Composites are made up of two main components:

  • Reinforcement
  • Matrix

The reinforcement is composed of fibres or fragments that make up the majority of the composite material. It typically provides the composite with strength and rigidity. Surrounding the reinforcement is the matrix, which is the material that binds the reinforcement together.

A key feature of composites is that they are formed from two or more materials with different properties. The properties of a composite depend on the reinforcement and matrix used and are different from the individual materials that constitute it.

Examples of Composites

Let’s look at three composites:

  • Carbon-fibre-reinforced polymer – Carbon fibres serve as the reinforcement, while a polymer resin functions as the matrix. Carbon fibre composites are incredibly strong and lightweight, making them ideal for high-performance applications such as cars, aircraft, and sporting equipment.
  • Fibreglass – This composite has glass fibres as the reinforcement and a polymer resin as the matrix.
  • Reinforced concrete – This composite uses steel as the reinforcement and concrete as the matrix. The steel bars provide reinforced concrete with exceptional tensile and compressive strength.

Tensile strength is the maximum load a material can withstand before stretching and breaking. On the other hand, compressive strength is the capacity of a material to resist breaking under compression.

As a result, reinforced concrete is useful for supporting large buildings and structures.

A block of cement with a crack down the centre labelled "concrete" and a thinner slab of concrete with steel bars adding tensile strength labelled "reinforced concrete".

  • Aggregate is a material made up of loosely compacted particles, and cement is a key ingredient in concrete.

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