Aggregates for Concrete Handout
Aggregates for Concrete
Aggregates are inert granular materials such as sand, gravel, or crushed stone that, along with water and cement, are an essential ingredient in concrete.
Aggregates are the most mined materials in the world.
For a good concrete mix, aggregates need to be clean, hard, strong particles free of absorbed chemicals or coatings of clay and other fine materials that could cause the deterioration of concrete.
Aggregates, which account for 60 to 75 percent of the total volume of concrete, are divided into two distinct categories--fine and coarse.
Fine Aggregates - generally consist of natural sand or crushed stone with most particles smaller than 5 mm (0.2 in.).
Coarse Aggregates - consist of one or a combination of gravels or crushed stone with particles predominantly larger than 5 mm (0.2 in.) and generally between 9.5 mm and 37.5 mm (3⁄8 in. and 11⁄2 in.).
Some natural aggregate deposits, called pit-run gravel, consist of gravel and sand that can be readily used in concrete after minimal processing.
Natural gravel and sand are usually dug or dredged from a pit, river, lake, or seabed.
Crushed stone is produced by crushing quarry rock, boulders, cobbles, or large-size gravel.
Crushed air-cooled blast-furnace slag is also used as fine or coarse aggregate.
The aggregates are usually washed and graded at the pit or plant.
Naturally occurring concrete aggregates are a mixture of rocks and minerals. Weathering and erosion of rocks produce particles of stone, gravel, sand, silt, and clay.
Recycled concrete, or crushed waste concrete, is a feasible source of aggregates and an economic reality, especially where good aggregates are scarce.
Aggregates strongly influence concrete's freshly mixed and hardened properties, mixture proportions, and economy. Consequently, selection of aggregates is an important process. Although some variation in aggregate properties is expected, characteristics that are considered include:
grading
Aggregates are inert granular materials such as sand, gravel, or crushed stone that, along with water and cement, are an essential ingredient in concrete.
Aggregates are the most mined materials in the world.
For a good concrete mix, aggregates need to be clean, hard, strong particles free of absorbed chemicals or coatings of clay and other fine materials that could cause the deterioration of concrete.
Aggregates, which account for 60 to 75 percent of the total volume of concrete, are divided into two distinct categories--fine and coarse.
Fine Aggregates - generally consist of natural sand or crushed stone with most particles smaller than 5 mm (0.2 in.).
Coarse Aggregates - consist of one or a combination of gravels or crushed stone with particles predominantly larger than 5 mm (0.2 in.) and generally between 9.5 mm and 37.5 mm (3⁄8 in. and 11⁄2 in.).
Some natural aggregate deposits, called pit-run gravel, consist of gravel and sand that can be readily used in concrete after minimal processing.
Natural gravel and sand are usually dug or dredged from a pit, river, lake, or seabed.
Crushed stone is produced by crushing quarry rock, boulders, cobbles, or large-size gravel.
Crushed air-cooled blast-furnace slag is also used as fine or coarse aggregate.
The aggregates are usually washed and graded at the pit or plant.
Naturally occurring concrete aggregates are a mixture of rocks and minerals. Weathering and erosion of rocks produce particles of stone, gravel, sand, silt, and clay.
Recycled concrete, or crushed waste concrete, is a feasible source of aggregates and an economic reality, especially where good aggregates are scarce.
Aggregates strongly influence concrete's freshly mixed and hardened properties, mixture proportions, and economy. Consequently, selection of aggregates is an important process. Although some variation in aggregate properties is expected, characteristics that are considered include:
grading