Best Mix Design and Mechanical Properties of ECC 16

Concrete is a very essential material in the construction industry but its use continues to raise concerns about the environmental impacts and costs. As a result of this, researchers, scientists and engineers have continued to develop alternative materials to conventional concrete. The materials are expected to improve the performance and durability, and reduce the cost of concrete structures. This project investigates the properties and performance of ECC by preparing its specimens and subjecting them to various tests in accordance with the relevant Australian standards. The main aim of this project is to investigate the mechanical properties and cost effectiveness and sustainability of ECC in comparison with that of the conventional concrete. The project will also determine the best mix design to give ECC with a minimum compressive strength of 45 MPa.

Best Mix Design and Mechanical Properties of ECC 1
INVESTIGATION OF SUITABLE MIX DESIGN AND MECHANICAL PROPERTIES OF
ECC
Name
Course
Professor
University
City/state
Date

Best Mix Design and Mechanical Properties of ECC 2
Executive Summary
Concrete is a very essential material in the construction industry but its use continues to raise
concerns about the environmental impacts and costs. As a result of this, researchers, scientists
and engineers have continued to develop alternative materials to conventional concrete. The
materials are expected to improve the performance and durability, and reduce the cost of
concrete structures. This project investigates the properties and performance of ECC by
preparing its specimens and subjecting them to various tests in accordance with the relevant
Australian standards. The main aim of this project is to investigate the mechanical properties and
cost effectiveness and sustainability of ECC in comparison with that of the conventional
concrete. The project will also determine the best mix design to give ECC with a minimum
compressive strength of 45 MPa.
It is expected that ECC will be found to have superior mechanical properties and higher
sustainability than conventional concrete. The cost of making an ECC cube with a specific mix
design is also expected to be lower than that of making a conventional concrete cube. Therefore
these findings will provide stakeholders in the construction industry an increased awareness of
the mechanical properties, performance, sustainability and cost effectiveness of ECC. The
findings and study in general will be useful in promoting use of ECC and bring its economic and
environmental benefits to the construction industry.

Best Mix Design and Mechanical Properties of ECC 3
1. Introduction
Concrete is the widely used construction material worldwide (Gagg, 2014). However, the
environmental impacts and other disadvantages associated with this material have necessitated
development of its alternatives. Some of the other disadvantages of conventional concrete
include: less ductile, has low tensile strength, is susceptible to cracking due to moisture
expansion and drying shrinkage, has high weight-to-strength ratio, and can develop creep when
subjected to sustained loads. One of the alternatives of conventional reinforced concrete (RC) is
engineered cementitious composites (ECC). This is a relatively new type of high-performance
fiber reinforced cementitious composite material with multiple-cracking and strain-hardening
properties (Yuan, et al., 2012). ECC has been in use for a few decades now and proven to have
superior mechanical properties than the conventional RC (Hou, et al., 2019). This material has
opened new possibilities to improve the durability, safety, functionality and sustainability of
concrete structures (Li, 2014). In this regard, investigating different elements of ECC will help to
determine the actual potential of this material and its structural, economic and environmental
feasibility to substitute conventional RC. This will provide useful information that promotes
adoption of ECC in the construction industry.
The main ingredients of ECC are cement, fly ash, sand, fiber, water and chemical
additives. Unlike fiber reinforced concrete (FRC), ECC do not have a high volume of fiber. This
makes ECC more cost effective than FRC and conventional RC but with high workability,
strength, ductility and durability characteristics. The procedure of mixing, pouring/placing,
compacting and curing ECC is similar to that of conventional RC. One of the main differences in
structural properties of ECC and the conventional RC is that during cracking, ECC strain hardens
whereas conventional RC develops cracks as a result of rupturing of the aggregates due to

Best Mix Design and Mechanical Properties of ECC 4
decreased stress bearing capacity of the concrete. The material also has greater tensile properties,
superior corrosion resistance and can deform without disastrous failure. ECC has numerous
applications including columns and beams, shear components that are exposed to cyclic and
seismic loading, hybrid steel connections and other all-purpose structural repairs. There are also
different varieties or types of ECC, including: lightweight ECC, self-compacting ECC, sprayable
ECC and extrudable ECC.
However, it is important to note that the strength, durability and general performance of
concrete is largely influenced by the mix proportions of its ingredients. Therefore this research
paper focusses on determining the most suitable design mix of ECC that will provide the greatest
mechanical properties, cost-effectiveness and environmental benefits of ECC for use in different
structural elements. The outline of the proposal comprises of the following: literature review,
research questions aims and objectives, methodology, results, project planning and Gantt chart,
and conclusion.
2. Literature Review
Several studies have shown that ECC has superior mechanical properties compared to
conventional RC. Yin, et al. (2018) conducted a study to examine the durability of ECC when
subjected to accelerated weathering, fatigue loading, tensile strain and free-thaw conditions.
They found that these conditions reduced the durability of structures made from ECC but the
effect was less compared to conventional concrete. ECC overly showed superior performance
than that of conventional concrete. Similar results were obtained from studies carried out by Liu,
et al. (2018) and Reddy & Ravitheja (2019). The main finding from these is that the long-term
flexural and compressive strength of ECC is higher compared to that of conventional concrete.

Best Mix Design and Mechanical Properties of ECC 5
As a result, structures made of ECC are more durable compared to those made of conventional
concrete even when exposed to varied environmental and loading conditions.
According to a study carried out by Yu, et al. (2018), use of fly ash reduces the amount of
cement used in concrete. Fly ash is a waste material from coal-based thermal power plants and it
poses a great environmental challenge globally. This material can be used to replace 80% of
cement to produce green structural concrete of up to 45MPa in compressive strength. The
concrete produced is cheaper and has lower carbon footprint compared with conventional
concrete. This study showed that the fly ash to cement ratio has a significant influence on various
properties of ECC including: initial fracture tensile strength, ultimate capacity of tensile strain,
ultimate capacity of tensile strength, and compressive strength. A comprehensive strength of 30
MPa can be achieved with fly ash content being less than 80%. Similar findings were obtained
from a study conducted by Joseph & Anand (2018), who found that the optimum content of fly
ash to replace cement is 75%.
Curing temperature is another factor that has an influences on the flexural performance of
ECC (J, et al., 2015). Findings from a study conducted by Du, et al. (2018) revealed that an
increase in temperature reduces the comprehensive strength, modulus of elasticity and flexural
strength of ECC whereas an increase in temperature results to a corresponding increase in the
comprehensive strain capacity of ECC. It shows that most of the mechanical properties and
performance of ECC decrease at elevated temperature. This requires engineers and designers to
consider the temperature when the structure will be used when designing ECC elements. Jiangto,
et al. (2015) and Sahmaran, et al. (2011) also carried out to determine the impact of volume of
fly ash on the performance of ECC at elevated temperature. The two studies found that an
increase in the volume of fly ash enhances the tensile and fire resistance properties of ECC.

Best Mix Design and Mechanical Properties of ECC 6
Another important parameter affecting the mechanical properties of ECC is the mix
design. The proportions of ingredients of ECC have a significant effect on the mechanical
properties and final performance of this concrete. These proportions are: water to cement ratio,
fly ash to cement ratio, sand to cement ratio, and fibre volume. The recommended water to
cement ratio for ECC ranges between 0.2 and 0.3. When water/cement ratio is higher than 0.3,
the strain of ECC will harden but its tensile strain and strength reduces. On the other hand, a
water/cement ratio that is below 0.2 results to a decrease in the drying shrinkage cracking an
increase in the tensile strain and strength of the ECC (Oliveira, et al., 2018). Thus the desired
properties of ECC can be achieved by maintaining the water/cement ratio within the ideal range
of 0.2 to 0.3. Use of fly ash reduces the amount and cost of cement in the ECC and it has been
found that the ideal fly ash to cement ratio is 0.8 to 1.2. Use of higher fly ash/cement ratio than
1.2 significantly reduces the amount of cement needed but also reduces the resistance of ECC to
scaling when it gets subjected to de-icing salt solutions (Reddy & Ravitheja, 2019).
Sand to cement ratio is another important mix proportion. According to a study
conducted by Arulmurugan (2018, the recommended sand/cement ratio is 0.8 to 1.2 but the best
tensile strengths of ECC can be achieved by using a sand/cement ratio of 1.0. The volume of
fiber content also affects the mechanical properties of ECC (Sun, et al., 2019). In most cases, 2%
fiber is used in ECC tests (Pakravan, et al., 2018). Studies have shown that an increase in fiber
volume results to an increase in the tensile strain and strength of ECC but this comes at a higher
unit cost of the concrete (Hajj, et al., 2016).
It is evident from the above literatures that ECC has superior mechanical properties than
the conventional concrete but these properties are affected by a variety of factors including
design mix, and loading or environmental conditions. However, most of the aforementioned

Best Mix Design and Mechanical Properties of ECC 7
studies have investigated the general mix designs of ECC but have not developed and suggested
a specific mix design that can be used to make ECC of a particular compressive strength. Thus
there is need to fill this gap.
3. Research Question, Aim and Objectives
3.1. Research Questions
The following are the main research questions:
1. Are the mechanical properties of ECC superior than those of conventional concrete?
2. What is the best mix design of ECC to achieve a minimum comprehensive strength of
45MPa after 28 days of curing?
3. Is ECC more cost effective and sustainable than the conventional concrete?
3.2. Aim
The aims of this research are to compare the mechanical properties of ECC and conventional
concrete, determine the suitable mix design of ECC that can provide a minimum comprehensive
strength of 45MPa after 28 days of curing, and establish the cost effectiveness and sustainability
of ECC in comparison with conventional concrete.
3.3. Objectives and Sub-goals
The objectives and sub-goals of the project are as follows:
1. To make ECC and conventional concrete cubes and perform various tests so as to
determine their mechanical properties.
2. To determine the best mix proportions of ingredients used to make ECC to achieve a
minimum compressive strength of 45 MPa after 28 days of curing.

Best Mix Design and Mechanical Properties of ECC 8
3. To determine the cost of materials used to make one cube of ECC and conventional
concrete.
4. To determine the durability and maintenance needs of ECC and conventional concrete
when subjected to earthquake and other loading conditions.
The motivation behind this research is to promote use of ECC as a sustainable alternative
material to conventional concrete, which is relatively expensive, vulnerable to some
environmental and loading conditions and environmentally unfriendly (Kewalramani, et al.,
2017). The project will also provide useful information to show proof of the superior mechanical
properties of ECC. The need to promote sustainability in the construction industry cannot be
overemphasized. Concrete is a widely used construction material hence use of ECC is one of the
strategies that can significantly promote green or sustainable construction.
4. Theoretical Content/Methodology
Workability, performance, durability and cost effectiveness of concrete are influenced by several
factors. Some of these factors are the type of concrete ingredients and the mix proportions.
Generally, engineered composite materials are deemed to be cheaper and have improved
properties and performance because they have a combination of materials with superior or more
desired properties. The strength, performance and durability of ECC largely depends on the mix
design of the concrete. The key mechanical properties of ECC to be investigated are compressive
strength, tensile strength, modulus of elasticity, flexural strength, tensile strength and creep &
shrinkage. These properties can be determined by preparing ECC concrete specimens of different
mix proportions and subjecting them to relevant concrete tests. These tests include: compression
test (using compression testing machine), flexure test, and tensile test. Compression test is
carried out by use of a compression testing machine that subjects the concrete specimen to a

Best Mix Design and Mechanical Properties of ECC 9
compressive load until it fails. The compressive strength is calculated by dividing the failure load
by the cross-sectional area of the specimen. Modulus of elasticity is also determined from
compression test that examines the stress developed in the concrete specimen again strain. The
modulus of elasticity is determined as the slope of the stress-strain curve obtained from the
compression test. Flexural test is used to measure the concrete’s tensile strength indirectly. It
examines the failure of concrete in bending. Tensile test is carried out to find the maximum
stress that the concrete sample can withstand when pulled or stretched before it breaks. The test
measures the stress against strain. Creep and shrinkage measuring device is used to measure the
change in strain of the concrete specimen with time when the specimen is subjected to constant
loading (Shraddhu, (n.d.)).
The hypotheses of this research are: ECC has superior mechanical properties than the
conventional concrete; and ECC is more economical and sustainable than the conventional
concrete. These hypotheses will be investigated using quantitative research methodology, which
involves using measurable data to prove the postulations.
5. Experimental Setup
5.1. Mix designs
The tests in this project will be conducted in the institution’s laboratory of civil engineering
department. The lab technicians will be informed about the project tests and requested to provide
the necessary assistance. Before starting the actual experiments, the mix designs of the concrete
will be determined. The four mix designs to be used are as shown in Table 1 below
Table 1: Concrete mix designs
Ingredients Mix design 1 Mix design 2 Mix design 3 Mix design 4
Water to cement 0.15 0.25 0.3 0.5

Best Mix Design and Mechanical Properties of ECC 10
Fly ash to cement 0.6 1.2 2.0 3.0
Sand to cement 0.7 1.0 1.4 2.0
Fiber volume 1.5% 2% 2.8% 5%
5.2. Materials and specimen preparation
The necessary concrete materials with desired properties will be collected, including cement,
fly ash, fiber, coarse aggregate, fine aggregates (sand), water and chemical additives. This will
be followed by assembling the concrete mixing, pouring and compacting tools and equipment
then preparing the concrete moulds (cubes). The next step will be to get familiarized with the
concrete testing machines under the guidance of the lab technician. After everything has been
prepared, a day will be set to prepare the concrete specimens.
Two specimens of each mix design for the two types of concrete (conventional concrete and
ECC) will be prepared. A total of 64 cubes will be prepared. The cubes will then be stored in
cold water for curing.
5.3. Testing
Concrete specimens for each mix design of the two types of concrete will be subjected to
each test (compression test, flexural test, tensile test and creep & shrinkage test). The tests will
be done in accordance with relevant Australian standards. The tests will be done after 7 days, 14
days, 21 days and 28 days. Test results will be collected and recorded in data sheets.
5.4. Calculations
The data obtained from the concrete specimen test will be used to calculate the required
mechanical properties of concrete. The cost of making each cube in every mix design will also
be determined.

Best Mix Design and Mechanical Properties of ECC 11
5.5. Limitations
There are no major limitations in this project. The probable limitation is lack of materials to
prepare and space to cure the 64 concrete cubes. However, this research will not evaluate the
impact of temperature or other environmental or loading conditions on the mechanical properties
and performance of the concrete specimens.
6. Results, Outcome and Relevance
The expected results from the experiment conducted in this project are as shown in Table 2
below. There will be a total of four similar tables (for 7 days, 14 days, 21 days and 28 days).
These results will be calculated using data collected from the concrete specimen test machines.
The computations will be done using a scientific calculator.
Table 2: Experimental results
Property Mix 1 Mix 2 Mix 3 Mix 4
Conv.
concrete
EC
C
Conv.
concrete
EC
C
Conv.
concrete
EC
C
Conv.
concrete
ECC
Compressive strength (MPa)
Tensile strength (MPa)
Flexural strength (MPa)
Modulus of elasticity (N/m2)
Creep
Shrinkage
Cost
The expected outcomes from this experiment are as follows:
 ECC specimens will exhibit superior mechanical properties than conventional concrete
specimens.
 Mechanical properties for each mix design and concrete type will increase gradually from
day 7 to day 28.

Best Mix Design and Mechanical Properties of ECC 12
 Mix design 2 will provide the best mechanical properties (highest compressive strength,
tensile strength, flexural strength, modulus of elasticity and creep & shrinkage).
 There will be similarities between conventional concrete and ECC specimens in relation
to the mechanical properties pattern for different mix designs and from day 7 to day 28.
 The cost of making ECC cubes will be less than that of the conventional concrete cubes.
The results and outcome from this experiment will be used to determine the null and
alternative hypotheses from the hypotheses stated in section 4. In other words, the results will
help to prove the benefits of using ECC over the conventional concrete.
7. Project Planning and Gantt Chart
The Gantt chart in Figure 1 below shows the overall schedule of the project. The activities
marked yellow represents the milestones of the project.
Activity
Wk1
Wk2
Wk3
Wk4
Wk5
Wk6
Wk7
Wk8
Wk9
Wk10
Revising the research proposal
Submitting the revised research proposal
Consulting the lab technicians
Collecting and preparing materials, tools and equipment
Preparing the concrete specimens/cubes
Curing the concrete cubes
Familiarizing with the test machines
Conducting the tests
Compiling data
Doing the necessary calculations
Analyzing and discussing the results
Drafting final report
Submitting final report
Revising and proofreading final report
Submitting final report
Project presentation
Figure 1: Gantt chart of the project

Best Mix Design and Mechanical Properties of ECC 13
The main milestones and expected deliverables of the project are provided in Table 3 below
Table 3: Milestones and deliverables
Milestone Expected deliverables
Submitting revised research
proposal
- Final research proposal
- Research schedule
Conducting the tests - Necessary materials and tools assembled
- Concrete specimens
- Equipment setup
- Equipment calibration
Analyzing and discussing results - Compiled data
- Data analysis
- Statistical analysis
Submitting final report and
presentation
- Summary of findings
- Revised final report
- Project presentation
8. Conclusions
Several studies conducted to investigate ECC have found that this material has superior
mechanical properties than the conventional concrete. However, there are no studies that have
recommended the best mix design to achieve ECC with specific compressive strength. In this
regard, it is important to understand a study to determine the best mix design for ECC to achieve
a comprehensive strength of at least 45 MPa after 28 days. Therefore this research will fill the
gap of the right ECC mix proportions for a compressive strength of 45 MPa.
The proposed experimental setup will also enable comparison of the strength development
trend and cost of the ECC and conventional concrete. Additionally, the experimental setup will
allow comprehensive analysis of the effect of different mix proportions on the mechanical
properties of ECC and conventional concrete. However, the research will not examine the effect
of temperature on the mechanical properties of concrete specimens evaluated.

Best Mix Design and Mechanical Properties of ECC 14
This project has the potential of bringing positive change in the construction industry by
providing a proof that ECC is cost effective, more sustainable and has superior mechanical
properties than conventional concrete. It will also provide very useful information about the mix
designs of ECC that can be used to achieve concrete of specific compressive strength.
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Best Mix Design and Mechanical Properties of ECC 15
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