preparation
- Cement must be kept dry, to avoid its quality deteriorating
- If mixing by hand, work on a hard, fairly smooth and waterproof surface.
- estimating how much concrete you need
- Measure the area to be concreted and multiply by the thickness to be laid
- Refer to manufacturer's mix guides to work out how much you need
- Add 10 per cent to final figure for wastage
- For bigger jobs of 2-3 cubic metres, you may need to hire a concrete mixer or buy
ready-mixed concrete.
mixing concrete
- Measure sand and gravel onto mixing board. Make a crater in the centre and add cement.
Mix together
- Form another crater, add water gradually until pile is well mixed - not too slippy
or too crumbly
- Test the mix by using the back of the shovel to flatten. The surface should be close-knit
and moist but not showing too much water.
moving concrete
- Try and mix the concrete close to where you will use it
- A bucket can be used for small quantities but you may need a wheelbarrow with a
pneumatic tyre for larger loads
- Laying scaffolding planks on any soft ground will stop the wheelbarrow from leaving
ruts.
- Cement is one of the most natural of all manufactured products because its raw materials
come from the ground. Here we show you how it is made.
- In very simple terms, you take a mixture of finely ground limestone or chalk, clay
and sand and heat it almost to melting point in a large rotating kiln. The cement
clinker that emerges is then ground to a powder with about five per cent gypsum,
added to control the setting time of the end-product.
- The manufacturing process depends on the moisture content of the raw materials.
Chalk has a high moisture content and chalk-based processes tend to be less energy
efficient than those based on hard limestone.
- Cement is an industry that operates at the very core of our existence. It quite
literally provides the foundation for many of the aspects of our daily lives that
we take for granted. To fulfil that role, it requires large manufacturing plants
that, because of the need to quarry raw materials, are usually set in attractive
countryside. Nevertheless, the works are always prominent on the local skyline and
their vehicles are familiar on the local roads.
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