bio-concrete as a means of concrete strengthening and repair leesa goodsell 31557693 photo source: ...
TRANSCRIPT
Bio-concrete as a means of
concrete strengthening
and repair
Leesa Goodsell 31557693
Photo source: www.disruptedhorizon.com
About the Author
Papers of Comparison
Executive Summary
Ghosh et al (2005)summary
Jonkers et al (2007)summary
Background
Paper comparison
Critical Comments
Personal Comments
References
Ghosh et al (2005)Summary cont
Jonkers et al (2007)Summary cont
About the Author
Home Back
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 bio-concrete 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.
About the Author
Papers of Comparison
Executive Summary
Ghosh et al (2005)summary
Jonkers et al (2007)summary
Background
Paper comparison
Critical Comments
Personal Comments
References
Ghosh et al (2005)Summary cont
Jonkers et al (2007)Summary cont
Photo source: bbc.co.uk
Papers of Comparison
Home Back
Jonkers , H. M., Schlangen, E. (2007). “Crack Repair by Concrete- Immobilised Bacteria”. Conference on Self Healing
Materials. Pp1-7
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
Use of microorganism to improve the strength of cement mortar
Crack Repair by Concrete-Immobilised Bacteria
About the Author
Papers of Comparison
Executive Summary
Ghosh et al (2005)summary
Jonkers et al (2007)summary
Background
Paper comparison
Critical Comments
Personal Comments
References
Ghosh et al (2005)Summary cont
Jonkers et al (2007)Summary cont
Executive Summary
Home Back
About the Author
Papers of Comparison
Executive Summary
Ghosh et al (2005)summary
Jonkers et al (2007)summary
Background
Paper comparison
Critical Comments
Personal Comments
References
Ghosh et al (2005)Summary cont
Jonkers et al (2007)Summary cont
Photo source: www.new-territories.com
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.
Background
Home Back
About the Author
Papers of Comparison
Executive Summary
Ghosh et al (2005)summary
Jonkers et al (2007)summary
Background
Paper comparison
Critical Comments
Personal Comments
References
Ghosh et al (2005)Summary cont
Jonkers et al (2007)Summary cont
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.
Photo Source: www.new-territories.com
Ghosh et al (2005)summary
Home Back
About the Author
Papers of Comparison
Executive Summary
Ghosh et al (2005)summary
Jonkers et al (2007)summary
Background
Paper comparison
Critical Comments
Personal Comments
References
Ghosh et al (2005)Summary cont
Jonkers et al (2007)Summary cont
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
Use of microorganism to improve the strength of cement mortar
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.
Ghosh et al (2005) summary
About the Author
Papers of Comparison
Executive Summary
Ghosh et al (2005)summary
Jonkers et al (2007)summary
Background
Paper comparison
Critical Comments
Personal Comments
References
Ghosh et al (2005)Summary cont
Jonkers et al (2007)Summary cont
Home Back
Figure 1:mortar without anaerobic microbes
Figure 2: cement with anaerobic microbes of 10^5 concentration/mL
As shown in the figures the addition of the Shewanella anaerobic microorganisms has apositive 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 microorganismsare included in these cement/mortar materials.
Jonkers et al (2007)summary
Home Back
About the Author
Papers of Comparison
Executive Summary
Ghosh et al (2005)summary
Jonkers et al (2007)summary
Background
Paper comparison
Critical Comments
Personal Comments
References
Ghosh et al (2005)Summary cont
Jonkers et al (2007)Summary cont
Jonkers , H. M., Schlangen, E. (2007). “Crack Repair by Concrete-Immobilised Bacteria”. Conference on Self Healing Materials. Pp1-7
Crack Repair by Concrete-Immobilised Bacteria
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)summary
Home Back
About the Author
Papers of Comparison
Executive Summary
Ghosh et al (2005)summary
Jonkers et al (2007)summary
Background
Paper comparison
Critical Comments
Personal Comments
References
Ghosh et al (2005)Summary cont
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.
Paper Comparison
Home Back
About the Author
Papers of Comparison
Executive Summary
Ghosh et al (2005)summary
Jonkers et al (2007)summary
Background
Paper comparison
Critical Comments
Personal Comments
References
Ghosh et al (2005)Summary cont
Jonkers et al (2007)Summary cont
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.
Critical Comments
Home Back
About the Author
Papers of Comparison
Executive Summary
Ghosh et al (2005)summary
Jonkers et al (2007)summary
Background
Paper comparison
Critical Comments
Personal Comments
References
Ghosh et al (2005)Summary cont
Jonkers et al (2007)Summary cont
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.
Personal Comments
Home Back
About the Author
Papers of Comparison
Executive Summary
Ghosh et al (2005)summary
Jonkers et al (2007)summary
Background
Paper comparison
Critical Comments
Personal Comments
References
Ghosh et al (2005)Summary cont
Jonkers et al (2007)Summary cont
Photo Source: http://creationrevolution.com/2011/12/speedy-stone/
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.
References
Jonkers , H. M., Schlangen, E. (2007). “Crack Repair by Concrete-Immobilised Bacteria”. Conference on Self Healing Materials. Pp1-7
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
Home Back
About the Author
Papers of Comparison
Executive Summary
Ghosh et al (2005)summary
Jonkers et al (2007)summary
Background
Paper comparison
Critical Comments
Personal Comments
References
Ghosh et al (2005)Summary cont
Jonkers et al (2007)Summary cont
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.