuous fibers, and an outer layer - a shell consisting of resin reinforced with chopped fibers. The outer shell is chemically and physically bonded to the core at one point in a continuous process. The outer and inner diameters of the reinforcement, their ratio, as well as the composition of the outer shell can be varied within fairly wide limits, which provides significant opportunities for adapting the product to the needs of a wide range of consumers. Among the advantages of such composite reinforcement, it is worth noting the possibility of using the cavity inside the core for laying electrical or fiber optic cables and placement of structural condition sensors, they can also be used to supply coolant and thus create a non-freezing bridge span. The presence of a hollow core will allow the reinforcement sections to be connected to each other, which will also expand the ways of its application. The outer layer, reinforced with chopped fiber, protects the core from mechanical damage during transportation and use, and also prevents the penetration of moisture into the reinforcement core.

The second development of Plasticomp LLC is a technology for manufacturing composite reinforcement using a thermoplastic matrix. The technological process begins with the production of a premix by pushing a continuous fibrous filler into a melt stream of a thermoplastic binder under high pressure and moving at high speed. A rotary knife located along the flow path cuts the fibrous filler-matrix mixture into short sections. Next, a screw mixer mixes the chopped fiber and thermoplastic matrix into a molten compound suitable for further extrusion. The resulting compound is fed into the T-shaped extruder head, where it is applied to a continuous reinforcing filler pre-impregnated with a thermoplastic polymer (for example, using classical pultrusion technology). Thus, a composite reinforcement based on a thermoplastic polymer matrix is ​​obtained, consisting of a core reinforced with a continuous fiber filler and an outer shell also made of a thermoplastic matrix reinforced with chopped fiber. The advantages of such a system are the greater resistance of the thermoplastic matrix to impacts and the formation of microcracks, the ability to heat and give the required shape to the reinforcement bar, the possibility of using recycled polymer raw materials and recycling the composite reinforcement itself. In addition, the use of recycled materials for the thermoplastic matrix, as well as the potential speed-up of the product manufacturing process (no resin curing time is required, as is the case with thermoplastic), can make the process more cost-effective than traditionally used composite rebar manufacturing technologies.

The main directions for the development of domestic production of composite reinforcement are the use of continuous basalt fiber as a reinforcing filler and modification of binder compositions and technological equipment in order to improve properties and increase production productivity.

Due to its low density and high resistance to negative impacts environment, PCMs can provide significant advantages over materials traditionally used in the construction of infrastructure, including bridge construction. Bridges, overpasses, overpasses are complex engineering structures that are subject to high requirements for reliability and durability. IN North America and Europe, active work is underway on the use of PCM in bridge construction. Bridges using PCM elements have been built for more than 15 years, and the volume of construction of such bridges is increasing. The class of bridges is also changing - from the first experimental pedestrian bridges to road bridges up to 20 m long. In foreign countries, the main areas of application of PCM in bridge construction are composite reinforcement, bridge decks and pedestrian bridges. Work is underway to develop and create cable-stayed cables made of PCM, as well as prefabricated bridges using load-bearing structural elements made of PCM. According to the author of the work, the most promising areas of application of PCM are pedestrian bridges and bridge decks. It is worth noting that in the Russian Federation, work is actively underway to develop technologies for the manufacture and design of pedestrian composite bridges; a number of facilities have been built and are successfully operating, while the development, design and use of bridge decks made of composite or hybrid materials using PCM for road and railway less attention is paid to bridges.

Bridge decks used abroad are divided according to the method of installation: laid on bridge supports or on longitudinal beams; and also by structure: multicellular (such as honeycomb structures) or sandwich panels (composite slabs with foam core between them). In the manufacture of decking, pultrusion and winding are used (the production of slabs and tubular/box-shaped structures between the slabs), and for the manufacture of sandwich panels, RTM technology is used. Glass fiber is used as a continuous fibrous reinforcing filler, and polyester, epoxy and vinyl ester resins are used as a polymer matrix. To connect the structural elements of the deck, gluing and/or mechanical fastening is used. The main methods of attaching PCM flooring both to supporting elements and to each other are mechanical method(usually using a bolted connection) and gluing. The traditionally used mechanical fastening method is a reliable and proven method, however, the need to make holes for fastening in the flooring elements worsens the strength characteristics and increases the sensitivity of the structure to environmental factors. The adhesive fastening method is more progressive, since it provides a strong and quick connection without disturbing the structure of the material (there is no need to make holes for fasteners), however, there are a number of disadvantages, such as the difficulty of meeting the requirements for surface preparation and environmental conditions when gluing during work on site, the current lack of methods for reliable non-destructive quality control of gluing on site - adhesive bonding does not work well in terms of “delamination”.

To increase the reliability and strength characteristics of decking, as well as reduce their cost, work is underway to create hybrid decking using concrete or reinforced concrete elements. In addition, it is possible to use various technological methods. Thus, the method described in the work of externally wrapping a decking, consisting of box-shaped profiles made by winding and composite sheets obtained by pultrusion, with a reinforcing filler makes it possible to increase the load-bearing capacity of the decking and its rigidity.

In addition to such advantages of PCM decking as low density, which allows reducing the load on supports and reducing their material consumption, ease of installation (requires equipment with a lower load capacity, simpler installation technology) and high corrosion resistance, which reduces operating costs, there are a number of disadvantages and problems. Among the disadvantages is the high cost of composite decking (in the USA, the cost of PCM decking is 2 times higher than the cost of a similar reinforced concrete deck); difficulties with development efficient designs panel-to-panel and panel-to-longitudinal beam fastenings; lack of comprehensive design standards and guidelines; insufficient amount of data on strength characteristics under the combined influence of mechanical loads and environmental factors. In this regard, relevant works are devoted to fastening systems, the development of recommendations for the design and operation of composite decking, methods for predicting the strength, nature of destruction and fatigue life of PCM decking. Work on the use of “smart” composites, the integration of sensors of the stress-strain state of a structure into its composite elements and the use of modern systems diagnosing the condition of the structure.

In conclusion, it should be noted that there is a lag behind the United States, a number of European countries and China in a number of positions:

In the field of development of regulatory and technical documentation for the production and use of composite reinforcement and bridge decks made of PCM;

In the field of manufacturing technologies for PCM products for construction purposes.

Significantly less experience has been accumulated in the use of PCM in building structures and operation of such structures. There are virtually no domestic equipment manufacturers. However, increasing interest in the use of PCM in construction, a number of government measures to stimulate the market for composite materials, as well as the efforts of composite manufacturers to improve the regulatory and technical framework create favorable conditions to intensify work on the development and use of competitive domestically produced PCM products in the construction industry.

LITERATURE

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their differences from other traditional products

Without modern innovative technologies it is impossible to create latest solutions in the field of construction, as well as in commercial and residential construction, in the restoration of highways. Previously, these technologies used products made of steel, aluminum, and reinforced concrete, but today there is nothing more modern, durable and environmentally friendly than synthetic composite products made from polymer compounds.

As a rule, the composition of a composite material includes two types of components: a binder (matrix) or a reinforcing material. Thanks to the matrix, the product is provided with a certain shape and fixes the reinforcing material. Due to this, the matrix is ​​strengthened and transfers its properties to the product. Such a combination of these characteristics in substances is guaranteed to create a fundamentally new composite material.

The type of reinforcing substance determines the types of composite materials. According to this characteristic, they can be filled, have a fibrous, layered structure, and also be bulk and skeletal. The properties that a particular composite material has depends on the combination of physical, mechanical, and chemical characteristics that the matrix and the reinforcing material will have. Composite materials have recently become very popular and are very often used in various fields. This can easily be explained by the fact that these materials have a number of advantages that distinguish them from other traditional products.

The main advantages of composite materials include properties due to which synthetic materials have higher strength and resistance to deformation, tearing, compression, shearing and twisting. In addition, polymer synthetic materials are lighter in weight, convenient for transportation and installation. At the same time, there is also a good opportunity to optimize costs for these items.

The composite is resistant to the chemical effects of aggressive environments, and precipitation will not harm it either. The material is not afraid of sudden temperature changes and can be used effectively in different temperature conditions under unfavorable climatic conditions. In addition to all of the above, we can say that this material is completely safe for the environment and fully complies with all environmental requirements.

Features of composites.

Composite materials have their own characteristics that distinguish them very favorably from traditional building materials. New materials are created thanks to the natural desires of developers to improve the characteristics of structures that are currently in use, as well as those that are being put into operation. These technologies, when mastered by builders, provide new opportunity to develop more modern structures and technologies. One of the most striking manifestations of the development features polymer materials, is the fact that the composite is very widely used in various fields of construction.

Composite materials can quite rightly be called the raw material for twenty-first century construction. They have the highest physical and mechanical properties at low density. They are stronger than steel and aluminum alloys.

Composite materials are complex heterogeneous (dissimilar) structures that are formed by combining reinforcing elements with an isotropic binder. The reinforcing element can be in the form of a thin fiber, thread, rope or fabric, provides the physical properties of this material, which is guaranteed to be strong and rigid in the direction of the fiber orientation, and the matrix ensures the integrity of the structure. Current composite materials have specific strength and rigidity in the direction of reinforcement, and this figure can be more than 4 times higher than that of steel, aluminum reinforcement and products made of titanium alloys.

Using the external load on the material at the moment of destruction, the strength of the structure is determined. Stiffness or modulus of elasticity refers to the characteristics of materials that determine the displacement of structures under the influence of external stress. This characteristic is directly proportional to the phenomenon of loss of stability of the structure, at the moment when variable values ​​develop in it and a large load on the base occurs. At such moments, the supporting structure may be destroyed. Specific strength and specific stiffness is the ratio of the ultimate stress to the elastic modulus in accordance with the density of the material. With higher specific properties of materials, the structure will be lighter and stronger and the threshold for loss of stability will be much higher.

To reinforce materials, as a rule, high-strength fibers from glass, basalt, aramid, carbon, boron, organic compounds, as well as metal wire and whiskers are used. These reinforcement components can be used in the form of monofilament, thread, wire, strands, as well as fabric or mesh.

In a composite material, the matrix is ​​the most important component, thanks to which the integrity of the composition is ensured, its shape and the location of the reinforcing fiber are fixed. Thanks to the matrix material, it is possible to provide an optimal method for manufacturing elements, as well as select the appropriate level of operating temperature of the composite, resistance to chemical irritants, and behavior of the composite under the influence of precipitation and elevated or reduced temperatures.

The matrix can be materials made of epoxy, polyester and some other thermosetting, polymer and thermoplastic materials. In composite materials with a fibrous structure, the stress that occurs under the influence of external loads is absorbed by high-strength fibers. They also ensure the strength of the structure in the direction of the reinforcement. Due to the directional nature of the properties of composite materials, they have excellent qualities. Composite materials can be used to create structures with properties that were specified earlier and that best correspond to the specifics and properties of the work. Thanks to the variety of fibers and materials for the matrix, as well as the scheme according to which the reinforcement process occurs when creating a composite, it is possible to purposefully regulate strength, rigidity, operating temperature level, chemical resistance and other properties.

The wide possibilities of the technological process for producing materials of different shapes determine the wide range of composite materials that can be made. Subject to all technologies, it is necessary to use special units and equipment, equipment and other machines. With this technique, reinforcing bars can be bent in different directions for the most unusual construction solutions.

In this section, we can look in detail at what is used to make composite materials, what type of reinforcing material and matrix can be used, as well as what types of technologies are used in production.

Composite materials and technologies.

Reinforcing materials for composites:

		1. Fiberglass. Composite materials production technology uses reinforcing materials such as fiberglass. This material is a derivative form of glass melted by extrusion. During the manufacturing process, molten threads are passed through spinning filters, which become very strong. This material, unlike glass products, does not break or break, but at the same time remains very durable and allows the production of fabrics and cables from it for various purposes. As a rule, it is very often and widely used in the construction of houses, foundations for capital construction, as well as reconstruction work on highways. Fiberglass is also used for thermal insulation of facades and sound insulation. Fiberglass is also regularly used for finishing and structural materials, such as fiberglass reinforcement, cladding panels, boards, and fiberglass tiles. This material is fire resistant, so it is safe for any premises, both commercial and residential. If you compare fiberglass with conventional materials, the composite compares favorably in price. This technology allows the production of materials with a specific strength higher than the specific strength of steel. It is also very important that fiberglass can be given absolutely any shape.
		2. Basalt fiber. Another very popular material for the production of composites is basalt fiber, which is made from rocks that are structurally similar to basalt, basanite and gabradiabase. Combinations of these materials are also used. This fiber is produced in special ovens at high temperatures. The materials melt and flow freely through a special outlet. Basalt fiber can be of two types - staple and continuous; the differences between these two types are in the properties of the material itself. It is very widely used in the production of filters. This material is lightweight and durable, which makes it successfully used for reinforcement concrete structures. Basalt fiber is used in construction, due to which the structure significantly improves its qualities in terms of impact strength, frost resistance and water resistance of structures. Basalt fiber is used to make thermal insulation and fire protection, basalt-plastic reinforcement, fillers for ultra-fine filters, mixtures for concrete reinforcement, insulation of various machines that operate in adverse weather conditions and at very low temperatures. Basalt mats and fiber slabs are made from this material, which are subsequently used for lining pipelines. The main advantages of products made from basalt fiber are properties such as high resistance to chemical attack, low weight and a very favorable price. The porous structure of basalt fiber does not inhibit transmission capacity, and fiber made from basalt fibers does not corrode and does not have a cathodic effect, unlike metal products.
		3. Carbon fiber. Carbon fiber is also used in the production of composite materials. This material is a substance that contains only carbonate carbon. First manufactured and patented by Thomas Edison in the late 19th century, this material is a super-strong element that can be produced by treating organic fibers at high temperatures. The production of composite materials from carbon carbonate is a very complex process that is carried out in a comprehensive manner. After the material has completely hardened and graphitized, the amount of pure carbon in the fiber will be about 99%. Carbon composites are mainly used in the production of fragments aircraft, as well as devices that experience constant high loads. This material melts at a very high temperature, so it is successfully used for thermal insulation in the production of vacuum furnaces. In addition, the carbon composite has the ability to effectively absorb electromagnetic waves, which is widely used in radio engineering. Carbon fiber has extremely high chemical resistance. It is used in production spacecraft, supersonic aircraft, racing car parts, screens that absorb electromagnetic waves, as well as for the production of professional sports equipment. If we compare carbon fiber with traditional materials, the new technological material is lightweight and durable, making it possible to replace any plastic and metal.
		4. Aramid fiber. Aramid fiber is also very often used in the production of composite materials. It is also sometimes called Kevlar. It is a durable synthetic material obtained from copolymer threads by heating them to five hundred degrees. This material comes in several varieties, such as para-aramid and meta-aramid fibers. The latter have very high heat resistance, so they can be used to create clothing accessories. Aramid fibers are widely used in many types of industries. They combine lightness and strength. They are used for the design of aerospace vehicles, racing car parts, as well as for the production of workwear and equipment for racers, the military, firefighters and other special fields. It is important that aramid is used for the production of body armor, cable braiding, heavy-duty cables, fire-retardant clothing, and car tire reinforcement. This material is very high level tensile strength, as well as high resistance to chemical attack and high melting point. Thanks to these qualities, aramid fiber has practically no analogues, which makes it possible to produce rovings from it. They are bundles assembled from threads of this fiber. Rovings can vary in density or thickness, this depends on the number of fiber threads in the bundle, the diameter of the thread, and the type of raw material from which it is produced.

Rovings are produced based on the fibers described above. Roving- is a bundle assembled from continuous fiber threads. Rovings differ in: density or thickness - the number of fiber threads in a bundle, the diameter of a single thread, the type of raw material from which they are made, the type of lubricant and purpose. They have their main designation in tex (“tex”) - this is the weight of 1 kilometer of roving in grams. Rovings are supplied in reels or coils, hermetically packed in film.

		Glass roving is a continuous strand woven from glass filament. In order to indicate the thickness of the roving, which depends on how many threads are included in it, the tex value (“tex”) is used. Basically, roving is produced on special woven-winding units using individual fiberglass strands. The finished glass rope is prescribed with a special thermoplastic glue called a lubricant. Using glass roving, it is possible to produce fittings, various profiles, as well as rotational cylinders, pipes, tanks, which can be used to store and transport chemical reagents. Roving can be used as a reinforcing material. Due to the fact that its price is very affordable, the material is light and plastic, it is very often used in finishing work and decorating facades. Also, roving is used for filling plastics, making pultruded profiles, building reinforcement, thermoplastic reinforcement, as well as for making fiberglass, improving the quality of asphalt concrete pavement, as well as for making pipes and containers that are used under high pressure. Products based on glass roving have many advantages. First of all, it is affordable, high strength, safe, resistant to adverse conditions, immune to damage and can be used as a thermal insulation material for a long time.
		Basalt roving is, in fact, a rope in which solid basalt threads are evenly stretched. To make threads, coarse-grained basalt crushed stone is crushed, sifted, washed and dried. Afterwards, this composition is loaded into recuperative smelting furnaces, where the crumbs are heated to 1500 degrees. The composition begins to melt and flow into the feeder, after which it enters the spinneret feeder, from where it is drawn out using a special device that forms continuous threads. The spinning method determines whether the roving will be single-rolled with straight threads or folded. The high strength and immunity of the substance to aggressive environments allows roving to be used in the production of pipes for transporting chemicals, gases at high temperatures and fuels and lubricants. Basalt-based roving is also used for the manufacture of fabric and prepregs, construction fittings, plastic reinforcement and concrete products, for the manufacture roof installations and facing material, in the production of thermal insulation mats, to improve asphalt pavement in construction and reconstruction work on roads.
		Carbon roving is strands woven from single carbon fibers. The fiber threads that make up the material have a very small diameter, up to 15 microns, due to which the bundle has very high tensile strength. Also, the material is very little weight. During production, they are heated to 1700 degrees and chemically treated, resulting in carbonization. Rovings are sold in coils, but they must be stored in a dry place. Carbon roving can be used in construction, shipbuilding and aircraft manufacturing. The high mechanical properties that rovings have make it possible to laminate and reinforce systems that contain epoxy, vinyl, or polyester resin. Rovings containing carbon filaments are used for medical purposes, in construction, electrical engineering, aircraft and rocketry, in the oil industry, the space industry, and in the manufacture of sports equipment. The advantages of carbon roving are obvious - compared to traditionally used materials, it has high tensile strength, does not rust, and can withstand extremely high temperatures. The carbon fibers that make up the tow are capable of trapping alpha particles, and their properties make it possible to create seamless products of complex shapes.

Types of composite binders. Composite matrices:

1. Epoxy binder.

Composite binders and matrices can be of various types. Very often an epoxy binder is used, which is formed from a substance of the epoxy group. This material has a three-dimensional structure that is resistant to alkaline, acid and halogen solutions. Epoxy binders are widely used in a wide variety of industries. It is used to glue various types of reinforcing elements and obtain a high-quality composite material. It is also used as a sealing agent for electronic devices, various circuit boards and other devices. This binder is widely used in construction work, as well as for domestic purposes.

2. Polyimide binders.

No less famous and popular is the polyimide binder. These substances belong to the heat-resistant class of materials with a complex structure, a large number of connections between particles. Due to the heat resistance of these particles, this material is used as a binder in thermal protection systems for spacecraft, in the rocket industry, and in many other products that are used at aggressively high temperatures. When choosing this type of binder, it is necessary to take into account the toxicity of this material, the very high level of viscosity at normal temperatures, and the fairly high price, which is associated with a long production process.

3. Polyester binder.

Polyester binders are a product that is formed during the polymerization of esters with saturated particles. The peculiarity of this substance is that it contains a high percentage of styrene, which appears during the polymerization process. This can lead to two negative features of this material - in addition to its porous structure, it can also be toxic. However, this binder is cheaper than an epoxy binder, and also has a lower viscosity and is easier to apply.

4. Phenol-formaldehyde binder.

The phenol-formaldehyde binder is characterized by the fact that the operating temperature level can be very high. It is also important that this material is very accessible, since it is a by-product of the synthesis of petroleum products. It has good fluidity, thanks to which it is possible to obtain products of various configurations. Thanks to the use of this binder material, it is possible to obtain a well-impregnated reinforcing element in the composite material.

5. Carbon binder.

The carbon binder will make it possible to produce a product with very high physical and mechanical properties. Its linear coefficient thermal expansion≈10-7-10-8; thermal conductivity coefficient up to 1000 W/m.K; elastic modulus E≈600 GPa. This substance also has excellent electrical properties, as well as high chemical inertness. This bond is used in the manufacturing of motor nozzle blocks, heat-resistant tiles, and also in electrical components.

6. Cyanate ester binder.

The cyanate ether binder has high radiation resistance, variable mechanical properties that depend on processing time, as well as low moisture absorption and low dielectric constant. In addition, cyanate ester binders are very resistant to temperature changes, which in other materials can cause microcracks and subsequent disintegration of the substance. Due to these properties, cyanate ester is widely used in composite materials for the space industry. The substance is used for the manufacture of reflectors, radomes, antennas, reflectors, as well as dimensionally stable spatial structures.

GELCOATS To coat composite materials, modified resins called gelcoats are used. They are made from polyester or epoxy resin, due to which the composite will have a smooth glossy surface. The gelcoat must be applied using a spray gun, which guarantees an even layer without peeling. In the process of forming a part, a special matrix-type gelcoat is often used, which can be applied in a thicker layer. As a rule, fiberglass products are coated with this resin, which creates additional protection and extends the life of the materials. Also, using gelcoat, the surface is painted in the required color.

Information about technologies for the production of composite materials can be read

Use of composite materials in construction

Inexpensive and versatile, concrete is one of the best building materials in many offerings. A true composite, typical concrete consists of gravel and sand bonded together in a cement matrix, with metal reinforcement usually added to enhance strength. Concrete behaves excellently under compression, but becomes brittle and weak under tension. Tensile stresses, as well as plastic shrinkage during curing, lead to cracks that absorb water, which ultimately leads to corrosion of metal reinforcement and a significant loss of concrete integrity when the metal fails.

Composite reinforcement has established itself in the construction market due to its proven resistance to corrosion. New and updated design guidelines and test protocols make it easier for engineers to select reinforced plastics.

Fiber-reinforced plastics (fiberglass, basalt plastic) have long been considered as materials that can improve the characteristics of concrete.

Over the past 15 years, composite rebar has moved from an experimental prototype to an effective substitute for steel in many projects, especially as steel prices have risen.

Composite Meshes in Precast Concrete Panels: High potential C-GRID carbon epoxy meshes are replacing traditional steel or rebar in precast structures as secondary reinforcement.

C-GRID is a large carbon/epoxy resin tow grid. Used as a replacement for recycled steel mesh reinforcement in concrete panels and architectural applications. The mesh size varies depending on the concrete and type of aggregate, as well as the strength requirements of the panel

The use of short fibers in concrete to improve its properties has been an established technology for decades, even centuries, considering that in the Roman Empire mortars were reinforced with horsehair. Fiber reinforcement enhances the strength and elasticity of concrete (the ability to undergo plastic deformation without fracture) by retaining part of the load when the matrix is ​​damaged and preventing crack growth.

The addition of fibers allows the material to deform plastically and withstand tensile loads.

Fiber-reinforced concrete was used to make these prestressed bridge beams. The use of reinforcement was not required due to the high elasticity and strength of the material, which was given to it by steel reinforcing fibers added to the concrete mixture.

Aluminum composite material is a panel consisting of two aluminum sheets and a plastic or mineral filler between them. The composite structure of the material gives it lightness and high strength combined with elasticity and resistance to fracture. Chemical and paint surface treatment provides the material with excellent resistance to corrosion and temperature fluctuations. Thanks to the combination of these unique properties, aluminum composite material is one of the most popular in construction.

Aluminum composite has a number of significant advantages, ensuring its growing popularity as a finishing material every year.

Minimum weight combined with high rigidity. Aluminum composite panels are characterized by low weight due to the use of aluminum cover sheets and a lightweight core layer, combined with high rigidity due to the combination of the above materials. When used on façade structures, this circumstance distinguishes aluminum composite materials from alternative materials, such as sheet aluminum and steel, ceramic granite, and fiber cement boards. The use of aluminum composite material significantly reduces the overall weight of the ventilated façade structure. composite concrete aluminum metal

Aluminum composite material can resist torsion. The reason is the application of the top layer by rolling. Flatness is ensured by the use of rolling instead of conventional pressing, which gives high uniformity of layer application. The maximum flatness is 2 mm per 1220 mm length, which is 0.16% of the latter.

• - Stability paint coating to environmental influences. Thanks to the extremely stable multi-layer coating, the material does not lose color intensity for a long time under the influence of sunlight and aggressive atmospheric components.
• - Wide selection of colors and textures. The material is produced with a coating made of paints: solid colors and metallic colors in any range of colors and shades, stone and wood coatings. In addition, panels are produced with chrome and gold coating, panels with a textured surface, panels with a polished coating of of stainless steel, titanium, copper.

Aluminum composite panels have a complex structure formed by aluminum sheets and a central layer of filler. The combination of these materials provides the panels with rigidity combined with elasticity, which makes aluminum composite materials resistant to loads and deformations created environment. The material does not lose its properties for an extremely long time.

The material's resistance to corrosion is determined by the use of aluminum alloy sheets in the panel structure, protected by a multi-layer paint coating. In case of damage to the coating, the surface of the sheet is protected by the formation of an oxide film

The composite structure of the aluminum composite material panel provides good sound insulation by absorbing sound waves and vibrations.

The panels are easily amenable to such types of mechanical processing as bending, cutting, milling, drilling, rolling, welding, gluing, without damaging the coating or disrupting the structure of the material. Under loads arising during the process of bending the panels, including the radius, no delamination of the panels or damage to the surface layers, such as cracking of aluminum sheets and paintwork, is observed. During production at the factory, the panels are protected from mechanical damage by a special film, which is removed after completion of installation work.

The panels easily take on almost any given shape, such as a radius. The suitability of the material for soldering allows achieving complex geometry products, which is impossible with any other facing material except aluminum, over which aluminum composite materials are significantly superior in weight.

The use of aluminum composite material allows the creation of cladding panels of various sizes and shapes, making this material indispensable for solving complex architectural problems.

• - Long service life. aluminum composite material is resistant to environmental influences such as sunlight, precipitation, wind loads, temperature fluctuations for a long time, thanks to the use of a stable coating and the combination of rigidity and elasticity achieved in the material. The estimated service life of the panels outdoors is approximately 50 years.
• - Minimal maintenance during operation. The presence of a high-quality coating helps the panels self-clean from external contaminants. The panels are also easy to clean with non-aggressive cleaners.

Combined materials reinforced with either fibers or dispersed solid particles offer two promising paths.

The first ones introduce the finest high-strength fibers of glass, carbon, boron, beryllium, steel or thread-like single crystals into an inorganic metal or organic polymer matrix. As a result of this combination, maximum strength is combined with a high elastic modulus and low density. Composite materials are precisely such materials of the future.

Composite material is a structural (metallic or non-metallic) material that contains reinforcing elements in the form of threads, fibers or flakes of a stronger material. Examples of composite materials: plastic reinforced with boron, carbon, glass fibers, strands or fabrics based on them; aluminum reinforced with steel and beryllium threads.

By combining the volumetric content of components, it is possible to obtain composite materials with the required values ​​of strength, heat resistance, elastic modulus, abrasive resistance, as well as create compositions with the necessary magnetic, dielectric, radio-absorbing and other special properties.

All these combined materials are combined into a system. Composite reinforcement systems are used for almost all types of structures:

• 1. Concrete and reinforced concrete
• 2. Metal (including steel and aluminum)
• 3. Wooden
• 4. Brick (stone) masonry.

They also provide a whole range of life support needs:

• 1. Protection from explosions, burglaries and damage.
• 2. Strengthening structures
• 3. Ballistic wall protection and explosion protection.
• 4. Protection of cables and wires from explosions

Let's consider the advantages and disadvantages of composite materials. Dignity:

• 1. Corrosion resistance
• 2. Tensile strength
• 3.Easy to use
• 4. Low labor cost
• 5. Short implementation time
• 6. No size restrictions
• 7. Extremely high fatigue strength
• 8. Does not require preservation
• 9. Possibility of using structures made of different materials

Flaws:

• 1. Relative cost of material
• 2. Limitation of scope

From the advantages and disadvantages stated above, we can conclude: that compared to conventional materials, composite materials have almost the only drawback - their rather high price. Therefore, there may be an opinion that this method is expensive, but if you compare the volume of materials consumed—steel for reinforcement—about thirty times more than composites. Other advantages of composite materials are a significant reduction in the cost of effort due to a reduction in production time, the use of labor and mechanical equipment. Consequently, composite reinforcement systems are the main competitors to the use of steel.

However, despite the advantages over conventional materials, composite materials have their characteristic disadvantages. These include low fire resistance, changes in properties when exposed to ultraviolet radiation, and possible crack formation when volume changes under conditions of limited freedom of deformation. The physical and mechanical properties of these materials make them susceptible to temperature fluctuations. At high temperatures they are prone to significant creep deformations.

When constructing foundations for almost any construction project, reducing loads on the ground and strengthening supports is achieved using steel reinforcement. However, this material is not only heavy, but also quite expensive. Attempts to find a more economical solution led to the creation of lightweight, durable and chemically inert composite materials. One of these is fiberglass reinforcement. You can buy fittings in Ufa from leading manufacturers of building materials.

How is fiberglass better than metals?

Among the advantages of fiberglass composite material are lower price, ease of transportation both to the construction site and at the site itself, the ability to use in conditions of high groundwater levels, as well as when they are chemically aggressive. Fiberglass reinforcement for foundations in Ufa turns out to be more profitable from an economic point of view and allows the building to last longer without the need to re-strengthen the foundation. Material properties:

• Long service. If metal reinforcement lasts up to a maximum of 40-50 years, then fiberglass does not react with moisture, heat, chemicals, and therefore lasts up to 40 years longer even in unfavorable environments.
• The material is environmentally friendly, it does not emit poisons, does not react to alkali and acids.
• Composite material can be easily shaped into any shape. The length and width of the reinforcement can be completely different. This means that at the design stage you can accurately calculate how much material will be used, and there will be no extra expenses.

The foundation, which is built using reinforcement based on composites, costs on average half as much. Even thin rods can be used as reinforcement.

Areas of application

Composites are successfully used in the construction of automobile and railways, underground structures - shopping centers, parking lots, pedestrian crossings, tunnels, as well as a wide variety of ASG facilities. Fiberglass can be used both in the construction of cottage villages and in the construction of nuclear power plants. Reduced load on the foundation, ease and simplicity of production of the material and its amazing strength characteristics open up more and more new areas of application for the material. As for private construction, bendable thin reinforcement bars can be transported to the construction site even in a passenger car. And when laying the foundation, you will not need to rent complex special equipment for excavation work.