III. Reading Comprehension

1. Skim the text first to define its general subject and the subject of each paragraph. Use the following phrases:

The text is about…

The subject of the text is…

There are…paragraphs in it.

The first (second, third, etc.) paragraph deals with (considers…, describes…, informs…).

2. Skim the text again and answer the following questions:

1. Is this text about concrete?

2. Are the properties of concrete mentioned?

3. Is the process of concrete production described?

4. Is the process of reinforced concrete described?

5. Are the disadvantages of concrete mentioned?

3. Read the text:

Text a. Concrete

1. There are many important building materials nowadays, concrete being one of them. Concrete may be considered an artificial conglomerate of crushed stone, gravel or similar inert material with a mortar. The fundamental object in proportioning concrete is the production of a durable material of requisite strength, watertightness and other essential properties at minimum cost. To attain these properties careful attention must be given to the selection of cement, aggregate, and water.

2. The most accurate method of measuring proportions is to weigh the required quantities of each material. It is widely used in large building construction, but in small building construction the less accurate method of measuring proportions by volumes being frequently used. Workability and strength are chief control tests made on concrete. To be able to undergo high compressive loads is a specific characteristic of this material.

3. Since concrete is only strong in compression, it will quickly fail if it is used for elements like beams and floor slabs, which are subjected to high bending forces. If it is reinforced with iron or steel bars, however the elastic metal will take the rigid forces, and the rigid concrete will resist the compressive forces. The reinforcing techniques developed the structural possibilities of concrete becoming almost unlimited. In its reinforced form it combines the elasticity of iron and steel with its own initial plasticity and final rigidity, an almost ideal combination of properties that makes it the most suitable of all building materials.

4. Reinforced concrete has become so popular because of its resistance to fire and weather, its durability and great strength under static and dynamic loads. It has, however, a number of disadvantages, low thermal insulating value being one of them. Besides it is very heavy and requires forms in which it must be held until it has hardened, and in winter it must be kept warm during setting.

5. Prefabricated reinforced concrete elements and modern reinforcing methods being used, the above mentioned disadvantages are now being eliminated or at least minimized. Reinforced concrete is used for many types of structures, it being now the main building material for factories, office buildings, power stations, bridges, etc. In recent years it has become the preferred material for housing.