 |
Главная Случайная страница Контакты | Мы поможем в написании вашей работы! | |
B) Explain the words in bold from the text and make up sentences of your own. Use English-English dictionaries to help you
|
|
7 Give the English equivalents to the following and use 5 of them in small situations:
застывать; дробленный; искусственный пуццолан; добавки; размельченный; промытый; просеянный; до обязательных размеров; известковая глина; аргиллитовый сланец; второстепенные компоненты; спекание (агломерация); начальное плавление; включение (добавление) стали; щебень; восприимчивый к разрушению от мороза.
8 Read and translate the text and make 5 questions to it:
Portland cement is produced from a slurried mixture of limestone and clay, burned at a high temperature in a kiln and the resulting clinker is then ground up, with ground calcium sulphate added to regulate its set. It is highly processed partly to ensure no variation in product. It is nothing like a hydraulic lime. It is called Portland cement because it was thought to set as hard as Portland stone, and to look like it.
The essential feature of a lime mortar or plaster is that it needs to carbonate in order to cure. A transformation takes place within it as calcium hydroxide changes to calcium carbonate, a process that requires moisture, as carbon dioxide in the atmosphere has to be carried into the lime plaster in solution. A hydraulic lime has the extra feature of also having a chemical set, so that it can feel hard to the touch within a few hours to a couple of days, depending on the strength of the hydraulic lime. It can remain workable for several hours or days, but it still needs to carbonate after it has set. Lime strengths vary greatly depending on the type of lime used, but it takes about 28 days to reach full strength.
Cement does not carbonate. It hardens because of a chemical reaction with water, usually setting within half an hour to an hour, after which time it cannot be re-worked. It takes about 28 days to reach its full strength, and is generally very much stronger than lime.
| LANGUAGE FOCUS |
9 Use the words below to complete the sentences:
Think mixing cement is easy? Cement is a bonding agent used in conjunction with sand, water, and 1) _____ (crushed stone) to create mortar and/or concrete. You need cement for a variety of projects – to set 2) _____ for decking or fences, to fill a sidewalk, or to patch a blemish in your house's foundation. If you are doing a project that requires concrete or 3) _____ application, you will need to know how 4) _____ the cement that bonds the materials together. Of course, if you'd simply like to dress up an existing or new expanse of concrete, then it's a good idea to take a look at the Decorate Concrete Overlay Guide - you'll learn 5) _____ that can improve the look of everything from concrete steps to sidewalks and more! Here is how you mix cement.
Materials: Portland Cement. This is pure cement mix. You will need to buy enough sand and aggregate to match the amount of cement you are buying (in the correct 6) _____) to mix in. Read the back of the manufacturer's label to find the cement sand mix ratio and match the amounts needed for the project at hand. This is the cheapest option for creating a concrete or mortar, but it involves more physical work and 7) _____. The basic formula for a cement mix ratio is1 part Portland cement, 1 part 8) _____, and 1 part crushed stone; the amount of water to add is not so clear cut – add 9) _____ water so that the mix is not too wet and not too dry - a little like cake mix. Some cement products 10) _____ how much water to use per bag.
| mortar, specify, sand, aggregate, enough, time, proportions, techniques, footings, to mix |
10 Fill in the gaps with derivatives of the words in capitals:
| MASONRY CEMENTS Portland cement mortar is 1) _____ strong and concentrates any differential movement within brickwork or blockwork into a few large cracks, which are unsightly and may increase the risk of rain 2) _____. Masonry cement produces a weaker mortar, which accommodates some differential movement and ensures a 3) _____ of hairline cracks within joints, thus 4) _____ the integrity of the bricks and blocks. Masonry cements contain water-retaining mineral fillers, usually ground limestone, and air-entraining agents to give a 5) _____ workability than unblended Portland cement. They should not normally be blended with further admixtures but 6) _____ with building sand in ratios between 1:4 and 1:6½ depending upon the degree of 7) _____ of the brick or blockwork. The air entrained during mixing increases the durability and frost resistance of the 8) _____ mortar. Masonry cement is also appropriate for use in renderings but not for floor screeds or concreting. It is therefore 9) _____ used as an alternative to Portland cement with hydrated lime or plasticiser. 10) _____ pigments, except those containing carbon black, may be incorporated for visual effect. (From Materials for Architects and Builders) | UNNECESSARY PENETRATE DISTRIBUTE PRESERVE HIGH MIX EXPOSE HARDEN GENERAL ORGANIC |
11 Fill in the gaps in the following passage with a suitable preposition given below:
Дата публикования: 2014-11-02; Прочитано: 510 | Нарушение авторского права страницы | Мы поможем в написании вашей работы!
