Recycled concrete is made from demolished or renovated concrete structures. The concrete is crushed and any rebar or other materials are removed. Crushed recycled concrete can be used as gravel for construction projects or as the aggregate in new concrete mixtures, providing it is free of contaminants. Using recycled concrete reduces costs and pollution compared to using newly quarried materials, and keeps concrete debris out of landfills. However, recycled concrete has reduced strength and density compared to natural aggregates.

1. RECYCLED CONCRETE

2. Recycled concrete

3. Recycled concrete
 When a structure made of demolished or
renovated concrete is called recycled
concrete.
 Concrete aggregate collected from demolition
sites is put through a crushing machine.
 Crushing facilities accept only
uncontaminated concrete, which must be free

4.  Metals such as rebar are accepted, since
they can be removed with magnets and other
sorting devices and melted down for recycling
elsewhere.
 Crushing at the construction site using
crushers reduces construction costs and the
pollution generated when compared with
transporting material from a quarry.

5. PROPERTIES OF RECYCLED
CONCRETE
 Less Specific gravity.
 High Water absorption.
 Less Bulk density.
 Relatively less Compressive strength.
 Less Modulus of elasticity of 15% from natural
aggregate.
 Flexural strength (0.95 – 7.2MPa).
 Splitting tensile strength (0.3 – 3.1MPa).

6. Recycled concrete production
 Simple process involving breaking removing
and crushing concrete into specified size and
quality.
 Reinforced steel and other embedded items
must be removed before the quality of the
aggregate can be produced.

7. Uses of concrete
 Smaller pieces of concrete are used as
gravel for new construction projects. Sub-
base gravel is laid down as the lowest layer
in a road, with fresh concrete or asphalt
poured over it.
 The US Federal Highway Administration uses
this techniques to build new highways from

8.  Crushed recycled concrete can also be used
as the dry aggregate for brand new concrete
if it is free of contaminants. Also, concrete
pavements can be broken in place and used
as a base layer for an asphalt pavement
through a process called Rubblization.

9.  Larger pieces of crushed concrete can be
used as riprap revetments, which are "a very
effective and popular method of controlling
streambank erosion."

10. REASONS FOR INCREASE OF QUANTITY
OF DEMOLISHED CONCRETE
 Many old buildings, concrete pavements,
bridges and other structures have overcome
their age and limit of use due to structural
deterioration beyond repairs and need to be
demolished;
 The structures, even adequate to use are
under demolition because they are not
serving the needs in present scenario;

11.  New construction for better economic growth;
 Structures are turned into debris resulting
from natural disasters like earthquake,
cyclone and floods etc.
 Creation of building waste resulting from
manmade disaster/war.

12. Advantages
 Keeping concrete debris out of landfills saves
landfill space.
 Using recycled material as gravel reduces the
need for gravel mining.
 Using recycled concrete as the base material
for roadways reduces the pollution involved in
trucking material.

13. Demerits
 Decrease in strength & modulus.
 Greater moisture shrinkage potential.
 Higher absorption capacity range from 3% -
9%.
 Reduced workability due to higher absorption
capacity.
 Lower bulk specific gravity.