2. INTRODUCTION
Concrete
World’s second most consumed material.
Basic need for urban development.
Out of all construction materials concrete is the main constituent.
It is estimated that 25 billion tonnes of concrete is manufactured each year.
Ingredients
Cement
Aggregate
Water
Admixtures
3. INTRODUCTION (contd.)
Construction and demolition waste
Demolition waste
Construction waste
Road work waste
Other construction waste
Environmental problems
Scarcity of landfills
Non biodegradable
Solution
RECYCLE
REUSE
4. RECYCLING OF CONCRETE
BENEFITS
Saves landfill space
Use as gravel reduces need for gravel mining
Use as base material for roadways reduce the pollution involved in
trucking material
Recycling of 1 ton of concrete could save 1360 gallons of water, 900
Kg of CO2
Rubblization
5. RECYCLED AGGREGATES
Production of recycled aggregates
Uses of recycled aggregates
Types of recycled aggregates
Recycled coarse aggregate(RCA)
Recycled fine aggregate(RFA)
6. METHODS TO PRODUCE RECYCLED
AGGREGATES
HEATING AND RUBBING METHOD
ECCENTRIC-SHAFT ROTOR METHOD
MECHANICAL GRINDING METHOD
ELECTRIC PULSE POWER METHOD
7. LITERATURE REVIEW
Sl.no Author Year Work done
1 P.C Khergamwala et al 2013 Studied on recycled coarse aggregates from
fresh concrete waste
2 N. Sivakumar et al 2013 Study on recycled coarse aggregate made
from demolition waste
3 Mamery Sérifou et al 2014 Studied about the possibility of using fresh
concrete waste as recycled aggregates in
concrete
7
8. CASE STUDY
CASE STUDY 1-EXPERIMENTAL STUDIES ON HIGH STRENGTH
CONCRETE BY USING RECYCLED COARSE AGGREGATE
CASE STUDY 2-EFFECT OF RECYCLED COARSE AGGREGATES ON
CHARACTERISTIC STRENGTH OF DIFFERENT GRADES OF CONCRETE
9. CASE STUDY 1
High strength concrete(HSC)
Concrete with characteristic compressive strength higher than
40MPa
Materials used
Cement
Water
Fine aggregate
Coarse aggregate
Mix design
1:1.97:3.35
wc ratio 0.4
11. TEST ON HSC
TEST ON FOR DURABILITY
HSC
Acid resistance test
Saturated water absorption
test
Porosity test
TEST FOR STRENGTH ON
HSC
Slump test
Compression test
Indirect tensile test
Modulus of elasticity
12. SLUMP TEST
Slump cone or Abrams cone
Filling and tamping of mix
Removal of cone
Measurement of slump
Result
Fig.1 Graph showing the result of slump test
(Source: N.Sivakumar et al, 2014)
13. COMPRESSION TEST
Compression testing machine
Specimen 150mm CUBE
After 24 hours immerse in water for curing
Strength after 7 and 28 day curing
Load till failure
Compressive strength is the ratio between load at failure to cross
sectional area
14. Fig.3 Variation of compressive strength after 28 days
(Source: N.Sivakumar et al, 2014)
Fig.2 Variation of compressive strength after 7 days
(Source: N.Sivakumar et al, 2014)
15. Fig.4 Graph showing percentage of Compressive Strength remained
(Source: N.Sivakumar et al, 2014)
16. INDIRECT TENSILE TEST
Compression testing machine
Cylinder of size 300mm AND 150mm diameter
After 24 hours immerse in water for curing
Strength after7 and 28 day curing
Loading as specified in figure
Load till failure
Fig.5 schematic representation of indirect tensile test
17. Fig.6 Variation of Tensile strength after 7
days (Source: N.Sivakumar et al, 2014)
Fig.7 Variation of Tensile strength after 28 days
(Source: N.Sivakumar et al, 2014)
18. Fig.8 Graph showing percentage of Tensile Strength remained
(Source: N.Sivakumar et al, 2014)
19. MODULUS OF ELASTICITY TEST
Compression testing machine
Specimen 152mm diameter and 312mm long cylinder
Fix the specimen in the compressometer and place it in compression testing
machine
Measure the average deformation of two diametrically opposite locations to
the nearest 5 millionths of strain
The modulus of elasticity is calculated
Obtain a stress-strain curve
20. Fig.9 Stress and Strain Relationship for 0%
RCA replacement(Source: N.Sivakumar et al,
2014)
Fig.10 Stress and Strain Relationship for 50%
RCA replacement (Source: N.Sivakumar et al,
2014)
21. Fig.11 Graph showing variation of modulus of elasticity
(Source: N.Sivakumar et al, 2014)
22. ACID RESISTANCE TEST
Specimen 150mm cubes
Weighed
Immersed in 3% Sulphuric acid for 45 days
Surface dried and weighed
The percentage loss in weight and the percentage loss in compressive strengths
are calculated
23. Table.1 Reduction in Compressive Strength based on Acid resistance Test
(Source: N.Sivakumar et al, 2014)
Percentage replaced
28 day compressive
strength (MPa)
After 45 days immersion of cubes in Sulphuric acid solution
Percentage reduction
in weight
Compressive strength (MPa)
Percentage reduction in
compressive strength compared
to 28 day strength
0 42.1 0.42 38.3 9.03
10 38.2 0.47 33.8 11.52
20 35.3 0.51 31.1 11.9
30 32.5 0.56 28 13.85
40 30 0.59 25 16.67
50 26.6 0.63 21.3 19.92
50 % with reduced water
content
37 0.52 32 12.33
24. SATURATED WATER ABSORPTION AND
POROSITY
Procedure
SPECIMEN 100mm CUBES
After 24 hours immerse in water for curing
After 28 and 90 days of curing
Weighed and dried at 1050C
Continued till weight at consecutive days remains same
Cooled at room temperature and immersed in water
Continued till weight at consecutive days remains same
25. SATURATED WATER ABSORPTION AND
POROSITY (contd.)
Saturated water absorption
Percentage water absorption =
(𝑊𝑠−𝑊𝑑)
𝑊𝑑
x 100
Porosity
Effective porosity =
(Ws –Wd )
(𝑊𝑠−𝑊𝑠𝑢𝑏)
x 100
26. Table.2 Test for saturated water absorption & porosity
(Source: N.Sivakumar et al, 2014)
Percentage
replaced
Saturated
water
absorption
Percentage
increase in
saturated water
absorption
Effective
porosity
Percentage
increase in
Effective
porosity
0 1.10 0 3.30 0
10 1.24 12 3.51 6
20 1.38 25 3.85 16
30 1.56 41 3.90 18
40 1.66 50 3.97 20
50 1.74 57 4.05 22
50% with
reduced w/c
ratio
1.37 24 3.59 9
27. CASE STUDY 2
Materials
Cement :- OPC grade 43
Fly ash :- the 45 micron passing fraction in the unprocessed fly ash
was more than 90 percent
Fine aggregates :-specific gravity 2.61
Coarse aggregates :-
Natural aggregates specific gravity:2.7
Recycled coarse aggregates made from laboratory waste and left over fresh
concrete specific gravity:2.45
Water
30. COMPRESSIVE STRENGTH TEST
Cubes of size 150 mm are casted for all the mixes
Immersed in water for curing
Compressive strength at 7 day and 28 days of curing is fount out
using compression testing machine
Compressive strength is the ratio between load at failure to cross
sectional area
Percentage reduction in characteristic compressive strength is
calculated
32. Fig.12 Compressive strength of concrete at 7
days(Source: P.C Khergamwala et al, 2013)
Fig.13 Compressive strength of concrete at
28 days (Source: P.C Khergamwala et al,
2013)
33. SUMMARY
Specific gravity of RCA is lower and Water absorption of RCA is higher than
natural aggregate.
The compressive strength of concrete containing 25% and 50% RCA is in close
proximity to that of normal concrete.
For M 20 it was seen that compressive strength increased by 3 % with addition of
RCA but only up to 50%.
When amount of RCA is increased above 50%, it adversely affects the
compressive strength of concrete.
34. CONCLUSIONS
Recycled aggregates can be used as an alternative for natural aggregates.
By using there recycled aggregates we can save our precious land from dumping
C&D wastes as landfills.
In modern times broken brick, marble, plastic, etc. are used as aggregates.
So these recycled aggregates can be used as fine aggregate as well as coarse
aggregates.
35. CONCLUSIONS (contd.)
For HSC 30%-40% recycled coarse aggregates with reduced wc ratio may give
same output as normal concrete gives.
For low grade concrete 50% RCA replacement will give almost equal results as
normal concrete gives.
Problem in recycled aggregate concrete is that due to the low wc ratio the
workability will be very low
Due to high water absorption rate of recycled aggregates the water content in the
mix should monitored carefully
36. REFERENCES
Pinal C. Khergamwala, Dr. Jagbir Singh, Dr. Rajesh Kumar International 6,
“Effect of Recycled Coarse Aggregates on Characteristic Strength of Different
Grades of Concrete” Journal of Civil Engineering and Technology, volume 4.
N.Sivakumar, S.Muthukumar, V.Sivakumar D.Gowtham, V.Muthuraj
“Experimental Studies on High Strength Concrete by Using Recycled Coarse
Aggregate” International Journal of Engineering and Science, vol.4, issue 01.
Mamery Sérifou, Z. M. Sbarta, S. Yotte, M. O. Boffoué,2 E. Emeruwa, and F.
Bos “A Study of Concrete Made with Fine and Coarse Aggregates Recycled from
Fresh Concrete Waste” Journal of Construction Engineering Volume 2013,
Article ID 317182.
S. K. Singh, and P. C. Sharma (2007) “Use of Recycled Aggregates in Concrete-
A Paradigm Shift”
http://www.buildingresearch.com.np