Structural behavior of reed evaluation of tensilestrength, elasticityand stress

INTERNATIONAL JOURNAL OF ADVANCED RESEARCH IN
International Journal of Advanced Research in Engineering and Technology (IJARET), ISSN 0976 –
6480(Print), ISSN 0976 – 6499(Online) Volume 4, Issue 1, January - February (2013), © IAEME
ENGINEERING AND TECHNOLOGY (IJARET)
ISSN 0976 - 6480 (Print)
ISSN 0976 - 6499 (Online)
IJARET
Volume 4, Issue 1, January- February (2013), pp. 105-113
© IAEME: www.iaeme.com/ijaret.asp ©IAEME
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STRUCTURAL BEHAVIOR OF REED: EVALUATION OF TENSILE
STRENGTH, ELASTICITY AND STRESS-STRAIN RELATIONSHIPS

Adil M. Abdullatif1 and Tareq S. Al-Attar2
1
(Civil Eng. Department, College of Engineering, University of Al-Nahrain, Iraq,
2
(Building and Construction Eng. Department, University of Technology, Iraq,

ABSTRACT

In southern part of Iraq, common reed is so available in very large quantities on river-
sides and marshes. With the global rise in environmental awareness (sustainability) and the
willingness to try using new construction materials, structural characteristics of reed need to
be well-investigated.
Three samples of common reed were collected from three different places of Baghdad. The
experimental program included testing for chemical composition, density, tensile strength,
modulus of elasticity, and stress-strain relationships.
The test results showed that reed has low density and that makes it very easy to handle and a
very good heat insulator. The tensile strength and modulus of elasticity of reed results ranged
from 89 to 234 MPa and from 5.59 to 13.91 GPa respectively. For design purposes and due to
high scattering in results it was recommended to adopt values equal to 70 MPa for tensile
strength and 5GPa for modulus of elasticity. The stress-strain relationships for the tested reed
were linear in the range of 10 to 20 percent of the ultimate applied stress. Otherwise, the reed
showed non-linearity outside this range.

Keywords: Modulus of elasticity, Phragmites australis, Reed, Stress-strain relationship,
Tensile strength.

1. INTRODUCTION

Reed (Phragmites) is a perennial grass that can grow to approximately 4.25 m (14
feet) in height. The leaves are often 200-400mm long and 10-40 mm wide. Phragmites
reproduces through wind dispersal and vigorous vegetative reproduction through rhizomes. It
often forms dense, virtually mono-specific stands [1]. In recent decades, common reed
(Phragmites australis) has become a serious conversation problem because it has spread into

105


ecologically valuable habitats and as a result of being a strong competitor it has eliminated most
other species [2, 3].
In southern part of Iraq, common reedis so available in very large quantities on river-sides
and marshes. In the far past, reed was used to build houses and there are many signs that old Iraqi
people had used reed reinforced bitumen as a binder in the ancient UR and Babylon. Also reeds
with bitumen were used in building small circular boats (al-Ghuffa) used in transportation [4, 5].
Many studies showed that reed was incorporated in reinforcing gypsum (Juss) or lime to make
arches and lintels before the first appearance of reinforced concrete [6].
In many places of Europe, reed was sometimes used as thatching (roofing) material on its
own, and sometimes mixed with straw. Reed roofs were seen particularly in coastal regions,
where the availability of straw is limited. A reed roof was stronger, and much ecological and
durable. A well-made reed roof withstood wind better than a straw roof and lasted for about 40
years [2, 7].
Similar plants, such as: bamboo had been used in World War II in constructing temporary
building for military purposes as reinforcement. Moreover, the use of natural organic fibers in
concrete and gypsum boards as reinforcement has been well investigated in the late of the 20th
century. These investigations proved that the characteristics of concrete reinforced with organic
fibers were as that of asbestos fiber reinforced concrete for example [8]. Reed could be a good
source for natural fibers.
2. RESEARCH SIGNIFICANCE
2.1 Reed is an invasive perennial grass that had spread rapidly throughout coastal and interior
wetlands. Therefore, incorporating reed in construction industry would partly give a solution to
the problem of its spread into ecologically valuable habitats.
2.2 Withthe global rise in environmental awareness (sustainability) and the willingness to try
using new construction materials, structural characteristics of reed need to be well-investigated
and the database should be enriched to give better tools and techniques for designers and users.
3. EXPERIMENTAL WORK
3.1 Reed
Three samples were collected from three different places of Baghdad. First sample was
from north (Kadimiya), second one was from west (Radwaniya) and the third was from south
(Latifiya). Chemical analysis was made for the three samples and the results are shown in Table 1.
Table 1: chemical analysis of reed samples
Material Sample 1 Sample 2 Sample 3
Cellulose, %.** 62.14 66.26 57.87
Lignin, %. 12.43 25.23 20.00
Zn, ppm. 10.80 11.80 10.20
Mn, ppm. 37.50 51.20 59.30
Fe, ppm. 69.60 150.00 85.70
Pb, ppm. 17.50 22.50 25.00
Ni, ppm. 1.20 2.50 2.50
Co, ppm. 12.00 4.00 12.00
Cr, ppm. < 5.00 13.00 16.00
Cd, ppm. < 0.50 < 0.50 < 0.50
Cu, ppm. < 5.00 < 5.00 < 5.00
** These values represent the summation of cellulose and hemicellulose.

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3.2 Testing Program
The following tests were carried out on reed samples:

3.2.1 Density
The density of the collected samples was measured according to the ASTM D2395-02
[9]. The measurements for dimensions were done to the precision needed by the standard
method of test. Ten specimens from each sample were tested. The density was calculated
according the following equation:

௠௔௦௦ ௢௙ ௧௛௘ ௦௣௘௖௜௠௘௡,௚
Density = (1)
௩௢௟௨௠௘ ௢௙ ௧௛௘ ௦௣௘௖௜௠௘௡,௖௠య

3.2.2 Tensile strength
The authors failed to carry out this test in a universal testing machine for concrete or
steel because the specimens crushed and badly damaged at the point of grips. Same
difficulties were reported by many researchers [10]. Therefore, twelve specimens (six with a
node in the free length and six without a node) for each sample were tested in the Zwick 1454
tensile testing machine with capacity of 10 kN (Fig. 1). This machine is designed to test
plastics and leather and available in the Central Organization for Standardization and Quality
Control, COSQC, Baghdad. The tested specimens were shaped as strips with the dimensions
of (25×200) mm.

Fig. 1: the Zwick 1454 tensile testing machine

3.2.3 Modulus of elasticity
A load-deflection test was conducted on specimens of each sample according to the
ASTM D1037-99 [11]. The modulus of elasticity of each sample was calculated by the
following equation:

107


௉௅య
‫ ܧ‬ൌ ସ଼∆ூ (2)

where:
E: modulus of elasticity, GPa.
P: applied load within elastic range, N.
L: span length between supports, mm.
I: moment of inertia, mm4.
: deflection, mm.

3.2.4 Stress-strain relationship
Part of the load-deflection test results were used to construct the stress-strain
relationships for the three tested samples. Also, the residual strains were measured for each
specimen by loading and unloading process.

4. RESULTS AND DISCUSSION

4.1 Density
Table 2 shows the values of density for the investigated samples. In general, these
values ranged from 0.413 to 0.852 g/cm3. The mean densities were 0.727, 0.602, and 0.575
g/cm3 for sample 1, 2, and 3 respectively. The overall mean density for all tested specimens
was 0.641 g/cm3. The low density of reed makes it very easy to handle and a very good heat
insulator.
Table 2: results of density test
Density, g/cm3.
Specimen No.
Sample 1 Sample 2 Sample 3
1 0.852 0.465 0.679
2 0.680 0.456 0.510
3 0.653 0.467 0.413
4 0.786 0.780 0.445
5 0.657 0.586 0.618
6 0.615 0.671 0.608
7 0.780 0.644 0.567
8 0.820 0.663 0.766
9 0.815 0.636 0.610
10 0.615 0.652 0.537
Mean 0.727 0.602 0.575
St. Dev. 0.092 0.108 0.106
Overall mean 0.641

4.2 Tensile strength
The tensile strength test results are shown in Table 3. According to Table 3, it could
be stated that:
a. The mode of failure for most of the tested specimen was the cutting of the specimen in
the middle third of its length. Five of the thirty six results were discarded because their
failure was near the grips of the machine due stress concentration [10].

108


b. The tensile strength results for specimens with a node were always lower than those for
specimens without a node. There was about 34 percent reduction in tensile strength
according to the overall mean of the two series. This could be attributed to the difference
in structural characteristics of the lignin in the nodes and faraway from the nodes [12].
c. For specimens without a node, the results ranged from 89 to 234 MPa with overall mean
of 154 MPa and overall standard deviation of 51 MPa. Meanwhile, for specimens with a
node, the results ranged from 58 to 159 MPa with overall mean of 101 MPa and overall
standard deviation of 35 MPa. Specimens taken from sample 1 showed the highest results
and specimens related to sample 3 had the lowest results. The present work results were in
agreement with Raouf [4].
d. Raouf [4] suggested that for reed, a tensile strength of 50 MPa could be adopted for
design purposes. According to the present work, this value could be raised to 70 MPa and
still there will be a considerable factor of safety.
Table 3: tensile strength test results
Tensile strength Tensile strength
for specimens for specimens
Sample No. Specimen No.
without a node, with a node,
MPa. MPa.
1 119 117
2 132 119
3 232 148
4 202 135
1
5 234 -
6 209 -
Mean 188 130
St. Dev. 46 15
1 184 115
2 222 139
3 - 159
4 129 81
2
5 126 95
6 128 -
Mean 158 118
St. Dev. 43 32
1 135 58
2 138 60
3 - 63
4 89 83
3
5 97 66
6 89 71
Mean 110 67
St. Dev. 25 9
Overall mean 154 101
Overall standard deviation 51 35

109


e. Table 4 displays the specific tensile strength of tested reed. The specific strength is a material's
strength divided by its density. It is also known as the strength/weight ratio. The values listed in
Table 4 show that reed has a good specific tensile strength if compared with certain known
materials. For example, the specific tensile strength values for concrete, polypropylene, aluminum,
steel, and carbon fibers are 4.5, 89, 214, 254, and 2457 kN.m/kg respectively [13]. Therefore, reed
represents a good lightweight reinforcing material with a considerable tensile strength.

Table 4: specific tensile strength of reed

Av. Tensile Av. specific tensile
Sample No. Av. Density, g/cm3.
strength, MPa. strength, kN.m/kg.

1 188 0.727 258.6
2 158 0.602 262.5
3 110 0.575 191.3

Table 5: modulus of elasticity of the tested specimens

Modulus
Sample Specimen Inner Outer Deflection, of
Load, N.
no. no. dia., mm. dia., mm. mm. elasticity,
GPa.
44.145 5.13 9.12
1 8.5 14.5 47.578 5.36 9.41
54.936 5.60 10.40
4.905 0.54 13.79
1 2 8.8 13.5 8.338 0.91 13.91
15.696 1.81 13.17
4.905 0.27 13.25
3 9.7 16.0 8.338 0.44 13.82
11.772 0.62 13.84
8.338 0.2 9.38
1 15.0 22.0 11.772 0.28 9.43
15.696 0.38 9.30
2
4.905 0.445 7.61
2 12.4 17.0 11.772 1.03 7.89
15.969 1.37 7.91
8.338 0.65 7.38
1 10.4 17.0 11.772 0.785 8.63
15.696 1.09 8.29
4.905 0.33 5.75
3 2 11.6 18.8 8.338 0.56 5.76
11.772 0.815 5.59
8.338 0.65 11.78
3 10.3 15.4 11.772 0.97 11.15
15.696 1.34 10.76
Overall average 9.89
Standard deviation 2.71

110


4.3 Modulus of elasticity
In Table 5, the results of load-deflection test according to the ASTM D1037-99 [11]
load deflection D1037
and the measured modulus of elasticity are listed.
a. The measured modulus of elasticity ranged from 5.59 to 13.91 GPa with overall mean of
9.89 GPa and overall standard deviation of 2.71 GPa. The test showed an obvious
deviation
variation in results. The variation was not only between samples from different sources but
also between specimens within the same sample. Similar variation was reported by Li [14]
when was investigating Bamboo structural characteristics.
boo
b. The aforementioned high variation, especially if considering the standard deviation,
makes the authors highly recommend to adopt a modulus value equals to 5.0 GPa for
structural design calculations.
c. Reed has a low modulus of elasticity if compared to steel, for example, which has a
ulus
modulus of 200 GPa. Therefore, using reed to reinforce structural elements is inconvenient
because these elements will exhibit deflections higher than the allowable limits or in other
words will be unsafe.

4.4 Stress-strain relationships
strain
The results of load-deflection test were used to plot the stress-strain relationship for
deflection stress strain
the three samples as shown in Fig. 2.

Fig. 2: stress-strain relationship for the tested reed samples
strain

a. The shape of the curve for the three samples is much like that of elastomer polymer than
e
of plastic polymer.
b. The relationship for the tested reed was linear in the range of 10 to 20 percent of the
ultimate applied stress. Otherwise, the reed showed non-linearity outside this range.
non y
c. Sample 1 possesses higher toughness (area under the curve) than samples 2 and 3 which
showed nearly the same values.
d. After removing the applied load (unloading), a mean residual strain was measured for the
three samples and it was as follows:
- 10.8 % for sample 1.

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5. CONCLUSIONS

For the investigated reed samples, the following conclusions could be made:
1. The density ranged from 0.413 to 0.852 g/cm3. The low density of reed makes it very
easy to handle and a very good heat insulator.
2. The tensile strength results for specimens with a node showed about 34 percent reduction
than those for specimens without a node.
3. For specimens without a node, the tensile strength results ranged from 89 to 234 MPa
with overall mean of 154 MPa. It could be recommended that a tensile strength of 70 MPa
could be adopted for design purposes.
4. Reed has a good specific tensile strength (strength/density) if compared with certain
known materials such as: concrete, polypropylene, aluminum, steel, and carbon fibers.
5. The measured modulus of elasticity of reed ranged from 5.59 to 13.91 GPa with overall
mean of 9.89 GPa. A modulus value equals to 5.0 GPa for structural design calculations is
recommended.
6. Using reed to reinforce structural elements is inconvenient because these elements will
exhibit deflections higher than the allowable limits.
7. The stress-strain relationship for the tested reed was linear in the range of 10 to 20
percent of the ultimate applied stress. Otherwise, the reed showed non-linearity outside
this range.

REFERENCES

[1] US Department of Agriculture, Natural Resources Conversation Service, NRCS:
Common reed – Phragmites australis, Conservation practice job sheet NH 315(USA, Sep.
2010).
[2] I.Ikonen, and E.Hagelberg, (Editors) Read up on reed, Report of Southwest Finland
Regional Environment Center (Finland, 2007).
[3] J.Giessow, J.Casanova, R.Leclerc, G.Fleming, and J.Giessow, Arundo donax (giant
reed): Distribution and impact report, California Invasive Plant Council (USA, California,
2011).
[4] Z. A. Raouf, Examples of building construction using reeds,Proc. of the Use of
Vegetable Plants and Their Fibers as Building Materials Symposium, (Iraq, Baghdad, 1986).
[5] J. A.Youngquist, A. M.Krzysik, B. W.English, H. N.Spelter, and P.Chow,
Agricultural fibers for use in building components,Proc. of the Use of Recycled Wood and
Paper in Building Applications Symposium(USA, 1996, 123 – 134).
[6] Z. A. Raouf, Structural qualities of reed, Proc. of the Use of Vegetable Plants and
Their Fibers as Building Materials Symposium, (Iraq, Baghdad, 1986).
[7] H.Stenman, (Editor), Reed construction in the BalticSearegion, Report No. 68, Turku
University of Applied Science (Finland, Turku, 2008).
[8] M. A.Al-Aussi, and B. T.Al-Ali, New Reinforced Concrete (Iraq, Baghdad, Al-
Mustansiryia University Press,1989).
[9] ASTM, Annual book of ASTM standards, ASTM D2395-02: standard test methods
for specific gravity of wood and wood-based materials (USA, ASTM, 2006).
[10] H. W.Reinhardt, M. H.Salahi, and T.Schatz, Strength of reed from Egypt, Materials
and Structures, 28, 1995, 345-349.

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[11] ASTM, Annual book of ASTM standards, ASTM D1037-99: standard test methods
for evaluating properties of wood-base fiber and particle panel materials (USA, ASTM,
2006).
[12] A. M. L.Seco, J. A. S.Cavaleiro, F. M. J.Domingues, A. J. D.Silvestri, D.Evituguin,
and C. P. Neto, Structural characterization of the lignin of the nodes and internodes of
Arundo-donax reed”Journal of Agricultural Food Chemistry, 48, 2000, 817-824.
[13] http://en.wikipedia.org/w/index.php?oldid=495597203, “WIKIPEDIA: The Free
Encyclopedia, Specific Strength”.
[14] X.Li, Physical, chemical, and mechanical properties of bamboo and its utilization
potential for fiberboard manufacturing,MSc thesis, Louisiana State University, USA,2004.
[15] Maridurai T, Shashank Rai, Shivam Sharma and Palanisamy P, “Analysis Of Tensile
Strength And Fracture Toughness Using Root Pass Of Tig Welding And Subsequent Passes
Of Smaw And Saw Of P91 Material For Boiler Application” International Journal of
Mechanical Engineering & Technology (IJMET), Volume 3, Issue 2, 2012, pp. 594 - 603,
Published by IAEME.

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Structural behavior of reed evaluation of tensilestrength, elasticityand stress

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