Structural materials

Structural materials

Construction materials which, because of their ability to withstand external forces, are considered in the design of a structural framework.

Brick is the oldest of all artificial building materials. It is classified as face brick, common brick, and glazed brick. Face brick is used on the exterior of a wall and varies in color, texture, and mechanical perfection. Common brick consists of the kiln run of brick and is used behind whatever facing material is employed providing necessary wall thickness and additional structural strength. Glazed brick is employed largely for interiors where beauty, ease of cleaning, and sanitation are primary considerations. See Brick

Structural clay tiles are burned-clay masonry units having interior hollow spaces termed cells. Such tile is widely used because of its strength, light weight, and insulating and fire-protection qualities. See Tile

Architectural terra-cotta is a burned-clay material used for decorative purposes. The shapes are molded either by hand in plaster-of-paris molds or by machine, using the stiff-mud process.

Building stones generally used are limestone, sandstone, granite, and marble. Until the advent of steel and concrete, stone was the most important building material. Its principal use now is as a decorative material because of its beauty, dignity, and durability.

Concrete is a mixture of cement, mineral aggregate, and water, which, if combined in proper proportions, form a plastic mixture capable of being placed in forms and of hardening through the hydration of the cement. See Concrete, Prestressed concrete, Reinforced concrete

The cellular structure of wood is largely responsible for its basic characteristics, unique among the common structural materials. When cut into lumber, a tree provides a wide range of material which is classified according to use as yard lumber, factory or shop lumber, and structural lumber. Laminated lumber is used for beams, columns, arch ribs, chord members, and other structural members. Plywood is generally used as a replacement for sheathing, or as form lumber for reinforced concrete structures. See Wood products

Important structural metals are the structural steels, steel castings, aluminum alloys, magnesium alloys, and cast and wrought iron. Steel castings are used for rocker bearings under the ends of large bridges. Shoes and bearing plates are usually cast in carbon steel, but rollers are often cast in stainless steel. Aluminum alloys are strong, lightweight, and resistant to corrosion. The alloys most frequently used are comparable with the structural steels in strength. Magnesium alloys are produced as extruded shapes, rolled plate, and forgings. The principal structural applications are in aircraft, truck bodies, and portable scaffolding. Gray cast iron is used as a structural material for columns and column bases, bearing plates, stair treads, and railings. Malleable cast iron has few structural applications. Wrought iron is used extensively because of its ability to resist corrosion. It is used for blast plates to protect bridges, for solid decks to support ballasted roadways, and for trash racks for dams. See Structural steel

Composite materials are engineered materials that contain a load-bearing material housed in a relatively weak protective matrix. A composite material results when two or more materials, each having its own, usually different characteristics, are combined, producing a material with properties superior to its components. The matrix material (metallic, ceramic, or polymeric) bonds together the reinforcing materials (whiskers, laminated fibers, or woven fabric) and distributes the loading between them. See Composite material

Fiber-reinforced polymers (FRP) are a broad group of composite materials made of fibers embedded in a polymeric matrix. Compared to metals, they generally have relatively high strength-to-weight ratios and excellent corrosion resistance. They can be formed into virtually any shape and size. Glass is by far the most used fiber in FRP (glass-FRP), although carbon fiber (carbon-FRP) is finding greater application. Although complete FRP shapes and structures are possible, the most promising application of FRP in civil engineering is for repairing structures or infrastructure. FRP can be used to repair beams, walls, slabs, and columns.