This document discusses the recycling of demolished concrete. It defines recycling as collecting materials that would otherwise be waste and reusing them for new purposes. When concrete structures are demolished, the rubble can be recycled rather than sent to landfills. The concrete is crushed and sorted, with smaller pieces used as aggregate in new construction projects and larger pieces used for retaining walls and erosion control. Research shows recycled concrete can make up around 35% of new concrete mixes with only small reductions in strength, though durability may be reduced. The document also outlines the benefits of recycling concrete such as reducing environmental impacts and construction costs.

1. BAGHDAD UNIVERSITY
SANITARY ENGINEERING DEPARTMENT
M.SC. STUDENT : MARWA MOHAMMED

2. REUSE OF
DEMOLISHED
CONCRETE

3. What is Recycling?

4. • Recycling is a term
used to describe a
series of activities
that includes
collecting recyclable
materials that would
otherwise be
considered waste.

5. • Construction waste: Unwanted materials
generated during construction processes. For
example: Demolished concrete fragments, Brick
pieces, Wood, Plastic wastes etc.
• Reuse: The process of using a material again for
same or a different function. For example:
Using coarse aggregate obtained from
concrete waste, for preparation of fresh
concrete.
• Recycling: The process of converting waste
materials into new ones for reduction of waste
of potentially useful materials.

6.  Its a democratic material
 Its low cost →compared
to steel/aluminium
 Availability of raw
materials →limestone
and aggregates are
naturally available
 Versatility
 Adequate engineering
properties

7. When structures made of concrete are demolished or
renovated, concrete recycling is an increasingly common
method of utilizing the rubble. Concrete was once routinely
trucked to landfills for disposal, but 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

8. 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 may use techniques such as these to build
new highways from the materials of old highways. 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.
Larger pieces of crushed concrete can be used as riprap revetments,
which are "a very effective and popular method of controlling
streambank erosion.
With proper quality control at the crushing facility, well graded and
aesthetically pleasing materials can be provided as a substitute for
landscaping stone or mulch.
Wire gabions (cages), can be filled with crushed concrete and
stacked together to provide economical retaining walls. Stacked
gabions are also used to build privacy screen walls (in lieu of fencing
Uses of recycled concrete

12. According to "The Effect of Recycled Coarse", the results of experiments
showed that "the recycled aggregate absorption value is 7.5% which is higher
than the WSDOT specification of aggregate in 3.7% maximum.This is because
of the paste on the gravel which will influence the absorption of water.
Therefore, the recycled aggregate satisfies the absorption specification. Also,
add different portions of recycled aggregate to the mixture will have different
degrees of influences on the specific gravity, characteristic strength,
compressive strength, modulus elasticity and flexural strength. They mix 0%,
35%, 50% and 65% of recycled aggregate into the mixture and found that as
the percentage of recycled aggregate are added increases, the specific
gravity, characteristic strength, compressive strength, modulus elasticity and
flexural strength decreases. We couldn't indicate that the recycled aggregate
is not good for using just by comparing these data with the natural aggregate
properties. If we use 65% of recycled aggregate or above, each physical
properties will drop greatly. However, if we limit the portion of recycled
aggregate adds to concrete, it won't affect each property much. Based on the
research and experiment test, "the maximum replacement of recycled coarse
aggregate that can be used in concrete is 35%“ Some experiment showed
that recycled aggregate don't have good durability like the natural coarse
aggregate but we can improve its durability by mixing with special materials
such as flying ash to produce high strength and durable concrete
Strength and Durability of the recycled aggregate

13. • Disposal has also emerged as a problem in India. India is
presently generating construction and demolition waste
to the tune of 23.75 million tons.
• Yet, no disposal method is being practiced in 70 percent of
the industry because of the easy availability of the raw
materials.
• Due to unlimited use of aggregates, the extinction of
naturally occurring materials will soon take place. Due to
this, the application of reusing and recycling of waste
materials is favoured.
RECYCLING Of CONSTRUCTION
WASTE

14. • Sometimes, the concrete
material has to be
demolished during ongoing
or old construction. The
concrete waste obtained
from these processes is
called Demolished concrete.
• It is a very common
type of waste
generated during Pile
foundations,
precasting etc.

15. • Collection of Construction
scraps from the site.
• Classify them according to
their properties.
• Send them to the Separation
and Treatment plant.
• Differentiating the components
i.e. the aggregates, treating
them, and finally reusing them
for constructing Fresh Concrete.

18. Application of Recycled Concrete in
Japan

19.  There are many processes for recycling.
However, the common procedure adopted
is:
• Collection of Waste from the Site.
• Transporting to the Recycle unit.
• Initial crushing and Sieving.
• Final crushing and Grinding.
• Forwarding it to the Constructing unit.

20. The advantages of using recycled concrete/
aggregates are:
• Conserve diminishing natural aggregate
resources
• Use of construction wastes
• Protection of environment
• Economical
• Create additional business opportunities
• Avoids excess Landfilling

21. However, the disadvantages and limitations
are:
• Inexperience with recycled aggregate
products due to lack of exposure still
remain a surmountable barrier to the
recycled concrete market.
• Water pollution can also happen during
recycling process.
• It is still not feasible in all sites and
requires heavy machinery and
equipments.

22. There are a variety of benefits in recycling concrete rather
than dumping it or burying it in a landfill.
1. Keeping concrete debris out of landfills saves landfill
space.
2. Using recycled concrete can conserve natural resources
by reducing the need for gravel mining, water, coal, oil and
gas.
3. Using recycled concrete as the base material for
roadways reduces the pollution involved in trucking
material.
4. Recycling concrete can create more employment
opportunities.
5. Recycling concrete drag down the cost for buying raw
materials and transporting the waste to landfill sites.
6. Recycling one ton of cement could save 1,360 gallons
water, 900 kg of CO2
Benefits

23. Savings on
Maintenance
expenditure
Economic
benefits

24. Marwa Mohammed Ali