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A
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Categories of wood
The two main categories of wood are:
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Hardwood – usually from
deciduous trees, which lose their leaves in autumn, although some hardwood
(for example, tropical hardwood) comes from other type of tree
·
Softwood – from coniferous
trees, which remain green throughout the year
In engineering, wood can be categorized as:
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B
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Solid
structural timber
The text
below is from a technical handbook about structural timber – wood intended
to support loads in a structure.
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Generally, timber is cut to
the required section – the width and depth that determine its
cross-section – at a sawmill, where a range of section sizes are
produced. Timber from sawmills is generally supplied in rough-sawn
sections. This refers to the surface texture produced by sawing timber
with a circular saw. If the timber needs to have a smooth finish – for example,
because it will be visible in the structure – it can subsequently be planned
to smooth its surface.
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C
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Engineered wood
Engineered wood covers a range
of softwood and hardwood materials. It includes:
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·
Cheap, low-strength boards, such as particle
board (often called chipboard) and medium density fibreboard (MDF)
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EXERCISES
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17.1
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Match the two parts to make correct sentences about wood. In each
case, there is more than one possible answer. Look at A opposite to help
you.
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1. Engineered wood
2. Softwood
3. Solid wood
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17.2
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Complete the sentences
below using words and expressions from B opposite.
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1. Wood has a smooth finish after
it has been ___________________.
2. Wood cut with a circular
saw is called ___________________
timber.
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17.2
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Complete the article about the
environmental considerations of wood using words from B and C opposite.
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From en environmental
perspective, wood has many advantages. Firstly, it comes from a
sustainable source. Coniferous trees grow relatively fast, providing a
rapidly replaceable source of (1)___________. Secondly, almost
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