Some Properties of Sustainable Concrete with Plastic Waste Aggregate · 2018-01-19 · waste used....
Transcript of Some Properties of Sustainable Concrete with Plastic Waste Aggregate · 2018-01-19 · waste used....
The First International Conference for Engineering Researches
March 2017
Some Properties of Sustainable Concrete with Plastic Waste
Aggregate Dr. Wasan Ismail Khalil 1, Khalaf Jumaa Khalaf 2
Professor in Building and Construction Engineering Department/University of Technology-
Baghdad- Iraq1
M.Sc. (Eng), 2
Abstract: Significant amounts of non-biodegradable solid plastic waste as by-products from
industrial activities and in disposal areas of waste are found in Iraq, all these waste lead to
environmental pollution. The present study covers the use of different volumetric replacement of
coarse PET shredded plastic waste bottles (10%, 20%, 30%, 40%, and 50%) as a replacement to
natural coarse aggregates to produce sustainable concrete. The experimental tests are involve the
workability, fresh density, water absorption, dry density, ultrasonic pulse velocity, compressive
strength, splitting tensile strength, flexural strength, and static modulus of elasticity. Despite of
some drawbacks like a decrease in compressive, splitting tensile and flexural strength, the use of
plastic waste aggregate presents various advantages. One of these advantages is that the use of
plastic aggregates results in the production of lightweight concrete depends on the content of plastic
waste used. For high contents of coarse PET plastic waste of 40% and 50% as volumetric
replacement to natural coarse aggregate, the dry density was 1910 and 1850 kg/m3 respectively.
These concrete mixes can be classified as lightweight concrete.
Keywords: Sustainable concrete, Mechanical properties, PET plastic waste aggregate.
I. INTRODUCTION
Conventional concrete typically contains about 12% cement and 80% aggregate by mass [1]. The
use of cement is a main contributor to high-energy usage, CO2 and dust emissions, natural resource
depletion, air pollution, ozone layer destruction, global warming, and continuous environmental
deterioration. In recent years, augmentation of plastic consumption is observed all over the world,
which increases plastic production and this leads to increase the plastic waste materials. These
waste materials are now cause environmental pollution. The slow degradation of waste plastic
materials causes a waste disposal crisis from environmental view point. Plastic is consisting of
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many venomous chemical materials, and therefore plastic causes pollution of, air, water, and soil.
Varieties of toxic chemicals are released into the air during the burning process of plastic wastes,
such as dioxins, which is one of the most poisonous materials. Recently, significant attention has
been given to the use of plastic wastes in concrete industry. The recycled and reused of plastic
waste in construction materials, such as concrete, has many advantages including, the reduction in
the cost of concrete production and disposing of plastic waste [2]. The substitution of natural
aggregate in concrete by waste materials can consume vast amounts of these waste materials. This
can solves problems of aggregate lack in construction sites and reduces environmental problems
related to aggregate mining and waste disposal [3]. The incorporation of plastics in concrete can
significantly improves some properties of concrete, as plastic has high toughness, good abrasion
behaviour, low thermal conductivity and high heat capacity [4]. Previous researches focus on
studying the effect of replacing natural fine aggregate by fine PET plastic waste aggregate in
concrete.
The influence of polyethylene terephthalate (PET) bottles waste plastic lightweight aggregate on
the workability, density, compressive strength, splitting tensile strength, flexural strength and
modulus of elasticity of concrete was investigated by Choi et al. [5]. Water-cement ratios were in
the proportions of 45%, 49% and 53% and the replacement ratios of plastic waste were 25%, 50%
and 75% by volume to natural fine aggregate. The results show that the incorporation of PET
plastic waste aggregate in concrete increases slump value with the increase in water/cement ratio
and the replacement ratio of PET plastic waste. It was found that the compressive, splitting tensile
and flexural strengths of concrete mixtures decrease with the increase of PET plastic waste
aggregate content.
Rahmani et al. [6] studied the mechanical properties of concrete containing PET plastic waste
particles of 5%, 10% and 15% as a substitution by volume of sand. The properties investigated
were, workability, fresh density, dry density, compressive strength, splitting tensile strength,
modulus of elasticity, flexural strength and ultrasonic pulse velocity. It was demonstrated that, as
the content of PET plastic waste aggregate increases, the workability, compressive strength,
splitting tensile strength and modulus of elasticity are decrease.
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II. RESERCH SIGNIFICANT
There is no detail study on properties of concrete with coarse PET plastic waste aggregate as a
replacement to natural coarse aggregate. The main objective of this study is to offer an attractive
low-cost concrete with sufficient properties and improves the sustainability in concrete industry by
using PET waste as a replacement to coarse aggregate in concrete instead of using it as a
replacement to fine aggregate. This will reduce the cost of grinding of the plastic waste to fine
particles. Also the use of silica fume as a by-product supplementary cementitious material in
concrete to replace a portion of cement weight has many benefits such as, decreasing the usage of
natural resources, wastes consumption, avoiding the environmental pollution and economizing
energy.
III. EXPERIMENTAL WORK
Materials Ordinary Portland cement Type (I) manufactured in Iraq with trade mark of (Al-Mass) was used.
The chemical composition and physical properties of cement used throughout this research indicate
that the adopted cement satisfies the requirements of the Iraqi Specifications No.5/1984. Natural
sand with maximum aggregate size of 4.75mm was used. The grading of fine aggregate lies in zone
(2). The test results show that sand grading; physical properties, and sulphate content conform the
requirements of the Iraqi Specifications No.45/1984. Natural crushed aggregate brought from AL–
Badrah region was used in this investigation. It has a maximum particle size of 10 mm. The grading,
sulphate content, and other properties of the coarse aggregate conform to the requirements of Iraqi
Specifications No. 45/1980. Coarse PET plastic waste aggregate was prepared by grinding waste
PET plastic bottles. The preparation process of PET plastic waste aggregate consist of many steps,
collecting the PET bottles wastes, removing the cover and trade label, washing and drying the
bottles, shredding and grinding the PET bottles to the specified particles size as that of natural
coarse aggregate used in concrete by plastic granulator machine (blade mill). The grinding process
was carried out in the Bob Al-Shaam area in Baghdad, and finally the grinded PET plastic waste
were screened on standard sieves and prepared with grading which conforms the grading of natural
coarse aggregate used in this investigation.
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Table (1) shows the grading of PET plastic waste aggregate. Table (2) illustrated the physical
properties of PET plastic waste aggregate, while Figure (2) shows samples of natural aggregate and
PET plastic waste aggregate used in this investigation. The water used for mixing and curing of
concrete was potable water from the water-supply network system (tap water). Chemical and
mineral admixtures were used in this research as follows:
A high range water reducing admixture (superplasticizer) with a trade name GLENIUM 54 was
used [7]. According to the manufacturer the recommended dosage is between 0.5 and 2.5 liters per
100 kg of the cementitious material. This admixture is free from chlorides and complies with
ASTM C494 type F. Silica fume is a highly active pozzolanic material. It is a by-product from the
manufacture of silicon or ferro-silicon metal. Silica fume used throughout this investigation is
commercially known as MEYCO MS 610 from the chemical company BASF as partial
replacement of cement weight. The physical and chemical properties of silica fume used in this
investigation satisfy the requirements of ASTM C1240.
Concrete Mixes Six concrete mixes were prepared in this study including, concrete mix with natural aggregate
(reference mix) and five concrete mixes containing different volumetric replacement of coarse
natural aggregate (10%, 20%, 30%, 40% and 50%) by coarse PET plastic waste aggregate.
Table (1) Sieve analysis of PET plastic waste aggregate
Table (2) Physical properties of PET plastic waste aggregate
Physical properties Results*
Specific gravity 1.34 Water absorption (24 hr) 0.00%
Thickness 0.15mm- 1mm
Shape of particles Flaky and shredded particles and some pellets
pieces with maximum size of 12 mm
Color Crystalline white to blue sky
*Carried out in the laboratory of the Building and Construction Engineering Department/ University of Technology
Sieve size (mm) % Passing Limits of Iraqi specification No.
45/1981984 with single size (10mm)
14 100 100
9.5 94 85-100
4.75 23 0-25
2.36 0 0-5
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(a) Natural coarse aggregate (b) PET plastic waste coarse aggregate
Figure (2) Types of coarse aggregate used in this investigation
Mixing of Concrete and Preparation of Specimens The mixing process was performed in an electrical rotary mixer of 0.1m3 capacity. The coarse and
fine aggregate were wetted to be in a saturated surface dry condition and mixed for one minutes.
Cement and silica fume were mixed by hand for two minutes, then two-thirds of mixing water was
added to the dry mixture and mixed for one minute. The superplascizer was mixed with the
remaining third amount of mixing water, then added to the mixture and the mixing process was
continued for two minutes. The steel moulds were well cleaned and their internal surfaces were
oiled to prevent adhesion with concrete after hardening. The moulds were filled with concrete in
layers (50 mm depth) and each layer was compacted by a vibrating table for about 20 seconds
which is a sufficient period to remove any entrapped air. After compaction, the specimens were
levelled by hand troweling, covered with polyethylene sheet and left in the laboratory. After 24
hours the specimens were demolded, marked and then cured. Then all specimens were completely
immersed in water until the time of testing at 28 days age.
Experimental Tests
A number of experimental tests were carried out to study some properties of sustainable concrete
containing PET plastic waste aggregate. These tests including, slump test according to ASTM C-
143, fresh density test according to ASTM C 138M, oven dry density test according to ASTM
C642, water absorption test according to ASTM C642, ultrasonic pulse velocity test according to
ASTM C597, compressive strength test according to B.S. 1881 (using cubes of 100 mm), splitting
tensile strength test according to ASTM C496–07 (using cylinders of 100×200 mm), flexural
tensile strength test according to ASTM C78-02 (using 100×100×400 mm prisms), and static
modulus of elasticity test according to ASTM C469-02 (using cylinders of 150×300 mm).
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IV. EXPERIMENTAL RESULTS
Selection of Mix Proportions of Sustainable Concrete
Concrete mix with minimum compressive strength of 40 MPa at 28 days without any admixtures
was designed in accordance with ACI 211.1 [8]. The mix proportion is 1:1.19:1.8 (cement: sand:
gravel) by weight, with cement content of 525 kg/m3, w/c ratio of 0.41, and slump value of 90±5
mm. The optimum dosages of superplasticizer and silica fume were selected after the preparation of
many trial mixes. The workability of these trial mixes was similar to that of concrete mix without
any admixtures (slump of 90±5 mm) by adjusting the water to cement ratio. The main function of
using superplasticizer is to reduce the quantity of mixing water while maintaining the same
workability of the reference mix. The details of the designed reference concrete mix containing
different dosages of superplasticizer (HRWRA) are given in Table (3). According to the
manufacturer the normal dosage of HRWRA is between 0.5 and 2.5 liters per 100kg of cement or
cementitious material. The experimental results in this investigation indicate that the optimum
dosage of HRWRA is 1.5 liters per 100 kg of cement which leads to a water reduction of about 44%
and maximum compressive strength of 84 MPa at age 28 days. A significant attention has been
given to the use of silica fume in concrete mixtures. Silica fume was used as an addition or as a
partial replacement to cement, or both. It is suggested that silica fume can be added in addition to
existing cement in very highly aggressive environments, in order to substantially increases the
chemical resistance and durability of the concrete [9,10]. In this investigation, different dosages of
silica fume were used as a replacement to cement weight including, 5%, 10%, and 15%. The results
listed in Table (4) show that the compressive strength increases with the increase of silica fume
dosage. This is due to the physical and chemical effect of silica fume. The results indicate that the
maximum compressive strength obtained is 110.4 MPa at 28 days age for concrete mixture
containing 15 % of silica fume as a replacement to cement weight.
Workability
The relationship between the workability and the volumetric replacement of PET plastic waste
aggregate is illustrated in Figure (3). It can be observed that as the content of PET plastic waste
aggregate increases to 30, 40% and 50% as volumetric replacement to natural coarse aggregate, the
slump value increases by about 4.4%, 6.66% and 7.77% respectively compared with the reference
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concrete. This is due to the smooth surface texture and low water absorption of PET plastic waste
particles.
Fresh Density
The fresh density of reference concrete mix and sustainable concrete mixtures containing various
contents of plastic waste aggregate are presented in Table (5). The results show that there is a
decrease in the fresh density as the PET plastic waste aggregates content increases. The percentage
reduction in fresh density for concrete containing 50% PET plastic waste aggregate as a volumetric
substitution to natural coarse aggregate is about 19.16% in comparison with the reference concrete.
This is due to the lower density of the PET plastic waste compared with natural coarse aggregate.
The same results were observed by Saikia and De Brito [11].
Table (3) Details of trail mixes for various dosages of HRWRA
Table (4) Details of trial mixes for various dosages of silica fume as a replacement by weight of cement
Mix
p
rop
orti
ons
by
wei
ght
Dos
age
of
HR
WR
A
(lit
er/1
00k
g of
cem
ent)
w/c
rat
io
S
lum
p
(mm
)
Wat
er
red
uct
ion
(%
) Compressive
strength (MPa) 14
d
ays
28
day
s
1: 1
.19:
1.8
C
emen
t:
San
d:
Agg
reg
ate
0 0.41 95 - 26.4 35.06
0.5 0.30 90 26.8 50.6 60.5
1 0.25 93 39 57.8 76.6
1.5 0.23 95 43.9 69.8 84.2
1.7 0.22 95 46.3 58.4 76.5
M
ix p
rop
orti
ons
by
wei
ght
Dos
age
of H
RW
RA
(l
iter
/100
kg
of c
emen
t)
Sil
ica
fu
me
as a
re
pla
cem
ent
by
wei
ght
of c
emen
t
w/c
rat
io
S
lum
p (
mm
)
Compressive strength (MPa)
14 d
ays
28 d
ays
1:1.
19:1
.8
Cem
ent:
S
and
: A
ggre
gat
e
1.5 0
0.23 95 69.8 84.2
1.5 5 0.20 92 73.8 90.0
1.5 10 0.22 93 85.2 92.5
1.5 15 0.23 90 84.0 110.4
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March 2017
Figure (3) Effect of PET plastic waste content on the workability of sustainable concrete
Oven Dry Density
The dry density of concrete containing coarse PET plastic waste aggregate decreases as the content
of PET plastic waste aggregate is increased, as shown in Table (5). This is due to the angular shape
of plastic particles, which contributes to the formation of large cavities in concrete, also due to the
low specific gravity of PET plastic waste compared with the natural coarse aggregate. Concrete
containing 40% and 50% PET plastic waste as volumetric replacement to natural coarse aggregate
has dry density of 1910 and 1850 kg/m3 respectively. These concretes are classified as lightweight
concretes according to ACI 213R [12].
Water Absorption
The results indicate that, as the content of PET plastic waste aggregate increases the water
absorption of concrete is increased, as shown in Table (5). This is because the inclusion of plastic
waste aggregate increases the porosity of concrete since the shape of PET plastics waste is angular.
Generally, the water absorption for all concrete specimens is less than 10 percent by weight. This
shows the good quality of all concrete mixes containing PET plastic waste as coarse aggregate [1].
Compressive Strength
The effect of PET plastic waste aggregate content as volume replacement to natural coarse
aggregate on the compressive strength of concrete is illustrated in Table (5). The results indicate
that the compressive strength decreases with the increase of PET plastic waste aggregate content.
The percentages reduction in compressive strength for concrete containing 10%, 20%, 30% 40%,
and 50% PET plastic waste as volumetric replacement to natural coarse aggregate are 33%,
41.39%, 68.47%, 69.61% and 84.4% respectively compared with the reference specimens. The
889092949698
0 10 20 30 40 50 60
Slu
mp
(m
m)
Percentage of PET plastic waste aggregate by volume
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compressive strength is between 17.15 MPa and 73.9 MPa for concrete specimens with PET plastic
waste aggregate. The results of dry density and compressive strength for concrete specimens with
40% and 50% PET plastic waste aggregate indicate that this concrete can be classified as structural
lightweight concrete according to ACI 213R [12]. The reduction in compressive strength is
attributed to the reduction in adhesive strength between the surface of PET plastics and the cement
paste. Also it is due to the mismatch of particles size and shape between natural and plastic waste
aggregate [11].
Ultrasonic Pulse Velocity (UPV)
The test results in Table (5) show a reduction in ultrasonic pulse velocity with the increase of PET
particles content in the mixture. This is due to the fact that substituting natural coarse aggregate by
PET particles makes concrete structure more porous. The cavities formed attenuate the ultrasonic
wave due to the acoustic impedance [6, 13].
Splitting Tensile Strength
The results of splitting tensile strength at 28 days age of reference specimens (without plastic
aggregate) and concrete specimens with different contents of PET plastic waste aggregate are
presented in Table (6). It can be noted that there is a slight reduction in splitting tensile strength of
about 10.4%, for concrete specimens containing 10% PET plastic waste aggregate relative to the
reference specimens without PET plastic waste aggregate. As the content of PET plastic waste
aggregate increases, the splitting tensile strength is significantly decreased. The percentage
reduction is 29.6%, 45.6%, 63.2% and 70.7% for concrete specimens containing 20%, 30%, 40%
and 50% PET plastic waste aggregate as a volumetric substitution to natural coarse aggregate
respectively. This is because of the weak cohesion between the cement paste and the PET particles.
The smooth surface of the plastic particles may causes weak bond strength between PET plastic
and the cement matrix [14].
Flexural Strength
The results of the flexural strength tests for all concrete specimens prepared in this investigation are
illustrated in Table (6). A slight decrease is observed for concrete specimens with low content (10%
and 20%) of PET plastic waste aggregate in comparison with the reference concrete specimens.
However a significant decrease of 31.5%, 42.05% and 43.5% is observed for concrete specimens
containing 30%, 40% and 50% PET plastic waste aggregate respectively. This is due to the
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formation of more voids with the high contents of PET plastic waste and the low bonding strength
between the cement matrix and plastic waste particles [14].
Static Modulus of Elasticity
Table (6) shows that, the value of modulus of elasticity decreases with the increase of PET coarse
plastic waste aggregate content. Concrete specimens with low content of plastic waste (10% and
20%) show slight reduction in modulus of elasticity, while there is a significant reduction in the
modulus of elasticity for concrete specimens with 30%, 40% and 50% coarse PET plastic waste
aggregate. The decrease in modulus of elasticity is due to the low modulus of elasticity for PET
plastic particles compared with the natural coarse aggregate. The low bond strength between the
cement paste (matrix) and plastic aggregates can also contribute to this drop [15].
Table (5) Some properties of PET plastic waste aggregate concrete
M
ix s
ymb
ol
PE
T p
last
ic w
aste
(%
) b
y vo
lum
e of
nat
ura
l co
arse
ag
greg
ate
Fre
sh d
ensi
ty (
kg/
m3)
Dry
den
sity
(k
g/m
3)
Per
cen
tage
of
wat
er
abso
rpti
on
UP
V (
km
/sec
)
Com
pre
ssiv
e s
tren
gth
at
28 d
ays
(MP
a)
Per
cen
tage
red
uct
ion
i
n c
omp
ress
ive
st
ren
gth
Reference R 0 2530 2418 1.12 6.8
110.4
-
Con
cret
e co
nta
inin
g P
ET
pla
stic
w
aste
ag
gre
gate
C- PET10
10 2435 2335 2.6 5.95 73.9 33.06
C- PET20 20 2380 2290 3.2 5.5 64.7 41.39
C- PET30 30 2260 2120 3.9 4.58 34.8 68.47
C- PET40 40 2105 1910 5.8 3.9 23.0 79.61
C- PET50 50 2045
1850
6.3 2.6 17.15 84.4
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Table (6) Effect of PET plastic waste aggregate content on some mechanical properties of concrete
V. CONCLUSIONS
The main conclusions that can be drawn from this investigation are:
1- The dry density of concrete containing coarse PET plastic waste aggregate decreases as the
content of PET plastic waste aggregate is increased. Concrete containing 40% and 50% PET
plastic waste as volume substitution to natural coarse aggregate has dry density of 1910 and
1850 kg/m3 respectively. This concrete can be classified as lightweight concrete.
2- The increase of plastic waste content in concrete increases the water absorption of concrete.
3-The compressive strength, splitting tensile strength, flexural strength, and static modulus of
elasticity of concrete decrease as the content of PET particles increased. The percentage
reduction in compressive strength, splitting tensile strength, flexural strength and static modulus
of elasticity for concrete specimens containing 50% coarse PET plastic waste aggregate by
volume is 84.4%, 70.7%, 43.4,% and 80.45% respectively compared with the reference
specimens.
M
ix s
ymb
ol
PE
T p
last
ic w
aste
(%
) b
y vo
lum
e of
nat
ura
l co
arse
ag
greg
ate
Cu
be
com
pre
ssiv
e st
ren
gth
at
28 d
ays
( M
Pa)
Sp
litt
ing
ten
sile
str
engt
h a
t 28
da
ys (
MP
a)
Red
uct
ion
in
sp
litt
ing
ten
sile
str
engt
h (
%)
F
lexu
ral
ten
sile
str
engt
h
at 2
8 d
ays
(MP
a)
Red
uct
ion
in
f f
lexu
ral
stre
ngt
h (
%)
S
tati
c m
odu
lus
of e
last
icit
y
at 2
8 d
ays
(GP
a)
Per
cen
tage
red
uct
ion
in
st
atic
m
odu
lus
of e
last
icit
y
Reference R 0 110.4
6.25
- 7.8
- 52.7 -
Con
cret
e co
nta
inin
g P
ET
pla
stic
w
aste
ag
gre
gate
C- PET10
10 73.9 5.6 10.4 7.3 6.4 47.7 9.4
C- PET20 20 64.7 4.4 29.6 6.24 20 46.8 11.2
C- PET30 30 34.8 3.4 45.6 5.34 31.5 34.9 33.7
C- PET40 40 23.0 2.3 63.2 4.52 42.05 22.8 56.7
C- PET50 50 17.15 1.83 70.7 4.4 43.5 10.3 80.4
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