2020-05-25
191
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7. Give a short summary of the text.
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Give annotation of the text
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BUILDING MATERIALS
The availability of suitable materials fostered the crafts to exploit them and influenced the shapes of buildings. Large areas of the world were once forested, and their inhabitants developed carpentry. Although it has become relatively scarce, timber remains an important building material.
Many kinds of stone lend themselves to building. Stone and marble were chosen for important monuments because they are incombustible and can be expected to endure. Stone is also a sculptural material; stone architecture was often integral with stone sculpture. The use of stone has declined, however, because a number of other materials are more amenable to industrial use and assembly.
Some regions lack both timber and stone; their peoples used the earth itself, tamping certain mixtures into walls or forming them into bricks to be dried in the sun. Later they baked these substances in kilns, producing a range of bricks and tiles with greater durability.
Thus, early cultures used substances occurring in their environment and invented the tools, skills, and technologies to exploit a variety of materials, creating a legacy that continues to inform more industrialized methods.
Building with stones or bricks is called masonry. The elements cohere through sheer gravity or the use of mortar, first composed of lime and sand. The Romans found a natural cement that, combined with inert substances, produced concrete. They usually faced this with materials that would give a better finish. In the early 19th century a truly waterproof cement was developed, the key ingredient of modern concrete.
In the 19th century also, steel suddenly became abundant; rolling mills turned out shapes that could make structural frames stronger than the traditional wooden frames. Moreover, steel rods could be positioned in wet concrete so as to greatly improve the versatility of that material, giving impetus early in the 20th century to new forms facilitated by reinforced concrete construction. The subsequent profusion of aluminum and its anodized coatings provided cladding (surfacing) material that was lightweight and virtually maintenance free. Glass was known in prehistory and is celebrated for its contributions to Gothic architecture. Its quality and availability have been enormously enhanced by industrial processing, which has revolutionized the exploitation of natural light and transparency.
The requirements to be fulfilled by concrete vary to a great extent. One of the essential properties of concrete is its compressive strength. From the time of its first production more than a century ago there was a steady and gradual improvement in the compressive strength of Portland cement until the beginning of the war. With the cements now available much higher strengths can be obtained than some 40 or 50 years ago. The increase in strength is partly due to the increased fineness to which modern cements are ground.
Cement develops heat during hydration. This is of considerable importance in certain types of concrete construction, particularly in structures of large volume, such as dams, massive retaining walls and the like. A very high rate of heat development is advantageous in work done in cold weather, so as to protect the fresh concrete from the effect of low temperatures.
It should be noted, of course, that not ail properties desired can be obtained in any one cement.
Selection of the cement alone does not ensure concrete with the properties desired, which depend also on the choice of aggregates and mixes, the control of the quantity of water added to the mix, and on a series of other factors.
Silicon is one of the most abundant elements found in the earth's crust. It is second to oxygen in abundance.
Silicon never occurs free, but in combination with oxygen or with oxygen and metals. It forms a great variety of organic and inorganic compounds.
Elementary silicon is used as an alloying constituent to strengthen aluminum, copper, magnesium and other metals. It has a deoxidizing effect on steel.
Silica (quartz) is a crystalline form of silicon dioxide.
Silica bricks, made of nearly pure silica, are extensively used in metallurgical industry.
Silica is also used as one of the raw materials for the manufacture of common glass.
New vocabulary:
The availability – пригодность suitable – подходящий
carpentry - плотницкие работы scarce – недостаточный
incombustible – невоспламеняющийся to endure – терпеть
to decline – снизиться amenable – поддающийся
to lack - испытывать недостаток kiln – печь
durability – долговечность substances – вещества
legacy – наследство masonry – каменный
to cohere – сцеплять gravity - сила тяжести
mortar - известковый раствор truly waterproof cement - настоящий
abundant – избыточный водонепроницаемый цемент
moreover - кроме того steel rods - стальные пруты
impetus - стимул
1. Translate the word combinations into Russian:
to foster the crafts
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to be forested
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remain
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to occur in the environment
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the availability of suitable materials their inhabitants developed carpentry
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tamping certain mixtures into walls or forming them into bricks to be dried in the sun
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to invent the tools
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skills and technologies
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to exploit a variety of materials
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creating a legacy that continues to inform more industrialized methods
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2. Find the English equivalents:
1. древесина остается важным строительным материалом;
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2. камень - также скульптурный материал;
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3. построения из камня или кирпича называются каменными;
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4. в начале 19-ого столетия был разработан действительно водонепроницаемый цемент;
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5. кроме того, стальные пруты могли быть помещены во влажный бетон, чтобы улучшить многосторонность этого материала.
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3. Practise the pronunciation of the new words and word-combinations:
carpentry, stone sculpture, assembly, durability, masonry, subsequent, profusion, cladding
