05-31557693 Bioconcrete

Report
Leesa Goodsell 31557693
About the Author
Papers of Comparison
Executive Summary
Bio-concrete as a
means of concrete
strengthening and
repair
Background
Ghosh et al (2005)
summary
Ghosh et al (2005)
Summary cont
Jonkers et al (2007)
summary
Jonkers et al (2007)
Summary cont
Paper comparison
Critical Comments
Personal Comments
References
Photo source: www.disruptedhorizon.com
About the Author
About the Author
Papers of Comparison
Executive Summary
Background
Ghosh et al (2005)
summary
Ghosh et al (2005)
Summary cont
Jonkers et al (2007)
summary
Jonkers et al (2007)
Summary cont
My name is Leesa Goodsell and I am in my last year of
university studying an undergraduate course in
Biotechnology, Molecular Biology and a minor in
Forensics.
The chemostat process was a fascinating part of the
current unit - Bioprocessing and Bioremediation and thus I
conducted a further study into the process of bioconcrete and its application into the repair of concrete.
Therefore the two papers chosen on this topic will further
discuss this theory and whether it is a viable way to
“heal” concrete long-term.
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Photo source: bbc.co.uk
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Papers of Comparison
About the Author
Papers of Comparison
Executive Summary
Use of microorganism to improve the strength of cement mortar
Background
Ghosh, P., Mandal, S., Chattopadhyay, D., Pal, S. (2005). “Use of
Sporosarcina pasteurii microorganism to improve
the strength of cement mortar”. Cement and
Concrete Research.35: pp1980-1983
Ghosh et al (2005)
summary
Ghosh et al (2005)
Summary cont
Jonkers et al (2007)
summary
Jonkers et al (2007)
Summary cont
Paper comparison
Crack Repair by Concrete-Immobilised Bacteria
Jonkers , H. M., Schlangen, E. (2007). “Crack Repair by ConcreteImmobilised Bacteria”. Conference on Self Healing
Materials. Pp1-7
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Executive Summary
About the Author
Papers of Comparison
Executive Summary
Background
Ghosh et al (2005)
summary
Ghosh et al (2005)
Summary cont
Jonkers et al (2007)
summary
The papers cited in this study both show the potential of
bio-cement and the microorganisms in it to both repair
and to improve the strength of concrete.
However the papers do look at different aspects, one
looks at the use of microorganisms to improve the strength
of the concrete whilst the other outlines the use of
microorganisms to fill cracks in the concrete.
The overall message of both papers is that this technology
may be the future of the concrete industry, in terms of
producing concrete that is self-renewing, durable, and
concrete that is environmentally friendly.
Jonkers et al (2007)
Summary cont
Paper comparison
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Background
About the Author
Papers of Comparison
Executive Summary
Background
Ghosh et al (2005)
summary
Ghosh et al (2005)
Summary cont
Jonkers et al (2007)
summary
Jonkers et al (2007)
Summary cont
Paper comparison
Bio-concrete is a phenomenon that certain microbes have shown
to possess by induction of precipitation of calcium carbonate and
as a result this is regarded as important factors in the formation of
carbonate sediments and deposits (Achal et al, 2009).
This process is known as the microbial plugging process (which is
also known as bio-cementation) to promote the precipitation of
calcium carbonate in the form of calcite.
Sporosarcina pasteurii (formerly Bacillus pasteurii) produces an
enzyme called urease which catalyzes the hydrolysis of urea to
ammonia and carbon dioxide:
NH2CONH2 + H2O → CO2 + 2NH3
This results in an increase in pH in the immediate environment,
which when in the presence of calcium and carbonate ions causes
them to precipitate together as calcium carbonate.
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Ghosh et al (2005)
summary
About the Author
Papers of Comparison
Executive Summary
Background
Ghosh et al (2005)
summary
Ghosh et al (2005)
Summary cont
Jonkers et al (2007)
summary
Jonkers et al (2007)
Summary cont
Use of microorganism to improve the strength of cement
mortar
Ghosh, P., Mandal, S., Chattopadhyay, D., Pal, S. (2005). “Use of microorganism to
improve the strength of cement mortar”. Cement and Concrete Research.35:
pp1980-1983
This article discusses the acknowledgement of the microbial metabolic
processes in the cement industry as a means of an improvement to the
durability and strength of the material. Ghosh et al (2005) employed
the use of the Shewanella species of anaerobic microorganism and
the use of an Escherichia coli species as a means of comparison.
The microorganisms of different cell concentration were added to the
mortar and over a period of 28 days we left to proliferate under the
under the cement to sand ratio of 1:3wt . And the results for the
Shewanella species are shown in Table 1 with a noted strength
increase in the mortar.
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Ghosh et al (2005)
summary
About the Author
Papers of Comparison
Executive Summary
Background
Ghosh et al (2005)
summary
Ghosh et al (2005)
Summary cont
Jonkers et al (2007)
summary
Jonkers et al (2007)
Summary cont
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As shown in the figures the addition of
the Shewanella anaerobic
microorganisms has a
positive effect on the compressive
strength of the mortar. However the E.coli
species had no effect on the strength of
the concrete.
SEM (scanning electron microscopy)
examination done by Ghosh et al (2005)
revealed that the growth of fibrous filler
material within the pores was put down
to the fact that the anaerobic
microorganisms were present in the
mortar. Compared with the mortar with
no microorganisms which the pore size is
still quite large as represented by Figure 1.
However the paper stated that further
investigation into the topic was necessary
to identify those specific mechanisms,
which alter the pore size distribution and
improve the compressive strength when
appropriate microorganisms
are included in these cement/mortar
materials.
Figure 1:mortar without anaerobic
microbes
Figure 2: cement with anaerobic
microbes of 10^5
concentration/mL
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Jonkers et al (2007)
summary
About the Author
Crack Repair by Concrete-Immobilised Bacteria
Papers of Comparison
Jonkers , H. M., Schlangen, E. (2007). “Crack Repair by Concrete-Immobilised
Bacteria”. Conference on Self Healing Materials. Pp1-7
Executive Summary
Background
Ghosh et al (2005)
summary
Ghosh et al (2005)
Summary cont
Jonkers et al (2007)
summary
This article looks at the long-term autonomous repair of concrete by
the genus of Bacillus, spore forming, alkali resistant bacteria. Jonkers et
al (2007) hypothesized that dormant but viable bacteria of this genus
within a concrete matrix would become metabolically active at water
entering into the cracks of concrete and therefore heal these cracks
through their metabolic activity of creating bio-cement. Bacillus
pasteurii or Sporosarcina pasteurii was used in this experiment.
Jonkers et al (2007) did tests for a period of 28 days on the tensile and
compressive strength of the 10^9cm3 S.pasteurii cells with no real
significant increase in strength during these 28 days shown in Table 2.
Jonkers et al (2007)
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Jonkers et al (2007)
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Executive Summary
Background
Ghosh et al (2005)
summary
Ghosh et al (2005)
Summary cont
Jonkers et al (2007)
summary
Jonkers et al (2007)
Summary cont
There was however a copious formation of minerals on the concrete
immobilized with bacteria therefore showing that the bacteria infused
into the concrete has a potential for self-healing properties (Figure 3).
The paper does state however that the minerals found on the concrete
were not tested, however due to the nature of the bacteria and its
metabolic process it can be determined as calcite crystals.
Jonkers et al (2007) theorizes that there is potential for the self healing
concrete due to the bacterium’s specialty for spore formation and in
the same way this being renewed after stimulation by various medium,
for example the water coming through the cracks of the concrete
containing an organic growth substance.
Therefore the concept of using bio-concrete making bacteria for the
self-healing concrete concept is a real possibility and with further testing
and investigation it could very well be implemented in industry.
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Paper Comparison
About the Author
Papers of Comparison
Executive Summary
Background
Ghosh et al (2005)
summary
Ghosh et al (2005)
Summary cont
Jonkers et al (2007)
summary
Jonkers et al (2007)
Summary cont
Paper comparison
Critical Comments
Ghosh et al (2005) discusses the use of microbes as a
means of concrete mortar strength improvement,
whereas Jonkers et al (2007) speaks of concrete crack
repair via a self-healing process using microbes infused
into the concrete.
Jonkers et al (2007), however stated that Ghosh et al
(2005) had a flaw, in terms of the bacteria used in the
study having a short life span therefore not being able to
meet the long-term requirements of their hypothesis. On
the other hand they themselves used Bacillus species
which is known to last for approximately 200 years.
Both papers mention the need for further investigation
and study into these areas, nevertheless they still claim
that it is possible to be able to reach these theories on a
large scale and incorporate them into industry.
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Critical Comments
About the Author
Papers of Comparison
Executive Summary
Background
Ghosh et al (2005)
summary
Ghosh et al (2005)
Summary cont
Jonkers et al (2007)
summary
Jonkers et al (2007)
Summary cont
Paper comparison
Critical Comments
Personal Comments
Ghosh et al (2005) didn’t give a description of the properties
of the bacteria they used in their introduction only
mentioned it was of Indian heritage and that it was
cultivated anaerobically and iron reducing in the methods.
Jonkers et al (2007) did not test the nature of the minerals
found on the concrete, only assumed that they were of
calcite nature, however they did state this fact.
In Ghosh et al (2005) there was not enough progress
achieved in terms of their study as it was to investigate
whether the use of microorganisms would improve the
strength of the mortar, which they did, however it felt like
more tests could be done to ascertain these results more
fully.
Other than that both papers used controls in their research
in addition to using their evidence to support their claims
and theories, whilst also acknowledging when further study
is needed to fully support such theories.
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About the Author
Papers of Comparison
Executive Summary
Background
Ghosh et al (2005)
summary
Ghosh et al (2005)
Summary cont
Jonkers et al (2007)
summary
Jonkers et al (2007)
Summary cont
Paper comparison
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The question of this study was
whether bio-concrete was the
long-term solution to the problems
of the concrete industry.
The answer is essentially yes,
however more time and research
needs to be put into this field of
study to further expand on this
topic in order for it to become a
reality.
However it is noted that the
papers used in this study were from
2005 and 2007 therefore there
may already be changes in place.
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About the Author
Papers of Comparison
Executive Summary
Background
Ghosh et al (2005)
summary
Ghosh et al (2005)
Summary cont
Jonkers et al (2007)
summary
Jonkers et al (2007)
Summary cont
Paper comparison
Achal, V., Mukherjee, A., Basu, P. and Sudhakara Reddy, M.
(2009). “Strain improvement of Sporosarcina
pasteurii for enhanced urease and calcite
production”. Journal of Industrial Microbiology and
Biotechnology. 36.7:981-988.
Ghosh, P., Mandal, S., Chattopadhyay, D., Pal, S. (2005). “Use of
microorganism to improve the strength of cement
mortar”. Cement and Concrete Research.35:
pp1980-1983
Jonkers , H. M., Schlangen, E. (2007). “Crack Repair by
Concrete-Immobilised Bacteria”. Conference on Self
Healing Materials. Pp1-7
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