What is FRP?
FRP is an abbreviation for Fiber Reinforced Polymer. FRPs have different applications in the construction industry. The most common use of FRP is the rehabilitation and reinforcement of concrete structures. FRP fibers can increase the strength of concrete by placing and installing them on concrete surfaces such as slabs, beams, columns, concrete walls and concrete foundation. The wide range of fibers applications consist of residential, commercial, offices and industrial buildings, heavy machinery and heavy equipment as well as water and sea structures such as dams and canals. In addition, FRP fibers can be used to repair engineering infrastructure such as road and rail bridges, water and chemical reservoirs, silos, and cooling towers.
Generally, FRP is a compound material, made up of two totally different parts. The first part is matrix and the other is the fiber. Its matrix is composed of some chemicals, such as epoxy resins and polyester. Additives of these materials economize and improve the properties of the compound. The role of the fibers is to provide sufficient mechanical strength in the FRP. Even though the matrix does not have a load carrying role, it is needed to protect the fibers from corrosion and damage. Matrix also carry out the load transfer in FRP. Another application of the matrix is to control the local buckling of the pressed fibers. Various factors affect the productivity of FRP fibers. Among these factors are the following:
- FRP fiber type
- The amount of FRP fiber
- How to place FRP fibers
- Heat transfer coefficient
CFRP is a fibrous filament that is obtained by heating of excellent materials, mainly carbon, in inert gas. The fiber made of carbon is referred to as carbon fiber, which at least contains 90% carbon and is obtained from specially controlled fiber pyrolysis. Black carbon fiber is non-solvent in water and odorless and has a very high resistance to corrosive materials, such as acids and solvents. In unidirectional fiber fabrics, the fiber is parallel to zero-degree orientation, while in bi-directional fabrics, the carbon fiber is placed in two directions, zero and perpendicular to it (90 degrees). Carbon fiber is used in many areas such as building retrofitting, defense industries, automotive, and many other important industries. The fibers used in making carbon fiber (CFRPs) are usually added by resins such as epoxy resin to elements and load carrying members of the structures to improve the shear, bending and torsion capacity of the members.
Carbon fiber has high heat resistance, which makes them categorized as non-explosive fibers. Also, their lightness and high resistance have resulted in widespread use of them in the composite industry and seismic retrofitting of structures. One of the most important advantages of carbon fiber, along with their light weight, is the high tensile strength of these fibers.
Carbon fiber is one of the mostly used fibers in the retrofitting and composite industry. This type of fiber has the most resilient coefficient of among other type of fibers. The linear thermal expansion coefficient of this fiber is very low at high and low temperatures, which causes the dimensional stability of the carbon fiber at different temperatures. Among the various advantages of carbon fiber, the most prominent one is the ratio of tensile strength to weight (carbon is about one third of the weight of steel and 5 to 10 times that of its resistance). In addition, carbon fibers and fabrics have good resistance to fatigue. The durability and long life against chemicals and impermeability against x-rays is one of the most prominent properties of carbon fiber. Besides, carbon fiber has excellent electrical conductivity. The ease of fabrication of lightweight composite and solid CFRP, and its heat resistance, distinguishes it from other engineering materials. Carbon fiber is an element of density 2,27 g / cm3 and has different crystalline forms. The carbon fiber strand formed from carbon fiber is far thinner than human hair in a diameter between 6 and 10 micrometers. The high price of carbon fiber is due to its high service life and high resistance over time, cost-effectiveness and being economical.
Carbon fiber and fabrics are offered in different elasticity modulus and tensile strengths and with unidirectional and bi-directional fiber fabrics by Afzir Company to produce composite materials of various industries and to reinforce various concrete structures. According to the needs of different industries, carbon fibers are offered in a wide range of fiber types from 3K to 50KK, with different weights and widths.
GLASS FIBER FABRIC
Fiberglass fibers consist of glass fibers, with warps of about 10 microns in thickness. The high tensile and chemical strength of the fibers has led to increasing use of them in the manufacture of parts for the aerospace, automotive, marine and building industries, furniture equipment and sports equipment. FRP fiber is the most common product for retrofitting, reinforcing and improving various structures in the building industry, and also for protecting various components in corrosive and chemical environments. FRP lining (isolating metal tubes and chemical protection in corrosive environments with pH Very high or low) are also widely used.
The GFRP glass fiber offered by Afzir company is the most popular and most consumable fiber used in the composite industry. The price of glass fiber in comparison with carbon and aramid fibers is very low, which has led to more glass fiber sales in recent years.
The main advantages of the glass fiber are as follows:
- The price of glass fibers is more suitable than other fibers.
- The high selling value of the glass fiber makes it available for various types.
- Tensile strength of glass fiber is high,
- Glass fiber is a good electrical insulator or, in other words, conductive glass fiber.
- The chemical resistance of the glass fiber is high and suitable for corrosive environments.
- Proper thermal resistance
ARAMID FIBER FABRIC
In general, the commercial definition of aramid is: a product in which a fiber material is formed that has a long chain of synthetic polyamide, in which at least 85% of aramid bonds are directly attached to two aromatic rings.
The aromatic polyamide (called Aramaid) was first introduced in the early 1960s by the Dupont company and branded by the name of Nomex. The main feature of this product was high resistance to heat. This product was used to provide protective coatings, air purification, thermal and electrical insulation and as a replacement for asbestos. The director of research and development at DuPont on Nomex, was Wilhelm Swiney, a Scottish scientist. Further research on aramides at the Dupont Company by a Polish chemist, Stephanie Kooleck, led to the creation of the Kraft Para-Aramide in 1973. At the moment, the Kevlar brand is known as the Aramid fiber in the industry. Also known as AFRP fibers.
Nowadays, various Kevlar fibers are used in the industry. Kevlar 49 is used for strengthening and reinforcement of concrete. The Kevlar 29, which has half of modulus of Elasticity of Kevlar 49 is used for applications requiring a very high impact resistance (such as bulletproof vests).
Kevlar fiber is lighter than carbon fiber and glass fiber and has the highest tensile strength among them. Aramid fiber is about 43% lighter than glass fibers and 20% lighter than carbon fiber. The low weight and high tensile strength of these fibers produce a stiff and impact-resistant structure. Bulletproof vest is one of the most successful applications of aramid fiber.