improving impact and mechanical properties of gap graded concrete
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International Journal of Civil Engineering and Technology (IJCIET), ISSN 0976 – 6308
(Print), ISSN 0976 – 6316(Online) Volume 4, Issue 2, March - April (2013), © IAEME
118
IMPROVING IMPACT AND MECHANICAL PROPERTIES OF GAP-
GRADED CONCRETE BY ADDING WASTE PLASTIC FIBERS
Dr. Abdulkader Ismail Abdulwahab Al-Hadithi
Assist. Prof. -College of Eng. / University of Anbar /Ramadi, Al-Anbar, Iraq.
ABSTRACT
This research includes the study of the effect of adding the chips resulting from
cutting the plastic beverage bottles by hand (which is used in Iraqi markets now) as small
fibers added to the gap-graded concrete. These fibres were added with different percentages
of concrete volumes. These percentages were (0.5%) , (1%) and (1.5%). Reference concrete
mix was also made for comparative reasons.
Results proved that adding of waste plastic fibres with these percentages leads to
improvements in compressive strength and Splitting Tensile Strength of concretes containing
plastic fibres, but the improvement in Splitting Tensile Strength appeared more clearly.
There is significant improvement in low-velocity impact resistance of all waste
plastic fibres reinforced concrete (WPFRC) mixes over reference mix. Results illustrated that
waste plastic fibres reinforced mix of (1.5%) give the higher impact resistance than others,
the increase of its impact resistance at failure over reference mix was (328.6%) while, for
waste plastic fibres reinforced mix of (0.5%) was (128.6%) and it was (200%) for fiber
reinforced mix of (1%).
Some photos were taken to the microstructures of concrete by using Scanning
Electronic Microscope (SEM) and Optical Microscope.
Keywords: Fiber Reinforced Concrete, Waste Plastic Fiber, Impact, Mechanical Properties,
Gap-graded Concrete.
1. INTRODUCTION
Since ancient times, fibers have been used to reinforce brittle materials. Straw was
used to reinforce sun-baked bricks, and horsehair was used to reinforce masonry mortar and
plaster. A pueblo house built around 1540, believed to be the oldest house in the U.S., is
INTERNATIONAL JOURNAL OF CIVIL ENGINEERING AND
TECHNOLOGY (IJCIET)
ISSN 0976 – 6308 (Print)
ISSN 0976 – 6316(Online)
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IJCIET
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International Journal of Civil Engineering and Technology (IJCIET), ISSN 0976 – 6308
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constructed of sun-baked adobe reinforced with straw. In more recent times, large scale
commercial use of asbestos fibers in a cement paste matrix began with the invention of
the Hatschek process in 1898. Asbestos cement construction products are widely used
throughout the world today. However, primarily due to health hazards associated with
asbestos fibers, alternate fiber types were introduced throughout the 1960s and 1970s (1).
2. FIBER REINFORCED CONCRETE
Concrete is considered a brittle material as it has low tensile strength and failure
strain. It is difficult to suppress the formation and growth of cracks developed therein and
is apt to be fractured by tensile load or dynamic load. To resolve these drawbacks and to
prolong the service duration of concrete, fiber-reinforced concrete has been developed in
which fibers are incorporated to improve the mechanical properties (2).
Fiber-reinforced concrete, or fiber concrete, is a composite. It takes the advantages of the
high compressive strength of concrete and the high tensile strength of fibers. Furthermore,
it increases the energy absorption capacity of concrete through the adhesion peeling off,
pulling out, bridging, and load transmitting of fibers in the concrete, and improves the
ductility, toughness, and impact strength(2).
The strength potential of nylon-fiber-reinforced concrete was investigated versus
that of the polypropylene-fiber-reinforced concrete by Song et al(3). The compressive and
splitting tensile strengths and modulus of rupture (MOR) of the nylon fiber concrete
improved by 6.3%, 6.7%, and 4.3%, respectively, over those of the polypropylene fiber
concrete. On the impact resistance, the first-crack and failure strengths and the percentage
increase in the post first-crack blows improved more for the nylon fiber concrete than for
its polypropylene counterpart.
Poly(vinyl butyral) (PVB) which has many special engineering aggregate
properties is utilized as the sole aggregate in a research done by Xu et al(4) to develop a
novel cementitious composite reinforced with Poly (vinyl alcohol) (PVA) fiber . Impact
energy absorption capacity is evaluated based on the Charpy impact test. The results show
that PVB composite material has lower density but higher impact energy absorption
capability compared with conventional lightweight concrete and regular concrete. The
addition of PVA fiber improves the impact resistance with fiber volume fractions. A
model based on fiber bridging mechanics and the rule of mixtures is developed to
characterize the impact energy. A good correlation was obtained for the materials tested
when experimental results are compared to those predicted by the developed model.
Experimental investigations were conducted by Song et al(5) on tyre fiber
specimens with different variables such as length, diameter of holes and percentage of
coarse aggregate replacement by tyre fibers. Impact resistance test was done by ACI
standard and acid and water absorptions tests were conducted by Indian standard. Results
obtained from the tests are use to determine the optimum size of the tyre fiber specimen
that could be used in the rubberized concrete mixture to give the optimum performance.
The rubberized concrete with tyre fiber specimen L50-D5 10% has shown good transport
characteristics and impact resistance.
International Journal of Civil Engineering and Technology (IJCIET), ISSN 0976 – 6308
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120
3. WASTE PLASTIC FIBER REINFORCED CONCRETE
Alhozaimy(6) study the effects of using recycled fibers (RP) from industrial or post
consumer recycled plastic waste as reinforcing fibers in concrete. The mechanical properties,
plastic shrinkage cracking and permeability of RP fibrous concrete were investigated. Four
different volume fractions (1, 2, 3 and 4%) of recycled plastic low density polyethylene fibers
(RP fibers) and control with no RP fibers were considered.
The results showed that at volume fraction of 1 to 2% of RP fibers, plastic shrinkage cracking
was almost similar to plain concrete without RP fibers (i.e., 0%) while at a volume fraction of
3 to 4 %, no plastic shrinkage cracks were observed. Also, it was found that RP fibers have
no significant effect on the compressive and flexural strengths of plain concrete at volume
fractions used in this study. However, the RP fibers increased flexural toughness up to 270%.
Yadav(7) investigates the change in mechanical properties of concrete with the
addition of plastics in concrete. Along with the mechanical properties, thermal characteristics
of the resultant concrete is also studied .This research found that the use of plastic aggregates
results in the formation of lightweight concrete. The compressive, as well as tensile strength
of concrete reduces with the introduction of plastics. The most important change brought
about by the use of plastics is that the thermal conductivity of concrete is reduced by using
plastics in concrete.
Thirty kilograms of waste plastic of fabriform shapes was used by Ismail (8) et al as a
partial replacement for sand by 0%, 10%, 15%, and 20% with 800 kg of concrete mixtures.
All of the concrete mixtures were tested at room temperature. These tests include performing
slump, fresh density, dry density, compressive strength, flexural strength, and toughness
indices. Seventy cubes were molded for compressive strength and dry density tests, and 54
prisms were cast for flexural strength and toughness indices tests. Curing ages of 3, 7, 14, and
28 days for the concrete mixtures were applied in this work. The results proved the arrest of
the propagation of micro cracks by introducing waste plastic of fabriform shapes to concrete
mixtures. This study insures that reusing waste plastic as a sand-substitution aggregate in
concrete gives a good approach to reduce the cost of materials and solve some of the solid
waste problems posed by plastics.
3. EXPERIMENTAL PROGRAM
3.1. Materials
3.1.1. Cement Ordinary Portland Cement (OPC) ASTM Type I is used. The cement is complied to
Iraqi specification no.5/ 1999(9)
3.1.2. Fine Aggregate Natural gap-graded sand is used in production of concrete specimens which was
used in this study. Results of sieve analysis of this sand are shown in Table (1).
3.1.3. Coarse Aggregate Gap-graded uncrushed course aggregate is used for all concrete mixes in this
study. Table (2) gives the sieve analysis results of that course aggregate.
International Journal of Civil Engineering and Technology (IJCIET), ISSN 0976 – 6308
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121
Table (1): Sieve Analysis Results of the Sand Used.
Percent Passing
Sieve Size (mm) No Limits of British Standard
Specifications (BSS. 882 (Zone 1))(10) Fine aggregate
90-100 100 4.75mm 1
60-95 46.6 2.36mm 2
30-70 4.6 1.18mm 3
15-34 0.28 600micron 4
5-20 0 300micron 5
0-10 0 150micron 6
Fig.1: Grading of fine aggregate used in this study.
Table (2): Sieve Analysis Results of the Gravel Used.
90
60
30
15
50
10095
70
34
20
10
100
46.6
4.60.28 0 00
20
40
60
80
100
120
Pe
rce
nta
ge
Pa
ssin
g %
Seive Size (mm)
Lower Passing
Percentage
Upper Passing
Percentage
Actual Fine Agg.
Grading
Percent Passing
Sieve Size (mm) No Limits of British Standard Specifications
(BSS. 882 (Zone 1))(10) Coarse aggregate
95-100 100 37.5 1
30-70 80 20 2
10-35 18.8 10.0 3
0-5 1.2 5.0 4
International Journal of Civil Engineering and Technology (IJCIET), ISSN 0976 – 6308
(Print), ISSN 0976 – 6316(Online) Volume 4, Issue 2, March - April (2013), © IAEME
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Fig.2: Grading of coarse aggregate used in this study.
3.1.4 Mixing Water
Ordinary tap water is used in this work for all concrete mixes and curing of
specimens.
3.1.5. Plastic Fiber Plastic fibers with average 1cm length and average 2mm width were produced by
cutting plastic beverage bottles by hand.
3.2. Preparation of Specimens and Curing. The moulds were lightly coated with mineral oil before use, according to ASTM
C192-88(11), concrete casting was carried out in three layers. Each layer was compacted by
using a vibrating table until no air bubbles emerged from the surface of concrete and the
concrete is levelled off smoothly to the top of moulds.
3.3 Mixing and Compaction of Concrete Mixing operations were made in the concrete laboratory in the civil engineering
department of University of. A 0.1m3
pan mixer was used. Pouring the coarse aggregates
made mixing and cement in two alternate times and mixing them dry while adding the fibers
until a homogenous dry mix is obtained. The water is added then and mixing continued until
final mixing mix is obtained.
The concrete mix is poured, in three layers, in the molds. An electrical vibrator made
compaction for not more than 10 sec.
95
30
10
0
100
70
35
5
100
80
18.8
1.20
20
40
60
80
100
120
37.5mm 20mm 10mm 5mm
Pe
rce
nta
ge
Pa
ssin
g %
Seive Size (mm)
Lower Passing
Percentage
Upper Passing
Percentage
Actual Coarse
Aggregate Grading
International Journal of Civil Engineering and Technology (IJCIET), ISSN 0976 – 6308
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123
3.4. Mixes
Table (3): Mix Proportions of Materials Used in this Work for Making One Cubic Meter of
Concrete.
Symbol Cement
(kg)
Sand
(kg)
Gravel
(kg)
Water
Liter
Waste Plastic Fibers
Waste
Plastic
Fibers(kg)
Waste
Plastic
Fibers%
RC 412.5 618.7 1237 185.6 0 0
F0.5 410.4 615.6 1231.2 184.7 5.5 0.5%
F1.0 408.4 612.6 1225.12 183.8 11 1%
F1.5 406.3 609 1218.94 182.8 16.5 1.5%
3.5. Tests
3.5.1. Compressive Strength Test The compressive strength of concrete is one of the fundamental properties used to
specify the quality of concrete. The digital hydraulic testing machine (ELE) with capacity of
(2000) KN and rate of 3 KN/Sec, is used for the determination of compressive strength of
concrete. Three cubes of (100×100×100) mm concrete were tested according to B.S.1881.
Part(5):1989(12). The average of three cubs was recorded for each testing age (7, 28 and 56)
days respectively for compressive strength.
3.5.2. Spletting Tensile Strength Splitting tensile strength was conducted on cylinders of (100mm diameter and 200mm
height according to ASTM C496-05 (13). The average of three specimens in each case was
taken. The splitting tensile strength was determined by using the digital hydraulic testing
machine (ELE) with capacity of (2000) KN and rate of (0.94) KN/Sec. The average of three
cylinders was recorded for each testing age (7, 28 and 56) days respectively for splitting
tensile strength.
3.5.3. Low Velocity Impact Test
Eight 56-day age (500 × 500 × 50) mm slab specimens were tested under low
velocity impact load. The impact was conducted using 1400gm steel ball dropping freely
from height equal to 2.4m. The test rig used for low velocity impact test consists of three
main components: Plate (1).
A steel frame, strong and heavy enough to hold rigidly during impact loading. The
dimensions of the testing frame were designed to allow observing the specimens (square slab)
from the bottom surface to show developing failure, during testing. The specimen was placed
accurately on mold which were welded to the support ensure the simply supported boundary
condition.
The vertical guide for the falling mass used to ensure mid-span impact. This was a
tube of a round section.
-Steel ball with a mass of 1400 gm.
-Specimens were placed in their position in the testing frame with the finished face
up. The falling mass was then dropped repeatedly and the number of blows required to cause
first crack was recorded. The number of blows required for failure (no rebound) was also
recorded.
International Journal of Civil Engineering and Technology (IJCIET), ISSN 0976
(Print), ISSN 0976 – 6316(Online) Volume 4, Issue 2, March
Plate (1): Test Rig Used for Low Velocity Impact Test
4-RESULTS AND DISCUSSION
4.1. Compressive Strength Figs. (3) and (4) show the variation the compressive strength with waste plastic fiber
percentages for all ages. From these figures it can be seen that, the compressive strength of all
specimens increases with time, but the percentage of increasing in compressive strength differs
between the reference concrete RC and the fiber reinforced concrete FRC. Table (4) show the
results of compressive strength of all mixes in this research.
All the mixes have shown strength val
mixes with waste plastic fibers percentage by volume (V
compressive strength more than that of reference mix at 56 age of test. The maximum value of
increment was equal to (7.5%) for concrete mix containing (1%) waste plastic fiber. The
compressive strength of mix with (V
and 56 day ages. The reason of this is the fiber after which (1%) had formed bulks and segregat
on mix. This led to form stiff bond about these bulks.
Table (4): Compressive Strength of FRCs at Different Ages with
Mix Waste plastic fibers
Vf %
RC 0
FR0.5 0.5
FR1.0 1
FR1.5 1.5
Journal of Civil Engineering and Technology (IJCIET), ISSN 0976
6316(Online) Volume 4, Issue 2, March - April (2013), © IAEME
124
Test Rig Used for Low Velocity Impact Test
Figs. (3) and (4) show the variation the compressive strength with waste plastic fiber
percentages for all ages. From these figures it can be seen that, the compressive strength of all
ut the percentage of increasing in compressive strength differs
between the reference concrete RC and the fiber reinforced concrete FRC. Table (4) show the
results of compressive strength of all mixes in this research.
All the mixes have shown strength values above (35) MPa at 56 day age. Fiber reinforced
mixes with waste plastic fibers percentage by volume (Vf%) equal to (0.5%) and (1%) have a
compressive strength more than that of reference mix at 56 age of test. The maximum value of
o (7.5%) for concrete mix containing (1%) waste plastic fiber. The
compressive strength of mix with (Vf=1.5%) decrease if comparing with reference mix at 28 day
The reason of this is the fiber after which (1%) had formed bulks and segregat
on mix. This led to form stiff bond about these bulks.
Compressive Strength of FRCs at Different Ages with
Waste plastic fibers Compressive strength (MPa) at indicated ages in
(day)
7 28
26.4 33
23.4 32
27.3 34
26 29
Journal of Civil Engineering and Technology (IJCIET), ISSN 0976 – 6308
April (2013), © IAEME
Figs. (3) and (4) show the variation the compressive strength with waste plastic fiber
percentages for all ages. From these figures it can be seen that, the compressive strength of all
ut the percentage of increasing in compressive strength differs
between the reference concrete RC and the fiber reinforced concrete FRC. Table (4) show the
ues above (35) MPa at 56 day age. Fiber reinforced
%) equal to (0.5%) and (1%) have a
compressive strength more than that of reference mix at 56 age of test. The maximum value of
o (7.5%) for concrete mix containing (1%) waste plastic fiber. The
=1.5%) decrease if comparing with reference mix at 28 day
The reason of this is the fiber after which (1%) had formed bulks and segregate
Compressive strength (MPa) at indicated ages in
56
41.2
41.3
44.3
35
International Journal of Civil Engineering and Technology (IJCIET), ISSN 0976
(Print), ISSN 0976 – 6316(Online) Volume 4, Issue 2, March
Fig. 3: The relationship between compressive strength and age for all mixes.
Fig.4: Development of Compressive Strengths for all Concrete Mixes at All Ages.
4.2. Splitting Tensile Strength The results of splitting tensile strength for various types of concrete specimens at age
(7, 14, 56) days. The relationship between splitting tensile strength and various ratios of
waste plastic fiber is shown in figures (5) and (6). It can be seen that the addition
plastic fibers leads to increase of remarkable splitting tensile strength but it decreases after
(Vf=1% ) of waste plastic fiber ,but it is still higher than the splitting of reference concrete. The
increase is due to the fact that the presence of
Also we can note that the plain concrete cylinders fail suddenly and split into two separate
parts, while the mode of failure in cylinders with waste plastic fibers is cracked at failure
without separation. The maximum splitting tensile strength is obtained at mixing containing
(1%) waste plastic fiber by volume.
85
23
28
33
38
43
20
25
30
35
40
45
Co
mp
res
siv
e S
tren
gth
(M
Pa
)
35
Age (Day)
Journal of Civil Engineering and Technology (IJCIET), ISSN 0976
6316(Online) Volume 4, Issue 2, March - April (2013), © IAEME
125
The relationship between compressive strength and age for all mixes.
Development of Compressive Strengths for all Concrete Mixes at All Ages.
of splitting tensile strength for various types of concrete specimens at age
(7, 14, 56) days. The relationship between splitting tensile strength and various ratios of
waste plastic fiber is shown in figures (5) and (6). It can be seen that the addition
plastic fibers leads to increase of remarkable splitting tensile strength but it decreases after
) of waste plastic fiber ,but it is still higher than the splitting of reference concrete. The
increase is due to the fact that the presence of waste plastic fibers arrests cracks progression.
Also we can note that the plain concrete cylinders fail suddenly and split into two separate
parts, while the mode of failure in cylinders with waste plastic fibers is cracked at failure
The maximum splitting tensile strength is obtained at mixing containing
(1%) waste plastic fiber by volume.
13 18 23 28 33 38 43 48 53 5810 15 20 25 30 35 40 45 50 55 60
Age (Day)
Vf% of waste plastic fibers
0%
Vf=0.5%
Vf=1%
Vf=1.5%
0%0.5%
1%1.5%
0
20
40
60
26.4
33
41.2
23.4
32
41.3
27.3
34
44.3
26
29
Vf% of waste plastic fibers
Co
mp
ress
ive
Str
en
gth
(M
pa
)0%
0.5%
1%
1.5%
Journal of Civil Engineering and Technology (IJCIET), ISSN 0976 – 6308
April (2013), © IAEME
The relationship between compressive strength and age for all mixes.
Development of Compressive Strengths for all Concrete Mixes at All Ages.
of splitting tensile strength for various types of concrete specimens at age
(7, 14, 56) days. The relationship between splitting tensile strength and various ratios of
waste plastic fiber is shown in figures (5) and (6). It can be seen that the addition of waste
plastic fibers leads to increase of remarkable splitting tensile strength but it decreases after
) of waste plastic fiber ,but it is still higher than the splitting of reference concrete. The
waste plastic fibers arrests cracks progression.
Also we can note that the plain concrete cylinders fail suddenly and split into two separate
parts, while the mode of failure in cylinders with waste plastic fibers is cracked at failure
The maximum splitting tensile strength is obtained at mixing containing
0.5%
1.5%
International Journal of Civil Engineering and Technology (IJCIET), ISSN 0976
(Print), ISSN 0976 – 6316(Online) Volume 4, Issue 2, March
Table (5): Splitting Tensile Strength of FRCs at Different Ages
Mix Waste plastic fibers
Vf %
RC 0
FR0.5 0.5
FR1.0 1
FR1.5 1.5
Fig.5: The relationship between splitting tensile strength and age for all mixes.
Fig.6: Development of Seplitting
85 10
0.90
1.10
1.30
1.50
1.70
0.80
1.00
1.20
1.40
1.60
1.80
Splittin
g T
ensile S
trength
(M
Pa)
56
Age (Day)
Journal of Civil Engineering and Technology (IJCIET), ISSN 0976
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126
Splitting Tensile Strength of FRCs at Different Ages
Waste plastic fibers Compressive strength (MPa) at indicated ages in
(day)
7 28
0.88 1
0.884 1.04
1.138 1.57
1 1.38
The relationship between splitting tensile strength and age for all mixes.
of Seplitting Tensile Strengths for all Concrete Mixes at All Ages.
13 18 23 28 33 38 43 48 53 580 15 20 25 30 35 40 45 50 55 60
Age (Day)
Vf% of waste plastic fibers
0%
Vf=0.5%
Vf=1%
Vf=1.5%
0%0.5%
1%1.5%
0
0.5
1
1.5
2
7
0.88
1
1.44
0.884
1.04
1.6
1.132
1.57
1.7
1
1.13
1.38
Vf% of waste plastic fibers
Sp
litt
ing
Te
nsi
le S
tre
ng
th (
Mp
a)
0%
0.5%
1%
1.5%
Journal of Civil Engineering and Technology (IJCIET), ISSN 0976 – 6308
April (2013), © IAEME
Compressive strength (MPa) at indicated ages in
56
1.44
1.6
1.7
1.38
The relationship between splitting tensile strength and age for all mixes.
all Concrete Mixes at All Ages.
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127
4.3. Impact Resistance and Mode of Failure
The impact resistance of concrete slabs was determined in terms of the number of
blows required to cause complete failure of the slabs. The mass of (1400 gm) was repeatedly
dropped for a (2400 mm) height up to the failure of slabs. Two sets of number of blows were
recorded depending on the mode of failure: at first crack and at failure. Total fracture energy
here is the product of the height of the drop (2.4 m) and weight of the dropped mass (1.4 kg)
by the number of blows to failure. The results of low velocity impact tests of all mixes at
age of (56) days are presented in Table (4) below, it can be seen that there is a significant
improvement in the low-velocity impact resistance for the all mixes containing waste plastic
over reference mix. Fig.(7) shows the effect of adding waste plastic which were added as a
percentage by volume of the concrete at first crack and failure. It can be seen that, when the
ratio of waste plastic: concrete percentage increased the impact resistance also increased. For
a (1.5%) ratio the number of blows reached to (30) blows at failure while they recorded as
(16) at first crack (each result average for two specimens). The increase of its impact
resistance at failure over reference mix was (328.6%). Fig.(8) showed the relationship
between impact resistance and splitting tensile strength at failure.
From figures (7), (8) and (9) it can be noticed that, at percentage of (1.5%) of waste
fiber add to concrete, the specimens show a good resistance to fracture due to the distribution
of fiber across the concrete. That means the increase in tension stress, ductility, more energy
absorption and bond strength.
Some photos were be taken to the microstructure of WPFRC by optical microscope in
the laboratories of Iraqi Ministry of Sciences and Technology and other photos were be taken
by Scanning Electronic Microscope Technology (SEM) in the labs of South West Jiaotong
University-China. Plate (2) and Plate (3) show the waste plastic fiber inside the
microstructure of concrete.
Table (4): Results of impact test at 56 days age
Panels Vf %
No. of blows to first
crack
No. of blows to
failure Total energy (Nm)
Results Mean Results Mean First
crack Failure
RC
0
6 5
8 7 164.8 230.72
4 6
FR0.5
0.5
9 9
17 16 296.64 527.36
9 15
FR1.0 1 14
13 18
21 428.48 692.16 12 24
FR1.5 1.5 15
16 33
30 527.36 988.8 17 27
International Journal of Civil Engineering and Technology (IJCIET), ISSN 0976 – 6308
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128
Fig. 7: The relationship between impact resistance (number of blows) and fiber content by
volume for all mixes.
Fig. 8: The relationship between splitting tensile strength and impact resistance (number of
blows) and for all mixes.
0.3 0.8 1.30.0 0.5 1.0 1.5
(Vf%) of Wast Plastic Fibers
5
15
25
0
10
20
30
Imp
ac
t R
es
ista
nc
e (
No
. o
f B
low
s)
Impact Resistance
First Crack
Final Failure
8 13 18 23 285 10 15 20 25 30
Impact Resistance (No. of Blows Until Failure)
1.3
1.5
1.7
1.2
1.4
1.6
1.8
Sp
litt
ing
Te
nsil
e S
trn
gth
(M
Pa)
Polynomial
International Journal of Civil Engineering and Technology (IJCIET), ISSN 0976
(Print), ISSN 0976 – 6316(Online) Volume 4, Issue 2, March
Fig. 9: The relationship between total energy and waste plastic fiber content by volume for
a
Plate(2):a-50X photo of WPFRC
b-200X photo of WPFRC microstructure by optical microscope.
First crack
Failure
Journal of Civil Engineering and Technology (IJCIET), ISSN 0976
6316(Online) Volume 4, Issue 2, March - April (2013), © IAEME
129
The relationship between total energy and waste plastic fiber content by volume for
all mixes.
b
50X photo of WPFRC microstructure by optical microscope.
200X photo of WPFRC microstructure by optical microscope.
0%0.5%
1%1.5%
0
200
400
600
800
1000
First crack
Failure
164.8
230.72296.64
527.36
428.48
692.16
527.36
988.8
Vf%
Journal of Civil Engineering and Technology (IJCIET), ISSN 0976 – 6308
April (2013), © IAEME
The relationship between total energy and waste plastic fiber content by volume for
microstructure by optical microscope.
200X photo of WPFRC microstructure by optical microscope.
400
600
800
1000
To
tal
En
erg
y (
Nm
)
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130
a
b
c
Plate(3):a-150X photo of WPFRC microstructure by SEM.
b-150X photo of WPFRC microstructure by SEM.
c-200X photo of WPFRC microstructure by SEM.
5. CONCLUSION
Based on the expiremental work and results obtained in this study, the following conclusions can
be presented:
1. Addition of waste plastic fibers with different volume ratios to gap-graded concrete slightly increases
the compressive strength up to (Vf=1%) at ages 7, 28, and 56 days comparing with the original mix. The
maximum values of increasing were about (3%) for 28 days and (7.5%) for 56 days age for WPFRC mix
with (Vf=1%) .
2. Addition of waste fiber with different volume ratios to gap-graded concrete increases the splitting tensile
strength for WPFRC mixes at ages 28, and 56 days comparing with the original mix. The max. value of
increasing is (57%) for 28 day while (18%) for 56 days age for the mix with (Vf=1%) of waste plastic fiber
to . Another mixes also show increasing in the splitting tensile strength but not as (1%) percentage.
3. A significent improvement in the low velocity impact resistance of all gap-graded mixes modified with
waste plastic fibers over reference mix. The increase in the waste plastic fibers percentage gives higher
number of blows at both first crack and failure comparing with reference mix. The amount of increasing
varied from (128.5% ) at (Vf= 0.5%) to (328.6%) for (1.5%) volume ratio at failure.
4. Results of this study open the way to use of waste plastic for developing the performance properties of
gap-graded concrete and extension in studying the hole properties of gap-graded concrete containing these
kind of fibers.
International Journal of Civil Engineering and Technology (IJCIET), ISSN 0976 – 6308
(Print), ISSN 0976 – 6316(Online) Volume 4, Issue 2, March - April (2013), © IAEME
131
ACKNOWLEDGMENT
I would like to express my extreme and very special thanks and appreciation to
Dr. Fuhi Li - Department of Civil Engineering Material - School of Civil
Engineering/Southwest Jiaotong University for his assistance in preparing samples and taking
SEM for these samples.
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