This document discusses the recycling and reuse of demolished concrete. It begins by defining construction waste and the processes of reuse and recycling. It then discusses the large amount of construction and demolition waste generated in India annually. It emphasizes the necessity of reusing and recycling this waste due to limited natural resources. The document outlines the common processes for collecting, sorting, and treating demolished concrete for reuse. It presents experimental results on the properties and quality of recycled concrete aggregates. Finally, it discusses challenges to using recycled aggregates in India and steps that could be taken to promote reuse of demolished concrete.

1. BY,
SHASHANK SRIVASTAVA
DEVIKA
ASHWIN SATHASIVAN
ANNAMALAI UNIVERSITY
OCTOBER 8th 2015
RECYCLING AND
REUSE OF
DEMOLISHED
CONCRETE

2. • 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.
INTRODUCTION

3. • 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.
NECESSITY OF REUSING AND
RECYCLING OF CONSTRUCTION WASTE

4. • It is the most commonly used Construction material (1 ton for every
man on earth)
• Aggregates are used in concrete for very specific purposes. Aggregates
typically make up about 60% to 75% of the volume of a concrete
mixture, and as they are the least expensive of the materials used in
concrete, the economic impact is significant.
• Compared to other comparable building materials, concrete is less
costly to produce and remains extremely affordable.
Why to focus on concrete

5. • 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.
Demolished Concrete

6. • 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.
Process of reusing demolished concrete

7. 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.
Process of recycling the demolished
concrete

9. Particle size distribution
• Sieve analysis is done after crushing and sieving as per IS Code
2386 to separate out coarse and fine aggregate.
• Recycled aggregate meets all the standard requirements of natural
aggregate
Specific gravity & water absorption
• Sp. Gravity(saturated surface dry condition) of recycled concrete
aggregate(RCA) was found from 2.35 to 2.58 which is slightly
lower than natural aggregate.
Properties and Experimental Verification

10. • Water absorption ranges 3.05 % to 7.40 % which is slightly higher than that of
natural aggregate.
Modulus of elasticity
• RCA has lower than NCA up to 15% only.
• It can be increased if hardened cement paste adhere to aggregate are removed
well.
Compressive Strength
• The average compressive strengths cube cast are determined as per IS 516 using
RCA and natural aggregate at age 1, 3, 7, 14, 28 , 56 and 90 days.
• Reduction in strength of RCA as compared to NCA:
• 2-14 % = M-20

11. Crushing and Impact Values
• As per IS 2386, the crushing & impact values for concrete , wearing surfaces should
not exceed 45% and 50% resp.
• RCA should satisfy the BIS specifications.

12. • For recycled concrete to be used in greater quantities in a country like
India, there are certain aspects that need to be taken care of initially.
• The setting up of a proper institutional mechanism for taking care of all
the steps, such as collection of the construction and demolition waste,
transportation, and disposal is of key importance.
• Outsourcing of such functions to private enterprise is an idea that the
concerned authorities could give a thought to in this day and age of
open economies.
Challenges in Indian Context

13. • Set up of the necessary processing infrastructure.
• Necessary infrastructure should also be available for testing the quality
of recycled aggregates.
• Project developers need to be educated on on-site waste management
plans.
• Concerned authorities need to plan an awareness campaign, using the
electronic and online media to promote the virtues of recycled
aggregates.
• Removing misconceptions about recycled aggregates as being of
inferior quality among the public.
Steps to be Taken

14. 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
Advantages and Disadvantages

15. 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.

16. Finally, it was concluded that by reusing and recycling the demolished concrete, a better
economy can be achieved without affecting the Environment and taking care of all the
concerns. The use of recycled aggregate has been found to be better than that of virgin
aggregates for certain applications. The salient points were:
• Initial moisture states of RCA is one of the most important variables that impact strength
and shrinkage.
• When oven-dried RCA is used, strength is used to be greatly reduced but free shrinkage
as measured in this study was low.
• The creep to free shrinkage ratio for RCA was similar to that of normal concrete at 7 days
under restrained conditions.
• When greater volume of recycled fine aggregates and fly ash was used, free shrinkage of
the specimens was reduced.
However, it is not favoured with unexperienced workforce and improper equipments.
Conclusion

17.  Bansal, Shishir & Singh, S.K., 2014, A sustainable approach towards construction and demolished waste, International Journal of Innovative Research in Science,
Engineering and Technology, pp (9227).
 Construction and Demolished Waste fact sheet, 2012, Public Works Library, New Delhi, pp (57-62).
 Department of Finance and Personal, 2012, Guidance notes on demolition, dismantling, recovery and reuse, United States of America, pp (2-5).
 Gumsha, Lalit & Gumsha, Swarna, Reuse of concrete waste in Construction to minimize Environmental Damages, 2006, Journal of Environmental Research and
Development, pp (65-67).
 Hussain, Asif, 2013, Utilization of Demolished Concrete Waste for New Construction, World Academy of Science, Engineering and Technology, pp (524-526).
 Parekh, D.N. & Malhotra, C.D., 2011, Assessment of Recycled aggregate Concrete, Journal of Engineering Research and Studies, pp (2-7).
 Shetty, M.L., 2013, Overview of Recycled aggregates, I.C.I. Journal, pp (3-6).
 Shivakumar, M.N. & Nitin K.S., 2014, Use of Building demolished waste, International journal of research in Engineering and Technology, pp (583-585).
 Yadav, S.R.,& Pathak, S.R., Use of recycled concrete aggregate in making concrete- an overview, 2009, 34th conference on Our World in Concrete and Structures,
Singapore, pp (3-6)
REFERENCES