Recycled concrete

• When used as a source of aggregfate for concrete , crushed concrete has in general lower strength and high water absorption characteristic than porimary aggregates . 
• This makes mix design more difficult 
• The proportion of cement paste in recycled concrete is much larger than in the original material , shrinkage and creep will be increase . 
• Too many recycled fines can produce a harsh and unworkable mixture 
• In crushing the concrete , it is difficult to control particle size distribution , meaning that the " aggregate " may fail to meet grading requirements . 
• The largest problems for  reuse as concrete is that large variations in quality can be expected . 
• The use of construction waste should focus upon non-structural applications and those without demanding exposure requirements . 

After removal of contaiminants through selective demolition , screening and / or air separation and size reduction in a crusher to aggregates sizes , crushed concrete can be used as : 

- new concrete for pavements , shoulders , median barriers , sidewalks , curbs and gutters and bridge foundations 

- Structural grade concrete ( technology developing and not widely used at the moment ) 

-Soil - cement pavements bases 

-Lean - concrete or econo-crete bases and 

- Bituminous concrete . 

Recycled concrete used as aggregates / crusher run to provide an leveled surface for road pavements .