Self-Healing Concrete: A Solution for Cracks in Construction

This study discusses the self-healing process of concrete in construction, focusing on the use of chemical and biological mechanisms. It explores the benefits of self-healing concrete, such as reducing repair costs and environmental impact. The disadvantages, including initial cost and reduction in strength, are also discussed. The future application of self-healing concrete, such as Microbially induced calcium carbonate precipitation (MICP), is explored.

Running head: SELF – HEALING CONCRETE
Self – Healing Concrete
Name of the Student
Name of the University
Author Note

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Executive Summary
The study discusses about the self-healing process of concrete in the construction process.
The occurrence of crack in the construction is one of the common phenomenon due to its low
tensile strengths. When a there is a crack in the concrete, the liquid materials and the water
can easily reach to the stills and there are more cracks in the concretes. In recent times, the
issue of concrete degradation has become one of the biggest problem in the construction
industry. With time, the concretes of construction will crack, although the whole process is
well maintained and well-constructed. The chemical self-healing process is the artificial
process in which chemical compounds are injected in to the cracked area of the concrete for
promoting the healing process. On the other hand, in the biological self-healing process, is
mainly based on the use of microorganisms. Along with this, the microbial calcium
carbonate can also be used as a precipitating materials formed by the process of urea
hydrolysis, photosynthesis, and sulfate reduction of the bacteria which are used in this
process. The use of self-healing concrete in the construction will reduce the number of repair
cases and as a result less amount of cement will be required for the repairing process.
Although, it is reported that, the cost of the self-healing concrete technology is almost 2
times more than that of the traditional concrete use.

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Table of Contents
Background...........................................................................................................................................3
Introduction...........................................................................................................................................3
Brief History..........................................................................................................................................4
Methodology.........................................................................................................................................4
Self-Healing Concrete.......................................................................................................................5
Benefits.............................................................................................................................................6
Future Application of Self- Healing Concrete.......................................................................................7
Disadvantages of Self- Healing Concrete..............................................................................................8
Conclusion.............................................................................................................................................8

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Background
In recent times, the issue of concrete degradation has become one of the biggest
problem in the construction industry. With time, the concretes of construction will crack,
although the whole process is well maintained and well-constructed (Muhammad et al. 2016).
Still this issue is faced by all the constructors. Hence, the water and the air can enter into the
structure and can react with the still material of the construction. As a result, the still erodes
and swells and therefore it causes more cracks. In order to reduce the repairing costs of the
construction building the, the use of self-healing concrete is very effective (Sh and Dopudja
2017).
Introduction
The occurrence of crack in the construction is one of the common phenomenon due to
its low tensile strengths. When a there is a crack in the concrete, the liquid materials and the
water can easily reach to the stills and there are more cracks in the concretes. The self-healing
concrete refers to the artificial substance that have the ability to repair the damage by
themselves without any external interventions by the human (Sh and Dopudja 2017). These
self-healing concrete materials generally can heal themselves after damage due to long
mechanical use. In the construction industry, the issue of cracks is very common and in most
of the cases those intrinsic cracks are not detected at all. So, it is very crucial to protect those
cracks so that the cost of the repairing can be lowered. It is reported that, the use of self-
healing concrete will cost three times more than that of the normal one, but it will reduce the
repair costs by 4 times. There are various types of self-healing mechanisms that are used in
recent times in the construction industry. For example it can be said that, the bacteria based
healing process, shape memory polymers. In addition to this, the use of bio-mineralization in
the healing of micro cracks has proven to be very effective. In this report concepts of self-

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healing concrete, its advantages and disadvantages and the use of self-healing concrete in
future construction are discussed in a brief manner (Wang et al., 2016).
Brief History
The word concrete has come from the Latin word “concretus” that stands for
hardened and condensed. The early use of concrete in the construction industry was reported
almost in 6500 BC. The main problem of using this ordinary concrete in the construction
industry is associated with its longevity issues. So many researchers have tried to make the
condition better so that, the cracks in the concrete can be prevented. The use of self-healing
concrete is first reported in 1994 and firstly adhesives were used as healing materials and
those materials were incorporated into the micro capsules. After that, the more effective
mechanisms were developed by the researchers (Sh and Dopudja 2017).
Methodology
For conducting this research, the researchers mainly uses the primary research articles
and during this process Google Scholar is used as the search engine. The time filter is used to
select the articles published in between 2014 to 2018. In this search process, the key words
such as self-healing, concrete, construction materials, bio concrete materials, cracks in the
construction, repair, smart materials are used.
Literature Review
In recent time, various type of self-healing designs are proposed by the researchers
and in this report, various kinds of the self-healing concrete are discussed in a brief manner.
According to the study of Seifan, Samani and Berenjian (2015), it is observed that the use of
biological self-healing technique is based on the concepts of precipitation. In this method,
mainly the precipitation of calcium carbonate is used to heal the cracked concretes. On the

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other hand the study of Da Silva et al. (2015) suggested that, ureolytic bacteria can be used
during the time of making for enhancing the strengths of sands. The study of Mignon et al.
(2015), reported that, the Superabsorbent polymers (SAPs) or smart can be used as healing
materials in the concrete. The study result indicated that SAP has immense capacity of
absorbing moistures. As this material has moisture absorbing capacity, hence it can be said
that, in the concrete healing process. Thereafter the, the tendency of low crosslinking of this
polymers also helps in preventing the swelling in the concretes.
Self-Healing Concrete
The chemical self-healing process is the artificial process in which chemical
compounds are injected in to the cracked area of the concrete for promoting the healing
process. Hollow pipettes are one of the popular material for designing a self healing concrete.
In this method, glue is placed into the hollow pipe and during the cracks, the glue is released
into the cracks and helps in the healing process. In various studies, the use of hollow pipette
along with the glue has been proven to be very successful. In the hollow pipes, methyl
methacrylate, ethyl cyanoacrylate, acrylic resin, epoxy resin can be used as glue. Another
method is encapsulated glue and they also come into play when the capsules are ruptured due
to swelling. On the other hand, in the biological self-healing process, is mainly based on the
use of microorganisms (Muhammed et al. 2016). According to the study of Cai et al. (2016),
the biological self healing process is an environmental friendly strategy and in this process
special type of bacteria. The bacteria are incorporated into the microcapsules or a precursor
like calcium lactate (Ca(C3H5O2)2) is used in this biological self-healing process. As the
microorganisms can germinate everywhere, they are used in this process. When, the water
enters into the concrete, the process of bacterial growth is initiated within the concrete along
with the help of water and air (Khaliq and Ehsan 2016). As a result, the precipitation of
calcium carbonate takes place as a part of their germination. In addition to this, the

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immobilized microorganisms can also be used on the silica gels as a part of the self-healing
(Tziviloglou, et al. 2016). Initially, the dry unaffected concrete has high temperature and
there is not adequate water for the growth of the bacteria. In order to resolve this,
thermophilic bacteria is recommended in case of self-healing process (Cai et al. 2016 ).
Along with this, the microbial calcium carbonate can also be used as a precipitating materials
formed by the process of urea hydrolysis, photosynthesis, and sulfate reduction of the
bacteria which are used in this process. The hydrolysis of formation of ammonia and CO2
during the process of urea hydrolysis is very crucial as after breaking of those products
through urease enzyme, those hydrolysed components can increase the pH and concentration
of carbonate (Dong et al. 2015). Hence, the precipitation is promoted. It is observed that, the
use of calcium carbonate precipitation on the surface of the concrete is capable of reducing
the permeability of the water and gas into the concrete. In the biological self-healing process
the use of Bacillus pasteurii and Bacillus sphaericus is very common (Seifan, Samani and
Berenjian 2016).
Benefits
The use of self-healing concrete in the construction industry is very advantageous in
many ways. It is reported that, almost 5% of overall CO2 emission is associated with the
production of concrete by the humans. The use of self-healing concrete can enhance the
lifespan of the existing structures and thus reduces the environmental impacts by reducing the
CO2 emission (Barcelo et al. 2014). In addition to this, the earth-quake prone areas of this
world can also use this technique for making the building more strong against the effect of
earth quake. It is reported that, the more use of cements are contributing in the more release
of CO2 in the environment. So, it can be said that, the use of cement in the construction
industry is passively promoting the global warming issue in the world. Moreover, it is
observed that, excessive CO2 can erode the ozone layer (Amiri, Majrouhi Sardroud and

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Golsoorat Pahlaviani 2018). The use of self-healing concrete in the construction will reduce
the number of repair cases and as a result less amount of cement will be required for the
repairing process. Hence. Less use of cement will cause low amount of CO2 emission in the
environment. So it can be said that the use of self-healing concrete in the construction process
will also help to make the environment less polluted. The study of Wang et al. (2016),
showed that, the use of biological self-healing technique can enhance the durability of the
building and use of environmental friendly material in the construction will also cause
reduction in the cost of the construction industry. As due to the use of such techniques in the
construction industry can cause low amount of damage and if there is a damage, there will be
a repairing mechanism as well. That repairing mechanism will enhance the cost of the
repairing of the construction building. The study of Gupta and Kua (2016), showed that, the
use of encapsulation technique will enhance the durability of construction building by
reducing the cracks in the concrete and simultaneously heals the cracked area of the
construction industry. The study of Muhammad et al. (2016), also supported that, the use of
self-healing concrete will reduce the consumption of cement in the construction industry.
Future Application of Self- Healing Concrete
The use of self- healing in the construction industry is greatly affecting the approach
of the construction industry. Recently the study of Lee and Park (2016), reported the use of
Microbially induced calcium carbonate precipitation (MICP). It is assumed that, this
component will be used in a huge manner in near future as part of the self-healing process.
The use of MICP in the biological self-healing process will cause incorporation of nutrients
and bacteria altogether and hence it is more effective in the healing process of the concretes.
In addition to this, it is reported that, with the advancement of technology the healing time of
the cracks in the concrete will be reduced in future and this will also enhance the
acceptability of this technology (Leng- Duei 2018).

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Disadvantages of Self- Healing Concrete
Although the use of self-healing technology is very advantageous in many ways, still
this technology has a few disadvantages. Firstly, it can be mentioned that, the clay pallets
holds the self-healing materials which is comprised of 20% of the concrete materials. The
clay used in this process generally is weaker and as a result, the concrete is also weakened by
25%. This reduction in the strength can be pointed as one of the disadvantages of this
technology. On the other hand the initial cost of the self-healing technology can be mentioned
as an disadvantage of this process. It is reported that, the cost of the self-healing concrete
technology is almost 2 times more than that of the traditional concrete use. Therefore, it is
also evident that the self healing concrete is only viable product in which the cost of the
actual concrete is very high and as a result the repair cost should also be very high.
Therefore, it can be said that, the use of self-healing concretes is only advantageous where, it
can be used as long term (Seifan, Samani and Berenjian 2016) . Otherwise, the use of this
technologies is not advantageous at all.
Conclusion
Hence it can be concluded that, in recent time, the use of self-healing technology has
become very common in the construction industry. In this technology, various biological and
chemical method can be used. Primarily this technology is based on the precipitation
properties of the calcium carbonate by a complex process inside the concrete. The use of this
technology is associated with the use of different type of bacteria which are either
incorporated into microcapsules or mixed with the materials during the construction process.
This technology helps in enhancing the durability of the building and simultaneously reduces
the overall costs of the maintenance of the building. In spite of a lot advantages, this
technology also has various disadvantages.

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