Reading task 2

1. Before reading the text answer the following questions:

a) Do you know how asphalt is obtained?

b) In your opinion what are the processes used in the refining of asphalt?

2. Match the equivalents:

1. oil pool a) примесь

2. crude oil b) несущий слой

3. light fractions c) водонепроницаемый

4. heavy residue d) нефтяная залежь

5.) gravity e) аэродром

6) deposit f) заполнитель

7) refinery g) универсальный

8) oil well h) гидроизоляция

9) aggregate i) плотность

10) waterproofing j) тяжелый осадок

11) waterproof k) сырая нефть

12) airfield l) нефтеочистительный завод

13) base course m) легкие частицы

14) impurity n) залежь

15) versatile o) нефтяная скважина

Reading task 2

3. Read the text carefully and do the tasks that follow:

Asphalt – an Ancient Constructional Material

Asphalt, the world’s most versatile construction material today, is by no means new. It was used in many ways in ancient Mesopotamia, Syria and Egypt. The asphalt used by the ancients was a native material obtained from many of the oil pools where crude oil rose to the surface and the lighter fractions were evaporated by nature. The remaining heavy residue usually contained various amounts of water, soil and other impurities; but by slow and crude methods of distillation, fuel for lamps and bituminous products for mastics, waterproofing and paving were obtained.

The most extensive sources of native asphalt 4,000 to 5,000 years ago were located in Iraq. Several large deposits are known to have existed along the banks of the Euphrates River.

The Egyptians obtained native asphalts for waterproofing and building from the Dead Sea and from a source near the River Jordan in Lebanon.

Asphaltic construction materials are a component of crude oil taken from the hundreds of thousands of oil wells throughout the world today. The amount of asphalt that a crude oil may contain is quite variable, depending upon the gravity of the crude. The lower the gravity of the crude oil the higher is the asphalt content.

The crude oil is transported by pipelines, tank cars or barges to the refineries where it is separated into its various components by a continuous-flow refining process.

In the refining of asphalt, two different processes are used: steam and vacuum distillation method and solvent extraction method. Another refining method used to obtain a higher percentage of motor fuel is the “cracking” process, which by intense heat and high pressures brings about a chemical change producing a bituminous type of material not widely used for paving.

The basic principles of soil-asphalt stabilization, as applied to highway and airfield construction, are methods of designing and mixing local soil or aggregate with asphaltic material to form a stable and waterproof base course. Properly constructed soil-asphalt base courses resist deformation through the cementing action of the asphalt which binds the soil particles together. The thin coating of asphalt around the soil particles also provides a high degree of waterproofing which is further aid to resistance to deformation.

Дата добавления: 2015-10-30