Text a building materials
In order to build a house the civil engineer must consider many important factors: the choice of materials, their physical properties, availability, cost, etc. Materials to be used for structural purposes should meet a number of requirements. In most cases they should be strong, durable and fire-resistant.
Steel, concrete, stone, timber and brick are the most commonly used building materials. Timber is the oldest structural material known to mankind. It is light, cheap and easy to work with. But timber has certain disadvantages: it burns and decays. Timber used for building purposes is divided into two groups: softwoods and hardwoods. Softwoods are chiefly used in construction, while hardwoods are generally used for decorative purposes.
Bricks were known many thousands of years ago. They are molded from clay into the required shape. Bricks are usually rectangular in shape. They are hardened by being fired in a kiln.
Concrete is one of the most important building materials. It is difficult to imagine modern structures without concrete. Concrete is made by mixing together a proportion of fine and coarse aggregates with cement and water. Crushed stone, broken brick and gravel are considered to be coarse aggregates. Sand is the best fine aggregate. Both quarry and river sands are extensively used.
Reinforced concrete is a combination of two of the strongest structural materials available - concrete and steel. There are two kinds of reinforced concrete: with ordinary reinforcement and concrete with prestressed reinforcement. Concrete is reinforced by the incorporation of steel rods.
Plastics and glass reinforced plastics are comparatively new building materials, but they have already found many uses in modern construction. Plastics combine all the best characteristics of building materials with good insulating properties. Plastics are produced from chemicals. Glass-reinforced plastics are produced from polyester resins reinforced with glass fibres. Plastics and glass-reinforced plastics are the materials to be used in modern construction on a large scale.
Exercise 1. Answer the questions:
What must a civil engineer consider to build a house?
What requirements should building materials meet?
What are the most commonly used building materials?
Into what groups is timber divided?
For what purposes are they used?
What does concrete consist of?
What fine and coarse aggregates do you know?
What components does reinforced concrete include?
What is the process of reinforcing ordinary concrete structures.
Why have plastics already found use in modern construction?
Exercise 2. Give the necessary English equivalents:
Materials used in modern construction should (отвечать нескольким требованиям).
(Лесоматериал) is light, cheap and easy to work with, but it has certain (недостатки).
(Кирпичи) are hardened (обжигом в печи).
Building materials should be (прочный, огнеупорный).
Concrete is made by mixing cement, sand, gravel and water (в нужных пропорциях).
(Ввести стальные стержни в бетон) is to reinforce ordinary concrete structures.
Plastics are produced from (химикаты).
Sand is the best (мелкий заполнитель).
Exercise 3. Translate into English:
Для строительства здания необходимы разнообразные строительные материалы.
Кирпич, лесоматериалы, бетон, железобетон и пластмассы - это наиболее важные материалы, применяемые в строительстве.
Сталь используется в качестве арматуры в железобетонных конструкциях.
Бетон изготовляется путем замешивания в соответствующих пропорциях мелкого и крупного заполнителей, цемента и воды.
Кирпич - это искусственный материал, изготовленный из глины и закаленный обжигом на солнце или в обжиговой печи.
Железобетон состоит из двух прочнейших материалов - бетона и стали. Он широко применяется для строительства жилых и промышленных зданий.
Пластмассы и стеклопластики являются новейшими стройматериалами. Они обладают хорошими изоляционными свойствами.
Exercise 4. Translate into Russian:
Text C. REINFORCED CONCRETE
Reinforced cocrete is a combination of two of the strongest structural materials, concrete and steel.
This term is applied to a construction in which steel bars or heavy steel mesh are properly embedded in concrete. The steel is put in position and concrete is poured around and over it, then tamped in place so that the steel is completely embedded. When the concrete hardens ans sets, the resulting material gains great strength. This new structural concrete came into practical application at the turn of the 19th century. The first results of the tests of the reinforced concrete beams were published in 1887. Since that time the development of reinforced concrete work has made great progress. And the reasons of this progress are quite evident. Concrete has poor elastic and tensional properties, but it is rigid, strong in compression, durable under and above ground and in the presence or absence of air and water, it increases its strength with age, it is fireproof.
Steel has great tensional, compressive and elastic properties, but it is not durable being exposed to moisture, it loses its strength with age, or being subjected to high temperature. So, what is the effect of the addition of steel reinforcement to concrete.?
Steel does not undergo shrinkage or drying but concrete does and therefore the steel acts as a restraining medium in a reinforced concrete member. Shrinkage causes tensile stresses in the concrete which are balanced by compressive stresses in the steel. For getting the best from reinforced concrete the following consideration should be kept in mind:
1. For general use the most suitable proportions of cement and aggregate are: I part cement, 2 parts sand and 4 parts of gravel.
2. only fresh water free from organic matter should be used for reinforced work. Sea water is not allowed.
3. Homogeneity of the concrete is a very important requirement.
Steel costructions with reinforced concrete have become the most important building materials invented in centuries and they have given modern architecture its peculiar features.
Exercise 5. Make up your own topic "Building Materials" on the base of the three texts.