Task 6. Make a resume of the text, using the list of expressions, given in the Appendix

Unit 4 Task 1. Read and translate the text:

Polyester asphalt reinforcement grid: preventing reflection cracks

A leading manufacturer of custom-made geosynthetics and technical textiles, Huesker Synthetic Company, claims, that polyester reinforcement grids demonstrate effective results in the prevention of reflection cracks in asphalt layers. The company says that cracks (even micro-cracks) in an existing asphalt layer continue to cause problems when these existing layers of roads or airfields are resurfaced.

As a result of daily temperature variations, but especially due to the frost-dew cycles, existing cracks in an old asphaltic layer reflect through to the surface of the newly applied layer of asphalt. The existing cracks which propagate very quickly through to the new layer of asphalt are called reflection cracks. By installing a polyester asphalt reinforcement grid, the development of reflection cracks can be substantially slowed down, or even completely avoided.

In order to simulate thermally induced reflective cracking, the Belgium Road Research Center developed a test method at the beginning of the 1990-s, investigating the effect which an asphalt reinforcement has on the reduction of cracks. For the test, a 65 mm thick layer of asphalt is installed over a pre-cracked surface. The simulated crack is 4 mm wide and is widened by 1 mm / cycle, then returned to a 4 mm width. The opening of the crack by 1 mm / cycle corresponds to the expansion volume of water which exists in the crack. The exact widening of the crack is achieved by means of a control liquid which freezes and then thaws.

This test method has now become so well established that nearly all products and systems which are available on the market have been tested. The reinforcement products differ mainly by the choice of the raw material and the use of a bituminous coating. The tested products which are available on the market consist of glass, carbon, polypropylene (PP), steel and polyester (PET).

The reference test without interlayer shows that the crack rises to the surface after very few cycles. The asphalt interlayer systems clearly show differences in their effectiveness, completely preventing reflection cracks. Even after completion of the tests, no cracks had been initiated, whereas all other systems made from synthetics, carbon or glass indicated cracks, many of which soon reached the surface. This clearly demonstrates that reinforcement stiffness must be matched to the total asphalt package (if the reinforcement is too stiff it will not interact with the surrounding asphalt matrix).

The polyester used by manufactures shows that it is the ideal raw material for asphalt reinforcement. It consists of special high modulus polyester covered with a protective bituminous coating. Furthermore this special coating ensures a high bond, considered to be an important parameter. Only when a good bond is obtained with the surrounding asphalt layers can the tensile forces be considered to be transferred to the reinforcement. In the case of cracked asphalt surfaces under heavy use, effective mobilization of tensile forces, through good bond and excellent system performance, provides a highly effective solution.

Vocabulary

1. custom-made специально сконструированный, изготовленный по техническим условиям заказчика

2. geosynthetics геосинтетики, геосинтетические материалы

3. polyester reinforcement grids полиэфирные армирующие сетки

4. prevention предотвращение, предупреждение, профилактика

5. reflection crack “зеркальная” трещина

6. resurface повторное выравнивание поверхности

7. frost-dew cycles циклы замерзания-оттаивания

8. propagate распространяться

9. completely полностью

10. to avoid избегать

11. thermally induced вызванный температурным воздействием

12. install укладывать; устанавливать

13. reduction снижение, уменьшение, сокращение

14. widening расширение

15. bituminous coating битумное покрытие

16. reference test эталонное испытание

17. interlayer прослойка

18. difference отличие, различие

19. to initiate начинать, приступать, вводить

20. to indicate означать, показывать, служить признаком

21. stiffness твердость, жесткость

22. to match подходить, соответствовать

23. furthermore кроме того, более того

24. tensile force растягивающая сила (напряжение)

25. to transfer переносить, переводить, относить на счет

Task 2. Answer the questions, concerning the contents of the text:

1. What results do polyester reinforcement grids demonstrate in road construction?

2. What type of cracks in the layer of asphalt are called reflection cracks?

3. How is the widening of a crack achieved during tests, investigating the effect, which asphalt reinforcement has on the reduction of cracks?

4. What factors do the reinforcement products differ by?

5. What tested reinforcement products are available on the market nowadays?

6. How long does it take for a crack to rise to the surface?

7. Should reinforcement stiffness be matched to the total asphalt package?

8. What is the ideal raw material for asphalt reinforcement according to tests?

9. What is considered to be an important parameter of protective bituminous coating?

10. What provides a highly effective solution in the case of cracked asphalt surfaces under heavy use?

Task 3. Find Russian words with the same roots to the following English words from the text and define the part of speech they belong to:

1. manufacturer

2. technical

3. demonstrate

4. effective

5. temperature

6. simulate

7. variation

8. bituminous

9. initiate

10. synthetics

11. special

12. parameter

Task 4. Choose correct Russian equivalents from column B to the English words from the text, given in column A:

A B

to claim 1. окружающий

layer 2. ширина

to exist 3. побуждать, вызывать

surface 4. производительность, работа

to cause 5. устанавливать

substantially 6. ясно, явно

to continue 7. переносить, передавать

volume 8. завершение, окончание

to induce 9. существовать

completely 10. кроме того, более того

pre-cracked 11. получать, достигать

width 12. слой, пласт

completion 13. объем

furthermore 14. полностью

to establish 15. вызывать, быть причиной

surrounding 16. заявлять, претендовать

to transfer 17. продолжать

performance 18. поверхность

to obtain 19. имеющий трещины

clearly 20. существенно