The two goals I have set for myself at the start of the module were overcome my stuttering and my to improve my vocabulary and grammar. Throughout the 13 weeks, I have picked up skills such as writing a summary, paraphrasing, crafting an email, report writing and oral presentation through the resources that were provided. This module has allowed me to develop and improve my own form of communication through various sharing and pitching sessions in these 13 weeks. My stuttering has also decreased notably as I have learned to overcome my anxiety through these sharing sessions. These sharing sessions involve peer teaching which I believed it boosted my confidence as a speaker. My grammar has definitely improved but certain old habits due to 'Singlish' will occasionally happen subconsciously. To further improve my grammar, I have an effort to structure my speech with 'Singlish' so that when I am writing, I will not make the same grammar mistakes due to 'Singlish'. I have also learned how to cite information in APA style from the second assignment (Reader's response).
During the research project, I was most proud of my oral presentation. Presentation has always been my bane and I have low confidence in my presentation skills. For the mock presentation, I take it as a test to test our understanding of our research report. this result in me being complacent as I was confident I can present what I have done. However, during the mock presentation, my mind went blank several times resulting in me stuttering and breaking my flow. After the mock, I realized the importance of practice as I have to get used to the flow of my speech and to further understand my content. I became motivated to do have a breakthrough in my presentation skills and rehearsed daily before the formal presentation. Thankfully, it went very well as I can convey the information that I had planned. Slides were a challenge as I have to include as little words as possible which makes it hard as I will not be able to refer when I am stuck in the presentation. Back in my Polytechnic days, my slides contains several phrases which I would read off whenever I am stuck. This further proves that presentations require a lot of preparation. From this experience, I realized the importance of pitching and presentation skills as there is no point in writing a good report if one is unable to explain its content to different audiences.
Friday, April 3, 2020
Friday, March 13, 2020
Annotated Summary
F.U.Rahman. Bacterial Concrete or Self Healing Concrete for Repair of cracks. Retrieved on 11 March 2020 from https://theconstructor.org/concrete/bacterial-concrete-self-healing-concrete/13751/
This article discusses the characteristics and properties of self-healing concrete using bacteria as an agent. According to the article, self-healing concrete is a result of the "biological reaction of non-reacted limestone and a calcium-based nutrient with the help of bacteria to heal the crack". A particular strain of bacteria called "Bacillus" is used in conjunction with a "calcium nutrient known as Calcium Lactate". The bacteria themselves can also survive up to 200 years in its "dormant state", and when cracks are formed, water seeps through. The bacteria will be woken up from its "dormant state" and reacts with the nutrients and produces limestone as a byproduct thus filling up the cracks without any external human intervention. Self-healing concrete is also superior to traditional concrete as they have higher "compressive strength". The article also highlighted the different benefits and limitations of the self-healing concrete. One of the notable benefits is that the bacteria "Bacillus" is nonpathogenic thus it is not harmful to humans. However, one of the limitations is that it is very costly to cultivate and produce the bacteria used in the self-healing agent.
This article plays a vital role in our research project as It allows us to further understand the role of the self-healing agent in the self-healing concrete. Since we are proposing this proposal to incorporate this self-healing agent into a concrete design, It is important for us to understand its characteristics and properties. Using those resources, we are capable of drafting the research with concise information.
Commented on
Derrick
Wai Yan
Cen Wei
This article discusses the characteristics and properties of self-healing concrete using bacteria as an agent. According to the article, self-healing concrete is a result of the "biological reaction of non-reacted limestone and a calcium-based nutrient with the help of bacteria to heal the crack". A particular strain of bacteria called "Bacillus" is used in conjunction with a "calcium nutrient known as Calcium Lactate". The bacteria themselves can also survive up to 200 years in its "dormant state", and when cracks are formed, water seeps through. The bacteria will be woken up from its "dormant state" and reacts with the nutrients and produces limestone as a byproduct thus filling up the cracks without any external human intervention. Self-healing concrete is also superior to traditional concrete as they have higher "compressive strength". The article also highlighted the different benefits and limitations of the self-healing concrete. One of the notable benefits is that the bacteria "Bacillus" is nonpathogenic thus it is not harmful to humans. However, one of the limitations is that it is very costly to cultivate and produce the bacteria used in the self-healing agent.
This article plays a vital role in our research project as It allows us to further understand the role of the self-healing agent in the self-healing concrete. Since we are proposing this proposal to incorporate this self-healing agent into a concrete design, It is important for us to understand its characteristics and properties. Using those resources, we are capable of drafting the research with concise information.
Commented on
Derrick
Wai Yan
Cen Wei
Tuesday, March 10, 2020
technical report draft #1
Implementing self
healing bacterial medium in concrete to heal cracks in monumental buildings.
- Introduction
This report is prepared to propose to
Building Construction Authority (BCA) on the adoption of self-healing concrete
to be incorporated into the historical buildings to prolong the longevity of
the building structure. This prevents the formation of cracks in monumental and
historical buildings.
1.1 Background
Information
Preserving our heritage through
buildings is essential to our future generations. Some of the heritage and
cultures were represented in buildings such as the Old Parliament House, which
was built in 1827. These buildings were constructed using mainly concrete
consisting of Ordinary Portland Cement (OPC), which is known to deteriorate
over a long period of time. The deterioration of the concrete in Singapore is
mainly due to the shrinkage caused by high temperatures and the acidity of
rain. According to Hu, Balasubramanian and
Wu(2003), Singapore’s rainwater is “typically acidic” due to impurities
from the atmosphere such as carbon dioxide. According
to “Types and Causes of Concrete Deterioration”, it is stated that concrete has
poor resilience against acid. Therefore this will lead to the deterioration of
concrete which may result in the formation of cracks.
According to “Types and Causes of Concrete
Deterioration”, it is also stated that the formation of cracks in concrete is
imminent due to the “drying shrinkage” phenomenon. This phenomenon is due to
the evaporation of moisture in the concrete over time. This results in
shrinkage of concrete due to the volumetric change.
Due to these cracks, water could seep in and as a result, corrode the
steel reinforcements inside the concrete. According to Arnold (2011), steel
reinforced bars are added into concrete structures as it improves the concrete
strength. The corrosion of these reinforcements could be detrimental to the
concrete structure as the overall weight-bearing capacity of the concrete
structure would be greatly reduced. Under such circumstances, the concrete
structure, thus, becomes unsafe for the building occupants and will be
required to be restored immediately.
By Introducing a self healing agent such as
bacteria, it aids in healing cracks effectively in structures. The bacteria
embedded in this self healing concrete behave in a way such that when triggered
by contact with water and air, it produces limestone, and in doing so they
repair the crack by filling the air and water voids. From an interview
conducted with Professor Fei Jin from Singapore Institute of Technology, he
stated that there are two methods to incorporate this self healing bacteria.
First method is incorporating the dormant bacteria into the design mix which
will be activated when cracks are formed. Second method is incorporating live
bacteria into grout for healing purposes as the grout will be injected into
cracks to fill up the cracks.
By incorporating this into existing buildings, we will ultimately be
able to heal concrete without any external actions, increase the structural
strength, and also reduce the corrosion of the inner steel reinforcements. Even
though self healing concrete costs more than normal concrete, when looking
toward the long term, one can expect to save much more on maintenance and
refurbishment works.
The
table below shows the comparison of strength between a typical concrete mix
used today and a concrete with self healing bacterial admixture.
S/N
|
Days
|
Normal Concrete Strength
(N/mm^2) |
Self-Healing Concrete Strength
(N/mm^2) |
1
|
7
|
20.35
|
26.90
|
2
|
28
|
30.50
|
37.97
|
Fig
1 -
Comparison of compressive concrete strength (What is Bacterial Concrete or Self
Healing Concrete?, 2019).
Ideally, structural concrete in monumental
buildings should have self-healing properties so the formation of cracks can be
alleviated. Without such self healing mechanisms, these cracks could lead to a structural
failure, thus reducing concrete longevity of the structure.
1.2 Problem
Statement
Traditional concrete such as Portland Cement (PC) does not contain
self-healing properties and tends to deteriorate over a certain time span,
which makes it susceptible to cracks. With the introduction of bacteria as a
self-healing medium, we aim to preserve structural monuments thus prolonging
the longevity and maintaining its structural integrity.
1.3 Purpose
Statement
The purpose of this report is to propose to Building Construction
Authority (BCA), the adoption of self-healing concrete to be incorporated into
the historical buildings to prolong the longevity of that monumental building
structurally.
2.
Proposed Solution
The team proposes a solution to prolong the longevity of monumental
buildings by incorporating self healing bacteria into a concrete mix design. There are two types of methods which are the injection
of self-healing bacteria into existing concrete structures and recasting of
concrete structures using concrete mix containing self-healing bacteria. Before
implementing it into high profile monumental buildings, a trial application of
the concrete mix to be used in historical shophouses in Chinatown, Singapore. A
street in chinatown with shophouses will be selected for inspection of cracks
on concrete structures. 2-3 shophouses in the selected street with numerous
minor cracks on their concrete structures will be shortlisted for the application
of grout injection.
2.1 Grout
Injection
Grout, by definition, refers to a
composite material used to fill in voids and openings in the surface. The
proposed grout consists of a mixture of Portland Cement (PC), sand, aggregates,
self healing bacteria, nutrient (calcium lactate) and water. With a proper mix
design of grout injection, cracks with thickness as slim as 0.08mm and as large
as 12mm could be filled. Grout injection could be carried out with little
disturbance to the surrounding structures. Therefore, it is a preferred method
for minor cracks that do not jeopardize the integrity of concrete
structures.
Add a picture of
grouting
2.1.2 Application
The grout injection mix containing
self-healing agents and traditional grout injection mix will be prepared
according to the sizes of the cracks. The mixes will be applied to separate
concrete structures with minor cracks in the shophouse. After the application
of the grout injection into the cracks, the results between the mixes will be
monitored and compared over the period of 2-3 years. (Shall add the parameter
we are going to record as results)
The accumulation of the results can be
used to determine whether it is feasible and viable for the self-healing
concrete to be incorporated in the maintenance of the concrete structures of
monumental buildings.
2.2 Recasting of
damaged concrete structure using Self-healing Concrete Mix
A concrete mix containing dormant self-healing
agent (bacteria) and nutrients (calcium lactate) shall be used to recast the
existing damaged concrete structure. If the similar type of damage occurs the
dormant self-healing agent will be activated. The reaction between the bacteria,
nutrients and water will produce limestones which will fill the gaps of the
cracks. This method is suitable for cracks which are so large that the
reinforcements within the concrete are being exposed.
2.2.2 Application
This method shall be applied to damaged concrete
structures which are carrying critical load (eg. Beams and slabs). The damages
occurring at these concrete structures can be detrimental to the overall
building. Therefore, they shall be fully replaced with a recasted concrete
structure.
3.
Benefits
3.1 Less Human
Intervention
As the self healing bacteria will only be activated when cracks are
formed, visual cracks can be seen when the bacteria are all used up. This
reduces the maintenance frequency needed for each monumental building. In
addition, building management may reduce manpower or even divert their manpower
elsewhere.
3.2 Less Cost of
Maintenance
With lesser human intervention, it will
mean that there will be a reduction of maintenance needed which will lead to a
decrease in manpower and materials. This will lead to a lower maintenance cost
as the frequency will be lower.
4.
Evaluation
In this section, the
feasibility and challenges of the proposed solution will be evaluated and
discussed.
The proposed solution
of incorporating self healing agent into grout injection and concrete design
mix to restore old concrete structures is feasible. From an interview with Dr
Fei Jin, he mentioned that there are alot of studies regarding this self
healing agent being incorporated in concrete design mix to achieve the self
healing properties. He also states that it is possible as there was research that
found success in using this self healing agent.
4.1 Limitation
In order to
incorporate this self healing agent, there are several challenges that will
surface.
The social stigma of
using bacteria as our main healing agent will not be supported. Bacteria are
associated with infection, virus and decomposition of living organisms. In
addition, bacteria produce a pungent smell which may lead to additional
challenges in future.
(to be continued)
5.
Methodology and Procedure
5.1 Primary
Research
Primary research in the form of an interview was
conducted with Dr Fei Jin, who is an Assistant Professor in University of
Glasgow Singapore. Dr Fei Jin specializes in Civil Engineering with a Doctor of
Philosophy (Ph.D.) from the University of Cambridge.
He mentioned that our two proposed methods were
feasible and could be incorporated into concrete mix designs to maintain and
conserve historical buildings in Singapore. However, he also mentioned that the
initial investment of utilising self-healing agents into concrete structures
would be at least twice as high compared to the typical ones being used today.
The benefits would rather play out in the long run when the cost of maintaining
the concrete structure would be greatly reduced which could lead to every
company’s goal of cost saving.
5.2 Secondary
Research
The main source of secondary research Ingenia Inc
(2011). The magazine issue published by Ingenia Inc, documented comprehensive
information on the topic of self healing agents being incorporated into
concrete. It covered the need of these in today’s world, including how these
agents specifically work and the advantages and disadvantages of the agent.
Other sources of secondary research include online publications and websites.
(Not complete)
6.
Conclusion
The National Heritage Board states that 73 buildings and structures in
Singapore is national monuments. This is a small number of national monuments
compared to other countries. Conserving these timeless buildings in Singapore
is crucial for our future generations. Most of these buildings were built with
concrete which is known to deteriorate over time. The frequency of the
maintenance for these buildings is high and costly. With the incorporation of
self-healing concrete into the maintenance process of the concrete structures
of the historic buildings, we will be able to bring down the maintenance cost
in the long run. (Not complete)
Monday, February 17, 2020
Summary response draft #3 (final)
In the article, “Hotel New World
Collapse”, Lim (2009) discuss the events leading up to the collapse of Hotel
New World, which was caused by a series of engineering faults and poor building
management. Hotel New World was a multi-storey building that was constructed in
1971 and was located along Owen Road. According to Lim, the collapse of Hotel
New World in 1986 was so devastating that it did not leave any walls and
columns standing. After the collapse, rescue teams consisting of both local and
foreign specialists were dispatched. Lim states that former president Wee Kim
Wee "appointed a commission of inquiry" for the collapse
investigation on 22 March 1986. Lim states that according to the investigation
report, the primary reason for the collapse “was due to inadequate structural
design of the building”. The additional installation on the roof also
contributed and accelerated the collapse. The investigation report also
mentioned that visible “cracks in the column, wall, and floor” were observed
prior to the collapse. Further investigation shows that the team behind the
construction consisted of unqualified personnel. Overall, the tragedy of the Hotel New World could have been prevented if
there were proper construction guidelines to follow and maintenance of the
building was carried out regularly. In this article, Lim has convincingly
conveyed that both adequate structural design and proper building management
are vital in maintaining the building’s structural integrity.
One reason why Lim is convincing is
that proper building management is vital in maintaining the building’s
structural integrity. According to Thean, Vijiaratnam, Lee, and Broms (1987),
cracks of various sizes were found on 5 columns during the remodelling of a
night club on the second floor by the contractor in 1980. He notified building
owner Ng Khong Lim who instructed him to carry on without bothering about the
cracks. Cracks are a clear indication of a structure failing and if they are
not rectified, it could lead to more complications. The report also stated that
when the same contractor returned to the nightclub in 1985 to wallpaper the
columns, he claimed that new cracks were found on other columns. If Ng Khong
Lim had rectified the cracks as soon as he was informed, the integrity of the
building would not deteriorate. It may also prevent the collapse of the Hotel
New World.
Another reason is that the
structural design of the building contributes to maintaining the building’s
structural integrity. According to Thean, Vijiaratnam, Lee, and Broms (1987),
the building was “grossly under-designed” and "it was a matter of time
before the building would collapse. If the structural design of the building
had been adequate, the building might still be standing today as it stood for
15 years despite being under-designed. This shows the importance of adequate
structural design in maintaining the building’s structural integrity.
The last reason is that the structural design did
not take into consideration the further installation of the building. According
to Thean, Vijiaratnam, Lee, and Broms (1987), substantial loadings that were
not included in the structural design were added to the building causing the
building to be overloaded even more. Any installation on the building has to be
considered during the designing phase such that there will be an allowance to
ensure that the building will be able to support the load in the future or consult a professional to check with the building is to able to support such
loadings. This is will ensure that the building will have adequate structural
design and additional installation will not jeopardize the integrity of the
building.
The collapse of the Hotel New World
is an important lesson for engineers because it could have been avoided if
there are adequate structural design and proper building management.
References:
Lim (2011) Hotel New World
collapse. Retrieved on 10 February 2020, from https://eresources.nlb.gov.sg/infopedia/articles/SIP_783__2009-01-02.html
Thean, L, Vijiaratnam, A, Lee, S.,
Broms, B (1987). Report of the Inquiry into the Collapse of Hotel New
World, p. 21, 61, 62, 63. Retrieved on 10 February
2020,
Thursday, February 13, 2020
Reader response draft #2
In the article, “Hotel New World Collapse”, Lim (2009) discuss the events leading up to the collapse of Hotel New World, which was caused by a series of engineering faults and poor building management. Hotel New World was a multi-storey building that was constructed in 1971 and was located along Owen Road. According to Lim, the collapse of Hotel New World in 1986 was so devastating that it did not leave any walls and columns standing. After the collapse, rescue teams consisting of both local and foreign specialists were dispatched. Lim states that former president Wee Kim Wee "appointed a commission of inquiry" for the collapse investigation on 22 March 1986. Lim states that according to the investigation report, the primary reason for the collapse “was due to inadequate structural design of the building”. The additional installation on the roof also contributed and accelerated the collapse. The investigation report also mentioned that visible “cracks in the column, wall, and floor” were observed prior to the collapse. Further investigation shows that the team behind the construction consisted of unqualified personnel. Overall, the tragedy of the Hotel New World could have been prevented if there were proper construction guidelines to follow and maintenance of the building was carried out regularly. In this article, Lim has convincingly conveyed that both adequate structural design and proper building management are vital in maintaining the building’s structural integrity.
Firstly, proper building management is vital in maintaining the building’s structural integrity. According to Thean, Vijiaratnam, Lee, and Broms (1987), cracks of various sizes were found on 5 columns during the remodelling of a night club on the second floor by the contractor in 1980. He notified building owner Ng Khong Lim who instructed him to carry on without bothering about the cracks. Cracks are a clear indication of a structure failing and if they are not rectified, it could lead to more complications. The report also states that when the same contractor returned to the nightclub in 1985 to wallpaper the columns, he claimed that new cracks are found on other columns. If Ng Khong Lim were to rectify the cracks as soon as he was informed, the integrity of the building would not deteriorate. It may also prevent the collapse of the Hotel New World.
Secondly, the structural design of the building contributes to maintaining the building’s structural integrity. According to Thean, Vijiaratnam, Lee, and Broms (1987), the building was “grossly under-designed” and "it was a matter of time before the building would collapse. If the structural design of the building is adequate, the building might still be standing today as it stood for 15 years despite being under-designed. This shows the importance of adequate structural design in maintaining the building’s structural integrity.
Lastly, the structural design did not take into consideration the further installation of the building. According to Thean, Vijiaratnam, Lee, and Broms (1987), substantial loadings that were not included in the structural design were added to the building causing the building to be overloaded even more. Any installation on the building has to be considered during the designing phase such that there will be an allowance to ensure that the building will be able to support the load in the future. Or consult a professional to check with the building is to able to support such loadings. This is will ensure that the building will have adequate structural design and additional installation will not jeopardize the integrity of the building.
The collapse of the Hotel New World is an important lesson for engineers. As it can be avoided if there are adequate structural design and proper building management.
References:
Lim Tin Seng (2011) Hotel New World collapse. Retrieved 10 February 2020, from https://eresources.nlb.gov.sg/infopedia/articles/SIP_783__2009-01-02.html
Thean, L, Vijiaratnam, A, Lee, S., Broms, B (1987). Report of the Inquiry into the Collapse of Hotel New World, p. 21, 61, 62, 63. Retrieved on 10 February 2020,
Friday, February 7, 2020
reader response draft #1
In the article, “Hotel New World Collapse”, Lim (2009) discuss the events leading up to the collapse of Hotel New World, which was caused by a series of engineering faults and poor building management. Hotel New World was a multi-storey building that was constructed in 1971 and was located along Owen Road. According to Lim, the collapse of Hotel New World in 1986 was so devastating that it did not leave any walls and columns standing. After the collapse, rescue teams consisting of both local and foreign specialists were dispatched. Lim states that former president Wee Kim Wee "appointed a commission of inquiry" for the collapse investigation on 22 March 1986. Lim states that according to the investigation report, the primary reason for the collapse “was due to inadequate structural design of the building”. The additional installation on the roof also contributed and accelerated the collapse. The investigation report also mentioned that visible “cracks in the column, wall, and floor” were observed prior to the collapse. Further investigation shows that the team behind the construction consisted of unqualified personnel. Overall, the tragedy of the Hotel New World could have been prevented if there were proper construction guidelines to follow and maintenance of the building was carried out regularly. Lim has convincingly conveyed that both adequate structural design and proper building management are vital in maintaining the building’s structural integrity.
Proper building management is vital in maintaining the building’s structural integrity. According to Thean, Vijiaratnam, Lee, and Broms (1987), cracks of various sizes were found on 5 columns during the remodelling of a night club on the second floor by the contractor in 1980. He notified building owner Ng Khong Lim who instructed him to carry on without bothering about the cracks. In my opinion, cracks are a clear indication of a structure failing and if they are not rectified, it could lead to more complications. The report also states that when the same contractor returned to the nightclub in 1985 to wallpaper the columns, he claimed that new cracks are found on other columns. If Ng Khong Lim were to rectify the cracks as soon as he was informed, the integrity of the building would not deteriorate. It may also prevent the collapse of the Hotel New World.
The structural design of the building contributes to maintaining the building’s structural integrity. According to Thean, Vijiaratnam, Lee, and Broms (1987), the building was “grossly under-designed” and it is a miracle that it stood for 15 years before its collapse. If the structural design of the building is adequate, the building might still be standing today. As it still stood for 15 years despite being under-designed. This shows the importance of adequate structural design in maintaining the building’s structural integrity.
The structural design did not take into consideration the further installation of the building. According to Thean, Vijiaratnam, Lee, and Broms (1987), substantial loadings that were not included in the structural design were added to the building causing the building to be overloaded even more. Any installation on the building has to be considered during the designing phase such that there will be an allowance to ensure that the building will be able to support the load in the future. Or consult a professional to check with the building is to able to support such loadings. In my opinion, this is will ensure that the building will have adequate structural design and additional installation will not jeopardize the integrity of the building.
The collapse of the Hotel New World is an important lesson for us engineers. As it can be avoided if there are adequate structural design and proper building management.
References:
Lim Tin Seng (2011) Hotel New World collapse. Retrieved 10 February 2020, from https://eresources.nlb.gov.sg/infopedia/articles/SIP_783__2009-01-02.html
Thean, L, Vijiaratnam, A, Lee, S., Broms, B (1987). Report of the Inquiry into the Collapse of Hotel New World, p. 21, 61, 62, 63. Retrieved on 10 February 2020,
Tuesday, February 4, 2020
summary draft #2
In the article, “Hotel New World Collapse”, Lim (2009) discuss the events leading up to the collapse of Hotel New World, which was caused by a series of engineering faults and poor building management. Hotel New World was a multi-storey building that was constructed in 1971 and was located along Owen Road. According to Lim, the collapse of Hotel New World in 1986 was so devastating that it did not leave any walls and columns standing. After the collapse, rescue teams consisting of both local and foreign specialists were dispatched. Lim states that former president Wee Kim Wee "appointed a commission of inquiry" for the collapse investigation on 22 March 1986. Lim states that according to the investigation report, the primary reason for the collapse “was due to inadequate structural design of the building”. The additional installation on the roof also contributed and accelerated the collapse. The investigation report also mentioned that visible “cracks in the column, wall, and floor” were observed prior to the collapse. Further investigation showed that the team behind the construction consisted of unqualified personnel. Overall, the tragedy of the Hotel New World could have been prevented if there were proper construction guidelines to follow and maintenance of the building was carried out regularly.
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