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Bricks & Tiles
Bricks and tiles are construction materials usually made by mixing finely ground clay or shale with water and firing, or baking, the mixture.
Bricks may be solid or pierced with holes. They range in color from a burned black, through red and buff yellow, to a cream white, depending on the kind of clay from which they are made. The standard size of bricks manufactured in the United States is 8 inches (20 cm) long by 3 1/2 inches (8.9 cm) wide by 2 1/4 inches (5.7 cm) thick. This is the basic size for bricks used in most construction work. New developments in construction methods have brought about limited production of other sizes of bricks, some slightly larger and others slightly smaller than the standard size.
Tiles are made of the same clay or shale as bricks and are formed into relatively thin sheets, tubes, or hollow blocks. They are often glazed and are made in many colors. Tiles are used mainly as surfacing material, as liners for chimney flues, or as pipes.
Kinds of Bricks
Common Bricks. Ordinary building bricks, or common bricks, are made from easily obtainable clays and are prepared without any special attention to their color and texture. They are graded according to the load they can support and are used to give mass, thickness, and structural strength to buttresses, un-exposed walls, and other interior structures.
Face Bricks. Face bricks are made from clays which fire evenly to give an attractive appearance to the brick. One or more surfaces of a face brick may be specially treated to give the brick a rough or textured appearance. A face brick may be given a smooth, sometimes colored, surface glaze by treating it with chemicals when it is fired.
Firebricks. Bricks that are specially resistant to damage from heat are called firebricks, or refractory bricks. They are made from fire clays containing alumina or other substances that help to make the brick resistant to heat. Firebricks are produced in several grades, each capable of resisting a different maximum intensity of heat. For example, firebricks made with clay containing less than about 35 percent alumina can withstand temperatures up to 3000° F. (1140° C.), while bricks made with clay containing silicon carbide can resist temperatures over 4000° F. (1700° C.). Firebricks are used to build chimneys, flues, furnaces, and industrial devices such as converters and crucibles.
Paving Bricks. Bricks used for paving are larger, harder, and more resistant to penetration by water than common bricks. During the firing operation, paving bricks are vitrified by heating them to a temperature at which the materials in the clay melt together to form a glassy mass that is impervious to water. When used for surfaces other than roads, paving bricks are sometimes glazed in order to make them easier to clean.
Acidproof Bricks. Acidproof bricks are similar to paving bricks but smaller. These hard, vitrified bricks resist damage by acids and other chemicals, and are used for floor surfacing in steel mills, chemical plants, and other industrial buildings and for lining storage tanks containing acid or alkali.
Insulating Bricks. Insulating bricks are made by mixing sawdust or straw with clay. When the clay is fired, the sawdust burns away and leaves a lightweight, porous brick that provides good insulation against heat and cold. Some insulating bricks are made from the clays used for firebricks, and are therefore heat-resistant as well.
Brickwork is usually composed of bricks held together by mortar, which is a mixture of sand, lime, cement, and water. Besides holding the bricks together, mortar also fills the joints of the brickwork and makes it weatherproof. Bricks are joined together in horizontal layers called courses, usually consisting of headers, or bricks laid flat with the short edge exposed, and stretchers, or bricks laid flat with the long edge exposed. Courses are laid one above the other, with the bricks in each course laid so that they overlap the bricks in the course below them. The resulting overlapping arrangement is known as bonding.
Bonding makes brickwork stronger by locking the bricks together and by transmitting the force exerted on one brick to the bricks below it, thereby distributing stresses throughout the entire structure. Bonding also helps tie together the inner and outer layers of bricks, making a stronger, more durable structure. The patterns created by bonding make brickwork visually attractive as well as structurally strong.
The three basic systems of bonding are running bond, Flemish bond, and English bond. Running bond consists of courses of stretchers which overlap one-half a brick length. Since it provides no bonding with layers of bricks behind it, however, running bond is not well suited to structural brickwork. In Flemish bond, each course consists of alternating headers and stretchers. The headers in every course are centered over the stretchers in the inner and outer courses below, tying the wall together from front to back. English bond uses alternate courses of headers and stretchers, with the bricks of every other course aligned vertically. American bond, also called common bond, is a modification of English bond. In American bond, single courses of headers are separated by four to six courses of running bond. It is the most widely used of all masonry bonds.
Kinds of Tile
Glazed Wall Tile. Glazed wall tiles are thin, flat tiles made of highly porous clay. They are usually glazed on one side to make them waterproof. The highly porous clay forms a good bond with mortar, making it possible to set the tiles on a vertical surface. They are often used for kitchen and bathroom walls.
Floor Tiles. Floor tiles are flat, unglazed tiles that have been vitrified to resist absorbing water. They are made from better grades of clay and are produced in many shapes and sizes.
Roofing Tile. Roofing tiles are flat shingles, slabs, or specially designed overlapping tiles. They are made both with and without a glazed surface.
Structural Tile. Structural tiles are hollow blocks of clay similar to bricks. They are used both for load-bearing portions of building and for nonload-bearing portions, such as partitioning walls. Glazed structural tile, called face tile, is used for exterior walls.
Tile Pipe. Pipe made of clay is produced in short, cylindrical sections. In one kind of pipe, both ends of each section are cut squarely to make a flush joint with the adjacent sections. In another kind, one end of each section has a flare, or bell, so that adjacent sections can form overlapping joints.
Structural tiles are set in much the same way as bricks. Surfacing tiles are applied to walls, floors, and other flat interior surfaces either with mortar or with oil-base or resin-base adhesives. A thin mortar is forced between surfacing tiles after they have set to make the surface waterproof.
To ensure a waterproof roof, roofing tiles are usually designed to interlock and overlap, and the joints are sealed with mortar. On sloping roofs, roofing tiles are nailed down; on flat roofs they may be nailed, cemented, or simply laid in place.