Eucalyptus Timber: Mechanical Properties and Structural Applications

This report presents a comprehensive analysis of eucalyptus timber, focusing on its mechanical properties and suitability for structural applications in the construction industry. The report begins with an overview of the increasing demand for timber in Australia, highlighting the sustainable benefits of eucalyptus timber and its role in addressing climate change concerns. It then delves into the properties of structural timber, including hardwoods and softwoods, and reviews relevant literature on tensile and compression tests. The study investigates the compressive and tensile strength of eucalyptus timber, aiming to determine its potential for structural applications, and to develop prediction models for its performance. The report also addresses the limitations of the research and the potential for eucalyptus timber to transform the Australian construction industry. The project includes a detailed literature review of 20 journal articles, and a draft thesis with an introduction, problem statement, project scope, aim, objectives, research questions, and a summary of the work completed. The report emphasizes the importance of testing eucalyptus timber to confirm its mechanical properties and ensure it meets industry standards, ultimately increasing confidence in its use as a structural material.

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EUCALYPTUS TIMBER
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SUMMARY OF WORK COMPLETED
This section briefly summarizes the work completed so far in the draft report. Reference has
been given to various sections included in this draft report. Section 1.1 provides information on
the overview of forest cover in Australia, factors driving increasing demand of timber in
Australia and the characteristics and usage of eucalyptus timber in Australian construction
industry. The problem statement has been discussed in section 1.2 stating the significance of
conducting this research and the suitability of eucalyptus timber for structural applications.
Project scope, aim and objectives are stated in Section 1.3.1-1.3.3 while research questions are
listed in Section 1.4. Section 2 provides a detailed discussion about structural timber. The
discussion has included introduction and uses of structural timber, advantages of using structural
timber in construction projects, a brief summary of hardwoods and softwoods/solid woods
(including their characteristics, examples, strengths and weaknesses) and the basic properties of
wood.
Relevant literature has been reviewed in section 3 to find out what other researchers have done
before particularly those that completed their studies by conducting tensile and compression tests
so as to investigate applicable properties of structural timber, with a focus on eucalyptus timber.
A total of 20 published journal articles have been reviewed. The review included a brief
summary of the reasons why the researchers conducted the study, methods used to complete the
study and findings from the study.
Several limitations that may hinder successful completion of the research or the ones likely to
affect the accuracy of results from the study have also been identified in Section 4. I have
completed the draft by writing its summary in Section 5.

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Table of Contents
1. Introduction.......................................................................................................................................4
1.1. Overview.....................................................................................................................................4
1.2. Problem statement.....................................................................................................................6
1.3. Project Scope, Aim and Objectives...........................................................................................7
1.3.1. Scope...................................................................................................................................7
1.3.2. Aim......................................................................................................................................7
1.3.3. Objectives...........................................................................................................................7
1.4. Research questions.....................................................................................................................8
2. Overview of structural timber..........................................................................................................8
2.1. Introduction...............................................................................................................................8
2.2. Uses.............................................................................................................................................9
2.3. Advantages.................................................................................................................................9
2.4. Hardwoods...............................................................................................................................10
2.5. Softwoods/solid woods.............................................................................................................10
2.6. Basic wood properties..............................................................................................................11
3. Literature Review............................................................................................................................12
4. Limitations.......................................................................................................................................25
5. Summary..........................................................................................................................................26
References................................................................................................................................................28

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1. Introduction
1.1. Overview
Timber is a natural common product in the Australian construction industry and has been in
use since the ancient times. The popularity of timber in Australia has been increasing over the
past few decades mainly because of global warming and climate change. Construction industry
contributes significantly to climate change due to use of large amounts of less sustainable
materials such as concrete, metals and plastics. To help resolve the problem, the Australian
government has formulated policies that promote sustainable development. One of these policies
is use of alternative natural materials that are more sustainable. As a result of this, stakeholders
in the Australian construction industry are rapidly turning to timber mass construction as an
alternative to reinforced concrete and metals (Kremer & Symmons, 2015).
Timber has properties that can meet most of the basic structural requirements of structures,
such as buildings. There are also numerous species of timber, each with unique properties. These
properties influence the performance and durability of the structures. The focus of this study is
on eucalyptus timber. Eucalyptus timber is a biodegradable, hypoallergenic, insulating and
recyclable material. It is natural, non-polluting, environment-friendly and 100% renewable hence
it is a sustainable material (Quartucci, et al., 2015). Some of the key benefits of eucalyptus
timber include: very durable hence can be used as a structural member (Nogueira, et al., 2019),
versatile thus suitable for use in indoor and outdoor construction, cost effective because it is
readily available, renewable, highly durable, and is available in different sizes (length and
diameter) and species. It is most likely that the sustainability aspect of eucalyptus timber is one
of the key factors that have contributed to its high demand not only in Australia but also in other
parts of the world such as the U.S., Europe, Asia, China and India (Liao, et al., 2017). In

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Australia, timber is no longer a material used for framing, fitout and features. There are new
engineered timber products that are changing Australia’s building game. The three main timber
materials used in Australia are: laminated veneer lumber (LVL), cross-laminated timber (CLT)
and glue laminated timber (GLT). 25 King in Brisbane and 55 Southbank Boulevard in
Melbourne are among the spectacular high-rise buildings in Australia that are made from CLT.
Eucalyptus is an evergreen hardwood tree that is native to Australia and there are nearly 900
species, most of which are native to Australia. It is the widely planted hardwood tree worldwide
and is estimated to cover more than 19 million hectares of land (Albaugh, et al., 2013). It is
estimated that 75% of forests in Australia are eucalypt forests. This makes supply and
availability of eucalyptus timber in Australia to be high hence stakeholders in the building and
construction industry can easily get and use it at a reasonable price. Eucalyptus timbers are very
tough and durable, which make them suitable for use in making structural components of
buildings and other structures (Lahr, et al., 2018). The eucalyptus timber also contains natural
oils that have water-, moisture- and insect-repelling properties that help in protecting the timber
from decay and rot thus increasing its durability.
Use of eucalyptus timber as a structural component is not a new concept in the building and
construction industry but has been ongoing for many centuries (Blackburn, et al., 2018);
(Derikvand, et al., 2017). The aboriginal population has been using this tree since ancient times
for several purposes, including in buildings, pulp industry and oil that is used in perfumery,
beverages, food, cosmetics, phytotherapy and aromatherapy (Vecchio, et al., 2016). The
sustainability aspect of eucalyptus timber has definitely increased its value in the building and
construction industry. However, it is always important to perform relevant tests on eucalyptus
timber before using it so as to confirm its mechanical properties. Since eucalyptus timber is

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anisotropic, it is important to perform tests both along and across the grain (Naylor, et al., 2012).
Several studies have shown that the compressive strength, tensile strength and modulus of
elasticity of wood is higher along the grain than across the grain (Manriquez & Moraes, 2010);
(Oh, 2011). The compressive and tensile strength values give an idea on how the timber will
behave when subjected to different design loads (Hein & Brancheriau, 2018). Therefore the
increase in intake of structural timber in Australia presents an opportunity for further research on
the properties of eucalyptus timber and how to use them in predicting the performance of timber
structures. This can improve the strength grading criteria of eucalyptus timber and also has the
potential of significantly increasing usage of eucalyptus timber in the Australian construction
industry.
1.2. Problem statement
Usage of timber in the Australian construction industry is increasing rapidly due to the
sustainable benefits of timber and its availability. Because of climate change and sustainable
development goals, there is need to build more structures using timber. But as more timber
structures are built, it is important to ensure that the properties of timber used meet the
requirements of industry standards. This includes the physical, chemical and mechanical
properties. Eucalyptus is the commonest tree species in Tasmania and several other states. It is
estimated that eucalyptus makes up 75% of forests in Australia. This means that if more
eucalyptus trees are planted, conserved and harvested to manufacture, structural and engineered
timber products, supply of construction timber in Australia can be significantly increased.
However, use of eucalyptus as a structural timber has been low in Australia due to the
misconception that it has inferior structural properties. This contrary to findings from various
studies, which have revealed that eucalyptus timber has properties that make it suitable for

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structural applications. Therefore it is important to perform studies that will evaluate the
properties of eucalyptus timber and prove that they meet the fundamental structural requirements
of relevant construction standards and building codes. This will improve confidence in
eucalyptus as a structural timber thus increasing its usage and overall supply of timber in the
Australian construction industry.
1.3. Project Scope, Aim and Objectives
1.3.1. Scope
This project will investigate the compressive and tensile strength properties of eucalyptus
timber from Tasmania, Australia, by performing applicable tests according to Australian
standards. The experimental data collected will be used to develop numerical models for
predicting the compressive strength and tensile strength properties, and the performance of
eucalyptus timber. The study will also assess the potential of eucalyptus timber transforming the
Australian construction industry if it is fully accepted by the stakeholders.
1.3.2. Aim
The main aim of this research project is to investigate the mechanical properties of eucalyptus
timber (particularly the compressive strength and tensile strength) so as to determine its
suitability for structural applications in the construction sector. This will improve people’s
confidence in eucalyptus timber and its overall use in the construction industry, which is
essential in achieving sustainable development.
1.3.3. Objectives
The main objectives of the current study are as follows:
1. To conduct tensile tests and compression tests on eucalyptus timber samples;

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2. To evaluate the compressive strength and tensile strength properties of eucalyptus timber;
3. To develop a prediction model for compressive and tensile strength properties of
eucalyptus timber, and the performance of eucalyptus timber structures.
4. To develop a numerical model for the prediction of the performance of eucalyptus timber
elements and/or structures.
1.4. Research questions
The main questions in this research project are:
1. Does the properties of eucalyptus timber meet the fundamental structural requirements of
relevant construction standards and building codes in Australia?
2. What is the potential of eucalyptus timber reducing the demand for construction timber in
Australia?
2. Overview of structural timber
2.1. Introduction
Wood is a natural material that has a wide range of uses. There are numerous species of wood
but the typical composition of wood comprises of cellulose, lignin, hemicelluloses and
extractives (Reyes-Rivera, et al., 2015). These chemical constituents influence the properties of
wood (Shanbhaq & Sundararaj, 2013). Wood can be processed into structural timber or
engineered timber for use in the construction of structural components, such as framing systems,
studs and joists. There are numerous types of wood products, including: sawn wood and round
wood, veneer, plywood, laminated wood, particle board, and fiber-board. In general, wood has
numerous uses, advantages. There are also different types of wood, each with unique properties
(Harte, 2009). It is important to investigate the properties of wood before choosing the most

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suitable type of wood for the intended use. Some of the main properties of structural timber are
compressive strength and tensile strength. These properties influence the ability of the timber to
resist compressive and tensile loads. Typical structures, such as buildings, have both
compressive and tensile loads. These structures require structural components that have the
capacity to support both the structural and tensile loads.
The chemical properties of timber are intrinsically sophisticated but studies and previous
experience have shown that the properties of timber make it suitable for use as a construction
material. This material has substantial amount of tensile strength and compressive strength that
meet the desired strength of most structures. Another major advantage of timber is that it is a
natural material, which is readily available in all parts of the world hence economically feasible.
2.2. Uses
Wood has a variety of uses. Some of these include: construction (making building
components such as frame systems, floorings, roofs, walls, partitions, formworks and
scaffolding) (Ramage, et al., 2017), decorating gardens, fencing, creating and making artworks,
utensils, sports equipment, toys, musical instruments, shipbuilding, producing furniture, making
stationery and used as fuel.
2.3. Advantages
There are numerous advantages of using wood in construction. Some of these include:
lightweight (Foster, et al., 2017); strong; versatile; low waste volume; low embodied energy;
quick build time (constructionability), reduced site labour; high durability; high energy
efficiency; superior thermal properties; low heat conductivity; easy to maintain; attractive (high
aesthetic appeal); elastic; provides great heat and noise insulation (superior acoustic properties);

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great electrical insulation properties; recyclable and reusable; natural, renewable and sustainable
hence environment-friendly (Kremer & Symmons, 2015); (Malone, et al., 2014).
2.4. Hardwoods
Hardwoods are one kind of wood that are mainly from deciduous trees that have broad
leaves (Diffen, 2013), which are shed during winter. Examples of hardwoods are: mahogany,
oak, beech, ash, walnut, maple, cherry, mango, rosewood, birch and teakwood. Hardwoods are
known for their attractive grains, which make them suitable for use in making decorative
woodworks and furniture. Other characteristics of hardwoods include: have slower growth rate,
are more expensive than softwoods, are denser than most softwoods, are more fire resistant than
softwoods and have greater compressive strength than softwoods (Aigbomian & Fan, 2013).
However, it is not always true that hardwoods are harder and stronger than softwoods.
2.5. Softwoods/solid woods
Softwoods are another type of wood that are mainly from evergreen trees (coniferous
trees) that have needlelike leaves. Examples of softwoods are: cypress, hemlock, cedar, redwood,
spruce, pine and fir. Softwoods are usually from tall, straight trees, which make them suitable for
use in construction works. Their surface is softer but they remain strong. Their softness and
lightweight properties make softwoods easier to work with compared with hardwoods.
Sometimes softwoods are mistaken to be weaker than hardwoods but this is not always the case.
There are some softwood species that have high tensile strength as hard as hardwoods, or even
greater than them (Antonsson, et al., 2009). Proper maintenance and treatment of softwoods can
also make them durable like hardwoods.
The cells of softwoods are open hence their microstructure does not have vessels. This
improves the ability of softwoods to absorb adhesives, preservatives and finishes. The superior

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absorption property makes softwoods very durable. They are also resistant to moisture, bacteria,
termites and fungal attacks, Softwoods are commonly used in making roofs, fencing posts,
partitions (internal wall structures), and other building components like doors, fittings, fixtures,
fireboards, ventilation panels, and plasterboards, among others. Generally, softwoods have
adequate properties for structural use, including moisture content, density, basic density, tensile
strength, bending strength, shear strength, hardness, modulus of elasticity, heat capacity, thermal
conductivity and calorific value.
2.6. Basic wood properties
Properties of wood influence its quality. These properties must be examined when selecting
wood to be sure of its qualities. The properties include both physical and mechanical properties.
Some of these properties include the following (Mou, (n.d.)):
Appearance and colour: wood has a dark colour, shining surface and give a sweet smell
when fresh. The appearance increases the aesthetic value of the timber elements and the timber
structure as a whole.
Shape and weight: wood is able to retain its shape during seasoning and is heavy enough
to resist substantial loads. Lightweight is a key characteristic of timber and should be maintained.
Proper storage can also help to preserve the shape of the timber.
Strength: wood has adequate strength that enables it to resist substantial structural loads.
The strength properties can be estimated from relevant tests, including compression and tensile
tests.
Hardness: wood is hard enough to resist different types of deteriorations. The hardness is
influenced by several factors, such as type of species, source, age and defects.

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Toughness: wood has adequate toughness that enables it to resist splitting and shocks
caused by vibrations and avoid breaking in bending. Toughness is also dependent on factors such
as type of tree species, growth conditions and defects.
Durability – wood has the capacity to resist worms, fungi and atmospheric effects for a
longer time. After harvesting, the wood must be stored properly and treated using appropriate
methods so as to increase its durability.
Elasticity: wood is able to regain its original shape when loads acting on it are removed.
The elasticity prevents it from buckling or breaking when subjected to loads.
Workability: wood is easily workable, meaning that it can be cut, shaped and sized quite
easily. This can be done using simple tools and equipment, or in the factory by use of advanced
machines, depending on the desired properties of the timber.
Defectless: wood has to be free from defects such as dead/live knots, sap, check, split and
shakes, so as to achieve greater mechanical and physical properties. This requires vigilant
selection of trees or throwing away sections with numerous defects.
Other wood properties include: grain, moisture content, specific gravity, density, swelling and
shrinkage, warping, elasticity, free of abrasion and soundness.
3. Literature Review
Chen (2017) conducted an empirical study to examine the mechanical properties of laminated
veneer lumber (LVL) (an engineered wood product), manufactured from eucalyptus nitens. This
study was motivated by the increasing demand for veneer products in Australian market and the
promising potential of using this product for structural applications. The author sought to
establish the relationship between veneer stiffness and LVL panels’ mechanical performance. To