In order to recycle concrete, it is generally necessary to find a construction materials or other disposal and recycling site that accepts this material. Most companies that recycle concrete generally crush it into a specified size and quality.
After the concrete has been crushed, it is usually run through a screen or series of screens that separates the crushed pieces out by size. One such screen that is used is a fine harp deck screen, which separates the finer materials from the coarse aggregate. Generally a scalping screen is also used, which separates dirt and other foreign particles from the concrete. Once the concrete has been crushed, it is further cleaned to remove all foreign particles. This can be done in a number of different ways, including water flotation, electromagnetic separators, air separators or hand picking.
After is has been crushed and cleaned, the recycled concrete can be used in numerous applications. Although the most common use is as an aggregate in a sub-base layer for new roads, the crushed concrete may also be used as an aggregate in new Portland cement concrete or other structural layers. Some landscaping companies also use recycled concrete when building retaining walls or other landscaping elements.