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Properties of porous concrete from waste crushed concrete (recycled
aggregate)
Muhammad Aamer Rafique Bhutta a,, Nor Hasanah b, Nur Farhayu b, Mohd Warid Hussin a,Mahmood bin Md Tahir a, J. Mirza c
a UTM Construction Research Centre (UTM CRC), Faculty of Civil Engineering, Universiti Teknologi Malaysia, Johor Bahru, Malaysiab Faculty of Civil Engineering, Universiti Teknologi Malaysia, Johor Bahru, Malaysiac Department of Robotics and Civil, Research Institute of Hydro-Qubec, Varennes, Qubec J3X ISI, Canada
h i g h l i g h t s
Recycled aggregate porous concrete properties investigated.
Higher total void ratio and water permeability exhibited by recycled aggregate.
Polymer modification significantly improved strength properties of recycled aggregate porous concrete.
Use of recycled aggregate along with optimum content of polymer produced acceptable porous concrete.
a r t i c l e i n f o
Article history:
Received 8 November 2012
Received in revised form 10 April 2013
Accepted 11 June 2013
Available online 7 July 2013
Keywords:
Porous concrete
Recycled aggregate
Permeability
Compressive strength
Flexural strength
Polymercement ratio
Total void ratio
a b s t r a c t
The purpose of this study was to develop porous concrete with acceptable permeability and strength
using recycled aggregate from waste crushed concrete. The optimum mix proportions were employed
to prepare porous concretes using normal and recycled aggregates. Tests carried out on porous concrete
were: void ratio, coefficient of permeability, compressive and flexural strengths. The effect of recycled
aggregate on total void ratio, strength and permeability was examined. Styrene butadiene rubber-basedredispersible polymer powder and latex were introduced to mixtures to improve strength properties. The
total void ratio of porous concrete incorporating recycled aggregate was larger than that of porous con-
crete with normal aggregate. The addition of polymer modification resulted in a slight decrease in total
void ratio regardless of type of aggregate. The compressive strength of porous concrete using recycled
aggregate was lower the one using normal aggregate. However, the compressive strengths of porous con-
cretes using normal and recycled aggregates were significantly improved by 57% and 79% respectively,
due to polymer modification. The use of recycled aggregate along with optimum content of polymer
could produce acceptable porous concrete with both enough drainage and strength properties.
2013 Elsevier Ltd. All rights reserved.
1. Introduction
The use of construction waste as a source of aggregate for the
production of new concrete has become more common in recent
years. The increasing cost of landfill, and the scarcity of natural re-
sources for aggregate, encourages the use of waste from construc-
tion sites as a source of aggregates. Recycled aggregate from
construction and demolition wastes could be an alternative to pri-
mary (normal) aggregates in construction, particularly recycled
aggregate from waste crushed concrete from demolished concrete
buildings can make up 75% of concrete[1]. Recycling of concrete is
a relatively simple process. It involves breaking, removing, and
crushing existing concrete into a material with a specified size
and quality. It conserves natural resources and reduces the space
required for the landfill disposal. The enormous quantities of
demolished concrete available at various construction sites can
easily be recycled as aggregate and used in concrete. In general,
applications for waste crushed concrete without any processing in-
clude many types of general bulk fills, bank protection, base or fill
for drainage structures, road construction and noise barriers and
embankments [2]. Extensive research and development on reuse
of waste crushed concrete (recycled aggregate) is going on globally
to prove its feasibility, economic viability and cost effectiveness
[3,4].
Most economical means to utilize recycled aggregate could be
porous concrete which uses more than 80% aggregates. Porous con-
crete contains little or no fine aggregate, using an adequate amount
of cement paste to coat and bind the aggregate particles to create a
0950-0618/$ - see front matter 2013 Elsevier Ltd. All rights reserved.http://dx.doi.org/10.1016/j.conbuildmat.2013.06.022
Corresponding author. Tel.: +60 7 5533109; fax: +60 7 5576841.
E-mail address: aamer.bhutta@gmail.com(M. Aamer Rafique Bhutta).
Construction and Building Materials 47 (2013) 12431248
Contents lists available atSciVerse ScienceDirect
Construction and Building Materials
j o u r n a l h o m e p a g e : w w w . e l s e v i e r . c o m / l o c a t e / c o n b u i l d m a t
http://dx.doi.org/10.1016/j.conbuildmat.2013.06.022mailto:aamer.bhutta@gmail.comhttp://dx.doi.org/10.1016/j.conbuildmat.2013.06.022http://www.sciencedirect.com/science/journal/09500618http://www.elsevier.com/locate/conbuildmathttp://www.elsevier.com/locate/conbuildmathttp://www.sciencedirect.com/science/journal/09500618http://dx.doi.org/10.1016/j.conbuildmat.2013.06.022mailto:aamer.bhutta@gmail.comhttp://dx.doi.org/10.1016/j.conbuildmat.2013.06.022http://-/?-http://-/?-http://-/?-http://-/?-http://-/?-http://-/?-http://crossmark.dyndns.org/dialog/?doi=10.1016/j.conbuildmat.2013.06.022&domain=pdfhttp://-/?-8/10/2019 1-s2.0-S0950061813005400-main
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system of high porosity and interconnected voids to quickly drain
off water, its poresity depends upon application and size of aggre-
gate. Porous concrete (no-fines concrete) is a unique and effective
environmentally friendly material that is being extensively devel-
oped and used for last four decades in North America, Europe
and Japan in various applications such as to reduce the amount
of runoff water and improve the water quality near pavements
and parking lots[510]. Due to water-permeating, water-draining,
and water-retaining performances of porous concrete, it has been
utilized in road pavement, sidewalks, parks and building extension,
as well as for plant bedding and permeable gutters [5,1115].
Unfortunately, no technical data and information are available on
development activities and applications of porous concrete in
South East Asia particularly, Malaysia. Located near the equator,
Malaysias climate is categorized as equatorial being hot and hu-
mid throughout the year. The average rainfall is 2500 mm a year
[16], necessitating the introduction and popularization of porous
concrete technology in Malaysia in order to minimize the adverse
effects of heavy rainfall as floods and mudslides.
The purpose of this research study is to entirely replace normal
aggregate with recycled aggregate into porous concrete to create a
very sustainable concrete product for pavement and for precast
porous concrete applications. Another aimof this research study is
to explore the characteristics of porous concrete using local materials
while keeping in view the climatic conditions of the region. Porous
concrete is prepared using recycled coarse aggregate from waste
demolished reinforced concrete structure (residential apartment
buildings) and results are compared with the normal aggregate
porous concrete. In general, porous concrete shows low strength
due to large void ratio, particularly, when recycled aggregate is
used. One of the effective techniques to enhance the strength prop-
erties of porous concrete could be to use polymeric admixtures
such as polymer latexes or dispersions [16,17]. Huang et al. [6]
and Aamer Rafique Bhutta et al. [10] also reported that the addition
of polymer significantly improves workability and strength proper-
ties of porous concrete at relatively lower watercement ratio.
Therefore, latex polymer styrene butadiene rubber (SBR) basedredispersible polymer powder and latex are selected and incorpo-
rated into the concrete mixture in order to improve the strength of
porous concrete using recycled aggregate.
2. Experimental work
2.1. Materials
Ordinary Portland cement was used in this study. Crushed granite aggregate
and waste crushed concrete were used as normal and recycled aggregates, respec-
tively. A source of recycled aggregate is shown inFig. 1. The crushing of waste con-
crete was carried out insidethe laboratory. Recycled aggregate was notwashed and
used as is.Table 1shows the properties of aggregates. The aggregate size distribu-
tion of normal and recycled aggregates is demonstrated in Fig. 2. Commercially
available styrene butadiene rubber (SBR) based redispersible polymer powder(RPP) and latex emulsion (Latex) were used as polymeric admixtures into the mix-
tures. The aim was to enhance the strength of porous concrete, particularly the one
incorporating recycled aggregate. The properties of polymeric admixtures are given
inTable 2.
2.2. Mix proportions
The porous concrete mixtures comprised of Portland cement, water and coarse
aggregate containing normal and recycled aggregates. To improve the strength of
porous concrete, latex polymer in powder and liquid forms were used. Various pre-
liminary mixes were prepared to obtain the optimum mix proportion of porous
concrete. Polymer was first mixed with mix design water and no extra water was
added. The optimum mix proportions are presented inTable 3. The polymerce-
ment ratios (P/C) of 0%, 3% and 5% by mass of cement were used. Porous concrete
has already low watercement ratio. Therefore, it is important to maintain the
mix design water content in porous concrete for proper mixing. High water absorp-
tion of recycled aggregate may result in lower water content in the mix. This could
affect the mixing adversely and the produced concrete will have large void ratio,
low strength and may not fulfil the specific mix design requirements. Therefore,
recycled aggregate used were first pre-soaked for 12 h prior to casting. Aim was
to avoid the absorption of mix water by the aggregates in fresh mixture.
2.3. S pecimens preparation
The specimens were prepared at ambient laboratory temperatures according to
the JCI Standard (draft) Method of Making Porous Concrete Specimens (draft),
Report on Eco-Concrete Committee on Design, Construction and Recent Applica-
tions of Porous Concrete. They were then cured at room temperature for 1-day.
According to this method, mixed porous concrete was filled into moulds up to
one third of its heightand subjected to 25 times hand tamping. The same procedure
was applied for the two third and complete fill-ups. Placing and consolidating the
porous concrete in molds can cause excessive void and strength losses, thus ad-
versely affecting the test results. Porous concretes contained SBR-based latex and
RPP. It is well known that for an optimum film formation, a dry cure is required
[17].On the other hand, cement hydration only takes place in the presence of suf-
ficient water. Since porous concrete has low W/C, therefore, both the specimens
were placed in water for 5-d and then subjected to 25 1 C and 60% R. H. for
22-d. The specimens were prepared as per JCI Standard (Method of Making Porous
Concrete Specimens (draft), Report on Eco-Concrete Committee at ambient labora-
tory temperature) [19]. The cube specimens sized 150 150 150mm for com-
pressive strength, beam specimens sized (100 100 400mm) for flexural
strength, cylinder specimens sized (u100200 mm) for total void ratio and water
permeability tests. To obtain mean value, three identical concrete specimens were
prepared for each test.
3. Tests
The tests carried out were: total void ratio, compressive
strength, flexural strength and co-efficient of water permeability.
3.1. Total void ratio
JCI Test Method (Report on Eco-Concrete Committee for Void
Ratio of Porous Concrete (draft) was employed to determine the to-
tal void ratio of porous concrete cylinders (u100200 mm)[19].
The total void ratio was obtained by dividing the difference be-
tween the initial mass (M1) of the cylinder specimen in the water
and the final mass (M2) measured following air drying for 24 h
with the specimen volume (V), where qMis the density of water.
Fig. 1. Recycled aggregate obtained from demolished residential apartment buildings.
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The specimens were placed inside the cage immersed in clean
water at room temperature. The mass of the specimen in water
(M1) was determined after removing the air bubbles on the parti-
cle surfaces and between the particles of specimen. The equation
used to obtain total void ratio (A) is as follows:
A% 1 M2M1=qMV
100
3.2. Coefficient of water permeability
The coefficient of water permeability of porous concrete was
determined in accordance with JCI Test Method for Permeability
of Porous Concrete (draft), Report on Eco-Concrete Committee
[19].Fig. 3demonstrates testing procedures for the water perme-
ability of porous concrete. Water permeability of porous concrete
was determined over a period of 30 s under a water head of
200 mm. The water permeability coefficient was calculated using
the following equation:
KrH
h Q
At2 t1
where Kr: permeability coefficient (cm/s); H: length of specimen
(cm); Q: amount of discharge water from t1 to t2 (cm3); h: difference
of water head; t2t1: time (s);A: area of cross section of cylindrical
specimen (cm2).
3.3. Compressive and flexural strengths
The compressive strength was performed according to JIS (Jap-
anese Industrial Standard) A 1108 (Method of Test for Compressive
Strength of Concrete). The flexural strength test was conducted in
accordance with JIS A 1106 (Method of Test for Flexural Strength of
Concrete) which is similar to ASTM C 78/C 78M-10e1 Standard
Test Method for Flexural Strength of Concrete (Using Simple Beam
with Third-Point Loading).
4. Results and discussion
4.1. Effect of recycled aggregate and polymer on total void ratio
Fig. 4shows the total void ratio of porous concretes using nor-
mal and recycled aggregates and the effect of polymer modification
on total void ratio. The total void ratio of porous concrete using
recycled aggregate was higher than that of porous concrete with
normal aggregate. Generally, porous concrete with recycled aggre-
gate contains not only the original aggregate, but also hydrated ce-
ment paste which reduces the specific gravity and increases the
porosity compared to similar normal aggregate. It was seen that
the total void ratio of porous concrete with recycled aggregatewas within the acceptable range of 2227%. Moreover, the addition
of polymer modification resulted in a slight decrease in total void
ratio regardless of type of aggregate. However, the total void ratio
of porous concrete incorporating recycled aggregate was higher
than that of porous concrete having normal aggregate. It is due
to the more internal friction among recycled aggregates provided
by the poor workability of recycled aggregate porous concrete
which is lower than the normal aggregate porous concrete. The
workability of fresh concrete would be affected by the presence
of recycled aggregate. This phenomenon is mainly attributed to
the angular shape and rough surface texture of the recycled aggre-
gates. The high water absorption decreases the workability of the
fresh concrete due to the presence of old mortar in the recycled
aggregate. The workability of fresh porous concrete with polymermodification has been determined using slump and slump-flow
test in one of the previous studies [for details, see Ref. [10]]. There-
fore, an addition of polymer modification into mixtures was made
to improve the workability of cement paste for porous concretes. It
was also observed that workable cement paste coated over the
recycled aggregate and kept in contact with each aggregate to min-
imize the total void ratio. The difference between the total void ra-
tios of porous concretes using normal and recycled aggregates is
due to the nature of polymer.
4.2. Effect of recycled aggregate and polymer on compressive strength
The compressive strength of porous concretes using normal and
recycled aggregates is shown in Fig. 5. At the same void ratio, areduction in strength is observed for porous concrete using recy-
Table 1
Physical properties of aggregate.
Type Gradation (mm) Density (g/cm3) Water absorption (%) Absolutea volume (%) Unit weight (kg/m3)
Normal aggregate 520 2.55 1.2 55.6 1620
Recycled aggregate 522 2.34 4.6 57.5 1542
a Absolute volume = aggregate mass/density.
Fig. 2. Aggregate size distribution of normal and recycled aggregates.
Table 2
Properties of redispersible polymer powder (RPP) and latex.
Type of
polymer
Appearance Particle
size (lm)
Density
(g/cm3)
Solid
content (%)
pH
RPP Grayish-white powder 0.15 0.50 50 78
Latex Milky white 200 0.98 49 1011
Table 3
Mix proportions of porous concrete.
Type W/C(%)
Voidratio (%)
Mix proportions (kg/m3
)
Water Cement Aggregate Polymer
Normal aggregate 30 2025 85 283 1620 0
8.5
14.0
Recycled aggregate 78 260 1542 0
7.8
13
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cled aggregate compared to porous concrete incorporating normal
aggregate. This could be due to reduction of bonding between
aggregate and cement paste when using recycled aggregate and
partly by the increased void ratio. Generally, it is expected that
the compressive strength of porous concrete is related to the
strength of aggregate and total void ratio. A polymer modification
is considered and incorporated into the mixtures to improve thestrength of porous concrete, particularly, the one using recycled
aggregate. It is evident that the addition of both RPP and latex
could increase the compressive strength of all porous concretes
as well as increase the contact area between neighbouring aggre-
gate particles, more importantly; these commingle along with ce-
ment hydration products and create two interpenetrating
matrices which work together, resulting in improved compressive
strength[6,17]. The mean value of compressive strength of porous
concrete is fairly uniform in three specimens as depicted by varia-
tion bars.
The compressive strengths of porous concretes using normal
and recycled aggregates improved significantly due to polymer
modification. At P/C ratios of 3% and 5% for RAA, the compressive
strength of porous concretes improved 26% and 57% for normal
aggregate, and 47% and 79% for recycled aggregate. The compres-
sive strength was also enhanced using latex with the same P/C ra-
tios and increments in strength were 19% and 47% for normal
aggregate, and 43% and 68% for recycled aggregate. It is believed
that the addition of RPP gave greatly improved internal cohesion
and water retention between cement matrix and aggregate and in-creased the bonding force between neighbouring aggregate parti-
cles[10].
4.3. Effect of recycled aggregate and polymer on relationship between
total void ratio and compressive strength
Fig. 6 represents the effect of aggregate type on relationship be-
tween total void ratio and compressive strength of porous concrete
without polymer. The variation in total void ratio is the mean of
three identical specimens. Effect of polymer type (polymerce-
ment ratio: 5%) on relationship between total void ratio and com-
pressive strength of porous concrete using recycled aggregate is
Difference of water head, h
Porous concrete specimen
Length of specimen, H
Over flow water tank
Constant water head Drainage pipe
Quantity of water, Q
Fig. 3. Water permeability set-up for porous concrete.
Fig. 4. Total void ratio vs. type of porous concrete. Fig. 5. Compressive strength of porous concrete.
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shown in Fig. 7. Regardless of aggregate and polymer type, thecompressive strengths of all porous concretes were decreased with
an increase in total void ratio. All Porous concretes having the total
void ratio of 2328% showed an almost linear relationship between
compressive strength and total void ratio.
4.4. Effect of recycled aggregate and polymer on coefficient of water
permeability
According to Fig. 8, the effect of recycled aggregate and polymer
on coefficient of water permeability is similar to that on total void
ratio. It is evident from Fig. 8 that all porous concretes showed
water permeability values of 2.43.7 cm/s, which is high enough
to be used for drainage purpose in pavement or precast productapplication [18]. The recycled aggregate showed consistent influ-
ence on the water permeability of porous concretes. Porous con-
crete prepared using recycled aggregate exhibited larger
permeability values. Although the addition of RPP and latex could
lead to a further reduction in permeability, however, the perme-
ability values are comparable and acceptable compared to the gen-
eral requirement of drainage[6].
4.5. Effect of recycled aggregate and polymer on relationship betweentotal void ratio and coefficient of water permeability
Fig. 9exhibits the effect of aggregate type on relationship be-
tween total void ratio and coefficient of water permeability of por-
ous concretes. Fig. 10 gives the effect of polymer type (polymer
cement ratio: 5%) on relationship between total void ratio and
coefficient of water permeability of porous concrete using recycled
aggregate. Regardless of aggregate and polymer type, the coeffi-
cient of water permeability for all porous concretes became larger
as the total void ratio increased. In the range of 2328% total void
ratio, the coefficient of water permeability of all porous concretes
increased linearly.
4.6. Effect of recycled aggregate and polymer on flexural strength
Fig. 11exhibits the effect of recycled aggregate and polymer on
the flexural strength of porous concretes. The effects of both aggre-
gate and polymer are evident. The use of recycled aggregate in por-
ous concrete decreased the flexural strength than that of normal
aggregate but the introduction of polymer modification enhanced
the flexural strength in all porous concretes. As mentioned above,
this is attributed to the polymer network formed during the com-
mingling and inter-penetration of the polymer and cement hydra-
Fig. 6. Effect of aggregate type on relationship between total void ratio and
compressive strength.
Fig. 7. Effect of polymer type on relationship between total void ratio and
compressive strength using recycled aggregate.
Fig. 8. Coefficient of water permeability vs. type of porous concrete.Fig. 9. Effect of aggregate type on relationship between total void ratio and
coefficient of water permeability.
Fig. 10. Effect of polymer type on relationship between total void ratio andcoefficient of water permeability using recycled aggregate.
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tion products [17]. Unlike the brittle cement paste, the polymer
network is relatively strong in tension zone, which contributes sig-
nificantly to the flexural strength of porous concrete.
5. Conclusions
An experimental study was conducted to investigate the prop-
erties of polymer-modified porous concretes prepared from nor-
mal and recycled aggregates. The effects of using recycled
aggregate and polymer modification on total void ratio, permeabil-
ity and strength were evaluated. Based on this study, the following
conclusions can be drawn:
(1) The total void ratio of porous concrete incorporating recy-
cled aggregate was higher than those having normal aggre-
gate. The addition of polymer modification resulted in a
slight decrease in total void ratio regardless of type of aggre-
gate. The total void ratios were achieved within the accept-
able range of 2228% for recycled aggregate porous
concretes.
(2) The compressive strength for porous concrete using recycled
aggregate was lower than the normal aggregate porous con-crete. However, the strength was significantly improved due
to polymer modification by 57% for natural aggregate and
79% for recycled aggregate at P/C of 5% for RPP.
(3) All the porous concretes showed coefficient of water perme-
ability values between 2.4 to 3.7 cm/s, which is high enough
to be used as a drainage pavement.
(4) Regardless of type of aggregate and polymer, results showed
an almost linear relationship between the compressive
strength and total void ratio, and between coefficient of per-
meability and total void ratio for all porous concretes.
(5) The addition of polymer increases the workability of cement
paste and allows the aggregate to flow better. This decreases
the void ratio and increases the strength of porous concrete.
(6) Use of recycled aggregate along with polymer modificationcould produce acceptable porous concrete having both
enough drainage and strength properties.
Acknowledgments
The authors are grateful to the Ministry of Higher Education,
Malaysia (Mohe) and Research Management Centre (RMC), Univer-
siti Teknologi Malaysia (UTM) for financial support under Grant:
Q.J.130000.7122.01J76. The authors are also thankful to the staff
of Materials & Structures Laboratory, Faculty of Civil Engineering
for the facilities and support for experimental work.
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Fig. 11. Flexural strength vs. type of porous concrete,Note, : total void ratio.
1248 M. Aamer Rafique Bhutta et al. / Construction and Building Materials 47 (2013) 12431248
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