The big idea: A composite consists of two or more materials combined to enhance their properties.
One is the matrix — continuous, gives shape and surface. The other is the reinforcement — carries the load. Each supplies what the other lacks.
Each constituent tested alone and failing, then combined. That is the definition doing work.
Interactive diagram
Explore the labelled diagram, charts and maps for this topic in full study mode.
Free preview
This is the free notes preview
You're reading the free notes. Aimnova Pro unlocks the full study experience — and you can try it with your first topic free to keep:
- FlashcardsLock in vocabulary and key terms with spaced repetition.
- Practice questionsAnswer exam-style questions and get instant AI marking.
- Mock exams & past-paper vaultSit full mocks and see exactly how examiners award marks.
- Personalised study planA daily plan built around your exam date and weak areas.
Glass-reinforced plastic, step by step
Resin alone
Rigid, mouldable into any shape, gives a surface — and cracks under very little load. It has form and no strength.
Glass fibre alone
Very high tensile strength for its weight — far stronger than the resin. But a bundle of loose fibres has no stiffness in compression, no surface and no shape.
Cured together
The resin transfers load into the fibres and stops them buckling; the fibres stop the resin cracking. The composite has the strength of one and the form of the other.
Better than either
That is what "enhance their properties" means — the composite outperforms both constituents, not just the weaker one.
See how examiners mark answers
Answer exam-style questions with model answers. Learn exactly what earns marks and what doesn't.
| Composite | Matrix | Reinforcement | Used for |
|---|---|---|---|
| GRP | Polyester resin | Glass fibre | Boat hulls, shower trays |
| Carbon-fibre composite | Epoxy resin | Carbon fibre | Bike frames, aircraft parts |
| Plywood | Adhesive | Cross-bonded veneers | Stiff in both directions |
| Reinforced concrete | Concrete | Steel bars | Strong in tension as well |
What it costs: Composites buy an exceptional strength-to-weight ratio and properties tuned by fibre direction.
They cost more per kilogram, are labour-intensive, fail suddenly rather than bending first, and are very hard to recycle — the constituents cannot easily be separated again.
Wood and glass composites the papers ask about
Plywood
Thin veneers glued with the grain of each layer crossed, so it is strong in both directions and comes in large flat sheets of consistent quality.
Particle board
Wood chips bonded with resin glue. Cheap, flat and made from waste wood: used for flat-pack furniture.
Laminated veneer lumber (LVL)
Veneers glued with the grain all in one direction, making long, straight, strong beams for buildings.
Laminated glass
Two sheets of glass with a plastic interlayer. When it cracks the pieces stay stuck to the plastic, so car windscreens hold together.
Layers that each do a job
Drinks carton
Paperboard for stiffness, aluminium foil to block light and oxygen, polyethylene to seal it watertight.
The advantage
Together the layers do what no single material could: the drink stays fresh in a light, stiff pack.
How this is tested — explaining why combining materials creates a more suitable material, using an example. It comes up two ways:
Paper 1 — multiple choice
- Identify the matrix or reinforcement in a named composite.
- Pick the property a composite gains over its constituents.
Paper 2 — analysing a product
- Explain why a composite suits a named product.
- Explain a disadvantage of using a composite.
The trap: Saying a composite is "stronger". Say which property is enhanced, which constituent supplies it, and what the other contributes.
Explain why a racing bicycle frame is made from carbon-fibre composite rather than from steel or from resin alone.
Model answer plan
See the answer broken into clear points, with guidance on how each point earns marks.