Composite building materials are formed from two or more distinctly different materials. When combined, the properties of the newly formed material are superior to those of the individual components. The process of combining is a physical practice rather than a chemical one, so the composite materials feature the combined properties of their ingredient materials.
Composite materials contain two types of constituent materials, matrix and reinforcement materials. At least one variety of each type is necessary. The matrix material surrounds and supports other constituents by keeping their relative positions. The reinforcement material imparts special physical properties, such as electrical and mechanical, to improve the matrix properties.
Composite materials are noted for characteristic properties such as high structural strength, lightweight, resistance to chemical wear and corrosion, toughness (impact strength), mechanical stiffness, heat resistance and ease of processing (manufacturing). Most materials are cost effective, cause less public inconvenience and require lower long-term maintenance and replacement costs.
Commonly used forms are fiber-reinforced plastics (fiberglass, thermoplastic composites, thermoset composites, etc), metal matrix composites (white cast iron, hard metal and metal-intermetallic laminate), ceramic matrix composites (cement, reinforced carbon-carbon, etc) and engineered wood (plywood, oriented strand board, and pykrete).
Composite materials are found in nature. An example is wood that contains cellulose fibers reinforced by a polymeric substance like lignin. Wood is one of the most common materials used in the construction industry. Straw and mud in the form of bricks are the most primitive composite building materials. Other varieties are organic matrix or ceramic aggregate composites (syntactic foam and asphalt concrete).
Concretes are made from the combination of aggregate and cement binder. They are used in the manufacturing of motorways/roads and all building structures. Natural fiber composites (NFCs) are made up of natural fibers like wood or hemp with artificial materials like recycled plastics. They are generally inexpensive and can be easily molded into sheets, boards and frames. NFCs are used as an alternative for timber in fences, railings, flooring, roofing, etc. The composite materials like imitation granite and cultured marble sinks are also widely used.