| Slabs Versatile Gravel Columns Rods Offset Vast Building Material |
| CONCRETE Concrete has been used as a _________ ________ for centuries. It is a mix of cement with an aggregate, traditionally stone chippings or ________. Concrete is generally used in construction, where it is poured to form ______ for floors and foundations, or into moulds (called shuttering) to form vertical features such as walls or ________. It is often used in conjunction with steel reinforcing _______ that combat tensile and shearing forces, but it is a very _________ material. It is increasingly used for its decorative qualities as it can be polished and coloured. The gravel aggregate can be exposed, or other materials (such as crushed recycled glass) may be substituted, which give new opportunities for colour and texture when the surface of the concrete is polished. However, the manufacture of cement used for concrete uses ______ amounts of energy and produces a great deal of pollution, to the extent that many construction engineers choose not to use the material because of the environmental harm that it causes. If used in large quantities in a structure, though, this damage may be ______ by the thermal store effect of the mass of concrete which helps to regulate temperature. Considered over a period of at least 15 years (depending on the installation), this can offset energy used during manufacture. | 
Fig.14. Concrete is a mix of cement with an aggregate
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Exercise 32. Answer the questions.
1. What is concrete made of?
2. Where is it generally used?
3. Concrete is often used in conjunction with steel reinforcing rods, isnt it?
4. Can it be polished and coloured?
5. What gives substitution of materials?
6. Does concrete production cause a great deal of pollution?
Exercise 33. Read the text again and choose the best alternative.
1. Concrete is a mix of cement/ clay with an aggregate.
2. Concrete is poured into moulds to form horizontal/ vertical features such as walls or columns.
3. It is a very limited / versatile material.
4. Other materials may / may not be substituted.
5. The manufacture of cement uses vast / small amount of energy.
Exercise 34. Write a list of advantages and disadvantages of concrete.
| ADVANTAGES | DISADVANTAGES |
Exercise 35. Work in pairs. Find 6 words in the text and make up sentences with them. Then read your answers to your groupmate. Your partner is to guess the keywords that were taken from the text.
Text F
Exercise 36. Match the words to their definitions.
| 1. Steel. 2. Sheet. 3. Bar. 4. Mesh. 5. Weave. 6. Rigid. 7. Warp. 8. Copper. | A. A long narrow piece of metal. B. A piece of material like a net, made from a lot of closely connected wires, strings etc. C. The pattern that is formed in a cloth when it is woven. D. A strong metal made from a mixture of iron and carbon. E. Stiff, hard, and difficult to bend or move. F. A thin flat piece of paper, metal, plastic, glass etc. G. A chemical element that is a redbrown metal. H. To become bent or curved, usually because of damage by heat or water. |
