CONSTRUCTION PROJECT MANAGEMENT FALL 2023
INNOVATION IN THE CONSTRUCTION INDUSTRY
(CSM 732-701)
Group Assignment 1: Innovative Building innovative Component
Topic: A STUDY ON BENDABLE, FLEXIBLE CONCRETE
PROFESSOR: MOHAMMAD ASHOURI
CENTENNIAL COLLEGE MORNINGSIDE CAMPUS
ARVA IIYAS KESARI (301315989)
DATE: OCTOBER 29, 2023
Table of Contents
1.
Introduction ........................................................................................................................ 3
1.1
2.
Product Analysis ................................................................................................................. 4
2.1
3.
Critical Factors ............................................................................................................ 3
Making of ECC ........................................................................................................... 5
Properties, Performance and Applications.......................................................................... 6
3.1 Properties of ECC ............................................................................................................ 6
3.2 Performance and durability of ECC ................................................................................. 8
3.3 Applications of Flexible concrete .................................................................................. 10
4.
Ecological and Green Specifications ................................................................................ 11
4.1 Sustainable Application of ECC .................................................................................... 11
4.2 Basic Green Alternatives................................................................................................ 12
5.
Cost Implications .............................................................................................................. 13
6.
Conclusion ........................................................................................................................ 14
References ................................................................................................................................ 16
1. Introduction
The significant role that buildings play in greenhouse gas emissions, exceeding 30% of total
emissions in numerous industrialized countries, has raised questions about their
environmental impact. Consequently, a transformation is underway in the way buildings are
designed, constructed, and operated. This transformation is being fuelled by advancements in
cutting-edge materials and intelligent building technologies designed to enhance a building's
longevity, eco-friendliness, and energy efficiency.
Choosing the right construction materials plays a crucial role when designing a building that
aligns with the principles of sustainable development. Among the most commonly employed
construction materials, concrete stands out as a prominent example. It holds the distinction of
being the most widely used material worldwide, with a multitude of applications and a
growing demand. Despite significant advancements in concrete and cementitious materials
over the past centuries, structures constructed using these materials, such as dams, roads,
bridges, tunnels, and buildings, require extensive repair and maintenance throughout their
lifespan. This maintenance necessity arises due to the increased brittleness of concrete as its
strength increases. Conventional concrete has a strain capacity of only 0.1%, which makes it
rigid and prone to brittleness, often leading to failures under stress. A cement-based
composite that overcomes this brittleness and exhibits strain hardening properties is known as
Engineered Cementitious Composite (ECC) or flexible concrete. ECC, with its strain capacity
ranging from 3 to 8%, behaves as a ductile material.
1.1 Critical Factors
Understanding bending flexible concrete requires an examination of various critical factors,
including its composition, ecological implications, performance issues, green specification
alternatives, relevant certifications, and cost implications. This paper aims to provide an
overview of flexible concrete, discussing its advantages, disadvantages, and applications
through a review of the existing literature.
2. Product Analysis
Engineered cementitious composite (ECC) is an advanced material that contains 2%
discontinuous fiber, along with cement, fine aggregate, fly ash, and a chemical admixture.
This high-performance fiber-reinforced cementitious composite (HPFRCC), as researched by
Victor Li, exhibits remarkable mechanical characteristics such as significantly improved
tensile strain hardening capacity, enhanced ultimate strain potential, and superior tensile
strength. (VC., 2007)
ECC material has gained recognition for its exceptional mechanical properties and the
presence of numerous micro-cracks, making it highly suitable for constructing protective
barriers and safety structures. This remarkable ability to absorb energy and resist impacts was
investigated by Victor Li and Kong H.J (Dr. S. Lavanya Prabha, 2023). The mechanical
properties of ECC are influenced by the composition, structure, and volume ratio of its
components, with the characteristics of the fibers playing a significant role in determining its
mechanical traits. In ECC material, the combination of fibers, matrices, and contact leads to
high ductility, and the formation of multiple cracks delays immediate failure.
ECC is produced using basic concrete components, but it requires the addition of a highrange water-reducing (HRWR) agent to improve its workability. Unlike traditional concrete,
ECC does not include coarse aggregates. Additionally, cementitious materials such as Silica
fume, blast furnace slag, and fly ash can be used in a manner similar to cement to increase the
paste content. ECC incorporates a small volume, approximately 2%, of short, discontinuous
fibers.
Fig -1: Behavior of ECC under flexural loading
These fibers in ECC are made of Polyvinyl Alcohol and are coated with a very thin
(nanometer-thick) and smooth coating, along with fine silica sand. This coating allows the
fibers to slide instead of breaking, preventing them from causing significant cracking. As a
result, ECC deforms more readily than conventional concrete. ECC's ability to absorb energy
makes it particularly suitable for use in seismic regions.
2.1 Making of ECC
ECC is created using common concrete components, such as cement, sand, fly ash, and a
super plasticizer. Notably, it doesn't incorporate coarse aggregates or require air entrainment.
Instead, it incorporates micro-fibers. The selection, dimensions, and quantities of these
ingredients, as well as the order in which they are mixed, are meticulously regulated to ensure
that the resulting composite maintains self-consolidating properties during the casting process
and exhibits ductile behaviour after it has hardened. Additionally, a standard concrete mix
design is included in the ECC mix design for the purpose of comparison.
Fig -2: Making of ECC
The figure illustrates the process of self-consolidating casting from a ready-mix truck. The
formulation of ECC mix components is the result of a body of knowledge, often referred to as
micromechanics, which delves into the interactions between the fiber, mortar matrix, and
their interface when subjected to mechanical stress. This deliberate approach eliminates
brittle fracture failure. Instead, when the composite material experiences an overload beyond
the elastic state (a state akin to pseudo-yielding), multiple micro-cracks form, and these
propagating micro-cracks maintain very narrow crack widths, in line with the specifically
designed bridging fibers.
The complete procedure of non-elastic deformation in ECC can be compared to the inherent
flexibility found in the human skeleton, enabled by the presence of muscles and ligaments. If
a human skeleton consisted solely of bones, it would be significantly more fragile. The
formulation of ECC's design is similar to crafting a meticulously engineered structure that
considers the load-bearing behavior of structural components such as beams, columns, and
connections, as well as the interactions among these elements. In ECC, the design of the
composite, encompassing the fiber, matrix, and interface, operates on a much smaller scale
but shares a conceptual similarity.
3. Properties, Performance and Applications
3.1 Properties of ECC
Self-Healing
In conventional concrete, water tends to exploit small, nearly invisible cracks. When
subjected to freeze-thaw cycles, these minor fractures often expand into visible cracks, which
can undermine the integrity of structures. The self-healing process primarily relies on the
existing materials found in conventional concrete. In ordinary concrete, a significant portion
of the cement particles remains unused and inactive because they never undergo hydration.
When the right conditions are met, these unhydrated particles react chemically with water and
atmospheric carbon dioxide to form robust compounds known as calcium carbonates. In
conventional concrete, the cracks are typically too large for these calcium carbonates to
provide any substantial benefit. However, when the cracks are sufficiently small, typically no
more than 50 μm in width, these compounds can accumulate and effectively fill the cracks,
thus repairing the concrete and leaving behind only a minor scar. Most importantly, selfhealing concrete regains its essential properties, including ductility, stiffness, and resistance
to corrosive agents like water and road salt.
In essence, self-healing concrete consists of the same components as conventional concrete:
Portland cement, water, sand, and chemical admixtures. The key distinction lies in the finetuning of the chemical, mechanical, and geometric properties, and proportions of these
ingredients to facilitate the self-healing process.
Reduced water permeability
In contrast to traditional concrete, which often requires external sealants for waterproofing,
Engineered Cementitious Composite (ECC) possesses inherent moisture resistance. This
intrinsic quality enhances its ability to withstand cracking. ECC incorporates fine aggregates
and waterproof fibers in its composition, resulting in a significant reduction in water
permeability. By combining these elements, ECC effectively repels moisture, minimizing the
risk of water infiltration and enhancing its overall durability. This reduced water permeability
not only reinforces its structural integrity but also makes ECC a superior choice for
applications where moisture resistance is paramount, such as in infrastructure exposed to
harsh environmental conditions.
3.2 Performance and durability of ECC
Flexibility under tension
Fibers play a pivotal role in augmenting the ductility of concrete. Some specific fiber types
exhibit the remarkable ability to deform by five percent or more when subjected to tension,
all while maintaining their strength. These exceptional characteristic grants flexible concrete
a significant advantage over conventional concrete, particularly in settings susceptible to
vibrations.
Comparison of Compressive Strength of Bendable Concrete of
1.5% Fibers with Convention Concrete of Grade M20.
Comparison of Split Tensile Strength of Bendable Concrete of
1.5% of Fibers with Conventional Concrete of Grade M20.
Performance in high temperatures
According to reports, ECC demonstrates superior performance compared to alternative
materials in elevated temperature conditions due to the preservation of its ductility, attributed
to the random dispersion of internal fibers. Additionally, ECC can effectively resist spalling,
enhancing its durability in high-temperature environments. (Mustafa Şahmaran, 2012)
Resistance to frost
Hezhi Liu observed that the frost resistance of concrete is assessed through freeze-thaw tests,
which are intricately linked to the internal distribution of pores. In general, the more porous
concrete is, the poorer its ability to withstand freezing. According to available information,
the pore fraction in ECC tends to rise as the volume fraction of fibers increases, making it
inherently more porous than regular concrete. (Hezhi Liu, 2017)
Fig: Comparison between normal concrete and flexible concrete.
3.3 Applications of Flexible concrete
Construction of roads and bridges
The use of flexible concrete in road and bridge construction obviates the need for expansion
and contraction joints. This is because flexible concrete can adapt its shape internally,
negating the requirement for such joints. A few examples of where ECC has been used
include:
•
The Mihara Bridge, stretching 1 kilometer (0.62 miles) in Hokkaido, Japan that was
inaugurated for traffic in 2015. The road surface, reinforced with steel, incorporates
almost 800 cubic meters of ECC material. The remarkable tensile ductility and
effective crack control properties of ECC resulted in a significant 40% reduction in
the amount of material required during the construction process.
•
In 2015, a 225-millimeter thick ECC bridge deck was successfully constructed on
Interstate 94 in Michigan, using 30 cubic meters of material transported to the site via
standard mixing trucks. Thanks to the distinctive mechanical characteristics of ECC,
this deck required less material compared to an initially planned deck composed of
standard Portland cement.
Building Earthquake-resistant Structures
The construction of earthquake-resistant buildings is motivated by safety concerns. Fiberreinforced concrete exhibits significantly higher tensile strain capacity compared to
conventional concrete, rendering it exceptionally resilient during seismic events. It can
endure a considerable degree of shaking and vibration without losing strength. PVAreinforced concrete specifically helps reduce vertical shear forces.
Concrete Canvas
Flexible concrete offers significant potential for various large-scale industrial uses, such as
water infrastructure and underground construction. Concrete canvas, primarily developed for
military applications, is designed to be exceptionally robust and long-lasting, and this
durability can be efficiently achieved through the utilization of flexible concrete.
The widespread adoption of ECC will necessitate a well-established supply chain and the
strategic utilization of the material to enhance cost-effectiveness. The most notable challenge
lies in the fact that ECC remains relatively unfamiliar to structural engineers, who have
traditionally been educated to believe that concrete lacks tensile strength.
4. Ecological and Green Specifications
The construction industry traditionally specifies materials based on performance and cost.
However, with growing environmental awareness, there is a shift towards incorporating green
specifications. Typical specifications in the industry consider factors such as strength,
durability, and workability, often without a primary focus on ecological impact.
4.1 Sustainable Application of ECC
Michael Lepech, a research fellow at the University of Michigan's Center for Sustainable
Systems and a co-author of the ECC link slab project, is deeply engaged in the process of
experimentation, which demands a comprehensive approach to development. “It comes down
to sustainability,” Lepech explains. “A sustainable system is one that takes all components
into consideration and creates cooperation and synergy among them.”
ECC presents an exciting avenue for those interested in sustainability. The very process of
designing ECC lends itself to experimentation with recycled, reclaimed, and waste materials.
Lepech notes that their evolving understanding of how fibers, sand, and cement interact
within ECC allows for precise adjustments of each element to accommodate variations in the
others. In an experimental ECC version, the combination of cement kiln dust and green
foundry sand, as replacements for some or all of the ordinary cement and sand, outperformed
a version using conventional materials. Both these alternative materials, produced in large
quantities in Michigan, were historically sent to landfills. Lepech highlights the value of
repurposing these otherwise unused and environmentally detrimental materials, stating that
they are continuously exploring new materials for use in ECC. (MDOT, 2007)
4.2 Basic Green Alternatives
Green specifications aim to minimize the environmental impact of construction materials.
Basic green alternatives include:
Recycled Content
Specifying materials with recycled content reduces the demand for virgin resources and
lowers the ecological footprint.
Low-Emission Production
Choosing materials produced with lower emissions, such as low-carbon concrete, can help
reduce the industry's environmental impact.
Sustainable Sourcing
Materials sourced from sustainable and responsible suppliers contribute to environmentally
friendly construction practices.
5. Cost Implications
Cost analysis entails the breakdown of components within a cost proposal, encompassing
factors like labor, equipment, materials, and the anticipated profit associated with a product
or service. This process is employed for assessing costs, particularly in situations where
competition or comparable offerings in the market are limited. Sometimes referred to as cost
assistance analysis or cost-effectiveness analysis, conducting a cost analysis requires
specialized skills and serves as a valuable tool for various aspects of business planning.
Material Cost
Bending flexible concrete can be more expensive than traditional concrete due to the
inclusion of reinforcing fibers and additives. However, economies of scale and improved
production processes can help reduce material costs.
Labour
Changes in construction techniques and design to accommodate bending flexible concrete
may lead to increased labour and construction costs.
Maintenance and Repair Savings
The extended lifespan and reduced need for maintenance and repairs can result in long-term
cost savings, making bending flexible concrete a cost-effective choice.
Environmental Cost
Considering the environmental cost and potential long-term ecological benefits is crucial in
cost assessments. The reduced ecological impact and resource efficiency can be significant
cost savings in the broader context.
Sl.
No.
1
2
3
4
Total
Materials
Cement
Fine Aggregate
Coarse Aggregate
Water
Quantity
(Kg)
562
843
1686
252.9
Cost/
Kg
7
4
5
3
Total
Cost(R)
3934
3372
8430
758.7
16494.7
Quantity
(Kg)
620
266
1330
8.86
8.56
354.4
Cost/
Kg
7
4
5
250
200
3
Total
Cost(R)
4340
1330
5320
2215
1772
1063.2
14977
Cost Analysis of conventional concrete
Sl.
No.
1
2
3
4
5
6
Total
Materials
Cement
Fine Aggregate
Coarse Aggregate
Jute
Coir
Water
Cost Analysis of conventional concrete
6. Conclusion
In summary, this paper has presented an extensive examination of Engineered Cementitious
Composite (ECC), a revolutionary construction material with exceptional properties and
wide-ranging applications. ECC's high tensile strain capacity, resilience under tension, and
self-healing attributes mark it as a significant advancement in sustainable construction. It
promises to transform the construction industry by offering enhanced durability, reduced
water permeability, and superior performance in diverse environmental conditions, including
seismic and high-temperature environments.
ECC exhibits versatility in its applications, from road and bridge construction to earthquakeresistant structures and innovative concepts like concrete canvas. Its potential to eliminate the
need for expansion joints, fortify structural integrity, and bolster safety in earthquake-prone
areas makes it an attractive choice for modern construction projects.
Moreover, ECC aligns harmoniously with green and sustainable construction practices, as it
facilitates the use of recycled and waste materials, promoting resource efficiency and
minimizing environmental impact. The prospect of long-term cost savings through reduced
maintenance and repairs, coupled with its eco-friendliness, positions ECC as an enticing
choice for environmentally conscious construction projects.
While ECC may involve higher initial material costs and potential labor adjustments, its longterm advantages, including prolonged lifespan and reduced environmental costs, make it a
cost-effective and sustainable selection. Embracing ECC in construction projects can be a
pivotal step toward curbing greenhouse gas emissions and realizing more eco-friendly,
resilient buildings, echoing the global trend toward sustainable development. This paper has
illuminated ECC's substantial potential and the benefits it can bring to the construction
industry and the environment.
References
1. Dr. S. Lavanya Prabha, R. L. (2023). A study on fiber reinforced bendable concrete.
European Chemical Bulletin, 72-90.
2. MDOT. (2007, August). Bendable Concrete Provides Insight into Sustainable Material
Development Process. (J. Ryynanen, Ed.)
3. VC., L. (2007). Engineered cementitious composites (ECC) material, structural, and
durability performance. (N. E., Ed.) Concrete construction engineering handbook.
4. Yadavalli , S., & Bandaru, A. (2019). Experimental investigation on Bendable
Concrete - IRJET. https://www.irjet.net/archives/V6/i12/IRJET-V6I12225.pdf
5. Flexible or bendable concrete - composition and uses. The Constructor. (2019,
October 23). https://theconstructor.org/concrete/flexible-bendable-concretecomposition-application/36008/
6. Hezhi Liu, Qian Zhang, ChongshiGu, Huaizhi Su, Victor Li, Influence of microcrack
self-healing behavior on the permeability of Engineered Cementitious Composites,
Cement and Concrete Composites, Volume 82,2017, Pages 14-22
7. Li VC. Engineered cementitious composites (ECC) material, structural, and durability
performance. In: Nawy E, editor. Concrete construction engineering handbook; 2007.
p. 24-1–24-45