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IV. Add the missing parts of the sentences from the text.



1....for building purposes are divided into two groups called softwoods and hardwoods.

2. However, timber is still employed...

3.... ordinary, hollow or porous, lightweight, multicolor bricks for decorative purposes, etc.

4.... they use natural stones such as marble, granite, basalt, limestone and sandstone.

5.... while brass is frequently used for decorative purposes in facing.

6. These materials are sufficiently rigid to stand...

7.... severe weather conditions for more than ten years without serious deformation.

8.... to ensure heat insulation of exterior wall panels, and in industrial construction.

9. It is non-inflammable, offers resistance to frost,...

 

V. Translate into English, and find sentences in the text with following word-combinations.

Прямоугольное твердое тело, держать кирпич с легкой уверенностью, восьмичасовой рабочий день, шлаковая вата, преднапряженный бетон, площадь поперечного сечения, выдержать напряжение растяжения (растягивающее напряжение).

 

VI. Tell the group about any of the building materials.

 

VII. discuss different building materials from the text finishing the following phrases:

1. What you need most of all is...

2. Another important thing is...

3.... can make a real difference.

4. I think... is pretty important too.

 

VIII. Read and remember.

on the other hand с другой стороны
bend сгибаться, гнуться, изгибаться
crack треск; трещина
desire желание, просьба, требование
gravel гравий,
load груз, нагрузка
sag оседать, обивать, падать
store запас, склад
tensile растяжимый

 

IX. Answer following questions. Then read the text and check your meanings.

1. Why is concrete more fit for foundation?

2. What floor covering is the best?

3. What colour should bedroom walls be? (kitchen walls, living-room walls)

4. What should a chimney be made of?

5. Why is it nice to have a mantelpiece?

6. What timber is considered to be the best for the window frames?

7. What professionals does a construction team need?

 

Modern Building Materials

Part II

Concrete is perhaps the most widely spread building material used nowadays. Concrete is an artificial stone, made by thoroughly mixing such natural ingredients or aggregates as cement, sand and gravel or broken stone together with sufficient water to produce a mixture of the proper consistency. It has many valuable properties. It sets under water, can be poured into moulds so as to get almost any desirable form, and together with steel in reinforced concrete it has very high strength, and also resists fire. Prestressed concrete is most widely used at present while prefabricated blocks are employed on vast scale for skeleton structures.

 

AGGREGATES FOR CONCRETE

By the simple definition from the dictionary " aggregates are the materials, such as sand and small stones, that are mixed with cement to form concrete". In other words aggregates (or cushioning materials) can be defined as a mass of practically inert mineral materials, which, when surrounded and bonded together by an ac­tive binder, form the rock. This rock is denoted by the general term concrete.

Aggregates have three principal functions in the concrete: they provide a relatively cheap filler for the concreting material, or bind­er; they provide a mass of particles which are suitable for resisting the action of applied loads, of abrasion, of percolation of moisture through the mass, and of climate factors; they reduce volume chang es resulting from the action of the setting and hardening of the con­crete mass.

All aggregates, both natural and artificial, which have suffi­cient strength and resistance to weathering, and which do not con­tain harmful impurities may be used for making concrete.

As aggregates such natural materials as sand, pebbles, broken stone, broken brick, gravel, slag, cinder, pumice and others can be used.

 

PRESTRESSED CONCRETE

Prestressed concrete is not a new material. Its successful use has been developed rapidly during the last two decades, chiefly because steel of a more suitable character has been produced. Concrete is strong in compression but weak when used for tensile stresses.

If, therefore, we consider a beam made of plain concrete, and spanning a certain distance, it will at once be realized that the beam's own weight will cause the beam to " sag" or bend. This sagging at once puts the lower edge of the beam in tension, and if the cross-sectional area is small, causes it to break, especially if the span is relatively large.

If, *on the other hand1, we use a beam of similar cross-section, but incorporate steel bars in the lower portion, the steel will resist the tensile stress derived from the sag of the beam, and thus assist in preventing it from breaking.

In prestressed concrete steel is not used as reinforcement, but as a means of producing a suitable compressive stress in the concrete. Therefore any beam (or member) made of prestressed concrete is permanently under compression, and is consequently devoid of crack under normal loading, or so long as the " elastic limit" is not ex­ceeded.

Prestressed concrete is not only used for beams but is now em­ployed extensively for columns, pipes, and cylindrical water towers, storage tanks, etc.

 

X. Translate following phrases.

1. A relatively cheap filler, the proper consistency, resistance to weathering, spanning a certain distance, the cross sectional area, negotiated fee.

2. Вредные примеси, удачное использование, цементируемый материал, искусственный камень, быть постоянно под напряжением, заполняющие материалы.

 

XI. Write out international words out from the text and translate them without a dictionary.

 

XII. Add the missing parts of the sentences from the text

1.... to produce a mixture of the proper consistency.

2. Concrete is an artificial stone, made by thoroughly...

3.... they provide a relatively cheap filler for the concreting material,

or binder; ...

4. This sagging at once puts the lower edge...

5.... as a means of producing a suitable compressive stress in the concrete.

6.... any beam made of prestressed concrete is permanently un­der compression...

7. This sagging at once puts the lower edge....

UNIT 5

SILICATE INDUSTRY

 

I. Read and translate the text paying attantion to the following words.

1. It embraces the production of cement, glass and ceramics. – она включает производство цемента, стекла и керамики.

2. … does not become hard at once. - … не застывает сразу.

3...., which is not subject to disintegration or decay. – который не подвержен разрушению или загниванию.

4.... on external agent for setting power – от внешнего фактора для застывания

 

bind связывать, скреплять
embrace включать, охватывать
grind размалывать
ignite зажигать, загораться; прокаливать
impurity примесь
lump глыба, комок
pit яма, копь, шахта
puty замазка
quarry каменоломня, карьер
roast обжигать, кальциновать
slake гасить (известь)

 

Silicate Industry

Silicate industry is the industry processing the natural compounds of silicon. *It embraces the production of cement, glass, and ceramics1.

The production of ceramic goods is based on the property of clay when mixed with water to form putty, from which various articles can easily be moulded. When these are dried and then for easily moulding baked, that is, ignited at a high temperature, they become hard and retain their shape, no longer being softened by water.

In this way clay, mixed water and sand is moulded into bricks, which are then dried and baked. The materials used to make silicate bricks are white sand and slaked lime.

Cement Production. Cement is made from limestone and clay, or from their natural mixture, marls. The materials roasted in cylindrical rotary kilns are charged into a slowly rotating kiln at its upper end and travel, mixing continuously, towards the lower end, while a current of hot gases, the products of the burning of fuel, flows in the opposite direction. During the period of their movement through the kiln the clay and the limestone react chemically, and the material emerging from the kiln in lumps of a caked mass is cement, which is then grounded.

When cement is mixed with water, it forms mortar, which hard­ens, binding various objects, such as bricks or stones, very firmly. It is for this reason that cement is used widely as a binding materials in large-scale construction, including underwater construction.

Cement is often mixed with sand or gravel, in which case we get concrete. Concrete has roughly the same coefficient of thermal ex­pansion as iron.

Glass Production. The initial materials for the production of or­dinary glass are mainly soda, limestone, and sand. A mixture of these substances is heated in a bath-shaped furnace.

When it cools, the liquid mass of glass *does not become hard at once2. At first it becomes viscous and readily assumes any shape. This property of glass is used in making various articles out of it. Definite portions of the cooling semiliquid mass are taken from the bath, and these are blown or pressed to make various glassware. By machine methods glass sheets, tubes, etc., can be drawn continuous­ly from the molten mass.

Sand is the chief material used as a fine aggregate. It is required in mortar or concrete for economy and to prevent the excessive crack­ing. Mortar made without sand would be expensive.

The word " sand" is applied to any finely divided material which will not injuriously affect the cement or lime and * which is not sub­ject to disintegration or decay. Sand is almost the only material which is sufficiently cheap and which can fulfil these requirements.

A mixture of coarse and fine grains is very satisfactory, as it makes a denser and stronger concrete with a less amount of cement than when only fine-grained sand is used.

The following sands are used for mortars: pit or quarry sand, river sand and sea sand.

Lime is a calcium oxide. It is used in great quantities for mortar and plaster. Lime (quicklime) is a white solid that reacts violently with water to form calcium hydroxide. It is made by heating lime­stone in a special kind of furnace called a " kiln". Lime must be stored in a dry place, otherwise it will absorb moisture.

Limes may be divided into three distinct classes:

1. Rich limes that contain not more than 6 percent of impurities, slake very rapidly, and are entirely dependent *on external agents for setting power4. These are widely used for interior plasterer's works.

2. Poor limes that contain from 15 percent to 30 percent of use­less impurities and possess the general properties of rich limes, only to a lesser degree.

3. Hydraulic limes that contain certain proportions of impurities, which when calcinated, combine with the lime and endow it with the valuable property of setting under water or without external agents.

Lime is a basic building material extensively used all over the world, but it was not until the later years of the 19th century that a greater appreciation of the fuel-burning problems involved became apparent. Until this time the requirement for lime was largely agri­cultural and it was produced by farmers or by small builders who used it for making mortar and plaster.

As industrial requirements increased " running" kilns were devel­oped. These were lined with firebrick and charged at regular inter­vals with stone and fuel.

Around the world there are many different types of kilns and variations in lime-burning practice.

 


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