Determination of Tensile Property of Bamboo for Using as Potential Reinforcement in the Concrete

peletonwhoopUrban and Civil

Nov 26, 2013 (3 years and 7 months ago)

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International Journal of Civil & Environmental Engineering IJCEE-IJENS Vol: 11 No: 05 47


112905-9494 IJCEE-IJENS © October 2011 IJENS

I J E N S


Abstract This research was undertaken to investigate the
possibility of using bamboo as a potential reinforcement in the
concrete beam to compensate the low tensile property of the
concrete. Even though steel reinforcement is a very suitable
material for complementing concretes low tensile strength,
considering the cost, some parts of the world people build their
houses by using only concrete or mud-brick which is very
vulnerable. To overcome these problems, bamboo may be the
alternative materials to substitute the reinforcing bar in concrete
for less important structures by investigating the physical
properties of this type of natural reinforcement. To evaluate these
properties, tension test was conducted on bamboo specimen. First
three samples of finished bamboo were tested in natural condition
(without treatment). Then five samples of finished bamboo were
tested with GI wire spiral at the ends for improved gripping.
From this test, the tensile strength, proof strength and modulus of
elasticity were determined from stress-strain curve for bamboo
reinforcement and satisfactory results are obtained in terms of
tensile strength and stress-strain characteristics of bamboo for
using as reinforcement in the concrete.

Index Terms Bamboo, Stress, Strain, Tension test, Tension
test grip.

1. INTRODUCTION
One of the properties that would make bamboo a good
substitute to steel in reinforced concrete is its strength. The
strength of bamboo is greater than many timber products
which are advantageous, but it is quite less than the tensile
strength of steel. Bamboo is easily accessible as it is available
in almost every tropical and subtropical regions, this lowers
the cost of construction and increases the strength of the
buildings that would otherwise be unreinforced. Tension test is
the most basic type of mechanical test. It is easy to perform

Manuscript received September 4, 2011.

1
Senior Lecturer, Department of Civil Engineering, Stamford University
Bangladesh; phone: 880-191- 469- 0318; e-mail: asabbir01@hotmail.com


2
Lecturer, Department of Civil Engineering, Stamford University
Bangladesh; e-mail: buet_ce_078@yahoo.com



3
Lecturer, Department of Civil Engineering, Stamford University
Bangladesh; e-mail: sfancy_cee@yahoo.com



and relatively inexpensive compared to other tests. The stress-
strain characteristics of bamboo have been derived from the
results of this tension test.
2. OBJECTIVES OF THE RESEARCH
Whereas the mechanical properties and behavior of steel
reinforcement have been thoroughly studied and well
documented, there exists no comprehensive data describing
bamboo reinforcement. Therefore, the aim of this study is to
provide a preliminary contribution toward the collection of the
mechanical properties and behaviors of bamboo
reinforcement. Some of the previous researches are mentioned
in connection with this. The mechanical properties vary with
height and age of the bamboo culm. Research findings indicate
that the strength of bamboo increases with age. The optimum
strength value occurs between 2.5 and 4 years. The strength
decreases at a later age [1]. Amada et al. (1997) investigated
the mechanical and physical properties of bamboo. They
conducted a thorough investigation into the structure and
purposes of the nodes, which they found to strengthen the
bamboo culm [2]. Lo et al. (2004) gave a detailed description
of the mechanical properties of bamboo in their study. They
found that the physical, as well as mechanical attributes vary
with respect to diameter, length, age, type, position along
culms, and moisture content of bamboo [3]. Amada and
Untao (2001) studied the fracture properties of
bamboo. In contradiction to other studies, this study states
that the tensile strength of bamboo fibers almost corresponds
to that of steel [4]. Ghavami (1995) discussed the
mechanical properties of bamboo, specifically pertaining to
bamboo in concrete. This study showed that the ultimate
strength of a concrete beam reinforced with bamboo is
approximately 4 times when compared with un-reinforced
concrete [5].
3. SAMPLE PREPARATION
First a bamboo was divided into two pieces length wise with
the carpenters tools like hammer, chisel etc. Each of the two
halves was further divided into three pieces. It was then
rounded to shape of a rod as shown in the Fig. 1, Fig. 2, Fig. 3
and Fig. 4.
Determination of Tensile Property of Bamboo
for Using as Potential Reinforcement in the
Concrete
Md Ahsan Sabbir
1
, S.M. Ashfaqul Hoq
2
, and Saiada Fuadi Fancy
3

International Journal of Civil & Environmental Engineering IJCEE-IJENS Vol: 11 No: 05 49


112905-9494 IJCEE-IJENS © October 2011 IJENS

I J E N S



Fig. 8. Splitting and grip failure (sample-1)


Fig. 9. Failure at knot(sample-2)


Fig. 10. Splitting and grip failure (sample-3)

Table 1: Results of tension test for bamboo reinforcement
Specimen
No.
Avg.
Area
(mm
2
)
Failure
Load
(kN)
Stress at
Failure
(MPa)
Failure type
1 200 17.6 88 Splitting and
failure at
grip
2 181 19.4 107.2 Failure at
node
3 155 24.2 156.1 Splitting and
failure at
grip
7.2 RESULTS OF TENSION TESTS FOR BAMBOO
SPECIMENS (BAMBOO SURFACE WITH GI WIRE AT
GRIP AREA)
During tension tests of bamboo reinforcement, an attempt was
made to avoid failure at the grip by wrapping the ends by GI
wire. According to the test, the failure pattern of bamboo
specimen was typical splitting without any slip at the grip
location as shown in the Fig. 11. The split is parallel to the
grain and propagates through the knot and finally failure
occurs more than one location. The failure patterns of other
four samples are similar to sample no-1 as shown in the Fig.
12 to Fig. 15. The failure loads of these samples are shown in
Table 2. From these results it can be said that the tensile
strength is nearly uniform and failure pattern is very similar for
bamboo specimens where failure at grip was avoided. The
tensile strength of bamboo specimens with prepared ends (to
avoid grip failure) is always higher than the corresponding
bamboo specimens without prepared ends (failure at grip).



Fig. 11. Typical splitting failure of bamboo reinforcement
(sample-1)


Fig. 12. Typical splitting failure of bamboo reinforcement
(sample-2)
International Journal of Civil & Environmental Engineering IJCEE-IJENS Vol: 11 No: 05 50


112905-9494 IJCEE-IJENS © October 2011 IJENS

I J E N S



Fig. 13. Typical splitting failure of bamboo reinforcement
(sample-3)


Fig. 14. Typical splitting failure of bamboo reinforcement
(sample-4)


Fig. 15. Typical splitting failure of bamboo reinforcement
(sample-5)

7.3 STRESS STRAIN RELATION

Stress-strain data are shown for sample-1 and sample-2 in the
Table 3 and Table 4. The gage length was taken between 203
mm and 254 mm for all the samples. The stress-strain curve
for sample-1 and sample-2 is shown in Fig. 16. From this
curve, the yield strength has been calculated by offset method.
The offset is the horizontal distance between the initial tangent
line and any line running parallel to it. The value of the offset
for a given material is usually expressed this way: Yield
Strength, 0.1% Offset. 0.1% Offset means 0.1% of the
fundamental extension units of inches per inch, or 0.001in./in.
along the X-axis. Now using that as the origin, a line (C-D)
parallel to the initial tangent line was drawn. It is noted that the
line C-D intersects the stress- strain curve at a certain point Y
shown in the Fig. 17. The ordinate of this point (the amount of
stress in psi) is the yield strength at 0.1% Offset.



Fig. 16. Stress- strain curve of bamboo samples

International Journal of Civil & Environmental Engineering IJCEE-IJENS Vol: 11 No: 05 51


112905-9494 IJCEE-IJENS © October 2011 IJENS

I J E N S


Table 3 Stress-strain data for bamboo (sample-1)
Load
(kN)
Area
(mm
2
)
Stress
(Mpa)
Displacement
(mm)
Strain( X 10
-
3
)
(mm/mm)
0 234 0.0 0 0.00
0.88 234 3.8 0.15 0.56
1.32 234 5.6 0.18 0.67
1.76 234 7.5 0.21 0.78
2.64 234 11.3 0.23 0.85
3.52 234 15.0 0.25 0.93
5.28 234 22.5 0.3 1.11
7.48 234 31.9 0.31 1.15
7.92 234 33.8 0.33 1.22
9.68 234 41.3 0.335 1.24
11 234 47.0 0.34 1.26
13.2 234 56.3 0.48 1.78
15.4 234 65.7 0.61 2.26
17.6 234 75.1 0.77 2.85
19.8 234 84.5 1.01 3.74
22 234 93.9 1.14 4.22
24.2 234 103.3 1.25 4.63
26.4 234 112.7 1.38 5.11
28.6 234 122.1 1.54 5.70


Table 4 Stress-strain data for bamboo (sample-2)
Load
(kN)
Area
(mm
2
)
Stress
(MPa)
Displacement
(mm)
Strain( X 10
-
3
)
(mm/mm)
0 197 0.0 0.00 0.00
0.88 197 4.5 0.03 0.12
1.76 197 8.9 0.04 0.14
2.64 197 13.4 0.06 0.25
3.52 197 17.8 0.08 0.33
4.4 197 22.3 0.09 0.37
5.28 197 26.8 0.14 0.57
6.16 197 31.2 0.16 0.65
7.04 197 35.7 0.17 0.69
7.92 197 40.2 0.21 0.86
8.8 197 44.6 0.22 0.90
10.56 197 53.5 0.27 1.10
12.32 197 62.5 0.30 1.22
14.08 197 71.4 0.40 1.63
15.84 197 80.3 0.41 1.653
16.72 197 84.8 0.42 1.714
17.6 197 89.2 0.5 2.041
18.48 197 93.7 0.57 2.327
19.36 197 98.2 0.62 2.531
20.24 197 102.6 0.67 2.735
21.12 197 107.1 0.71 2.898
22 197 111.6 0.77 3.143
24.2 197 122.7 1.1 4.49
26.4 197 133.9 1.4 5.714
29.832 197 151.3 1.6 6.531

Therefore, from this method, the yield strength fy = 109 MPa.
To be on the conservative side the value of fy = 105.7. The
modulus of elasticity was found to be 51428.6 MPa.
8. CONCLUSION
Based on the experimental studies presented in this paper, the
following conclusions can be drawn:
(i) If tension tests are conducted without specimen end
preparation, actual results may not be found due to smashing at
the grip location especially for bamboo twig specimen but if
the grip is prepared by using GI wire then no smashing and
slippage occurs at that location. Without end preparation, the
strength is considerably low because of premature failure at
the grip.
(ii) In general, sample failure was accompanied by tension
failure for bamboo specimens.
(iii) In case of specimens with ends wounded by G.I wire,
the tensile strength failure was observed is nearly uniform and
their failure pattern is also similar as splitting parallel to the
grain. The average tensile strength with prepared ends
(wounded with G.I wire) has been found to be higher than the
specimens without prepared ends. This reduced strength is due
to the premature failure at the grip.
(iv) Bamboo specimen shows some nonlinearity before its
failure.
(v) The modulus of elasticity, E of bamboo is found to be
much lower than the steel reinforcement. Therefore, the
deflection will be higher considering the steel reinforcement.
A comprehensive study could be made by involving both
experimental and finite element study to understand the
behavior of bamboo more accurately. For further research of
natural reinforcement, the tensile property of bamboo twig and
cane can be investigated.

REFERENCES
[1] Amada, S. and Untao, S., Fracture Properties of Ba mboo, Composites
Part B. Vol. 32, 2001, pp. 451-459.
[2] Amada, S., Lchikawa, Y., Munekata, T., Nagase, Y. and Shimizu, H.,
Fiber Texture and Mechanical Graded Structure of B amboo,
Composites Part B, Vol.288,1997, pp 13-20.
[3] Lo, Cuo, Leung , The Effect of Fiber Density on St rength Capacity of
Bamboo, Materials Letter, vol. 58,2004, pp. 2595-2 598.
[4] Amada, S. and Untao, S. (2001), Fracture Propertie s of Bamboo,
Composites Part B. Vol. 32, pp 451-459.
[5] Ghavami, K. (1995), Ultimate Load Behavior of Bamb oo-Reinforced
Lightweight Concrete Beams, Cement & Concrete Comp osites, Vol.
17, pp 281-288.