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brick,ceramic structural material that, in modern times, is made by pressing clay into blocks and firing them to the requisite hardness in a kiln. Bricks in their most primitive form were not fired but were hardened by being dried in the sun. Sun-dried bricks were utilized for many centuries and are used even today in regions with the proper climate. Examples from approximately 5,000 years ago have been discovered in the Tigris-Euphrates basin, and the ancient races occupying this region may have been the first users of brick. In Babylonia there was a lack of both timber and stone, and the thick clay deposited by the overflowing rivers was the only material adaptable to building. The Persians and the Assyrians used sun-dried blocks of clay for walls of great thickness, facing them with a protective coating of fired bricks. The Egyptians and the Greeks used bricks only to a limited extent, as they had access to plentiful supplies of stone and marble. The Romans manufactured fired bricks in enormous quantities and gave them an important role as a basic structural material in buildings throughout the Roman Empire. Bricks played an important part in early Christian architecture until the decline of the empire. Whereas the Romans had usually concealed their brickwork beneath a decorative facing of stone or marble, the Byzantines devised a technique for exposing the bricks and giving them a full decorative expression. This technique influenced the Romanesque style and brought especially good results in Lombardy and in Germany, where bricks came to be arranged in immensely varied patterns. Since the Middle Ages, brickwork has been in constant use everywhere, adapting itself to every sort of construction and to every change of architectural style. At the beginning of the 19th cent. mechanical brick-making processes began to be patented and by the latter half of the century had almost entirely replaced the ancient hand-fashioning methods. Contemporary American building bricks are rectangular blocks with the standard dimensions of about 2 1-4 by 3 3-4 by 8 in. (5.7 by 9.5 by 20.3 cm). Good bricks are resistant to atmospheric action and high temperatures and are more durable than stone. Where heat resistance is especially important, fire bricks are used; these are made of special refractory clays called fire clays and are fired at very high temperatures.
an artificial regularly shaped stone formed from mineral materials that takes on stone-like properties—durability, impermeability to water, and frost resistance—after firing or steaming.
The two types of brick, silica brick (lime-sand), which is made by the autoclave method, and fired clay brick (ordinary and facing), differ in initial raw material and manufacturing method. Ordinary brick is used basically as a wall material. Usually bricks are rectangular. In the USSR, brick is produced chiefly with dimensions of 250 × 120 × 65 mm, but it is also manufactured with dimensions of 250 × 120 × 88 mm (a size known as the 1½). Depending on the maximum compressive strength (1 kg per sq cm ≈ 100 kilonewtons per sq m), brick is divided into the grades 75, 100, 125, 150, 200, 250, and 300. The raw materials for brick are low-melting clays and loams in a pure form or with the addition of sand, sawdust, ash, and so forth. Facing brick is used primarily for facades and interiors of buildings. It is made out of light-firing and red-firing clays. If red-firing clays are used, a layer of light-firing clays is applied to the face of the brick, or the face is covered with a glazing, engobes, or other materials.
Brick is the oldest artificial building material. Although from ancient times until recently the most widely used brick in many countries was unburned cob brick, often with the addition of cut straw to the clay to produce adobe, fired brick has also been used since antiquity (the structures in Egypt and in Mohenjo-Daro, dating from the third and second millennia B.C.). Brick played a particularly important role in the architecture of Mesopotamia and later in ancient Rome, where it was used for complex structures, including arches and domes. In the Middle Ages, in addition to its use as a building material, brick was developed for its decorative possibilities in patterned masonry; curved, shaped, and glazed brick was used, often with terra-cotta and majolica details (the Samanidov Mausoleum in Bukhara, built in the late ninth and early tenth century; the “brick Gothic” of Germany and the Baltic littoral of the 13th-16th centuries; Russian “patterned” architecture of the 17th century). The artistic possibilities of brick have been explored in the 20th century—for example, the buildings of F. Höger in Hamburg in the 1920’s. Modern brick architecture exploits the attractiveness of facing brick and of the combination of clay and silica brick.
Until the 19th century, the methods of brick production remained primitive and labor intensive. The bricks were shaped manually; they were dried only in the summer and were burned in outdoor kilns (clamps or stove kilns) made from dried unfired brick. In the middle of the 19th century, the ring kiln and the ribbon press were developed, revolutionizing brick production. At the same time clay mills, roll mills, and pugmills appeared. In the late 19th century, driers began to be built.
Modern brick production has been considerably mechanized. The primary crushing of the clay and the removal of stones are done in stone separators. The crushed clay and water (or steam) go to the pugmill, and then the clay mass is passed through rollers and flat mills and goes to the ribbon vacuum press, which extrudes a continuous column with a cross section corresponding to the shape and dimensions of the brick. The column is automatically cut by a wire device into individual bricks; the bricks are placed on trays, and the trays are loaded onto carts that are sent to the tunnel drier. The dried brick is reloaded manually or automatically onto kiln carts that pass through the tunnel kilns, where the brick is burned at a temperature of 900°–950°C. The fired brick is graded, stacked on pallets, and sent to be stored at the finished-product warehouses.
The USSR produces solid, slotted, and holed brick as well as hollow enlarged ceramic stone possessing high insulating properties. The shaped clay brick is used especially for the masonry and lining of smokestacks, and brick is also used for the surfacing of roads (hard-burned building brick or clinker).
In the USSR, more than 80 percent of all the brick is produced at enterprises operating year-round, including large mechanized plants with a productivity of more than 200 million pieces a year. Around 34 billion pieces of ordinary brick were produced in 1972.
REFERENCESTekhnologiia glinianogo kirpicha. Edited by M. M. Naumov. Moscow, 1969.
Iushkevich, M. O., and M. I. Rogovoi. Tekhnologiia keramiki. Moscow, 1969.
M. I. ROGOVOI
A construction material usually made of clay and extruded or molded as a rectangular block. Three types of clay are used in the manufacture of bricks: surface clay, fire clay, and shale. Adobe brick is a sun-dried molded mix of clay, straw, and water, manufactured mainly in Mexico and some southern regions of the United States.
The first step in manufacture is crushing the clay. The clay is then ground, mixed with water, and shaped. Then the bricks are fired in a kiln at approximately 2000°F (1093°C). Substances in the clay such as ferrous, magnesium, and calcium oxides impart color to the bricks during the firing process. The color may be uniform throughout the bricks, or the bricks may be manufactured with a coated face. The latter are classified as glazed, claycoat, or engobe.
The most commonly used brick product is known as facing brick. Decorative bricks molded in special shapes are used to form certain architectural details such as water tables, arches, copings, and corners.