Look at the example of the letter of order and use expressions from Appendix 3
18 Translate the sentences from Russian into English. Be ready to present them not looking at the English equivalents:
1. На цементных заводах производится крупное, среднее и мелкое дробление твердых известняковых материалов.
2. Проницаемость цементного камня определяется его пористостью и наличием трещин.
3. Бетоны относятся к самым массовым по применению в строительстве благодаря их высокой прочности, надежности и долговечности при работе в конструкциях зданий и сооружений.
4. Простейшим видом древнего бетона был камневидный материал из смеси глины с песком и соломой (глинобетон).
5. Под действием внешних нагрузок в бетоне возникают внутренние напряжения сжатия, растяжения и изгиба.
| SPEAKING |
19 Study the table, find information about each property and make reports in groups of 2-3:
Table 4.1 Cement Admixtures
|
20 Read the text. Make up a dialogue based on the text. Use the linking words/phrases from Appendix 1:
CEMENT VS. MORTAR
The difference between cement and mortar is that cement is the binding agent, whereas mortar is a product composed of cement, sand and lime. Both these substances have distinct purposes, such as cement is activated with water and forms a bond with other elements to form one solid object, whereas mortar is useful for holding bricks or stone together, and cannot stand alone like concrete. Cement is a substance that is used to make mortar grout and concrete, etc.
There are different kinds of uses for each mortar, grout or concrete mixed with cement, such as grout can fill gaps between tiles, but if the joints in the blocks have missing pieces, you need mortar. Cement has many types itself, such as Portland, white or Masonry cement. Portland cement is used for structural applications to form an object. Mortar, as it may contain either Portland cement with lime, or Masonry cement, lime and sand, assembles masonry units into structural systems. The mix ratio of cement and the other ingredients determines the compressive and bond strength, including the absorption potential.
Mortar contains bonding enhancers used for filling the spaces between stone, brick or concrete blocks during building. It is also used for repairing and renovating purposes. Mortar is applied as a thick paste, and it sets hard after a short time to create a tight seal between stones or bricks to prevent air and moisture from entering the structure. Mortar has the ability to bond with joint reinforcements, etc, in the bricks. It helps to make an aesthetically pleasing and structurally sound building. The first man-made mortar construction was of mud and clay, apart from the ancient Egyptians who used limestone bricks. Mortar is commonly in use nowadays, and available in different types such as Portland mortar, which is made by Portland cement, sand and water. Another type is called lime mortar, which allows moisture to move freely, and evaporate from the surface. Mortar has a long life without having the need for constant repairs. Cement with lime and sand is called mortar; cement with sand is cement.
21 Read the text, find additional information and make a report:
CONCRETE PROPERTIES
Tracing some of the fresh and hardened concrete properties back to the influences of the cement can often answer both fundamental questions and more complex problems in concrete construction.
Admixture Compatibility.Admixtures are chemicals added to concrete in small quantities for a specific function (e.g. water-reducing, set-retarding, or set-accelerating). These chemicals affect the hydration and/or are adsorbed by the cement particles. Certain combinations of chemicals and cement properties may adversely affect the setting behavior and be deemed incompatible. Examining the chemistry of the hydration reactions and the components of the cement can give clues to the source of the incompatibility.
Strength Gain.The ultimate compressive strength and rate of strength development of concrete is strongly influenced by the chemical reactivity of the Portland cement. Varying hydration rates of the different cement compounds can help explain how the relative proportions of these compounds affect the rate of strength gain. For instance, the C2S reacts slowly and contributes to long-term strength gain. C3S, on the other hand, has a much faster hydration rate, and contributes to higher early-strength gain. Thus, cement with a higher proportion of C3S – as is the case with most of today’s cements – will tend to have a higher early strength, and allow for early form removal or post-tensioning.
22 Topics for projects and presentations:
1. Cement plants.
2. Environmental impacts of cement.
3. Building with concrete.
4. Use of concrete in infrastructure.
5. The technology and use of hydraulic lime.
“A good building reveals different things about itself when viewed from different distances.”
Matthew Frederick (architect)
Unit 5
| TIMBER |
 |  |  |
| a) logging | b) sawn timber | c) wood house |
| LEAD-IN |
1 a) Explain how the following words are connected with “timber”:
boards, lumber, cut wood, foresters, to harvest, loggers, mill, to be processed.
b) Read the information below and compare your answers:
Timber is another name for wood, whether still standing in the form of trees or felled and turned into boards for construction. Some people may also refer to timber as lumber, or differentiate between timber as unprocessed wood and lumber as cut wood packaged for commercial sale. The timber industry around the world is huge, providing wood for a variety of products from paper to particle board.
Before timber is felled, it must be assessed by foresters, who determine how valuable it is and whether or not it is safe to harvest. In many regions of the world, a timber harvest plan must be filed with a government agency, indicating intent to fell trees in a particular region. If the plan is approved, a logging company sends in loggers and support staff to fell the trees and prepare them for shipment to an offsite mill. In some cases, a mill may be established in the forest, if there is a lot of timber which needs to be processed.
2 Speculate on the areas of timber application.
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| "Good timber does not grow with ease. The stronger the wind, the stronger the trees." (J. William Marriott) |
|
• Write a paraphrase.• Say whether you agree or not, and why.
| READING |
4 a) Transcribe the following words:
versatility, diversity, fuel, cellulose, lignin, polymers, glucose, crystalline, deciduous, knots, rustic, lacquer.