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23. Render the text in English.

Бетоны на основе неорганических вяжущих веществ представляют собой искусственные строительные конгломераты (ИСК), получаемые в результате твердения рациональной по составу, тщательно перемешанной и уплотненной бетонной смеси из вяжущего вещества и заполнителей. Кроме основных компонентов в состав бетонной смеси могут вводиться дополнительные вещества специального назначения. Среди других ИСК бетоны относятся к самым массовым по применению в строительстве вследствие их высокой прочности, надежности и долговечности при работе в конструкциях зданий и сооружений.

Кроме высокой прочности, у бетонов на основе неорганических вяжущих веществ имеется много и других достоинств: лёгкая формуемость бетонной смеси с получением практически любых наперед заданных форм и размеров изделий и конструкций, доступность высокой механизации технологических операций и т. п. Большая экономичность изделий из бетона состоит в том, что для их производства применяют свыше 80 % объема местного сырья – песка, щебня, гравия, побочных продуктов промышленности в виде шлака, золы и др. По некоторым зарубежным данным, количество энергии, требующейся для производства бетонных материалов является минимальным по сравнению с энергией (приведенной к единому эквиваленту), необходимой для изготовления стали, алюминия, стекла, кирпича, пластмасс. Для затворения порошкообразных вяжущих в тестообразное состояние и получения бетонной смеси используют обычную воду – питьевую из водопровода или речную, озерную и др. Расход воды также ниже, чем при производстве стали. После твердения тесто образует камень. Часть объемов в бетоне, заполнителе и камне занимают поры и капилляры разного размера и в различ­ном количестве.

Для бетонов применяют почти все разновидности неорганических вяжущих, в соответствии с чем бетоны разделяются на цемент­ные, гипсовые, силикатные, шлаковые, специальные (на фосфатных, магнезиальных и других вяжущих). Для них используют также все разновидности заполнителей, вследствие чего бетоны разделяют на плотные, пористые, специальные. При объединении вяжущих и за­полнителей в принятых по составу количествах получают множество технических решений при производстве искусственных строительных конгломератов различного назначения. Если этих двух компонентов окажется недостаточно, вводят дополнительные веще­ства (добавки). Еще более сильным фактором, которым пользуются при получении бетонов с заданными свойствами, является технология с её многообразными операциями, режимами (теп­ловыми, механическими и пр.) и характеристиками оборудования и энергетики.

Chapter 2. To the history of building materials

1. In pairs answer the following questions:

  • Do you know who discovered Portland cement and when?

  • How long has reinforced concrete been used?

2. Write phonetic symbols for the following words, pay attention to their correct pronunciation and read them aloud:

architect; era; machinery; manufacture; patent; reservoir; scarce; substance; superiority; therefore; tunnel.

3. Learn new words and phrases.

available

доступный, имеющийся в распоряжении

inventor

изобретатель

lattice

решётка, сетка

reinforcement

укрепление, упрочнение, усиление

scarce

недостаточный, скудный

slab

плита, лист, пластина

tension

напряжение, напряжённое состояние

to discover

обнаруживать, раскрывать, узнавать

to eliminate

устранять, исключать

to neglect

пренебрегать, игнорировать

to obtain

получать, добывать, приобретать

to strengthen

усиливать(ся), укреплять(ся)

4. Translate the following words and phrases into Russian:

break-through; hard substance; improved materials; on a large scale; powder; prestressed concrete; reinforced concrete; the biggest boost; to be embeded; to erect; to realize.

5. Make up your own sentences using the words and phrases from tasks 2-4.

6. Skim the text and say what the general idea of the text is.

7. When skimming divide the text into parts.

With the introduction of the railways and steam machinery, trans­portation and manufacturing costs were considerably reduced and concrete came to be more widely used, but it was still very much a neglected material. Therefore, good concrete was scarce and a great deal of poor concrete was used.

The big break-through was the discovery of Portland cement by Joseph Aspdin in 1824, a worker in an English town.

When he was working an idea came to him as to how to make his work better. He started his experiments. After some time he obtained a powder. When it was mixed with water and allowed to stand it "sets" forming a hard substance. This substance was so much like the building stone from Portland that the powder was named Port­land cement. As years passed different materials were found in many countries from which Portland cement could be made.

Portland cement was first used on a large scale in the construction of the Thames tunnel in 1828.

As early as 1830 the first idea of reinforced concrete was men­tioned in a publication, which suggested that a lattice of iron rods could be embedded in concrete to form a roof.

Lambort, a French contractor, built a concrete boat for the Paris International Exhibition of 1855, with 2 inches sides reinforced with a skeleton of iron rods.

W. Wilkinson, who patented a method of constructing a concrete floor in 1854, is considered to be the inventor of reinforced concrete as well.

But many people say that a Frenchman, J. Monier, who, took out a patent in 1867 for the construction of plant tubs, tanks, etc, made of concrete reinforced with a mesh of rods or wires, should be credit­ed with the invention. Certainly Monier did a great deal to develop the use of reinforced concrete and his name became so closely linked with reinforced concrete that reinforced concrete was known as the Monier System.

Wilkinson, however, certainly appears to have been the first. His patent covered for concrete floor slabs reinforced with a network of flat iron rods placed on edge. One of his main claims was the good fire resistance of the floor. He appears to have understood the princi­ples of reinforced concrete, for he stated that the reinforcement was to be placed in the concrete to take the tension.

A number of buildings were erected, using Wilkinson's system. He also described method for the construction of pipes, reservoirs, and walls of concrete reinforced with metal sheets, bars and chains.

Freyssinet is known for his work in prestressed concrete for which he had his first ideas before First World War. With the improved materials and the new knowledge available, Freyssinet realised the advantage to be obtained from prestressing; and he used his system in prestressed works.

The post-war era has given the biggest boost to concrete, both reinforced and prestressed. After the war steel was short in Europe and many architects had to use either reinforced or prestressed con­crete in their structures in order to economize in steel.

Architects were perhaps a little surprised to discover that in many cases reinforced concrete structures, apart from using the minimum of steel, were also cheaper than other forms of construction, and could be erected as quickly. They also discovered that they had more freedom for planning than they had ever before, and a larger number of solutions to each structural problem were available.

Beams could be eliminated, floor spans could be increased, and shells were available for roofing large areas.

Another big factor, which encouraged the use of concrete, was the introduction of fire regulations, which recognized the superiority of concrete over other structural materials in its fire resistance properties.

8. Compare your number of parts with that of your fellow students.

9. Read and translate each part using a dictionary.

10. Underline the sentences that best sum up the main idea of each part and use key words from them to make plan of the text in order to retell it according to your plan.

11. Find Russian equivalents to the following words and phrases in the text:

steam machinery; manufacturing costs; were reduced; neglected material; scarce; poor concrete; break-through; obtained; mixed with water; substance; powder; reinforced concrete; a lattice of iron rods; contractor; inventor; invention; floor slabs; fire resistance; construction of pipes; reservoirs; metal sheets; bars; chains; prestressed concrete; advantage; architects; in order to; cheaper than other forms of construction; could be erected; available; beams; eliminate; increase; encourage; fire regulations; recognize; fire resistance properties.

12. Match pairs of words having the opposite meanings.

tension

supply

scarce

liquid

neglect

inferiority

discover

submit

solid

plentiful

increase

reduce

remove

dismantle

encourage

looseness

resist

conceal

erect

discourage

superiority

appreciate