Concrete recycling is becoming an increasingly popular way to utilize aggregate left behind
when structures or roadways are demolished.
In the past, when structures made of concrete are demolished or renovated, the rubbles
was once routinely trucked to landfills for disposal, but with more attention being paid to
environmental concerns ,recycling has a number of benefits that have made it a more
attractive option in this age of greater environmental awareness, more environmental laws,
and the desire to keep construction costs down.
Concrete aggregate collected from demolition sites is put through a crushing machine.
Crushing facilities accept only uncontaminated concrete, which must be free of trash, wood,
paper and other such materials. Metals such as rebar are accepted, since they can be
removed with magnets and other sorting devices and melted down for recycling elsewhere.
The remaining aggregate chunks are sorted by size. Larger chunks may go through the
crusher again. After crushing has taken place, other particulates are filtered out through a
variety of methods including hand-picking and water flotation.
Crushing at the actual construction site using portable crushers reduces construction costs
and the pollution generated when compared with transporting material to and from a
quarry1.
Large road-portable plants can crush concrete and asphalt rubble at up to 600 tons per hour
or more. These systems normally consist of a rubble crusher, side discharge conveyor,
screening plant, and a return conveyor from the screen to the crusher inlet for reprocessing
oversize materials. Compact, self-contained mini-crushers are also available that can handle
up to 150 tons per hour and fit into tighter areas. With the advent of crusher attachments -
those connected to various construction equipment, such as excavators - the trend towards
recycling on-site with smaller volumes of material is growing rapidly. These attachments
encompass volumes of 100 tons/hour and less