Bio-concrete as a means of concrete repair

BackgroundHomeBackAbout the AuthorPapers of ComparisonExecutive SummaryGhosh et al (2005)summaryJonkers et al (2007)summaryBackgroundPaper comparisonCritical CommentsPersonal CommentsReferencesGhosh et al (2005)Summary contJonkers et al (2007)Summary contBio-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.comPapers of ComparisonHomeBackJonkers , H. M., Schlangen, E. (2007). Crack Repair by Concrete-Immobilised Bacteria. Conference on Self Healing Materials. Pp1-7Ghosh, 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: pp1980-1983Use of microorganism to improve the strength of cement mortarCrack Repair by Concrete-Immobilised BacteriaAbout the AuthorPapers of ComparisonExecutive SummaryGhosh et al (2005)summaryJonkers et al (2007)summaryBackgroundPaper comparisonCritical CommentsPersonal CommentsReferencesGhosh et al (2005)Summary contJonkers et al (2007)Summary contExecutive SummaryHomeBackAbout the AuthorPapers of ComparisonExecutive SummaryGhosh et al (2005)summaryJonkers et al (2007)summaryBackgroundPaper comparisonCritical CommentsPersonal CommentsReferencesGhosh et al (2005)Summary contJonkers et al (2007)Summary cont

Photo source: www.new-territories.comThe 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. Ghosh et al (2005)summaryHomeBackAbout the AuthorPapers of ComparisonExecutive SummaryGhosh et al (2005)summaryJonkers et al (2007)summaryBackgroundPaper comparisonCritical CommentsPersonal CommentsReferencesGhosh et al (2005)Summary contJonkers et al (2007)Summary contGhosh, P., Mandal, S., Chattopadhyay, D., Pal, S. (2005). Use of microorganism to improve the strength of cement mortar. Cement and Concrete Research.35: pp1980-1983Use of microorganism to improve the strength of cement mortarThis 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.

Jonkers et al (2007)summaryHomeBackAbout the AuthorPapers of ComparisonExecutive SummaryGhosh et al (2005)summaryJonkers et al (2007)summaryBackgroundPaper comparisonCritical CommentsPersonal CommentsReferencesGhosh et al (2005)Summary contJonkers et al (2007)Summary contJonkers , H. M., Schlangen, E. (2007). Crack Repair by Concrete-Immobilised Bacteria. Conference on Self Healing Materials. Pp1-7Crack Repair by Concrete-Immobilised BacteriaThis 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.

Critical CommentsHomeBackAbout the AuthorPapers of ComparisonExecutive SummaryGhosh et al (2005)summaryJonkers et al (2007)summaryBackgroundPaper comparisonCritical CommentsPersonal CommentsReferencesGhosh et al (2005)Summary contJonkers et al (2007)Summary contGhosh et al (2005) didnt 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 CommentsHomeBackAbout the AuthorPapers of ComparisonExecutive SummaryGhosh et al (2005)summaryJonkers et al (2007)summaryBackgroundPaper comparisonCritical CommentsPersonal CommentsReferencesGhosh et al (2005)Summary contJonkers 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. Ghosh et al (2005) summaryAbout the AuthorPapers of ComparisonExecutive SummaryGhosh et al (2005)summaryJonkers et al (2007)summaryBackgroundPaper comparisonCritical CommentsPersonal CommentsReferencesGhosh et al (2005)Summary contJonkers et al (2007)Summary contHomeBack

Figure 1:mortar without anaerobic microbesFigure 2: cement with anaerobic microbes of 10^5 concentration/mLAs 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. Bio-concrete as a means of concrete strengthening and repair

Leesa Goodsell 31557693Photo source: www.disruptedhorizon.comAbout the AuthorPapers of ComparisonExecutive SummaryGhosh et al (2005)summaryJonkers et al (2007)summaryBackgroundPaper comparisonCritical CommentsPersonal CommentsReferencesGhosh et al (2005)Summary contJonkers et al (2007)Summary cont