Vocabulary notes

live load переменная нагрузка

dead load постоянная нагрузка

spread foundation уширенный фундамент

pier foundation столбчатый фундамент

pile foundation свайный фундамент

girder балка; ферма; прогон

joist балка; брус

purling обрешетина; прогон

lintel перемычка

truss ферма

arch арка

EXERCISES

I. Read the text and translate it.

II. Put up questions to the following sentences:

1. Foundations carry both the dead and live loads.

2. Spread foundations are long slabs of reinforced concrete between the outer edges of the building.

3. Pier foundations go down through the topsoil to a bed of firm rock.

4. Pile foundations transmit the load to the supporting soil.

III. Answer the questions to the second part of the text:

1. What is the main function of beam, girder and columns?

2. What is the difference between beam and girder?

3. What is joist? purlin? lintels?

IV. Make up the summary of the text.

Brickmaking

Brick is formed in three ways: the soft-mud, stiff-clay, and pressed brick processes. In the soft-mud process, clay is mixed with water to form a stiff paste which is then thrown by hand or forced by machine into wooden or metal box-like molds the size of a brick. Sand or water is sprinkled on the inside of the molds to keep the clay from sticking. The sand or water also gives the brick a pleasant finish. Such bricks are called “sand-struck” or “water-struck” bricks. The soft, wet bricks are removed from the molds for drying. The molds are used again.

In the stiff-clay process, the ground clay is mixed with water in a long trough containing a revolving shaft with blades. The blades mix the clay with water as they revolve and at the same time push it forward into an extrusion machine. This forces it through a rectangular opening in the same way as toothpaste is squeezed from a tube. It comes out, or is extruded, in a long bar the length and width of a brick. A moving belt carries the clay bar to a cutter, which is a metal frame with a number of wires stretched across it. The wires are spaced 65 millimeters (2 inches) — the height of a brick — apart. The wires are brought down on the bar to cut it into bricks, which are then dried. Bricks formed in this way are known as extruded wire-cut bricks.

In the pressed brick system, the clay is semidry, and is pressed by heavy machine into metal molds under such high pressure that the clay particles hold together. Because pressed brick has very little water, it needs little drying.

After being formed, both the soft-mud and the stiff-clay bricks are loaded on to carts on rails and pushed into driers, and then into kilns to be fired. The driers are long rooms or sheds through which hot air is forced by large fans. Water must be removed from the bricks before firing, as a wet brick warp when fired. Drying takes two to three days and then the bricks are ready for firing.

Until the 17^th century a lot of brick-making was carried out in brick-fields near where the bricks were to be used. The clay was dug from the field and molded there. It was then fired in a “clamp”, which a temporary kiln was built of fuel and bricks. The inside of this stack consisted of unfired bricks and fuel, usually small coals, while the outside was made of fired bricks. The clamp was then set alight and allowed to burn itself out. This took several weeks.

In permanent brickyards, an early type of kiln was used. This was a separate building which, after the unfired bricks stacked inside it, was closed and the fires lit. The kiln gradually warmed up until the necessary heat was reached, and after about two days the fire was allowed to die down and the kiln became cool enough for the bricks to be carried out.

The problem with both the clamps and the early kilns was that they did not give evenly fired bricks. This meant that the bricks were very variable in quality. Some bricks would have to be re-fired and the cracked ones would be thrown away. They were also uneconomical with fuel.

Nowadays kilns usually allow a continuous process. There are many different types, the most modern of which is the tunnel kiln. This kiln is 90 meters (300 feet) or more in length. The fire burns all the time in a zone about half way through the tunnel. The dried bricks are drawn slowly through the fire on carts, taking two or three days to travel the whole length of the tunnel. This speeds up production, is easily controllable, and economical with fuel.

Materials. Clay is the material most often associated with bricks, but since the late 19^th century other materials have been used. For example, calcium silicate bricks, sometimes known as sand-lime bricks, are made by pressing a mixture of moist sand and lime into brick shape by machine. The bricks are then steamed under high pressure in an autoclave (a sort of giant pressure cooker). This process produces bricks of an attractive light sandy color which can be textured and pigmented in a variety of ways.

Pigments and texturing can also add interest to concrete bricks which are naturally light gray in color. These are made from a mixture of crushed rock and Portland cement mixed together and moistened. The cement sets and hardens to bind the particles of rock together.

Shape. Not all bricks are completely solid. Some have “frogs” in them. A frog is a recess in the brick named after the frog in horse’s hoof. They make it easier to press and fire the bricks and also reduce the weight. Lighter bricks are easier to handle and cheaper to transport. Nowadays many machine-made bricks have holes in them for similar reasons. These are called perforated bricks. “Specials”, as the name suggests, are bricks made for a specific purpose. They are usually shaped to fit angles and curves or to produce a decorative effect. There are various commonly made ones such as “angled”, “radial”, and “bull-nosed”.

Color. The color of clay bricks depends on several factors. The type of clay used, chemicals in the clay, the supply of oxygen while the bricks are being fired, and the temperature the bricks reach during firing. The colors range from dark purple to light yellow. The red color of ordinary brick is due to the iron found in most clay. A large amount of iron gives a bright-red color; reducing the supply of oxygen may give dark-blue. By adding manganese to the clay a brown color is produced. Clay combined with lime produces yellow bricks. Facing bricks, to be used in the outer walls of buildings, can be given a rough or textured surface, or they may be glazed to add to their attractiveness.

Sand-lime bricks are naturally white, off-white, or pink, depending on the sand used to make them. By adding pigments, any colors from pale pastels to dark tones can be produced.

Blocks are essentially oversize bricks — commonly about the size of six bricks. They may be made of clay or concrete. Clay blocks are usually hollow; concrete blocks may be solid or hollow. The advantage of blocks over bricks is that building can be carried out faster with them.