Unit IV building materials (I)

TEXT 4A. THE PROPERTIES OF BUILDING MATERIALS

Read and translate the text:

Materials that are used for structural purposes should meet several requirements, hi most cases it is important that they should be hard, durable, fire-resistant and easily fastened together.

The most commonly used materials are steel, concrete, stone, wood and brick. They differ in hardness, durability and fire-resistance.

Wood is the most ancient structural material. It is light, cheap and easy to work. But wood has certain disadvantages: it burns and decays.

Stone belongs to one of the oldest building materials used by man. It is characteristic of many properties. They are mechanical strength, compactness, porosity, sound and heat insulation and fire-resistance.

Bricks were known many thousands of years ago. They are the examples of artificial building materials.

Concrete is referred to as one of the most important building

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получили высокое распространение бетонные конструкции, внедрение которых было тесно связано с промышленным изготовлением портландцемента.13. Железобетонные изделия и сооружения появились после успешного использования стальной арматуры. 14. Железобетон как строительный материал очень молод.

III. Read the text carefully and then translate it:

„ Concrete is made by binding together particles of sand and gravel stone or broken brick. The binding agent used is a paste of Portland cement and water, in suitable proportions. When water is added to the cement, hydration takes place. This causes the whole mixture to set and harden, forming a solid mass. The sand, gravel (or broken stone) arc termed "aggregate"; sand is known as "fine aggregate", and gravel as "coarse aggregate". Concrete can be made on a building site and poured into position as a wet mix, or it may be used as the material for making prefabricated units in a factory. That is why there is another classication into" in-situ" (or cast-in-place) concrete and "precast" concrete.

!V. Answer the following questions:

1. How is concrete made? 2. What takes place when water is added to the cement? 3. Does the whole mixture set and harden when hydration takes place? 4. A solid mass is formed, right? 5. Do you know what is termed "aggregate"? 6. Is sand known as "fine aggregate"? 7. And what is meant by "coarse aggregate"? 8. Can concrete be made on a building site and poured into position as a wet mix? 9. Are you able to explain what is meant by "in-situ" concrete?

V. Complete the sentences using the English equivalent for the Russian words in brackets:

1. All metals are divided into (черные и цветные). 2. Ferrous metals include (железо, сталь и их сплавы). 3. Copper, aluminium and some other metals are referred to as (цветные металлы). 4. Metals in general, and especially ferrous metals are of (большое значение в строительстве). All metals have specific metallic (блеск), 6. All metals, except mercury, are (твердые вещества). 7. All metals are good

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3. The basic materials for making concrete are cement, aggregate and water, aren't they? 4. What is the most essential material for making concrete? 5. Can we make cement if we take limestone and clay? 6. How is cement made? 7. What are Portland and blast furnace cement suitable for? 8. When does cement start hardening? 9. How long does the process of hardening last? 10. Can you tell us what process is called concrete hardening? 11. Are you able to say what the characteristics of concrete depend on? 12. Should concrete be hard, strong, durable fire-resistant and economical? 13. Into what two classes can concrete be divided? 14. Is Yes the use of concrete and ferro-concrete most universal? 15. Do builders now produce two or three types of new building materials? 16. Where is silica concrete widely used?

II. Render the following in English:

1. Прочность хорошего кирпича, стали, природных камней со временем не меняется. 2. Бетон в течение длительного времени способен становиться прочнее. 3. Бели применять прочность бетона за 100 процентов, то через 1 1/2 года она будет - 150, через 2 года - 200, а через 5 лет - 225%. 4. Плотный бетон морозостоек. 5. Прочность, водостойкость, плотность, морозостойкость делают бетон очень хорошим строительным материалом, пригодным для возведения гидротехнических сооружений. Бетон хорошо защищает от ударной волны и светового излучения. 6. Официальной датой появления железобетона считают 1867 год, когда французский садовник Ж.Монье получил первый патент на железобетон как строительный материал. 7. Ж.Монье делал из бетона цветочные горшки и кадки, небольшие бассейны для воды и другие изделия. 8.. Первый железобетонный мост был построен в 1875 году. 9. Русские инженеры оказали большое влияние на развитие железобетонного строительства. Русские инженеры использовали железобетон как прекрасный строительный материал в Ленинграде, Новороссийске и других городах. 10. Несколько промышленных и гражданских зданий, выполненных, частично из железобетона, сохранились и по сей день. 11. В 1904 году недалеко от Николаева был построен первый в мире железобетонный маяк. 12. С конца XIX века в строительстве

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materials. Concrete is a mixture of cement, sand, crushed stone and water.

Steel has come into general use with the development of industry. Its manufacture requires special equipment and skilled labour.

Plastics combine all the fine characteristics of a building material with good insulating properties. It is no wonder that the architects and engineers have turned to them to add beauty to modem homes and offices.

All building materials are divided into three main groups: 1) Main building materials such as rocks and artificial stones, timber and metals. 2) Binding materials such as lime, gypsum and cement. 3) Secondary or auxiliary materials which are used for the interior parts of the buildings.

We use many building materials for bearing structures. Binding materials are used for making artificial stone and for joining different planes. For the interior finish of the building we use secondary materials.

Natural building materials are: stone, sand, lime and timber. Cement, clay products and concrete are examples of artificial building materials.

Exercises

I. Answer the following questions:

1. What are the properties of the building materials?

2. What are the most commonly used building materials?

3. Do building materials differ from each other?

4. What can you say about the most ancient building materials?

5. What can you say about bricks?

6. Is concrete an artificial or natural building material?

7. Into what groups do we divide building materials?

8. Can you give an example of a binding material?

9. What artificial building materials do you know?

10. What natural building materials do you know?

II. Render the following in English:

Пластмассы как материал для строительных конструкций

Пластмассы - это материал, который состоит из полимеров или их сочетаний. Большая легкость, значительная прочность, водостойкость являются основными достоинствами большинства

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пластмасс. Эти свойства пластмасс позволяют издавать легкие, прочные, красивые, экономически выгодные конструкции.

Основными компонентами пластмасс являются синтетические смолы. Эти смолы представляют собой высокомолекулярные соединения, полученные путем синтеза из низкомолекулярных соединений. Уголь, торф, нефть, являются основным сырьем для смол. Смолы - это полимеры малых молекул - мономеров.

TEXT 4B. TIMBER

Study the text and then translate it orally using a dictionary:

Timber is the most ancient structural material. In comparison with steel timber is lighter, cheaper, easier to work and its mechanical properties are good. On the other hand, timber has certain disadvantages. First, it burns and is therefore unsuitable for fireproof buildings. Second, it decays.

At present an enormous amount of timber is employed for a vast lumber of purposes. In building timber is used too.

Timber is a name applied to the cut material derived from trees. Timber used for building purposes is divided into two groups: softwoods and hardwoods. Hardwoods are chiefly used for decorative purposes, as for panelling, veneering in furniture, and some of them are selected for structural use because of their high strength and durability. In modern construction timber is often used for window and door frames, flooring, fences and gates wallplates, for temporary buildings and unpainted internal woodwork.

Timber cannot be used for either carpenters' or joiners' work immediately it has been felled because of the large amount of sap which it contains. Most of this moisture must be removed, otherwise the timber will shrink excessively, causing defects in the work and a tendency to decay. Elimination of moisture increases the strength, durability and resilience of timber.

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(ferro-concrete) where it is necessary to introduce steel. Plain or mass concrete can be used for almost all building purposes. Ferro-concrete is used in building bridges and arches, dams and dock-walls, for structures under water, for foundations, columns, girders, beams. The use of concrete and ferro-concrete is almost universal.

Builders now produce two types of new building materials: alkali-slag concrete and silica concrete. In alkali-slag concrete cement is replaced by a mixture of granulated blast-furnace slags and sodium

\ and potassium compounds. The fillers can be sand or sandy loams containing various amounts of clay, which usually cannot be used with conventional cement. The new material has been tested successfully and is now being used for irrigation systems, roads, pavements and other structures. Silica concrete is light, fire-resistant and acid-proof. It contains no cement whatever. Silica concrete is widely used in aviation and in under water constructions.

The term "concrete" is used to describe a dense material composed of cement and aggregate mixed with water. The density of such a material, and therefore many of its properties, depend upon the density of the aggregate. Therefore 'there is a broad division of concrete types into:

a) Dense concretes - composed of heavy aggregates.

b) Light-weight concretes - composed of light aggregates.

The aggregates are graded in size from fine to coarse in order to reduce the amount of void space to be filled by cement.

There are "cellular" concretes made by using materials which foam or form gas during the mixing of the concrete. These give a product of very light weight, because after setting it contains a large number of small voids.

The reduction in weight is accompanied by a considerable decrease in strength Another type of light weight concrete is made by "entraining"air bubbles in the mix to which a substance has been added to keep the bubbles stable during setting.

Exercises.

I. Answer the following questions:

1. Is it possible to put up modern structures without using concrete?

2. Do you know what the most important quality of concrete is?

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Dialogue 4

A.: Do you agree that an aluminium domed roof makes it simple to provide lighting in the walls beneath?

В.: I do. Besides, the domes can be assembled at ground level and lifted into position.

A.: That's remarkable! Don't you think dome roofs pack economically for sea transport?

В.: It's exactly what I was going to tell you.