Unit 2

Professional English

Cambridge English for

Engineering

UNIT 2

CASE STUDY Concrete research

Part 1 In pairs, discuss the ollowing questions about  reinorced  reinorced concrete . Be prepared to sum up your answers using your notes. 1 What are the main applications o reinorced concrete? 2 What specifc materials does it consist o? 3 What dierent categories o material do material  do reinorced concrete and the materials it is made o belong to? 4 What are some o the properties the properties o reinorced concrete? The ollowing sections rom Unit 2 o  Cambridge English or Engineering may be useul. Categorising materials (pages 16 and 17) Speciying and describing properties (pages 18 and 19)

Part 2 Read the ollowing extract rom an engineering journal.

Recylability in Engineering  In the environmentally-conscious world we live in today, recyclability is an important issue with all engineering materials. But reinorced reinorced concrete is especially attractive in this respect, or three key reasons (see next page). Consequently, identiying recycled materials that are suitable or putting into concrete is currently a major area o research, research, and the race is on to fnd alternative aggregates and reinorcing materials. However, recycled ingredients that are suitable or use in concrete must satisy a number o technical requirements.

In pairs, come up with some suggested answers to the ollowing questions. l

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Why is reinorced concrete especially attractive as a way o using recycled materials? What might the three key reasons mentioned in the article be? What technical requirements would reinorcing reinorcing materials, such as aggregates, aggregates, need to have?

Part 3  You  You and your partner are researchers at a recycling frm looking into recycled materials, such as coarse aggregates, fne aggregates and reinorcing fbres or use in reinorced concrete. In pairs, use the ollowing steps and make notes o   your ideas. l

think o some possible recycled recycled materials - there’s no need to analyse them technically at this stage

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assess each material in your list and make a shortlist o the most promising possibilities

Give a short presentation to the group including an explanation o the most promising materials, together with reasons or your suggestions, as well as some examples o materials you considered but rejected or technical reasons. 1

Cambridge English for Engineering Cambridge University Press 2009 www.cambridge.org/elt/englishf www .cambridge.org/elt/englishforengineering orengineering

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UNIT 2 Case study: Concrete research

Recylability in Engineering Suggested answers to Part 2 The potential or using recycled materials in reinorced concrete is especially  attractive or the ollowing reasons. l

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as the world’s most extensively used engineering material, it has t he potential to use enormous quantities o recycled material its composite construction – coarse aggregate + ne aggregate + reinorcement – allows a range o dierent types o recycled material to be used aggregate and reinorcement are hidden inside the concrete, meaning that colour and appearance – oten problem issues with recycled materials – are not important.

However, there are many technical requirements that reinorced concrete needs to satisy. These include: l l

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Strength – materials must be able to carry the required loads. Chemical stability – materials must not react aggressively with cement, or attack steel reinorcement and cause it to corrode. And since most concrete structures are designed to last several decades, engineers must be sure that materials remain chemically stable or long periods – something which can be dicult to test in a laboratory. Thermal stability – as most concrete is located outside, it is exposed to signicant variations in temperature. These variations cause it to expand and contract. Consequently, all the materials used in reinorced concrete must have the same coecient o thermal expansion, so that the concrete does not break apart due to thermal movement. Workability – wet concrete requires good plasticity to allow it to be ed through the pipes o concrete pumps, and to be placed and compacted. Any materials mixed in with concrete must thereore allow it to be moved and placed.

Cambridge English for Engineering Cambridge University Press 2009 www.cambridge.org/elt/englishforengineering

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UNIT 2 Case study: Concrete research – Teacher’s Notes

Unit 2 Case study: Concrete research – Teacher’s Notes  Beore you begin...  Ask students what is meant by  reinorced concrete and recycling . Tell the students that these two key terms will be the basis o this case study. Ask them to think  about what the interesting link between reinorced concrete and recycling might be.

Part 1 Students discuss the questions in pairs and eed back their ideas to the group. Suggested answers and useul vocabulary  1 Reinorced concrete is used widely in construction or structural members o  concrete rame buildings. For example, beams (horizontal members), columns (vertical members), slabs (foors), walls. It is also used or oundations (which support structures, including piles – see Cambridge English or Engineering pages 12 and 13. It is also used in large civil engineering structures, such as bridges and dams. 2 Cement , fne aggregate (sand), coarse aggregate(gravel), and steel reinorcing bars. 3 Reinorced concrete is a composite material . Concrete is a ceramic - although it isn’t ormed by heat, it hardens due to a chemical reaction triggered in the cement ater water is added and is thereore classed as a ceramic . The concrete – excluding the reinorcement – is non-metallic. The steel reinorcement is metallic, and is a errous metal . Steel is an alloyo iron and carbon. 4 Reinorced concrete is a very strong/tough material. It is reasonably hard , with reasonable abrasion resistance. It has very low elasticity/modulus (modulus o  elasticity). It has airly good thermal stability. A key property o concrete is that it’s very strong in compression, but weak in tension – see Cambridge English or  Engineering page 80 or more on compression and tension. Concrete’s weakness in tension is t he main reason or adding steel reinorcement, as steel is very strong in tension. Concrete is also very durable and it is thought to be capable o lasting hundreds o years.

Part 2 Students read the journal extract and then discuss the questions in pairs, making notes o their suggestions. Each pair then eeds back their suggestions to the group or collective comparison and discussion. Page 2 has suggested answers to the questions that students have discussed in Part 2. Give each student a copy o these and ask them to compare them with their predicted answers.

Part 3 Students work in pairs to brainstorm ideas an d prepare notes or their presentation. When each pair has presented their ideas, fnish with a group discussion to assess the best proposals. Note One o the main recycled materials currently used in reinorced concrete is recycled concrete itsel, i.e. old concrete that has been crushed to be reused as aggregate. A  promising material being researched is crushed glass – though there are problems with chemical reactions between glass and cement. Recycled carpets are another possibility, potentially useul as reinorcing bres.  You could look at the ollowing sites or urther inormation and reading material or discussion. http://www.civil.columbia.edu/meyer/ www.concreterecycling.org 3

Cambridge English for Engineering Cambridge University Press 2009 www.cambridge.org/elt/englishforengineering

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