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ABN: 69 893 345 889
PO Box 51 Blakehurst
NSW Australia 2221
Tel: +61 2 9484 0577
Fax: +61 2 9484 0766
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Resources For Schools
What are aggregates used for?
For tens of thousands of years, humans have used rocks in the most ingenious ways to provide shelter, to make tools and to build important structures. This legacy continues today. We use aggregates in an amazing variety of ways.
Aggregates are used to help build our houses, schools, roads, bridges, commercial and industrial buildings, airports, railways, sport fields and to solve environmental problems. It is hard to imagine what life would be like without aggregates. Aggregates are needed in large quantities. On average we use about 400,000 tonnes of aggregates every day in Australia!
Aggregates can be used on their own or combined with other materials to form 'man-made' rocks like concrete, bricks or asphalt pavement.
Some main uses of aggregates are:
- Making concrete for houses, buildings, roads, bridges, airports etc
- Foundations for roads, driveways, carparks and footpaths
- Making concrete products such as pipes, blocks and roof tiles
- Surfacing and repairing roads
- Making asphalt paving
- Railway ballast
- Landscaping
A typical brick veneer house with a tile roof needs about 60 tonnes of crushed rock, sand and clay aggregates for its construction. If we include the driveway and landscaping the amount is closer to 100 tonnes.
In Australia each person uses on average about 7 tonnes of aggregates a year. (Compare this with the amount of food we consume each year which averages about 2 tonnes per person!).
Concrete is the most widely used construction material in the world. Concrete is made by mixing with crushed rock and sand aggregates, cement and water. The cement and water form a paste that hardens to glue or 'bind' the aggregates together to make the concrete.
Cement is different from concrete. Cement is made by grinding limestone and clay into a powder. The mixture is then melted in a kiln at very high temperatures. A 'new' rock called 'clinker is formed. A mineral called gypsum is then added and the clinker ground into the fine grey powder we call Portland cement.
Most of the estimated 130 million tonnes of aggregates we produce in Australia each year are used for building and construction purposes. But not all. Aggregates are also used to make agricultural products that improve soil quality and to help solve environmental problems. Aggregates are even used in medicines and in the manufacture of plastics, paint and cosmetics.
Some people say we are entering the 'second stone-age'. Silica sand is used to help make silicon chips that run computers. More and more buildings are being made from 'tilt up' concrete panels. Rock products are being used in increasing quantities for environmental protection ... from the protection of land, rivers, beaches and harbours against erosion, through to the use of certain finely ground rocks to replenish topsoils with minerals, and so increase crop yields.
Aggregates are even used in ostrich farming - the birds swallow the aggregates to help with the digestion of their food!
Examples of uses of aggregates
The pie chart shows an estimate of where aggregates are used in building and construction in Australia.
- ROADS AND HIGHWAYS use about 35% of all aggregates produced;
- OTHER PUBLIC WORKS AND BUILDINGS (bridges, airports, schools, sports grounds etc) use about 20%;
- HOUSING (including single houses and apartment blocks) use about 20% of all aggregates that are produced and;
- COMMERCE AND INDUSTRY (supermarkets, factories, business premises) use about 20%
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