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 the main types of buildings?

2. Does the author mention the main factors which influence the choice of materials?

3. Does the author name the main building materials?

4. Does the author describe a precast concrete plant?

3. Read the text:

Text a. The Most Important Building Materials

1. All the buildings erected nowadays are of two main types: they are intended either for housing or industrial purposes. While projecting any of them a designer must be able to select and adapt such materials of construction that will give the most effective result by the most economical means. To make his choice a civil engineer must consider many factors: availability, cost, physical properties of materials being the most important. Which material can be used to the best advantage for a particular part of building, depends as well on the kind of load to which it is subjected and on the shape of the part.

2. At present the main building materials are considered to be timber, stone, brick, concrete, steel, light metals, glass and plastics. Timber was one of the first materials used by man for constructional purposes. The buildings made of stone or brick are durable and fire-proof, they have poor heat conductivity.

3. Portland cement was produced more than a century ago. From the time of its first production there was a steady and gradual improvement in its compressive strength.

4. Concrete made with natural hydraulic binders was used in antiquity, particularly by the Romans. After the decline of the Roman Empire the art of making concrete has been forgotten, and the revival came much later.

5. Reinforced concrete is hardly 100 years old but its practical application in building began 90 years ago. Today reinforced concrete is used in all civilized-countries as one of the most important building materials. One of the properties of concrete is its compressive strength.

6. Cast-in-place concrete is mixed and placed on the building site. Precast concrete is produced in a factory and used for the production of prefabricated elements. Usually they are made of dense concrete but in recent years the use of lightweight concrete has increased considerably. A precast concrete plant consists of two parts: a large mixing installation and a casting yard where the plastic concrete mass is placed in moulds. It is an advantage of this method that prefabricated elements of a constantly high quality can be produced to a very high standard of precision. Another important advantage of precast concrete is that the work on the building site is largely replaced by operations in the factory where working conditions are far better. This allows continuous production which is not influenced by weather conditions; therefore this method is of special interest for countries with long hard winters.