The history of road markings
In 1911 in Wayne County (oкруг), Michigan, an automobile driver observed a collision on a narrow bridge between a horse and a buggy (noвозка), and an automobile going into opposite directions. Each of the drivers was sure that he was on his own side of the road. The observer was Edward Hines, the governor of the county.
Mr. Hines immediately decided that it must be possible for drivers to determine with certainty where their side of the road was. He ordered a white line painted on the centre of every bridge and every turn within his county.
Subsequently he had his idea extended to all the highways of the county. The centre line and various pavement markings have unquestionably saved many lives. They are now one of the most effective means of controlling traffic.
Task 16. Make your own questions for any 3 sentences of the text above.
Unit II.
Building materials.
Task 1. Read and translate the text.
Building materials.
Building materials - natural and artificial material and products, used at the construction and building repair. Differences in the purpose and conditions to erecting and usages the buildings define varied requirements to the building materials and their extensive nomenclature.
Building materials are distinguished on strictly building materials and building products - ready details and elements, assembled in the building on the place of construction.
The list of building materials is extensive and varied. Alongside with traditional materials - ceramic, natural, stone, glass and other - in the modern construction broadly use new building materials on the base of metal.
At the building activity and erecting it is necessary in the first place to use local building materials (sand, gravel, lime, brick and others) that shorten transport expenses, forming much of the material cost. The greater value for cheapen building materials has a salvaging the departures of industry.
Requirements to the building material and products are kept in state sin formation on the building material, given its determination, specified raw material application, categorization, and division by the sort and marks, methods of test, condition of keeping and transporting.
Official document for builders is also “Building rates and rules”, where are kept nomenclature and sizes of main building materials, requirements to their quality, instructions upon their choice and using depending on conditions of usages of raising building standards, standard specifications and other normative documents.
Task 2. Read the sentences from the text with the verbs in Passive Voice, paraphrase them using Active Voice.
Example: This bridge is made of concrete.
1). It is the concrete bridge.
2). They made this bridge of concrete.
___________
______________________
Task 3. Write out the names of natural and artificial building materials.
1. natural building materials: ___________________________________________
2. artificial building materials: __________________________________________
Task 4. Read and translate the text.
Properties of materials.
Density (specific weight) is the amount of mass in a unit volume. It is measured in kilogram per cubic meter. The density of water is 1000 Wm3 but most materials have a higher density. Aluminium alloys, with typical densities around 2800 kg/m3 are considerably less dense than steels, which have typical densities around 7800 kg/m3. Density is important in any application where the material must not be heavy.
Stiffness (rigidity) is a measure of the resistance to deformation such as stretching or bending. The Young modulus is a measure of the resistance to simple stretching or compression. It is the ratio of the applied force per unit area (stress) to the fractional elastic deformation (strain). Stiffness is important when a rigid structure is to be made.
Strength is the force per unit area (stress) that a material can support without failing. The units are the same as those of stiffness, but in this case the deformation is irreversible. The yield strength is the stress at which a material first deforms plastically. For a metal the yield strength may be less than the fracture strength. It is the stress at which it breaks. Many materials have a higher strength in compression than in tension.
Ductility is the ability of a material to deform without breaking. One of the great advantages of metals is their ability to be formed into the shape that is needed, such as car body parts. Materials that are not ductile are brittle.
Toughness is the resistance of a material to breaking when there is a crack in it. For a material of given toughness, the stress at which it will fail is inversely proportional to the square root of the size of the largest form present. Toughness is different from strength. For example, the toughest steels are different from the ones with the highest tensile strength. Brittle materials have low toughness. For example, glass can be broken along a chosen line by first scratching it with a diamond. Composites can be designed to have considerably greater toughness than their constituent materials.
Creep resistance is the resistance to a gradual permanent change of a shape, and it becomes especially important at higher temperatures. A successful research has been made in materials for machine parts that operate at high temperatures and under high tensile forces without gradually extending. For example, they can be the parts of plane engines.
Task 5. Name all properties of materials.
1. ________________________________
2. ________________________________
3. ________________________________
4. ________________________________
5. ________________________________
6. ________________________________
Task 6. Match the following words with their Russian equivalents:
| density | a | вес | |
| weight | b | количество | |
| a volume | c | объем | |
| an amount | d | плотность | |
| stiffness | e | жесткость | |
| rigidity | f | твердость | |
| a force | g | сила | |
| strength | h | прочность |
1 ____, 2 ____, 3 ____, 4 ____, 5 ____, 6 ____, 7 ____, 8 ____.
Task 7. Make up your own sentences with the words from above.
Task 8. Find out 8 words:
| x | s | t | i | f | n | e | s | s | i |
| u | d | e | f | r | m | s | t | d | |
| w | i | z | u | r | a | r | g | ||
| p | e | e | r | c | w | z | y | e | e |
| x | i | s | t | e | e | n | h | ||
| w | y | a | z | g | g | ||||
| s | s | e | n | h | g | u | t | n | |
| f | r | a | c | t | u | r | e | h | c |
1. _______________________
2. _______________________
3. _______________________
4. _______________________
5. _______________________
6. _______________________
7. _______________________
8. _______________________
Task 9. Read the text and answer the following questions.
1. Is density (specific weight) the amount of mass in a unit volume?
2. Is it measured in kilograms per cubic meter?
3. Is density important in any application where the material must not be heavy?
4. Is stiffness (rigidity) a measure of the resistance to deformation such as stretching or bending?
5. Is strength the force per unit area (stress) that a material can support without failing?
6. Is toughness the resistance of a material to breaking when there is a crack in it?
7. Is creep resistance the resistance to a gradual permanent change of shape?
Task 10. Read the text again and complete the following sentences:
1. Aluminium alloys, with typical densities around..........are considerably less dense than steels, which have typical densities around.........
2.........is important in any application where the material must not be heavy.
3.The Young modulus is a.............. to simple stretching or compression.
4. It is the ratio of the applied force per unit area (stress) to the................
5.The yield strength is the stress at which a ................
6. For a metal the yield strength may be which the stress at which it breaks is; many materials have a................... tension.
7. One of the great advantages of metals is............. such as car body parts.
8. Materials that are not ductile are......................
9.Toughness is the........... of a material to breaking when there is a crack in it.
10. ....................is a measure of the resistance to deformation such as stretching or bending.
Task 11. Read the following statements and tell whether they are true or
false. Correct all false statements.
1. Density (specific weight) is not the amount of mass in a unit volume.
2. Aluminium alloys, with typical densities around 3000 kg/m3 are considerably less dense than steels, which have typical densities around 7800 kg/m3.
3. Density is not important in any application where the material must not be heavy.
4. The Young modulus is a measure of the resistance to simple stretching or compression.
5. It is the ratio of the applied force per unit area (stress) to the fractional elastic deformation (strain).
6. Strength is the force per unit area (stress) that a material can support without failing.
7. Many materials have not a higher strength in compression than in tension.
8. Ductility is the ability of a material to deform without breaking.
9. Toughness is the resistance of a material to breaking when there is a crack in it.
10. It is measured in a kilogram per cubic meter.
Task 12. Put the following sentences in negative and interrogative form:
1. Density (specific weight) is the amount of mass in a unit volume.__________________________________________________________
2. Stiffness (rigidity) is a measure of the resistance to deformation such as stretching or bending._______________________________________________
3. Toughness is the resistance of a material to breaking when there is a crack in it._______________________________________________________________
4. Ductility is the ability of a material to deform without breaking._________________________________________________________
5. Strength is the force per unit area (stress) that a material can support without failing. __________________________________________________________
Task 13. Make up sentences.
1. any, in , density, important, application, is _______________________________
2. important, a, is, stiffness, rigid, structure, is, to, when, mad, be _________________________________________________________________
3. from, toughness, is, strength, different___________________________________
4. low, brittle, have, materials, toughness __________________________________
5. a, many, in, materials, have, higher, strength, in, tension, than, compression._______________________________________________________
Task 14. Read and translate the text.
Brick
A brick is best described as "a building unit". It may be made of burnt clay, of concrete, of mortar or of a composition of sawdust and other materials; in shape it is a rectangular solid and its weight is from 6 1/2 to 9 pounds.
The shape and convenient size of a brick enables a man to grip it with an easy confidence and, because of this, brick-building has been popular for many hundreds of years. The hand of the average man is large enough to take a brick and is able to handle more than 500 bricks in an eight-hour working day.
It is necessary, therefore, for the "would-be" bricklayer to practice handling a brick until he can control it with complete mastery and until he is able to place it into any desired position.
Task 15. Answer the following questions.
1. What materials is brick made of?
2. Why brick-building has been popular for many hundreds of years?
3. What is the shape of a brick?
4. What is the brick's weight?
Task 16. Find English equivalents from the text above.
1. форма и размер кирпича ___________________________,
2. ширина кирпича __________________________________,
3. строительство из кирпича __________________________,
4. из обожженной глины _____________________________,
5. практиковаться в укладке __________________________,
6. достаточно большая _______________________________,
7. с полным мастерством _____________________________,
8. лучше всего характеризуется ________________________.
Task 17. Make sentences using the words below.
1. clay, a brick, of, can, made, be, burnt.______________________________________
2. Brick-building, popular, has, years, of, been, hundreds, for, many.________________
_______
3. A "would-be", a brick, must, bricklayer, until, practice, mastery, handling, control, with, he, complete can, it.________________________________________________
_______
4. able, a bricklayer, is, any, a brick, to place, position, into, position._______________
_______
5. pads, the bricklayer's, with, and, thumb, the fingers, be, protected, must, leather._________________________________________________________________
Task 18. Read and translate the text.
Prestressed concrete
Prestressed concrete is not a new material. Its successful use has been developed rapidly during the last four decades, chiefly because steel of a more suitable character has been produced.
Concrete is strong in compression but weak when used for tensile stresses. If, therefore, we consider a beam made of plain concrete, it will at once be realized that the beam's own weight will cause the beam to "sag" or bend. This sagging at once puts the lower edge of the beam in tension, and if the cross-sectional area is small, causes it to break.
If, on the other hand, we use a beam of similar cross-section, but incorporate steel bars in the lower portion, the steel will resist the tensile stress derived from the sag of the beam, and thus assist in preventing it from breaking.
In prestressed concrete steel is not used as reinforcement, but as a means of producing a suitable compressive stress in the concrete. Therefore any beam (or member) made of prestressed concrete is permanently under compression, and is consequently devoid of cracks-under normal loading, or so long as the "elastic limit" is not exceeded.
Prestressed concrete is not only used for beams but is now employed extensively for columns, pipes, and cylindrical water-towers, storage tanks, etc.
Task 19. Choose correct variant and complete the sentences.
1. Prestressed concrete is ...
a) a completely new building material, b) not really a new material
2. The successful use of prestressed concrete has been developed rapidly ...
a) long ago, b) during the last four decades
3. Plain concrete is ...
a) strong in compression, b) weak in compression
4. Plain concrete is ...
a) weak when used for tensile stress, b) strong when used for tensile stress
5. Prestressed concrete is used ...
a) only for beams, b) for beams, columns, pipes, etc.
Task 20. Complete the sentences.
1. Prestressed concrete has been used during ... .
2. Plain concrete is strong in ... .
3. The sagging of a beam made of plain concrete may cause it to ... .
4. Incorporated steel bars in the lower portion of a beam prevent ... .
5. A beam made of prestressed concrete is permanently under ... .
6. Prestressed concrete is now employed extensively for ... .
Task 21. Answer the following questions.
1. Is prestressed concrete a new building material?
2. How long has prestressed concrete been used in construction?
3. What disadvantages has plain concrete?
4. What is steel used in prestressed concrete for?
5. What will happen if "elastic limit" of a beam is exceeded?
6. What is prestressed concrete used for?
Task 22.a) In the text above find the sentence with the verb used in the Present Perfect.
b) Write this sentence in interrogative and negative form.
Task 23. Read and translate the text.