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Composites are materials consisting of two or more chemically distinct constituents on a macro-scale, having a distinct interface separating them, and with properties which cannot be obtained by any constituent working individually.
There are two categories of constituent materials: matrix and reinforcement. The reinforcement imparts its special mechanical and physical properties to enhance the matrix properties. Due to the wide variety of matrix and reinforcement materials available, the design potentials are incredible.
Miracle and Donaldson(2001) stated that the composites are categorized at two different levels. The first level of classification is based on the matrix constituent such as polymer matrix composite (PMCs), metal matrix composite (MMCs), and ceramic matrix composite (CMCs) whereas the second level of classification is derived from matrix constituent forms like particulate reinforced composite, flake composite, fiber-reinforced composite, and laminated composite.
Types of Composites in Construction
Composites are classified into two distinct levels; based on matrix constituents and their forms.
Composite Types Based on Matrix Constituents
There are three major types of composites based on matrix constituents. In each of these systems, the matrix is typically a continuous phase throughout the component.
1. Polymer Matrix Composite (PMCs)
It consists of various short or continuous
Lightweight, high stiffness, high strength along the direction of their reinforcements, abrasion resistance, and corrosion resistance are some properties of polymer matrix composite.
2. Metal Matrix Composite (MMCs)
Metal matrix composites are usually made up of aluminum to give it enough strength as it is less dense than iron, and hence is preferred in the aerospace industry. It is a material in which continuous carbon, silicon carbide, or ceramic fibers are embedded in a metallic matrix material.
Most common metal matrix composites are aluminum matrix composites. Major advantages of aluminum matrix composites are increased specific strength, specific stiffness, and elevated temperature strength in addition to improved wear resistance, lower density, and good corrosion resistance.
3. Ceramic Matrix Composite (CMCs)
These are materials consisting of a ceramic or carbon fiber surrounded by a ceramic matrix such as silicon carbide.
Composite Types Based on Matrix Constituents Forms
1. Particulate Reinforced Composites
Particulate reinforced composites are composed of hard particle constituents which are scattered in a softer matrix in an arbitrary manner. Metallic particle dispersed in metallic, polymeric or ceramic matrices is an example of particulate composite. A widely used particulate composite is concrete in which gravel is embedded in the cement paste.
2. Flake composites
This type of composite is produced by blending matrix material and thin flakes. Despite the fact that flakes dispersion in the matrix is random, the flakes can be made to align with one another forming a more orderly structure compared to particulate composites.
3. Fiber Reinforced Composites (Fibrous Composites)
It is composed of strong and stiff fibers which are held together by a matrix. Fibers act as primary load-carrying constituent due to their strong characteristics. The matrix serves as an agent to redistribute the loads from a broken fiber to the adjacent fibers in the material when fibers start failing under excessive loads.
This property of the matrix constituent contributes to one of the most important characteristics of fibrous composites, namely improved strength compared to the individual constituents.
Reinforcement composites are usually glass
4. Laminated Composites
Laminated composites are made from completely bonded thin elementary layers. These layers can be composites themselves; for instance, fibrous composite layer. This type of composite is the most commonly encountered laminated composite material used in high-performance structures.
- Composites are widely used in the aerospace industry for the construction of military and commercial aircraft and spacecraft structures.
- Composites provide significant improvements in structural response and corrosion response.
- Construction of structures such as Kodak exhibition pavilion, bridges, lighthouses, hydraulic construction, storage tanks, and door and window components
- Strengthening of deteriorated structures.
- Manufacturing of yacht, lifeboat, cruise ship, fishing boat.