properties of concrete made with recycled coarse...
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3755
www.ijifr.com Copyright © IJIFR 2015
Research Paper
International Journal of Informative & Futuristic Research ISSN (Online): 2347-1697
Volume 2 Issue 10 June 2015
Abstract
Using waste materials for new products is a growing global trend. In the construction field, this trend has gained importance because of natural aggregate depletion and land fill space depletion. This paper gives results of studies undertaken to assess suitability of construction demolition waste as coarse aggregate in new concrete production. In this paper the difference in properties of recycled aggregate (RA) and evaluating the influence of the RAs on the mechanical and durability properties of recycled aggregate concrete (RAC) are presented. While experimenting with fresh and hardened concrete, mixtures
containing RA in amount of 25%, 50%, 75% and 100% were prepared. The experimental results showed that the RAC can be designed to achieve comparable hardened properties, relative to the corresponding properties of natural aggregate concrete (NAC).
1. Introduction
Concrete is a composite material, basically consisting of different constituents such as binding
materials, water, aggregates and admixtures. Among these ingredients, aggregate plays a very
crucial role in concrete which occupy the largest volume of about 60–75% of total concrete volume.
Properties of Concrete Made With
Recycled Coarse Aggregate
Paper ID IJIFR/ V2/ E10/ 064 Page No. 3755-3761 Subject Area Civil
Engineering
Key Words Waste Management, Recycled Aggregate, Recycled Aggregate Concrete,
Mechanical Properties, Durability
Received On 12-06-2015 Reviewed On 25-06-2015 Published On 29-06-2015
Shaikh Mohd. Akib 1
M.Tech. Student
Department of Civil & Environmental Engineering
Veermata Jijabai Technological Institute,
Mumbai-Maharashtra
Sameer U. Sayyad 2
Assistant Professor,
Department of Civil & Environmental Engineering
Veermata Jijabai Technological Institute,
Mumbai-Maharashtra
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ISSN (Online): 2347-1697 International Journal of Informative & Futuristic Research (IJIFR)
Volume - 2, Issue - 10, June 2015 22ndEdition, Page No: 3755-3761
Shaikh Mohd. Akib , Sameer U. Sayyad : Properties of Concrete Made With Recycled Coarse Aggregate
It is indispensable for any construction work (Behera et al. 2014). In recent years, the accelerating
urbanization has led to excessive demolition work and construction activities, which consequently,
resulted in the production of large quantities of construction and demolition (C&D) waste,
especially concrete waste. More than 10 billion tons of construction and demolition waste are
produced every year (Mehta 2002). In most cases, this type of waste is incorrectly managed through
illegal deposits causing landfill space depletion.The main problems that industry of construction
materials faces are: natural aggregate depletion, large amount of generated construction and
demolition (C&D) waste and land fill space depletion. Recycling of waste concrete and producing
recycled coarse aggregate (RCA), not only saves landfill space but also reduces the demand for
extraction of natural raw materials for new construction activity (Radonjanin et al. 2013).
Reuse of recycled aggregate (RA) to fully or partially substitute natural aggregate (NA) has
been extensively studied (Limbachiya et al. 2000, Sagoe et. al. 2001, Topcu and Sengel 2004, Zega
and Di Maio 2011, and Duan and Poon 2014). From these studies it is worth noting that the
properties of RA are generally poorer compared with those of NA, which are reflected in higher
water absorption, porosity, aggregate crushing value (ACV), aggregate impact value (AIV) and Los
Angeles abrasion value (LA), and lower specific gravity and 10% fines value (TFV). Limbachiya et
al. (2000) found that recycled concrete aggregate had 7 to 9% lower relative density and 2 times
higher water absorption than natural aggregate. Sagoe et al. (2001), Topcu and Sengel (2004), and
Zega and Di Maio (2011) found that RA drastically lowers the workability of recycled aggregate
concrete (RAC). Literature reports conforms that RAC suffers lower strengths, lower modulus of
elasticity, and significant reductions in the energy of fracture and consequently on the fracture zone
size, compared with natutal aggregate concrete (NAC). The use of RA in practical application is
generally limited to non-structural concrete, and the replacement ratio of NA by RA is
recommended not to exceed 30% (Limbachiya et al. 2000, Topcu and Sengel 2004).
2. Experimental Program
2.1 Materials
Ordinary Portland cement of 53 grade conforming to IS 8112-1989 was used throughout the present
work. As the present study aims to predict the effect of the RA on the performance of RAC, only
conventional fine aggregate (locally available crushed sand) is used.Both NA and RA were used as
the coarse aggregate in this study. Crushed gravel obtained from local quarry was used as NA. RA
was obtained from an old demolished building. The nominal size of the natural and recycled coarse
aggregates was 10 and 20 mm. The properties of NA and RA were determined in accordance with
IS 2386-1963 and presented in Table 1. Superplasticizer conforming to IS 9103-1999 was used in
this study.
Table 1: Properties of Coarse Aggregate
Sr. No. Properties Size
(mm)
Aggregate type
NA RA1
1 Specific gravity
4.75-10 2.76 2.3
10-20 2.76 2.44
2 Water absorption (%) 4.75-10 2.8 6.6
10-20 2.77 4.38
3 Crushing value (%) 10-12.5 22.81 27.68
4 Impact value (%) 10-12.5 12.98 23.59
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ISSN (Online): 2347-1697 International Journal of Informative & Futuristic Research (IJIFR)
Volume - 2, Issue - 10, June 2015 22ndEdition, Page No: 3755-3761
Shaikh Mohd. Akib , Sameer U. Sayyad : Properties of Concrete Made With Recycled Coarse Aggregate
NA RA 25% RA 50% RA75% RA 100%
(mm) 195 150 130 115 100
0
50
100
150
200
250
Slu
mp
(m
m)
2.2 Concrete mixes and specimens preparation
Mix proportioning was done for M-40 grade concrete with target strength of 48 MPA at 28 days as
per IS 10262-2009. A control mix (NAC) was prepared with 100% NA while RAC were made
with 25, 50, 75 and 100% RA. The details of these concrete mixes are given in Table 2. All the
concrete mixes were designed using absolute volume method with aggregates at saturated surface-
dried (SSD) condition and the actual proportions of the mixes at mixing were adjusted according to
the moisture contents and water absorption capacity of the aggregates. A total of five mixes of
concrete were prepared. For each concrete mix thirteen 150 mm cubes and three 150 mm diameter,
300 mm height were cast. All the test specimens were cured in water curing tank until the age of
testing. The compressive strength was determined at age 3, 7, and 28 days as per IS 516-1959.
Splitting tensile strength (IS 5816-1999), water permeability test (DIN 1048), and rapid chloride
penetration test (ASTM C-1202) was conducted at age 28 days.
Table 2: Mix proportions for various concrete mixes (kg/m3)
Mix series Cement Sand NA RA
Water Admixture 10 mm 20 mm 10 mm 20 mm
NA 450 795 484 592 - - 165 4.95
RA 25% 450 795 363 444 101 131 165 4.95
RA 50% 450 795 242 296 202 262 165 4.95
RA 75% 450 795 121 148 303 393 165 4.95
RA 100% 450 795 - - 404 524 165 4.95
3. Results and discussion
3.1 Properties of aggregate
The physical and mechanical properties of the investigated aggregates are shown in Table 1.
Compared with NA, the RAs had a lower specific gravity and higher water absorption. This is
attributable to the old mortar adhered to the recycled aggregate. The aggregate crushing value and
aggregate impact value of RAs were also lower than NA due to separation and crushing of old
mortar adhered to it (Duan and Poon 2014).
3.2 Properties of concrete
3.2.1 Workability
The workability of fresh
concrete mixes was
determined by slump test and
the results are shown in Fig.1.
The results showed that the
workability of the concretes
was gradually decreasing
when the percentage of RAs
increased. The reason is that
Figure 1: Slump of various concrete mixes
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ISSN (Online): 2347-1697 International Journal of Informative & Futuristic Research (IJIFR)
Volume - 2, Issue - 10, June 2015 22ndEdition, Page No: 3755-3761
Shaikh Mohd. Akib , Sameer U. Sayyad : Properties of Concrete Made With Recycled Coarse Aggregate
the presence of porous adhered mortar in the RA increases water absorption, thereby reducing the
workability of the fresh mix.
3.2.2 Compressive strength
The compressive strength of concrete made with NA and RA for the different replacement
percentages are shown in Fig. 2. Each of the reported values represents the average of three values.
Figure 2: Compressive strength of various concrete mixes
The general trend observed for 3- and 7-day strength is similar: the strength increases with
increasing RCA content. This phenomenon may be because the free water content required for
cement hydration was partially absorbed by RCA because of its absorptive nature. Consequently,
there was a reduction in the effective W/C ratio. With the reduction in the effective W/C ratio, the
mortar strength of RCA concrete was likely superior to that of the control mixes. Unlike the 3-day
and 7-day strength test results, the 28-day compressive strength of RCA concrete did not show an
upward trend with the increase in RCA content. A reduction in strength was observed when the
RCA replacement level was more than 50%. The 28 days compressive strength of 100% RA was
only 89% of NAC. In summary, the compressive strength of all the concrete mixes with up to 50%
RCA replacement level showed higher strength than that of the control mix.
These trends can be attributed to two factors: effective W/C ratio and ITZ. Analogously, there
was a reduction in the effective W/C ratio of RCA concrete because of its absorptive nature. In
general, the higher the replacement level, the lower the effective W/C ratio. However, there is only
one ITZ for the control mix, whereas RCA concrete has two ITZs, i.e., the interface between NCA
and adhesion mortar (old ITZ) and the interface between the adhesion mortar and new mortar (new
ITZ). Hence, the adhered mortar may play an important role in determining the performance of
RCA concrete, particularly with respect to strength and permeability (Ryu 2002; Otsuki et al.
2003).Neville (1995) also noted that the influence of the type of coarse aggregate on the strength of
concrete varies in magnitude and depends on the W/C ratio of the mix. For a W/C ratio below 0.4,
the strength of the concrete is manipulated by the properties of the aggregate rather than the
strength of the mortar. With an increase in the W/C ratio, the influence of aggregate declines,
presumably because the strength of mortar itself becomes paramount. As the strength of the mortar
NA RA 25% RA 50% RA 75% RA 100%
3 days 26.25 30.38 30.60 30.70 30.78
7 days 33.99 40.71 37.78 37.86 37.92
28 days 51.29 54.56 52.18 48.99 45.76
0.00
10.00
20.00
30.00
40.00
50.00
60.00
Co
mp
ress
ive
stre
ng
th (
MP
a)
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ISSN (Online): 2347-1697 International Journal of Informative & Futuristic Research (IJIFR)
Volume - 2, Issue - 10, June 2015 22ndEdition, Page No: 3755-3761
Shaikh Mohd. Akib , Sameer U. Sayyad : Properties of Concrete Made With Recycled Coarse Aggregate
depends considerably on the mortar class, a lower effective W/C ratio will produce higher mortar
strength and, consequently, the strength properties of concrete will be enhanced.
3.2.3 Splitting tensile strength
The splitting tensile strength of conventional and recycled aggregate concrete are shown in Fig. 3.
The result indicates that the concrete made with RA had splitting tensile strength similar to that of
the corresponding natural aggregate concrete. This can be attributed to the rough surface of the RA
that might improve the microstructure of the interfacial transition zone (Duan and Poon 2014).
Figure 4: Tensile strength of various concrete mixes
3.2.4 Water penetration test under pressure
The effect of different replacement percentages on the depth of water penetration under
pressure are shown in Fig. 4. The results show that the average values of water penetration of
recycled concretes are similar to, and in some cases better than those of conventional concrete. This
can be attributed to an improvement in the transition zone of mortar-recycled aggregate (Zega and
Di Maio 2011).
Figure 4: Depths of water penetration for various concrete mixes
NA RA 25% RA 50% RA75% RA 100%
Mpa 2.93 3.34 2.90 2.88 2.84
0.0
0.5
1.0
1.5
2.0
2.5
3.0
3.5
4.0
Ten
sile
str
engt
h (
MP
a)
NA RA 25% RA 50% RA 75% RA 100%
mm 11 9 11 10 9
0
2
4
6
8
10
12
Dep
th o
f w
ate
r p
enet
rati
on
(m
m)
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ISSN (Online): 2347-1697 International Journal of Informative & Futuristic Research (IJIFR)
Volume - 2, Issue - 10, June 2015 22ndEdition, Page No: 3755-3761
Shaikh Mohd. Akib , Sameer U. Sayyad : Properties of Concrete Made With Recycled Coarse Aggregate
3.2.5 Rapid Chloride penetration test
Figure 5 shows the effect of different replacement percentages on the resistance of chloride ion
penetration of the concrete. The results show that all concrete made with recycled aggregates
generally had better resistance to chloride ion penetrability, and it decreased as the percentage of
recycled aggregate increased.
Figure 5: Chloride ion penetration values for various concrete mixes
4. Conclusion
The following conclusions can be made based on the results of this study:
I. Quality of recycled concrete aggregate is lower than natural aggregate quality, due to the
mortar that remains attached on the surface.
II. The workability of the concrete was gradually decreasing as the amount of replacement of RA
increased.
III. The compressive strength of the concrete mixes with up to 50% RA replacement level showed
higher strength than that of the control mix. But when the percentage of recycled aggregate
used increased, the compressive strength was reducing.
IV. For 100% replacement the compressive strength of recycled aggregate concrete was 11 %
lower than natural aggregate concrete.
V. Despite the increase in the RCA replacement level, the splitting tensile strength, water
penetration and chloride penetration of the various concrete mixes did not show any
significant difference.
VI. Hence, this study recommends the recycling of waste concrete as an aggregate material in
production of new concrete.
VII. In conclusion, recycling coarse aggregates in concrete production may help solve a vital
environmental issue apart from being a solution to the problem of shortage of natural
aggregate in concrete.
NA RA 25% RA 50% RA 75% RA 100%
Coulombs 5524 3836 3856 4165 4430
0
1000
2000
3000
4000
5000
6000
To
tal
Ch
arg
e P
ass
ed (
Co
ulu
mb
s)
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ISSN (Online): 2347-1697 International Journal of Informative & Futuristic Research (IJIFR)
Volume - 2, Issue - 10, June 2015 22ndEdition, Page No: 3755-3761
Shaikh Mohd. Akib , Sameer U. Sayyad : Properties of Concrete Made With Recycled Coarse Aggregate
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