Some interesting facts
One of man's oldest building materials is finding its way into a lot of new places these days. Concrete, first discovered by the Romans, is now more widely used in construction than all other materials together.
The magic ingredient that makes concrete possible is cement, about which, according to one expert, more has been learnt in the past three decades than in the preceding 2,000 years. Concrete is a synthetic stone which can be formed while soft into practically any shape the builder wants. Portland cement mixed with water is the paste that binds sand, gravel, clinker (шлак) into an artificial rock that becomes harder as the years pass. Portland cement does not come from a place of that name; it was called Portland because Joseph Aspdin, the English builder who invented the first dependable, scientifically made cement about 1824, thought it resembled (напоминать) the rock excavated on the Isle of Portland on the Dorset Coast.
Portland cement is called …
1. after the name of the person invented it;
2. after the name of the place it had been formed;
3. after the name of the island where the mineral it is similar to was excavated.
UNIT IV. THE ROAD. GENERAL INFORMATION
1. Translate the following words and memorize them:
|structure to withstand subgrade moisture load distribution stability to vary to cause||subsoil content excessive disintegration site complete (adj.) maintenance to subject earthwork|
2. Match the equivalents:
1. engineering structure a. распределение влаги
2. road subgrade b. инженерное сооружение
3. moisture distribution c. дробление каменных материалов
4. gravel quarrying d. грунтовое основание дороги
5. subsoil moisture content e. эксплуатационные качества дорожной одежды
6. pavement performance f. содержание влаги в подстилающем слое
7. engineering solution g. вводить в эксплуатацию
8. put into service h. инженер, ответственный за
9. repair shops i. плотность движения
10. utmost importance j. вписывать в ландшафт
11. traffic density k. первостепенная важность
12. fit into landscape l. выдерживать нагрузки
13. withstand loads m. ремонтные мастерские
14. stone crushing n. разработка гравийного карьера
15. engineer in charge of o. техническое решение
3. Read the text carefully and do the tasks that follow:
Modern highways are complex engineering structures. They are intended for high-speed motor traffic. The road pavement must continuously provide good riding qualities and be capable of withstanding the dynamic loads influenced by passage of vehicles. Pavements and road subgrades are subject to the influence of many natural factors such as heating by the sun, freezing, thawing, moistening by rain, etc. Complex physical processes develop in the subgrade caused by variations in moisture distribution and an increase in subsoil moisture content. An excessive moisture content quickly causes the subsoil to lose its strength and may lead to disintegration of the road foundation. The many and varied factors of pavement performance have to be taken into account by the designer and constructor who have to provide for the maximum stability of the subgrade and for the maximum strength of the pavement.
Roads are built in the most varied natural conditions - in broad plains and hills, sandy deserts and in mountains. In all these diverse and complex conditions the road engineer has to be able to find correct engineering and economic solutions. Because of this, A highway paved with concrete
when solving construction problems related to road he has to make use of natural and historical sciences, i.e. geology, climatology, hydraulics, hydrology, etc. He must be able to design highways so as to ensure comfort and safety of transportation.
The road-building operations become complicated because of the extensive length of the construction site – often tens and hundreds of kilometers. The task of the road engineer is to mechanize and technically develop the road-building operations and to provide for the most efficient and complete mechanization of the entire construction process. This is true to such operations as earthworks, sand and gravel quarrying, stone crushing and cement-concrete surfacing.
Finally, when the highway is put into service, its maintenance and the provision for uninterrupted traffic become of the utmost importance of the national economy. The engineer in charge of the highway operation must ensure the maintenance of the road quality under all traffic and weather conditions.
With the growth of traffic density a demand for greater amenities will come. It will be necessary to provide the national road system with hotels and restaurants, service stations and repair shops, where drivers and passengers may rest and vehicles be serviced and repaired. Attention should be given to such questions as fitting roads into the landscape in plan and in profile, planting trees, so as to improve their aesthetic value.
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