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BÚLK AND CONSTRUCTIONAL MATERIALS Characteristics

1. Deposits are very large therefore no shortages foreseen. 2. Easily and cheaply quarried because often unconsolidated. 3. Often quarried open cast. 4. Do not require extensive processing before use. 5. Expensive to transport in “raw” form therefore some processing usually done on site. 6. Quarries destroy look of environment. 7. Extracted on a large scale. 8. Often extracted close to where materials will be used.

For more information, look in ‘Geology and Environment in Britain and Ireland’

Cement production p.53

Brick clays/brick making P53

Aggregates for concrete p.54

Aggregates for roadstone p.54

Glass making p.55.

Dimension stone p.55 USES OF LIMESTONE

1. Aggregate or crushed stone

Half of total production used as aggregate. Used in many different ways (refer to the table & make a list).

Aggregate should be (a) of uniform grain size (b) free from pyrite, chert (SiO2 ) (c) non-porous

Most important uses – concrete, road metal, railway ballast, water filtration.

2. Cement

Usually 3 parts chalk or limestone and 1 part clay or shale.

Mixture crushed and heated to 1500C.

The mixture must contain CaO, SiO2, AI2O3 and iron oxides.

3. Fluxstone Used in the smelting and refining of iron ores and to promote plant growth. Limestone + coal + iron ore

Slag* Blast Molten furnace Iron ore

Slag formed by Silicon impurities reacting with CaCO3

4. Soil conditioner – to make soils less acid and to promote plant growth.

5. Source of lime. CaO (A raw material for chemical industry) Crushed limestone heated to 1000 – 1100C.

Ca CO3 CaO+CO2

6. Building stone e.g. Carboniferous Limestone, North Wales e.g.Oolitic Limestone, Cotswolds

Properties needed (a) joints and bedding planes (breaks into blocks) (b) uniform colour and grain size (c) strength to support weight above (d) attractive

7. Roadstone

Crushed rock used.

Advantages of limestone are: tough – doesn’t break up resistant to physical weathering binds easily with tar