A Study on Strength Properties of Concrete Replacing Partially the Natural Coarse Aggregates with Recycled Aggregates

International Research Journal of Engineering and Technology (IRJET) e-ISSN: 2395 -0056
Volume: 04 Issue: 02 | Feb -2017 www.irjet.net p-ISSN: 2395-0072
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A Study on Strength Properties of Concrete Replacing Partially the
Natural Coarse Aggregates with Recycled Aggregates
Surendra . B.V1, Rajendra T N2
1Associate Professor, Department of civil Engineering
New Horizon college of Engineering, Bengaluru, Karnataka, India 560103
2 Assistant Professor, Department of civil Engineering
New Horizon college of Engineering, Bengaluru, Karnataka, India 560103
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Abstract – Some of the importantissuesarethe reduction
in the consumption of energy and natural raw materials, as
well as the increase in consumption of waste materials. The
use of recycled concrete aggregates(RCA)formconstruction
and demolition waste (C&DW) in construction, as an
alternative to natural aggregates, has strong potential. The
use of RCA preserves the natural resources and reduces the
space required for the disposal of RCA in landfill. The
quantity of C&DW is also increasing rapidly every year
finding their way to landfill sites. It will be an important
breakthrough for our society if a solution for excess waste
production is found by means of utilizing RCA and C&DW
with an improvement in their final qualities.
The aim of the study is to determine the suitability of
using RCA in structural concrete based on its strength,
stiffness, dimensional stability and durability. Threetypesof
RCA designated as RCA1, RCA2 and RCA3 in this study, were
taken from three different sources. These materials were
tested to establish their mechanical properties for use as
aggregate in concrete. In the experimental programme, RCA
was used at replacement percentages of 0%, 10%, 20% and
30% concrete and to determine what level of NA
replacement is satisfactory for structural application.
Key Words: Cement concrete, Recycled Aggregates,
Construction & Demolition waste, M.Sand Compressive
Strength, Split tensile strength, Flexural Strength.
1. INTRODUCTION
All over the world many old buildings, concrete
pavements, bridges and other superstructureshavereached
the end of their design life. The condition of some of them is
beyond repair and they need to be demolished. The
structures are not servingpresetdayneeds,anddemolishing
them is often the only way for meeting the demand.
Economic growth in many countriesneedsnewconstruction
methods with better performance. Natural disasters suchas
earthquakes, tsunamis, cyclones,tornadoesandfloodscause
structures to collapse turning them into debris. Manmade
disasters such as war create waste from buildings and
infrastructures.
The disposal of these huge amounts of waste material
places strain on landfill sites. On theotherhand,theconcrete
industry uses vast amounts of natural stone from quarries a
aggregate all around the world. Both these practices are
damaging to the environment and are no longer considered
sustainable.
2. MATERIALS AND METHODS
2.1. Materials
2.1.1 Cement: Ordinary Portland cement of 43 grade
confirming to Indian Standards was used in the present
investigation and the specific gravity of the sample was
evaluated. The results have been tabulated in table2.1.
2.1.2 Fine aggregates: River sand with fineness modulus
2.92 conforming to zone II was used in the present
investigation and the specific gravity of the sample was
evaluated. The results have been tabulated in table2.1.
2.1.3 Coarse aggregates: NA used are Crushed granite with
fineness modulus 7.1 having size between 20 mm and 4.75
mm was used in the present investigation and the specific
gravity of the sample was evaluated.
RCA is produced by crushing sound & clean demolition
waste. The size of RCA varies from 20 mm to 10 mm and the
specific gravity of the sample was evaluated.
The results have been tabulated in table 2.1.
2.1.4 Water: Drinking water was used for the experimental
study
Table 2.1: Significant properties of materials used
Materials Specific gravity
Cement 3.12
Fine aggregates (M.Sand) 2.51
Natural Coarse aggregates 2.75
Recycled Coarse
Aggregates
2.68

2.2 Mix Proportion
M20 grade concrete was designed for the present
study. The quantities of ingredients were calculated as per
the guidelines of IS 10262-2009. The various mix
proportions for conventional concretewith0%RCA(Control
specimen) as well as concrete with RCA at different
percentages is shown Table2.2.1.
Table 2.2.1: M20 Mix proportion
Mix
Proportion
Cement
content
(Kg/m3)
F.A
(Kg/m3)
NA
(Kg/m3)
RCA
(Kg/m3)
W/C
Control
specimen
360 690 1090 0 0.55
RCA 10%
NA 90%
360 690 981 109 0.55
RCA 20%
NA 80%
360 690 872 218 0.55
RCA 30%
NA 70%
360 690 763 327 0.55
3. Experimental Program
The experimental program consisted of casting and
testing of M20 grade concrete specimens of cube (150 mm),
cylinder (150 X 300 mm), beam (100X100X500) mm.
3.1 Compressive strength
Six numbers of cubes (3 for 7 days and3 for 28 days)
were cast for each mix and tested using 200T capacity
Compression Testing Machine (CTM).
3.2 Split Tensile strength
Six (3 for 7 days and3 for 28 days) numbers of
cylinders were cast and tested using 200T capacity
3.3 Flexural Strength
Six (3 for 7 days and3 for 28 days) numbers of beam
specimens were cast and tested using 200T capacity
4. Results and discussions
4.1 Compressive strength: The compressive strength was
determined after normal curing for 7 days and 28 days. The
results are presented in Table 4.1.1 and the variation of
compressive strength with % of RCA is shown figure 4.1.1.
Table 4.1.1 Compressive Strength Test results
Specifications Compressive strength
(N/mm2)
7 days 28 days
Control
specimen
13.97 23.73
RCA 10% NA
90%
12.54 22.98
RCA 20% NA
80%
11.23 21.75
RCA 30% NA
70%
9.35 20.49
Fig. 4.1.1 Variation of Compressive strength with%RCA
4.2 Split Tensile strength
The split tensile strength was determined after normal
curing for 7 days and 28 days. The results are presented in
Table 4.2.1 and the variation of split tensile strength with %
of RCA is shown figure 4.2.1.
Table 4.2.1 Split tensile test results
Specifications
Split Tensile
Strength (N/mm2)
7 days 28 days
Control specimen
1.59 2.35
RCA 10% NA 90%
1.35 2.29
RCA 20% NA 80%
1.28 2.10
RCA 30% NA 70%
1.15 1.93
Fig. 4.2.1 Variation of split tensile strength with % RCA

4.3.1 Flexural Strength test results
The flexural strength was determined after normal
curing for 7 days and 28 days. The results are presented in
Table 4.3.1 and the variation of flexural strength with % of
RCA is shown figure 4.3.1.
Table 4.3.1 Split tensile test results
Specifications
Flexural Strength
(N/mm2)
7 days 28 days
Control specimen
1.85 2.66
RCA 10% NA 90%
1.77 2.61
RCA 20% NA 80%
1.66 2.51
RCA 30% NA 70%
1.49 2.41
Fig. 4.3.1 Variation of flexural strength with % RCA
The results of the above experimental program have
shown that the compressive strength, split tensile strength
and flexural strength for concrete with various % of RCA
various are marginally less compared to conventional
concrete. It is also observed that the strength is reducing
with % increase in RCA and accordingly RCA can replace
natural aggregate up to 30% for low cost constructions.
5. Conclusions
The following conclusions have been arrivedfromthestudy:
1. The total demand for aggregates is expected to
increase due to the fast growing urbanization trend
worldwide.
2. The recycling of construction materials has also
grown along with the demand for aggregates.
Potential sources for recycled materials will
certainly increase as maintenance and replacement
of infrastructure continues.
3. Less energy is requiredinprocessingRCAleadingto
lowering of the project cost
4. This study concludes that up to 30% of RCA
replacement can be used with confidence in
structural concrete without any noticeable change
in the properties.
5. REFERENCES
1. Gomez M V, “Shrinkage of concrete with
replacement of aggregate with recycled concrete
aggregate” ACISpecial publication,(2002)209,475-
496.
2. Katz A, “ Properties of concrete made with recycled
aggregates from partially hydrated old concrete”,
Cement and ConcreteResearch33(2003)703 – 711
3. Paul S. C and Van Zijl, “Mechanical properties of
concrete containing recycled concrete aggregates”,
Proceedings of theConcreteSocietyConference,3rd
– 4th August 2010 Emperor’s Palace ISBN Number:
978-1-920017-46-0
4. Ravindra R S et al. “Shrinkage modelingforrecycled
aggregate concrete”, Vol. 3, Page 1-23 ISSN 1983-
4195
5. Hirokazu S et al. (2005), “An advanced concrete
recycling technology” and its applicability
assessment through input-output analysis”,Journal
of advanced concrete technology,Vol.3,No.1,53-67,
February 2005, Japan Concrete Institute
No. 1, 53-67, February 2005, Japan Concrete
Institute.
Surendra B V (M.E, (PhD))
Associate Professor
Rajendra TN (M.Tech)
AssistantProfessor

A Study on Strength Properties of Concrete Replacing Partially the Natural Coarse Aggregates with Recycled Aggregates

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