recycled concrete aggregate

1. 1

2. 2

3. 3

4.  Introduction
 Demand of aggregate on construction
 What is recycled concrete aggregate (RCA)?
 Benefits of RCA
 Procedure of RCA
 Experimental verification on various properties
→ compressive strength
→ Specific gravity & water absorption
→ Particle size distribution
→ Crushing and impact values
→ Modulus of elasticity
4

5.  Recent research of Fredonia group has found:
 Global demand of aggregates
for construction
› 46 billions tones by 2011
› 49 billions tones by 2012
5

6. 6

7.  No any natural aggregates
 No one can construct any buildings,
industries, bridges ,dams ,roads
pavements…… 7

8.  Construction and demolition wastes are
generated annually in world
14.5 Million Tons (india)
 13 Million Tons (France)
 10-15 Million Tons (Japan)
 20 Million Tons ( Hongkong)
 Investigation results of Environmental
resources ltd(1979) for EEC member
countries found
 55 Million Tons - by 1980
 302 Million Tons – by 2020 8

9. Terrorist attack Age limit
Natural calamities 9

10. 10

11. 11

12.  The final product collected
from crushing and separated
from other contamination
obtained from construction and
demolition wastes such as
concrete wastes, broken bricks,
gravel, bridge supports, road
pavements, concrete roadbeds
etc. that has been previously
used in construction are
recycled aggregate.
12

13.  Conserve diminishing natural aggregate
resources
 Use of construction wastes
 Protection of environment
 Save money
 Create additional business opportunities
13

14. Breaking up & removing
the old concrete
Crushing in primary
and secondary
crushers 14

15. Finally , stockpiling and separation of coarse and fine
aggregate
Grading and washing
15

16. (Collecting waste concrete aggregate) (Making M20 Concrete mixture )
(Making 150 mm
cube for
comparing RCA
& NCA
properties.)
.) 16

17.  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.
 Water absorption ranges 3.05 % to 7.40 % which is slightly
higher than that of natural aggregate.
 Modulus of elasticity
 RCA has lower than NAC upto 15% only.
 It can be increased if hardened cement paste adhere to
aggregate are removed well.
17

18.  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
 As per IS 2386, the crushing & impact values for concrete ,
wearing surfaces should not exceed 45% and 50% resp.
 RAC satisfy the BIS specifications.
18

19.  The use of recycled concrete aggregate is
proved to be a valuable, buildings materials
in technical, environmental & economical
respects.
 Recycle & reuse is an appropriate solution to
problems of dumping hundred of thousands
of tons of demolition wastes.
However,more research and initiation
of pilot project for application of RCA is
started for modifying our design codes,
specifications & procedure for use of RCA.
19

20.  Hansen. T.C. (1992) , “ Recycling of Demolished
Concrete Masonry, Rilem Report NO. 6, E & FN
Sports, London , Great Britain , pp. 316
 Oilonomou,N.D.(2008) “ Recycled Concrete
Aggregates,” Cement and Concrete
Composites , Vol. 27 , pp315 – 318.
 Thieien, G.(2010)” Concrete Technology Reports
2001-2003,” German Cement Works Association.
20

21. 21

22. 22