Determination of Basic Mechanical Properties of Locally Available
Bamboo Species.
RESEARCH REPORT
BACHELOR OF ENGINEERING
IN
CIVIL ENGINEERING
By
Choeying Dema – 02200008
Dechen Wangchuk – 02200009
Dechen Zangmo – 02200010
Under the guidance of
Mr. Tshewang Nidup (Guide)
DEPARTMENT OF CIVIL ENGINEERING
COLLEGE OF SCIENCE AND TECHNOLOGY
ROYAL UNIVERSITY OF BHUTAN
PHUENTSHOLING: BHUTAN
2022
Acknowledgement
First and foremost, we would like to express our deep and heartfelt gratitude to Mr. Tshewang
Nidup, our research guide, for his patient guidance, enthusiastic encouragement and continued
support. It was a great privilege and honor to work under his guidance. This research could not
have been accomplished without his supervision.
We are also sincerely thankful to our module tutor Dr. Sangey Passang for introducing us to this
field of study. Moreover, for helping in keeping and maintaining our development on track. We
would also like to extend our gratitude to the college of science and technology for giving us this
opportunity to conduct such research that helped us develop valuable lessons and strengthening
our knowledge in this field.
We would like to thank all of our research panel members, Dr. Chimi Wangmo, Mr. Nimesh
Chettri and Mr. Rigzin Norbu for their constructive criticism which helped us to work on our
research better. The guidance and support received from all the members was vital for the
success of this research. We are extremely grateful for the time and knowledge that you have
given us to conduct this research.
We are deeply grateful to all the people who were involved in this research work directly or
indirectly. Their contributions are sincerely appreciated and delightedly acknowledged.
2
Abstract
Bamboo has emerged as a possible material to be used instead of steel as it is found to be
versatile and inexpensive in contrast to other building materials. They are the largest members of
the grass family and are the fastest growing in the world. In Bhutan, the use of bamboo has
mostly been restricted to non-structural and lower grade buildings due to insufficient information
about them. Due to high demand of existing construction material like steel and the wood,
bamboo is the good alternative material. Bamboo is natural, cheap and widely available material
and the most importantly bamboo has strong tension and compression in strength that can be
used in construction. The main objective of this paper is to determine the various physical
properties of bamboo and to compare it with other materials. In order to compare bamboo with
other materials, the mechanical properties of steel and concrete were collected. We will be
collecting a material known as “So” by the locals, which is found within the campus. Various
mechanical and physical properties of the sample will be tested in order to compare it with other
materials.
Key Words: Bamboo, building material, non-structural, physical property and mechanical
property.
3
Table of content
1. Introduction……………………………………………………………………5-9
1.1 Conventional construction materials……………………………………..5
1.1.1 Properties of conventional construction materials………………....5
1.1.2 Drawbacks of conventional construction materials……………….. 5
1.2 General introduction on bamboo…………………………………………5-6
1.2.1 Bamboo structures in the world…………………………………....6
1.2.2 Properties on bamboo………………………………………………6
1.2.3 Advantage of bamboo over other materials………………………..6-7
1.2.4 Limitations of bamboo……………………………………………..7
1.2.5 Types of bamboo species found in Bhutan………………………...8
1.3 Problem statement………………………………………………………..9
1.4 Aim……………………………………………………………………….9
1.5 Objective…………………………………………………………………9
2. Materials and method………………………………………………………...10-12
2.1 Conduct of experiment…………………………………………………...11
2.1.1 Selection and preparation of bamboo……………………………....11-13
3. Result and data analysis………………………………………………………13-17
3.1 Tensile strength test………………………………………………………13-14
3.2 Flexural strength test……………………………………………………..14-15
3.2.1 Load and deflection analysis……………………………………..15-16
3.3 Moisture content test……………………………………………………..17
4. Conclusion……………………………………………………………………..18
References……………………………………………………………………..19-20
4
Introduction
Conventional construction materials
The existing construction industry is heavily dependent on two materials, concrete and steel.
However, the two materials prove out to have several disadvantages over bamboo (Shastry &
Unnikrishnan, 2017).The selection of construction materials is based mainly on the price and the
type of facility used for production or processing. Industrialized materials, such as ordinary
Portland cement (OPC) and steel, find applications in all sectors and in the world to which a road
leads.
Properties of conventional construction materials
Steel and concrete being one of the widely used construction materials have numerous
mechanical properties like strength in tension, strength in compression, strength in shear, yield
strength, durability, hardness and many more. Steel is said to have equal strength in both tension
and compression making them more suitable for construction purposes whereas concrete is much
stronger in compression than in tension. Steel has a yield strength of 460 N/mm2(PRASAD,
2019)and concrete has 224 N/mm2 which means concrete can withstand lower stress than steel.
Steel is the strongest and the hardest construction material used and some of the unique
properties of steel could be the ductility and malleability. Ductility is the ability of a material to
bend and deform under tensile stress without failure and malleability is the ability of the material
to be shaped below compression without fracturing. Concrete is only malleable when it is wet.
Drawbacks of conventional construction materials
Steel has high susceptibility to corrosion where the corrosion reaction makes the steel brittle and
flaky. Gradually it can also hamper its mechanical strength and elasticity. There are also
fireproofing costs involved as steel is not fireproof. Buckling could also be one of the major
issues with steel structure where the chances of buckling increases as we increase the length of
the steel. The initial cost of the steel structure is also high.
Concrete has high strength to weight ratio making them occupy more space unnecessarily.
Concrete is less ductile material and the tensile strength of concrete is low.
General introduction on bamboo.
The demand for steel is increasing day by day in most of the developing counties. There are
instances where there is insufficient steel manufacturing to meet demand. So, in order to counter
the scarcity of steel, it is imperative to have an alternative which has the same properties as that
of steel. The most desirable option in this situation is bamboo, as it is found in abundance. There
are various articles, discussing the possibility of bamboo as an alternative construction material.
5
Bamboo as a fast-growing renewable material with a simple production process, is expected to
be a sustainable alternative for more traditional materials like concrete, steel and timber (van der
Lugt et al., 2003).Activities in rural areas or even small towns are curtailed as a result of
consumers choosing industrialized goods, and renewable resources are wasted, resulting in longterm pollution. In this sense, it becomes obvious that ecological materials satisfy such
fundamental requirements. Bamboo is one material, which will have a tremendous economic
advantage over conventional construction materials.
Bamboo structures in the world.
1. Green school, Bali: Green School is a school building build using bamboo as main
structure materials. (Bijapure & Patil, 2020)
2. Bangkok Tree House: a hotel on the PhraPradaeng Peninsula in the city, which is
renowned for its durability and abundance. The material, which is employed in the
ceiling and floor of this lounge area, serves as both decoration and structural
support.(Allen, 2017)
3. Sharma Springs, Indonesia: Nearly all of the 750 square meter house is made of bamboo.
It features 6 levels and 4 glass-enclosed bedrooms, a playroom, a library, and other
amenities for air conditioning.(Allen, 2017)
Properties of bamboo
Bamboos are giant grasses and not trees as commonly believed. They belong to the family of the
Bambu-soideae. The bamboo culm, in general, is a cylindrical shell, which is divided by
transversal diaphragms at the nodes. Bamboo shells are orthotropic materials with high strength
in the direction parallel to the fibers and low strength perpendicular to the fibers respectively.
The hallow nature of bamboo makes it 4 times stronger than other solid materials. The nodes
which are the ring like structures stiffen the walls of the element which makes the structure less
susceptible to buckling. But most importantly, bamboos are closer together where they are most
needed. The fibers are 3 times stronger than structural steel and are very cleverly distributed.
They are concentrated more towards the perimeter which makes the section more efficient.
Bamboo is a cheaper alternative than most materials as it is commonly found.
Advantage of bamboo over other materials.
The biggest advantage of bamboo over other material is the energy consumption. Embodied
energy is the calculation of all the energy that is used in the production of a material. The amount
of embodied energy will differ between different materials.
6
Figure 1. represents a graph which was used to compare the carbon emission of steel and
bamboo. The comparison was made fair by considering a hypothetical size for steel. The carbon
emission associated with the production of the steel section was found to be 10kg. In case of
bamboo, it requires for huge amounts of CO2 to be absorbed during its rapid growth. This factor
by itself provides an incentive for the investment in the development of bamboo as a building
material.
Figure 1. Carbon emission by steel and Bamboo
Materials like steel have high degree of embodied energy since it takes a lot of energy to produce
them. The major disadvantage of employing steel is the high initial cost of the material. Bamboo
on the other hand being an eco-friendly material, comes with a surprisingly good tensile
capacity. Embodied energy, which is currently unregulated, can contribute significantly to the
overall carbon footprint that is used to evaluate environmental and sustainability performance
over the long run. Bamboo grows from 30cm to 1m per day in a standard 250 C to 500 C which
indicates that it requires less or no energy for its production. Bamboo fibers had smaller
diameters and larger aspect ratio which favored an improved reinforcing aspect. The light weight
property of bamboo over steel makes bamboo more desirable for construction.
Limitations of bamboo.
1. Durability- Durability of bamboo in practical application of the construction is the
primary concerned in many clients. Bamboo material are usually prone to fungus, insect
and moth in untreated conditions, which leads to damage in mechanical and physical
properties.
2. Standard and specification- The absence of standards and specifications subsidizes to the
lack of confidence in using bamboo among building clients. If there are proper standard
and specification, the quality of bamboo in application will be protected.
3. Industrialization and production of bamboo- There is no industry for management
bamboo materials, subsequently the creation cost is exceptionally high.
7
Types of bamboo species found in Bhutan
There are more than 1,500 bamboo species and even more subspecies from which 88 types can
be used in construction. According to a rapid resource assessment done Department of Forest
and Park Services of Bhutan (SFED) 19 species of bamboo were found in the surveyed areas
(Zhemgang, Samdrup Jongkhar, Tsirang and Samtse), among which, 12 are used in structural or
non-structural construction applications(Frith et al., n.d.). The INBAR membership of Bhutan
has been given the expertise and knowledge needed to build and maintain bamboo houses. The
Ministry of Agriculture & Forests has also been given many advantages in terms of information
exchange and networking, capacity growth through training possibilities. The study done by
INBAR and Bhutan’s Social Forestry and Extension Division (SFED) not only evaluates the
potential viability and markets for increasing the use of round culm bamboo in construction in
Bhutan, but also aids in overcoming some of the traditional difficulties associated with it (Frith et
al., 2019).
Table 1. List of Species surveyed
Scientific Name
Bambusaalamii
Bambusaarundinacea
Bambusabalcooa
Bambusaclavata
Bambusanutans
subsp.Cupulata
Bambusatulda.
Local Names
Dingso(Sha)/Mugibans(Lho)
Katha/valka/kantabans(Lho)
Dhanubans(Lho)
Chiley/Chilebans(Lho)&Pagshing(Dzo)
Malbans/Molabans/Molibans/Maglabans/Makla
bans/Malabans(Lho)/Tsai(Khe)
Bangaybans/Shingaraybans/
Singari/Shingaray/Shingari/Shigaribans(Lho)
Telibans(Lho)
Bambusavulgaris
Cephalostachyumcapitatu Phusreybans/Phursenigalo/dulloobans(Lho)/Jhi
m
(Dzo)/pishima (Khe)
Chimonobambusacallosa
Kareybans/Karaybans(Lho)
Dendrocalamusgiganteus Balu/Bhalubans(Lho)
Dendrocalamushamiltonii Shushing(Khe)andGuliyotamabans(Lho)
Dendrocalamushamiltonii Songopa/So,Lishingorleeshing(Sha),Choyaor
tamabans (Lho) or Tsu(Khe)
Dendrocalamuhookeri
Bombans(Lho)
Dendrocalamussikkimens Demchar/Demcharbu/Demtshar/Demchherring
is
(Sha)/Bhalubans(Lho)
Kalang(Sha)/Nigalo(Lho)
Drepanostachyumspp.
Neomicrocalamusandrop Yula(Khe)
ogonifolius
Local Uses
Lightconstruction
Heavyconstruction
Heavyconstruction
Lightconstruction
Construction
Heavyconstruction
Construction
Mostlyforbamboomats;
canbeusedinconstruction
Usedtomakeroughtypeof
bamboomat
Goodconstruction
Construction,
averagequality
Construction
Construction
Construction,average
quality
Constructionofhuts
Handicrafts
Pseudostachyumpolymor
phum
FillingorPhillingbans(Lho)/Dai(Khe)
Constructionofhuts
Yettoidentify
Yettoidentify
Darabans(Lho)
Serlingaybans(Lho)
Beamsinhutconstruction
Constructionofhuts
Source: Bamboo construction in Bhutan: a feasibility and market and study.
8
Problem statement.
Bamboo has only been used for non-structural and low-grade buildings, particularly in Bhutan
due to the lack of available mechanical property data and design values. Although the ultimate
aim of this research is to determine the feasibility of bamboo as an alternative building material
in Bhutan, the idea of bamboo being used as a substitute for steel structures raises important
questions about its structural capability and compatibility. This being the reason why the
practical application of bamboo is yet to see the light of day. For this reason, we will be
performing an experiment to determine various properties of locally available bamboos and
compare the results with the other materials. In spite of the fact that the strength of a bamboo is
incomparable to that of steel, by taking the properties like energy requirement of a bamboo into
consideration, bamboo too can be considered as a reasonable choice.
Aim
•
•
To determine the physical and mechanical properties of locally available bamboo and
compare it with other materials.
To compare the mechanical properties between wet bamboo and dry bamboo.
Objective
•
•
To determine the properties of the bamboo species found in CST.
To compare the mechanical properties of the tested sample to other materials.
9
Materials and method
The scheme of the research was systematically designed in order to ensure valid results that
addresses the aims and objectives. Due to the lack of knowledge and interest about bamboo, not
many people were aware of the bamboo species growing within our campus. Taking this into
account we decided to narrow down our research to this specific sample found in CST. After the
collection of bamboo samples, we will be carrying out three tests to determine the physical and
mechanical properties.
Figure 2. Methodology
Figure 3. Sample found within CST
10
Conduct of experiment
For the intended outcome of the research to be achieved, a proper and error-free execution of all
tests and activities in the experiment is absolutely essential. The experiment's operations should
be correctly carried out, starting with the selection and preparation of appropriate bamboo
species for testes.
Selection and preparation of bamboo
The following factor should be considered in the selection of bamboo culms:
1. Select a large diameter culm available.
2. Use only the bamboo showing a brown pronounced color. This will ensure that the plant
is at least three years old.
3. Do not use unseasoned bamboo. Make sure the bamboo is dried properly before
conducting any experiment.
Preparation of bamboo for:
1. Tensile Strength test: For this experiment we will make the sample into strips pf
appropriate size. We will be drilling both ends of the sample to be able to hang the
sample and to put weight on the sample. The load will be increased linearly until the
bamboo strip fail.
Figure 4: Sample for tensile testing
11
2. Flexural strength test
For this experiment the set up will be as shown in the figure below. The load will be
applied at the mid span of the length (L/2) of the sample until it fails. This value will
indicate the stress and force the sample can withstand to resist the bending failure.
Figure 5: Experimental set up for flexural strength testing.
3. Moisture Content Test
The moisture content test was done by using the green weight of bamboo pieces and their
oven dried masses were used for evaluating the moisture content in bamboo specimen.
Figure 6: Moisture Content Test
12
1. For tensile strength
Ultimate tensile strength = Pmax/A
Where, Pmax is the Maximum load at which the sample strip is fails in N
A is the cross section of failure point in square mm
2. For flexural strength
Fb = 3Pa/bd2
Where, b is the width in mm
d is the depth in mm
Pa is the maximum load applied
3. For Moisture content
Moisture content %= (m1-m2/ m1)*100
Where, m1=mass of bamboo in g
m2= oven dried mass in g
Results and Data Analysis
1. Tensile Strength test
Table 2. Tensile strength of Dry sample
SL.NO
Total load
Pmax
(kg)
Total load
Pmax
(N)
Breadth
B
(mm)
Depth
D
(mm)
1.760
Area
A
(Square
mm)
4.840
Ultimate
tensile
stress
(Mpa)
126.215
1
62.271
610.879
2.750
2
62.108
609.279
2.905
1.690
4.909
124.103
3
63.204
620.031
2.850
1.720
4.902
126.485
Average
(MPa)
125.601
13
Table 3. Tensile strength of Wet sample
SL.NO
Total load
Pmax
(kg)
Total load
Pmax
(N)
Breadth
B
(mm)
Depth
D
(mm)
1.760
Area
A
(Square
mm)
4.733
Ultimate
tensile
stress
(Mpa)
118.672
1
57.251
561.632
2.689
2
58.882
577.632
2.771
1.732
4.799
120.356
3
58.021
569.186
2.850
1.672
4.765
119.446
Average
(MPa)
119.491
The results for tensile strength of the wet and dry bamboo are shown in Table 2 and 3. The
tensile strength of both the bamboo were quite high but the dry sample had 6.11 MPa more
tensile strength than the wet sample.
For the dry bamboo sample, the ultimate tensile strength was recorded to be 125.601 MPa which
is 50.24% of mild steel (250 MPa) and for the wet sample it was recorded to be 119.4901 MPa
which is 47.79% of mild steel.
2. Flexural Strength Test
Table 4. Flexural strength test for dry sample
SL.NO
Total
load
Pmax
(N)
264.017
Total
length
L
(mm)
830.000
Breadth
B
(mm)
Depth
D
(mm)
Moment of
inertia
I
1
Total
load
Pmax
(kg)
26.913
20.000
7.000
571.667
Flexural
strength
F
(MPa)
223.606
2
27.116
266.008
830.000
20.000
7.100
596.518
218.991
3
26.852
263.418
830.000
20.000
7.200
622.080
210.877
Average
F
(MPa)
217.824
14
Table 5. Flexural strength test for wet sample
SL.NO
Total load
Pmax
(kg)
Total
length
L
(mm)
830.000
Breadth
B
(mm)
Depth
D
(mm)
25.081
Total
load
Pmax
(N)
246.045
1
6.920
Moment
of
inertia
I
552.290
Flexural
strength
F
(MPa)
213.231
20.000
2
24.681
242.121
830.000
20.000
7.120
601.574
198.207
3
24.876
244.034
830.000
20.000
7.020
576.581
205.505
Average
F
(MPa)
205.648
Flexural strength which is also known as the bending strength is the property of the material
which represents the maximum amount of stress before it fails due to bending. The results for the
flexural strength test for dry and wet sample are shown in the table 4 and 5. The average flexural
strength was found out to be 217.824MPa for dry sample, while wet sample has found out to be
205.648MPa.
Load and deflection analysis
The deflection value for dry sample was higher than that of wet sample as the flexural strength of
the dry sample is greater than that of the wet sample. This is because higher flexural strength
produces tougher structures hence resulting in higher deflection. For the dry sample the
maximum deflection recorded was 88mm and 79mm for the wet. Figure 7 and 8 illustrated the
load and deflection of dry and wet sample of bamboo.
Figure 7. Load and deflection for dry sample
15
Figure 8. Load and deflection for wet sample
From the data obtained for tensile and flexural strength for both dry and wet bamboo samples,
we could plot the following graph. The graph can be used to compare the mechanical strength of
the dry and wet samples. As we can interpret from the graph, the values for dry samples are
higher than that of wet samples. This is due to the amount of moisture present in the sample.
Strength and stiffness increase with the decrease in moisture content.
Figure 9. Comparison between dry and wet bamboo
16
3. Moisture Content Test
Moisture content indicates how much moisture is present in a material. In the present research,
moisture content was found to be 60.169%. Results of moisture content test are shown in table 6.
Table 6. Moisture content test.
SL.NO
Weight of bamboo
M1
(kg)
Moisture
content
(%)
0.028
Oven dry weight of
bamboo
M2
(Kg)
0.010
1
2
0.045
0.017
62.222
3
0.050
0.023
54.000
Average
(%)
64.286
60.169
17
Conclusion
The objective of this work was to determine the mechanical and the physical properties of
bamboo found within the campus. It was found that the moisture content of the sample affected
the strength of the bamboo which is a very important consideration that should be taken into
account as bamboo is widely used as an exterior building material. From the results we could
observe that both tensile and the flexural strength for dry bamboo was found to be more which
shows that the mechanical properties like tensile and flexural strength are all reduced when
exposed to water. Flexural bending test showed that bamboo can turn into its original form after
the removal of the load. This knowledge is useful for bamboo as one of the structural building
materials. These results will help to check the materials sustainability and durability. In the event
of a natural disaster, such as an earthquake or hurricane, this can significantly reduce structural
member damage.
From the result analyzed above, it was concluded that the dry bamboo is the most recommended
and desirable construction material. It had the leading tensile and flexural strength. The only
downside is the time required to dry those bamboos. By making bamboo widely used building
material, we will be able to respond to the call of promoting sustainability and lowering
construction cost by utilizing easily accessible raw resources. The use of bamboo in construction
field will eliminate the use of steel as it eventually reduces the emission of greenhouse gases in
huge quantities. Taking these into consideration, it is good idea to promote the growth and use of
bamboo to ensure lower costs of living and a better environment for our future generations.
18
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