Wood itself is a natural composite which can be used in its original form or as sawn sections. It can also be converted to particles, strands or laminates which can be combined with other materials such as glues, to form composite wood products.
The principal reasons for transforming wood into wood products include
to transcend the dimensional limitations of sawn wood
to improve performance; structural properties, stability or flexibility
to transform the natural material into a homogenous product
to utilise low-grade material, minimise waste and maximise the use of a valuable resource.
Wood composites may be divided into three categories; layered composites, particle composites and fibre composites.
Layered composites are used to produce both sections and sheets.
Glued laminated timber (glulam) is formed by gluing together a series of precision cut small sections of timber to form large cross-section structural members of long length. The timber laminates are strength graded before fabrication. The member can be straight or curved, and can be made with a variable section according to structural requirements.
A newer type of parallel laminate product is known as Laminated Veneer Lumber [LVL]). Made from thin sheets of wood peeled from the log (in a similar manner, but thicker than plywood veneers), the veneers are glued together to provide the required thickness, and then cut into structural sized sections.
The most familiar sheet laminate is plywood. It comprises thin sheets of wood (veneers) bonded together, most frequently with synthetic glues. The grain of the wood in the different veneers is normally arranged at right angles to each other.
