Recycled concrete

1. Recycled aggregate concrete (RAC) is usually the concrete produced
from construction and demolition wastes, which either
partially or completely replaces conventional natural
aggregates (NAs).

2. CONTENTS
=> INTRODUCTION
=> WHAT IS RE-CYCLED AGGREGATE CONCRETE ?
=> CHARACTERISTICS OF RE-CYCLED AGGREGRATE
=> CLASSIFICATION
=> PROCESS OF RE-CYCLED AGGREGRATE
=> HOW TO PRODUCE RE-CYCLE AGGREGRATE CONCRETE
=> USE OF RE-CYCLED AGGREGRATE CONCRETE
=> APPLICATION OF RE-CYCLED AGGREGRATE
=> BENEFITS OF RE-CYCLED AGGREGRATE CONCRETE
=> ADVANTAGES AND DIS-ADVANTAGES
=> CONCLUSION

3. INTRODUCTION
• To achieve sustainable issue in construction area ,
researchers and companies focus on using waste
concrete as a new construction material . It is
called re-cycled aggregate which can be produced
by concrete crushers .
• The aggregate are categorized by size as coarse
and fine aggregates
• The Characteristic of re-cycled aggregate could be
different by its parent concrete because the parent
concrete was designed for its purposes such as
permeable , durable and high strength concrete .

4. WHAT IS RE-CYCLED AGGREGATE CONCRETE ?
Recycled concrete aggregate is the term used to describe the
material produced from crushed construction and demolition
waste. primarily consisting of concrete but also including
aggregate materials such as sand, gravel, slag, and crushed
stones.
Recycled aggregates are only classified as recycled concrete
aggregates (RCA) when the primary material is concrete.
By crushing and compressing existing waste concrete and
combining it with aggregate, producers can create concrete
aggregate to a specific size and quality, which makes it very cost
effective to purchase.
It also involves recycling waste materials, which would usually
have taken up valuable space in landfill sites.

6. HOWIS RECYCLEDCONCRETE AGGREGATEPRODUCED?
The first step in producing recycled concrete aggregate is to collect demolished
concrete from places such as roads, bridges, and demolished buildings.
This concrete is then refined, which means checking that it doesn’t contain any other
materials such as wood or metal chunks that could affect the final product’s strength.
Next, the concrete is put through crushing machines which use impact force to break
down large chunks and stones.
Finally, the crushed concrete is mixed with an aggregate such as sand, to help it reach
the required consistency and density.

7. PROCEDURE TO OBTAIN RCA
* Recycled concrete aggregates (RAC) contain not only the original
aggregate. But also Hydrated cement paste.
• re-cycling of aggregate can take place either at the site from which the
material is sourced using mobile crushers , or the material may be
transported to a central re-cycling facility where large stockpiles may
accumulated.
• Re-cycled aggregates from these central re-cycling facilities undergo a
number of processes to ensure higher quality .

8. • Various process involve , crushers , pre-sizing , sorting, screening and
contaminant elimination .
• Then to start with clean , quality aggregate in order to meet the design
criteria easily and ultimately get a quality product that will go into end
use .
• Future cleaning is also done to ensure the re-cycled concrete product is
free of dirt , clay , wood , plastic and organic materials. This is done by
water floatation , hand picking , air separators, and electromagnetic
separators.

12. What are the benefits of using recycled aggregates?
There are many economic, environmental and social benefits to using recycled aggregates.
Cost Saving
•Producing recycled aggregate for resale is more cost-effective than sending un-wanted
materials to landfill and incurring landfill tax.
Eco-Friendly
•Recycled Aggregate is regarded to be a ‘green’ construction material
Versatile
•Recycled aggregates can be used for various different functions, suitable for use with
construction projects, landscaping and in home improvement applications.
Durable
•Studies prove that Recycled Aggregate is as structurally reliable as natural aggregate and is as
safe to use.

13. Applications of RecycledAggregate
Recycled Aggregate can be used in the following constructions
•Can be used for constructing gutters, pavements etc.
•Large pieces of crushed aggregate can be used for building
revetments which in turn is very useful in controlling soil erosion.
•Recycled concrete rubbles can be used as coarse aggregate in
concrete.
•Production of RAC also results in generation of many by-products
having many uses such as a ground improvement material, a
concrete addition, an asphalt filler etc.

14. APPLICATIONS OF RE-CYCLED AGGREGATE

15. Advantages & DIS-Advantages
• High use of crushed aggregate can lead to
lowering the strength of the concrete.
• Should ensure the aggregate to be properly
cleaned before use else it will lead to the
generation of cracks in the concrete
surface.
• To achieve the desired strength compared
to the natural aggregate, certain
admixtures are added.
• Proper inspection is required before the
use.
l Cost-efficient
l Environment friendly
l Sustainable material
l No need for extra space for disposal

16. Advantages of Recycled Aggregate
•Reduces the amount of virgin aggregates to be created, hence less
evacuation of natural resources.
•While being crushed into smaller particles a large amount of carbon dioxide
is absorbed. This reduces the amount of CO2 is the atmosphere.
•Cost saving – few research studies have shown a significant reduction in
construction costs if RAC is used.
•Conserves landfill space, reduces the need for new landfills and hence
saving more costs.
•Creates more employment opportunities is recycling industry.

17. Disadvantages of Recycled Aggregate
•Downgrading of quality of concrete.
•Increase in water absorption capacity ranging from 3% to 9%
•Decrease in compressive strength of concrete (10-30%)
•Reduces workability of concrete.
•Lack of specifications and guidelines.
•Less durability of RAC, however few papers have shown an
improvement in the durability by mixing it with special materials like
fly ash.

32. Conclusion
Recycling and reuse of building wastes have been found to be an appropriate solution to the
problems of dumping hundred of thousands tons of debris accompanied with shortage of
natural aggregates.
The use of recycled aggregates in concrete prove to be a valuable building materials in
technical, environment and economical respect.
Recycled aggregate posses relatively lower bulk density, crushing and impact values and
higher water absorption as compared to natural aggregate.
The compressive strength of recycled aggregate concrete is relatively lower up to 15% than
natural aggregate concrete.
Recycling reduces waste and reduces energy consumption and hence contributes to a
more sustainable construction industry.

33. THANK YOU
PRESENTED BY :
BATCH – 8 (103 – 108)
2451-20-732-103 – B.SAI SRI VARDHAN
2451-20-732-104 – N.SAI VISWA SASI PAVAN
2451-20-732-105 – K. SUNIL KUMAR
2451-20-732-106 – G.MANISH
2451-20-732-107 – E.GOUTHAM
2451-20-732-108 – E.AKHIL