17 Your company is ready to place an order with the cement plant. Write the letter of order in which you should:

• thank for the catalogue and price-list you got 2 days ago;

• specify description, minimum and maximum quantity of goods;

• specify terms of payment;

• ask to send you a letter confirming your order .

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.

19 Study the table, find information about each property and make reports in groups of 2-3:

Table 4.1 Cement Admixtures

CEMENT ADMIXTURES
Plasticiers	Super-plasticiers	Accelerators	Retarders	Air-entraining admixtures	Pigments	Foaming agents	Pumping agents	Water-resisting 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.