Glass fiber reinforced concrete
Encyclopedia
Glass Fiber Reinforced Concrete (GFRC) is a type of fiber reinforced concrete
. Glass fiber concretes are mainly used in exterior building façade panels and as architectural precast concrete.
damage. In fact, the fibers provide reinforcement for the matrix and other useful functions in fiber-reinforced composite materials. Glass fibers can be incorporated into a matrix either in continuous lengths or in discontinuous (chopped) lengths.
, obtained by adhering and consolidating thin layers of fibers and matrix into the desired thickness. The fiber orientation in each layer as well as the stacking sequence of various layers can be controlled to generate a wide range of physical and mechanical properties for the composite laminate. However, GFRC cast without steel framing is commonly used for purely decorative applications such as window trims, decorative collumns, exterior friezes, or limestone like wall panels.
ns in the 1940s. The early work on glass fiber reinforced concrete went through major modifications over the next few decades
There are a number differences between structural metal and fiber-reinforced composites. For example, metals in general exhibit yielding and plastic
deformation
whereas most fiber-reinforced composites are elastic
in their tensile stress-strain characteristics. However, the dissimilar nature of these materials provides mechanisms for high-energy absorption on a microscopic scale comparable to the yielding process. Depending on the type and severity of external loads, a composite laminate may exhibit gradual deterioration in properties but usually would not fail in catastrophic manner. Mechanisms of damage development and growth in metal and composite structure are also quite different. Other important characteristics of many fiber-reinforced composites are their non-corroding
behavior, high damping capacity and low coefficients of thermal expansion.
Glass fiber reinforced concrete architectural panels have general appearance of pre-cast concrete panels, but are different in several significant ways. For example, GFRC panels will, on the average, weigh substantially less than pre-cast concrete panels due to their reduced thickness. The low weight of GFRC panels decrease superimposed loads on the building’s structural components. The building frame
becomes more economical.
of three or more materials bonded together to form a structural panel. It takes advantage of the shear strength
of a low density core material and the high compressive and tensile strengths of the GFRC facing to obtain high strength to weight ratios.
The theory of sandwich panels and functions of the individual components may be described by making an analogy to an -beam
. Core in a sandwich panel is comparable to the web of an -beam, which supports the flanges and allows them to act as a unit. The web of the -beam and the core of the sandwich panels carry the beam shear stresses. The core in a sandwich panel differs from the web of an -beam in that it maintains a continuous support for the facings, allowing the facings to be worked up to or above their yield strength without crimping or buckling. Obviously, the bonds between the core and facings must be capable of transmitting shear load
s between these two components thus making the entire structure an integral unit.
The load
carrying capacity of a sandwich panel can be increased dramatically by introducing light steel framing. The light steel stud framing will be similar to conventional steel stud framing for walls, except, that the frame is encased in a concrete product. Here, sides of the steel frame are covered with two or more layers of GFRC, depending on the type and magnitude
of external loads. The strong and rigid GFRC provides full lateral support on both sides of the studs, preventing studs from twisting and buckling laterally. The resulting panel is light weight in comparison with traditionally reinforced concrete, yet is strong and durable and can be easily handled.
Fiber reinforced concrete
Fiber-reinforced concrete is concrete containing fibrous material which increases its structural integrity. It contains short discrete fibers that are uniformly distributed and randomly oriented. Fibers include steel fibers, glass fibers, synthetic fibers and natural fibers...
. Glass fiber concretes are mainly used in exterior building façade panels and as architectural precast concrete.
Composition
Glass fiber reinforced concrete(GFRC) consists of high strength glass fiber embedded in a cementitious matrix. In this form, both fibers and matrix retain their physical and chemical identities, yet they produce a combination of properties that can not be achieved with either of the components acting alone. In general, fibers are the principal load-carrying members, while the surrounding matrix keeps them in the desired locations and orientation, acting as a load transfer medium between them, and protects them from environmentalEnvironmental quality
Environmental quality is a set of properties and characteristics of the environment, either generalized or local, as they impinge on human beings and other organisms...
damage. In fact, the fibers provide reinforcement for the matrix and other useful functions in fiber-reinforced composite materials. Glass fibers can be incorporated into a matrix either in continuous lengths or in discontinuous (chopped) lengths.
Laminates
A widely used application for fiber-reinforced concrete is structural laminateLaminate
A laminate is a material that can be constructed by uniting two or more layers of material together. The process of creating a laminate is lamination, which in common parlance refers to the placing of something between layers of plastic and gluing them with heat and/or pressure, usually with an...
, obtained by adhering and consolidating thin layers of fibers and matrix into the desired thickness. The fiber orientation in each layer as well as the stacking sequence of various layers can be controlled to generate a wide range of physical and mechanical properties for the composite laminate. However, GFRC cast without steel framing is commonly used for purely decorative applications such as window trims, decorative collumns, exterior friezes, or limestone like wall panels.
History
The potential for using a glass fiber reinforced concrete system was recognized by RussiaRussia
Russia or , officially known as both Russia and the Russian Federation , is a country in northern Eurasia. It is a federal semi-presidential republic, comprising 83 federal subjects...
ns in the 1940s. The early work on glass fiber reinforced concrete went through major modifications over the next few decades
Properties
The design of GFRC panels proceeds from a knowledge of its basic properties under tensile, compressive, bending and shear forces, coupled with estimates of behavior under secondary loading effects such as creep, thermal and moisture movement.There are a number differences between structural metal and fiber-reinforced composites. For example, metals in general exhibit yielding and plastic
Plastic
A plastic material is any of a wide range of synthetic or semi-synthetic organic solids used in the manufacture of industrial products. Plastics are typically polymers of high molecular mass, and may contain other substances to improve performance and/or reduce production costs...
deformation
Deformation
In materials science, deformation is a change in the shape or size of an object due to an applied force or a change in temperature...
whereas most fiber-reinforced composites are elastic
Elasticity
Elasticity may refer to:*Elasticity , continuum mechanics of bodies that deform reversibly under stressNumerous uses are derived from this physical sense of the term, which is inherently mathematical, such as used in Engineering, Chemistry, Construction and variously in Economics:*Elasticity , the...
in their tensile stress-strain characteristics. However, the dissimilar nature of these materials provides mechanisms for high-energy absorption on a microscopic scale comparable to the yielding process. Depending on the type and severity of external loads, a composite laminate may exhibit gradual deterioration in properties but usually would not fail in catastrophic manner. Mechanisms of damage development and growth in metal and composite structure are also quite different. Other important characteristics of many fiber-reinforced composites are their non-corroding
Corrosion
Corrosion is the disintegration of an engineered material into its constituent atoms due to chemical reactions with its surroundings. In the most common use of the word, this means electrochemical oxidation of metals in reaction with an oxidant such as oxygen...
behavior, high damping capacity and low coefficients of thermal expansion.
Glass fiber reinforced concrete architectural panels have general appearance of pre-cast concrete panels, but are different in several significant ways. For example, GFRC panels will, on the average, weigh substantially less than pre-cast concrete panels due to their reduced thickness. The low weight of GFRC panels decrease superimposed loads on the building’s structural components. The building frame
Frame
A frame is a structural system that supports other components of a physical construction.Frame may also refer to:-Engineering & construction:* A-Frame, a basic structure designed to bear a load in a lightweight economical manner...
becomes more economical.
Sandwich panels
A sandwich panel is a compositeComposite material
Composite materials, often shortened to composites or called composition materials, are engineered or naturally occurring materials made from two or more constituent materials with significantly different physical or chemical properties which remain separate and distinct at the macroscopic or...
of three or more materials bonded together to form a structural panel. It takes advantage of the shear strength
Shear stress
A shear stress, denoted \tau\, , is defined as the component of stress coplanar with a material cross section. Shear stress arises from the force vector component parallel to the cross section...
of a low density core material and the high compressive and tensile strengths of the GFRC facing to obtain high strength to weight ratios.
The theory of sandwich panels and functions of the individual components may be described by making an analogy to an -beam
I-beam
-beams, also known as H-beams, W-beams , rolled steel joist , or double-T are beams with an - or H-shaped cross-section. The horizontal elements of the "" are flanges, while the vertical element is the web...
. Core in a sandwich panel is comparable to the web of an -beam, which supports the flanges and allows them to act as a unit. The web of the -beam and the core of the sandwich panels carry the beam shear stresses. The core in a sandwich panel differs from the web of an -beam in that it maintains a continuous support for the facings, allowing the facings to be worked up to or above their yield strength without crimping or buckling. Obviously, the bonds between the core and facings must be capable of transmitting shear load
Shear stress
A shear stress, denoted \tau\, , is defined as the component of stress coplanar with a material cross section. Shear stress arises from the force vector component parallel to the cross section...
s between these two components thus making the entire structure an integral unit.
The load
Load
Load may refer to:*Structural load, forces which are applied to a structure*Cargo*The load of a mutual fund *The genetic load of a population*The parasite load of an organism...
carrying capacity of a sandwich panel can be increased dramatically by introducing light steel framing. The light steel stud framing will be similar to conventional steel stud framing for walls, except, that the frame is encased in a concrete product. Here, sides of the steel frame are covered with two or more layers of GFRC, depending on the type and magnitude
Magnitude
Magnitude Is A Part Of An EarthquakesMagnitude may refer to:In mathematics:*Magnitude , the relative size of a mathematical object*Magnitude , a term for the size or length of a vector...
of external loads. The strong and rigid GFRC provides full lateral support on both sides of the studs, preventing studs from twisting and buckling laterally. The resulting panel is light weight in comparison with traditionally reinforced concrete, yet is strong and durable and can be easily handled.