CEMENT

ТЕМА: CEMENT

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Active Vocabulary

requirements вимоги

to fulfill виконувати

to obtain отримувати

extent міра

to a great extent в значній мірі

fineness дрібнозернистість

to develop heat нагріватися

hydration приєднання води, гідратація

volume об'єм

advantageous вигідний, зручний

to select вибирати

selection вибір

to grind (ground, ground) розмелювати, молоти

to ensure забезпечувати, гарантувати

aggregate заповнювач (бетону)

Read and translate the following text.

CEMENT

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 tine 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 50 or 60 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 instructures 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 all 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.

Answer the following questions:

1. What is one of the essential properties of concrete?

2. What occurs with cement during hydration?

3. What protects the fresh concrete from the effect of low temperatures?

Fill in the right word or word combination:

monolithic units, framework, concrete, reinforced concrete, concrete curing, aggregate, limestone

1. Cement is the most important component of …

2. The most important quality of concrete is its property to be formed into large and strong …

3. The basic materials for making concrete are cement, … and water.

4. Cement is made of … and clay.

5. The process of hardening lasts for about twenty-eight days and is called …

6. Concrete may be divided into two classes: mass or plain concrete and … where it is necessary to introduce steel.

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