МУ англ ПГС
.pdf4.Study the following text and then give it a title:
Concrete – unlike many buildings materials – is equally a framing and an
enclosing material. It can be used to construct a skeleton; it can also be used to construct a complete weather tight shell of floor, walls and roof. In this respect it is one of the few total building materials.
It is hardly surprising that for a long time reinforced concrete was treated in a similar manner to a steel frame, clad in some other material.
Steel needs protection from the external elements and from internal fire; concrete need neither of these. Steel was a construction material of parts connected together; concrete could be handled to produce a monolithic structure including enclosing surfaces.
The present stage of evolution shows and appreciation of concrete as a total material.
5.Render the text in Russian:
Concrete. Concrete is and artificial stone. It is made by mixing a paste of
cement and water with sand and crushed stone, gravel, or other inert material. After this plastic mixture is placed in forms, a chemical action takes place and the mass hardens. Concrete, although strong in compression, is relatively weak in resisting tensile and shearing stress which develop in structural members. To overcome this lack of resistance, steel bars are placed in the concrete at the proper positions, and the result is reinforced concrete. In beams and slabs the principal function of the concrete is to resist compressive stresses, whereas the steel bars resist tensile stresses.
6.Render the following in English:
1.Лёгкие бетоны изготовляют на пористых естественных или искусственных заполнителях. 2. Лёгкие бетоны на пористых заполнителях применяют для изготовления панелей для стен, плит перекрытий и конструкций каркаса. 3. Конструкции из легких бетонов следует применять при отсутствии агрессивных воздействий. 4. Когда конструкции находятся в агрессивной среде (наличие агрессивных газов,
31
паров, кислот и т. д.), мелкие трещины растянутой зоны бетона способствуют активному развитию коррозии арматуры. 5. Это приводит к снижению несущей способности конструкций. 6. Для борьбы с коррозией бетонных и железобетонных конструкций применяют плотные бетоны, кислотостойкие бетоны, полимербетоны.
7.Complete the sentences:
1.Prefabrication means...
a)… reinforcement of brickwork with steel. b) … preassembly in a workshop, so that the building can be more quickly erected on the site. c)... craft operation at the building site.
2.Reinforced concrete is a building material in which...
a) ...such properties as small volume weight and high thermal conductivity are combined. b) ...physical and mechanical properties at a normal temperature of 20°C make it semi-rigid and soft. c)...the joint functions of concrete and steel are advantageously utilized.
3.Like any other stone material, concrete offers...
a)…the ability of binding together masonry units such as stone, brick and plaster. b) … a good resistance to compressive loads. c) ...a lower volume weight and it is manufactured from a mixture of unslaked lime and quartz sand.
8.Read this passage:
Concrete is made from cement, coarse aggregate (stones), fine aggregate (sand or crushed stone) and water. Coarse aggregate ranging from 5 mm to 4 mm may be used for normal work. The maximum size of the aggregate should not be greater than one quarter of the minimum thickness of the finished concrete. The normal maximum sizes are 20 mm and 40 mm (20 mm being more common. The maximum size of aggregate which should be used in small concrete sections, or where reinforcement is close together, is 10 mm.
In concrete with widely spaced reinforcement, such as solid slabs, the size of the coarse aggregate should not be greater than the minimum cover to the
32
reinforcement otherwise spalling will occur, i.e. the breaking off of pieces of concrete below the reinforcement. For heavily reinforced sections, e.g. the ribs of main beams, the maximum size of the coarse aggregate should be either:
(I)5 mm less than the minimum horizontal distance between the reinforcing rods, or,
(II) 5 mm less than the minimum cover to the reinforcement, whichever is the smaller.
Now say whether these statements are true or false. Correct the false statements.
a)Concrete is made from three different materials.
b)Coarse aggregate ranges in size from 20 mm to 40 mm.
c)Then the minimum thickness of the finished concrete is 100 mm, the maximum size of aggregate should not be greater than 25 mm.
d)When the reinforcing rods are close together, the maximum size of aggregate used should be 10 mm.
e)Cover is the thickness of concrete between the reinforcing rods.
f)The reinforcing rods are placed near the bottom of the rib of a concrete beam.
g)Spalling can occur in a solid concrete slab when the cover to the reinforcement is greater than the maximum size of the coarse aggregate.
h)Then the minimum horizontal distance between reinforcing rods is 15 mm, the maximum size of aggregate should be less than 12 mm.
9.Discussion: Your ideas about the material.
33
UNIT 6
TEXT A. Gas concrete.
Lime and silica are ground together to very fine limits. The siliceous material can vary considerably in its composition. Much use is made of such waste materials as fly ash from power-stations, blast furnace slag, as well as natural pozzolanas, pumice, etc. The degree of foaming in the gas concrete, and thus its specific gravity, is determined by the amount of aluminium powder or other agent added. The practical limits of the final density are between 13 and 90 Ib. Per cu. ft. If he gas concrete is allowed to harden on its own, it usually takes about three weeks before, the final strength is achieved. It is more customary to accelerate the setting of the gas concrete by steam hardening it in autoclaves with superheated steam at about 140 Ib. per sq. in. The steam hardening process takes about 15-20 hr. Air-cured gas concrete can be used for the manufacture of special components for the refrigeration industry. Such blocks are cast to special dimensions.
Gas concrete can be cast horizontally to form roomsized outer wall units. It is possible to incorporate electric conduit pipes, piping for the cold and hot water systems and also drainage pipes. The units usually include windows
and doors, and are reinforced by embedding steel mesh in the mix.
Gas concrete can be used as thermally insulating floor screeds or as an additional thermally insulating layer a top of concrete roof.
Cast gas concrete is often used as the thermally insulating layer in “sandwich wall” units.
Gas concrete is often used as a thermally insulating layer when casting buildings by a continuous easting technique.
Text B. Steam treatment process to produce thermoplastic materials and hydraulic cements
This invention relates to the manufacture of thermoplastic materials and hydraulic cements from certain glass compositions. More particularly, this invention relates to the manufacture of such products through the steam treatment of glass powders in the alkali metal silicate composition field.
34
A thermoplastic material is one having the property of softening when heated and of hardening and becoming rigid again when cooled. Hence, such a material is normally hard at room temperature but will soften and become moldable, adhesive, and cohesive when heated to some higher temperature. This property of thermoplasticity is well-recognized in such organic materials as cellulose acetate, polyethylene, and vinyl polymers and in glasses at temperatures around and somewhat above the softening points thereof. The value of this property is apparent in the forming of articles through molding, pressing, extrusion, rolling, etc., and in forming composite structures, laminates, and the like.
Hydraulic cement is one that is capable of hardening under the influence of water. Hence, such a material, when mixed with water and allowed to stand, gradually sets up as a hard, massive solid structure. Portland cement is probably the best known material commercially of this type.
Text C. New types of concrete
Not long ago a new building material was born. Called alkali-slag concrete, most of its components come literally from under foot. Cement is replaced by a mixture of granulated blast-furnace slags and sodium and potassium compounds. The filler can be sand or sandy loams containing various amounts of clay, which usually cannot be used with conventional cement.
The new material has been tested successfully and is now being used for roads, pavements, irrigation systems and other structured. Specialists estimate that the use of alkali-slag concrete will help save hundreds of millions of rubles on the country's construction projects.
Chemically resistant concrete (кислотоупорный) may be sometimes used in the construction of structures attacked by chemically active media (среда), i.e. industrial, hydraulic and underground structures. It has been proposed to prepare a chemically resistant concrete using a binder (вяжущее), a vitreous sodium silicate (стекловидный силикат натрия). Then such a vitreous silicate is dissolved in water, liquid (жидкий) glass is obtained. In order to assist in the solidification (затвердение) of a liquid glass and increase its water resistance
35
certain elements are added to the concrete composition. They serve to neutralize the alkali (щелочь) in the liquid glass and convert it into a water-insoluble (нерастворимый) compound. Thus, during the course of the neutralization of the alkali, free silica is evolved (выделяется кварц) from the liquid glass in the form of a gel which serves as a binder.
Chemically resistant concrete has not found wide application because it is completely permeable to aggressive, corrosive solutions. The Soviet scientist V. P. Kirilishin decided to provide and improved alkali-metal-silicate based concrete. In accordance with his invention high-silica-alkaline glasses are practically insoluble in water even at elevated temperatures and are not suitable for the production of liquid glass. However, when subjected to heat in the presence of finely divided quartz sand, the high silica alkaline glass on the finely divided particles of the quartz sand.
In the present invention the silica binding agent is not present in the form of a gel that has the more thermodynamically and chemically stable crystalline form of free silica, namely quartz. This leads to good chemical, physical, thermal and mechanical characteristics for the binder and the chemically resistant concrete.
Text D. Concrete structures
The world has suddenly become aware of the great resources of ocean and their potential for providing many of man's most pressing needs: energy, food, transport, minerals and waste-disposal. However the seas present an extremely hostile environment, requiring cooperative efforts by many engineering disciplines in order to achieve the necessary structures.
These structures must be strong, save, durable and economical. Reinforced prestressed concrete meets these criteria extremely well for many of the proposed structures, both fixed and floating. These include drilling, breakwaters, ocean pipelines, offshore nuclear power plants; ocean bridges and tunnels; offshore airports and terminals; Arctic Ocean structures; Barges, ships and floating stable platforms; offshore expositions and even cities; sea floor chambers etc.
36
The first reinforced concrete skyscraper in the world was built in 1902-03 in Cincinatti, Ohio. The 16-storey structure demonstrated for the first time the safety and economy of reinforced concrete frames for high-rise construction, and was a vital stimulus for using reinforced concrete in fireproof construction.
Concrete was chosen as the structural material chiefly for economics; it offered the equivalent of steel frames in load bearing capacity and other physical properties, yet was somewhat lower in cost. Engineers all over the world watched with great interest as construction proceeded smoothly along its 16-storey route. Today this building is recognized by engineers as having revolutionized the building industry.
Text E. Sand concrete
For many, many years nature has been destroying stone, changing it into sand. Now man is learning to do the opposite: he is using sand and cement to create materials which could compete with stone in strength and beauty.
At first the idea of making concrete by using sand was completely rejected. It is common knowledge that concrete is made from gravel and cement, while a mixture of sand and cement is considered useful only to bind bricks. This idea has gripped the attention and minds of scientists and engineers to such an extent that it is no easy task to cast doubt upon this universally accepted truth.
“Sand” concrete is made by putting the matrix under vibration which almost completely eliminates its weak points. Sand concrete has now become almost twice as strong as ordinary concrete with a course aggregate, and much cheaper as well. At present several varieties of sand concrete have been developed.
1.Render it in Russian:
Gas concrete containing fly ash and blast furnace slag is often used as structural. The method of substituting heavy aggregates by light ones is a rather common practice today. There are several chemical reactions taking place
37
during the air entrainment. Portland cement is widely used in building. Various concrete and reinforced concrete constructions are made from it. White Portland cement is used in exterior and interior architectural and decorative finishing ornamental works.
2.Fill up the blanks with English equivalents:
1.(Самым важным качеством) of concrete is its property to be formed into large and strong monolithic units. 2. Concrete is made by mixing cement, sand, gravel and water (в нужных количествах). 3. The characteristics of concrete depend (от качества используемых материалов). 4. (Бетон применялся египтянами, римлянами) in the construction of aqueducts and bridges. 5. (Так как цемент не был известен в то время) concrete was made of clay and later of gypsum and lime.
3.Read and translate the following word-combinations:
To put in position, to pour concrete, to lose strength, to come into practical application, to cause tensile strength, to undergo shrinkage, at the turn of the century.
4.What is the English for:
1.применять термин; 2. заливать бетон; 3. набирать прочность; 4. быть опубликованным; 5. увеличивать, уменьшать прочность; 6. подвергаться усадке; 7. вызывать растягивающие усилия; 8. использовать железобетон.
5.Complete the sentences using the English equivalents for the Russian words in brackets.
1.The resulting material gains great strength when (он затвердевает). 2. At the turn of the 19th century new structural concrete (стал применяться). 3. Steel has great tensional, compressive and elastic properties but (со временем она теряет прочность). 4. Steel does not undergo shrinkage and therefore it acts (как сдерживающая среда). 5. Shrinkage causes tensile stresses in concrete which are balanced (сжимающими усилиями в стали).
38
6.Translate into English:
1. Железобетон - это вид бетона, полученного в результате сочетания бетона и стали. 2.Стальные стержни и стальная арматура укладываются в нужном положении и заливаются бетоном. 3. Бетон затвердевает, схватывается и приобретает большую прочность. 4. Сталь не подвергается усадке, она действует как сдерживающая среда в железобетонном элементе.
6. Render the following in English:
Проблема снабжения строительными материалами в пустыне чрезвычайно остра. Даже обычный гравий приходится везти сюда за сотни километров.
Ячеистый бетон представляет собой разновидность легкого бетона с равномерно распределенными по всей массе материала замкнутыми воздушными порами (85%).
Пористая структура ячеистых бетонов достигается применением пеноили газообразователей.
По способу образования пористой структуры ячеистые бетоны подразделяются на пенобетоны и газобетоны.
Газобетон почти в два раза легче железобетона, из него удобно монтировать дома. Технология изготовления различных деталей проста и хорошо освоена. Уже действует первый завод по выпуску газобетона
7. Discussion: Your ideas about the material.
39
UNIT 7
TEXT A. PILE FOUNDATIONS
The durability of a structure depends on how the foundation is built and on the property of the ground.
Prior to the beginning of the last century buildings were put up mostly on stable ground. Bands of stone and baked bricks bound together by lime mortar served as foundations.
Our ancestors could not even imagine on what kind of ground we would build. Towns and cities have appeared in places where there had recently been swamps, on the permafrost ground of the northern regions of the country. Pile foundations are widely used there. They cut through the unstable thickness of the ground and rest upon firm layers.
Piles were also used in ancient times. Peter I widely used piles in building the city. Interestingly, Ivan the Great’s bell tower in the Kremlin (about 500 years old) also stands on a peculiar pile foundation. The base is comprised of round, closely bound upright logs from 120 to 180 cm high. In those days there were no mechanisms to drive in piles – that accounts for their being so short. Upon the piles rests a massive stone slab. The piles are submerged in water to protect the wood from destruction.
Ferro-concrete was discovered about 200 years ago. Wooden piles gradually became a thing of the past. The have been replaced by ferro-concrete and metal piles.
During the last few decades pile boring has found wide application. A bore hole is first filled with steel framework, then with concrete, and the pile is ready
A group of specialists has developed piles without using building materials for the purpose. At the depth of 16-18 m a hole is drilled. A special burner is then inserted. At 1,400 o C the earth fuses. It then hardens and becomes a bearing pillar. Several buildings have already been erected on such “piles”.
The foundation of the Alma-Ata TV tower is quite original. The tower was built on a small site in the mountains, where force 10 earthquakes can
40