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What is Biocement?

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It’s safe to say that without microbes, biotechnology would be an extremely limited science. Microbes are microscopic organisms such as fungi (which include yeasts), bacteria and viruses. They not only provide the foundation for much of the basic research involved in biotechnology, they help to create durable building materials and structures.

The early scientific study of microbes concentrated on their effects, such as causing disease. Eventually, scientists discovered microbes could be used for the study of processes which are common to all living organisms. An innovative alternative approach lies in the combined use of microorganisms, nutrients and biological processes naturally present in the subsurface soils to effectively improve their engineering properties. Considerable research on carbonate precipitation by bacteria has been performed using ureolytic bacteria. These bacteria are able to influence the precipitation of calcium carbonate by the production of an enzyme, urease (urea amidohydrolase, EC 3.5.1.5). Calcium carbonate precipitation occurs as a consequence of bacterial metabolic activity that raises the pH of the proximal environment.

Recently I discovered and improved few bacterial species which were able to precipitate calcite at higher rate and eventually this process lead to improved compressive strength, reduced permeability and low corrosion rate of reinforcement.

Biocement, a self-healing material to enhance durability of building structures and conservation of cultural heritages

Although hundreds of thousands of successful concrete and buildings are annually constructed worldwide, there are large numbers of concrete structures (including historical monuments) that deteriorate or become unsafe due to changes in loading, changes in use or changes in configuration. The constant developments in the field of civil engineering and the growth of industrial activity have created a growing demand for materials for the construction industry that do more and more to comply with structural requirements and meet stricter demands for working conditions and environment. Traditionally, mechanical strength has been the main criterion used when choosing building materials such as cement, concrete or bricks. Compressive strength, permeability and corrosion analysis are the most common used measures in designing of buildings structures. Considerable effort has been devoted to develop high-strength materials. However, with increasing volumes of constricted facilities that need to be maintained the focus is shifting towards durability.

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Besides building materials preservation of the cultural heritage, socioeconomic growth and sustainable development is finding considerable resonance amongst specialists in the field. It calls for an innovative strategy for the maintenance of our cultural heritage. This strategy implies that the protection of historical buildings represents an important prerequisite for peace and stability and provides social and economic opportunities at the same time. The preservation of culture contributes to the identity of the citizens, creates jobs, supports the economy and promotes the responsible handling of societal resources. Although there is a great deal of knowledge and information on world heritage monuments, this is lacking in respect of standard monuments both at national level and international level. There is a need for research at this level into the number and quality of monuments and historical sites. Large sums of money are being spent worldwide on measures for the preservation of monuments and historical buildings. The economic and ecological commitment to the preservation of monuments and historical buildings requires, however, a prudent handling of the appropriate funds. This demands an optimization of damage analysis procedures and damage process controls as well as the development of monitoring and early warning systems for damage prevention. Therefore, the goal needs to be the implementation of permanent preservation measures, which requires long-term maintenance.

All building materials are porous. This porosity of building material along with ingress of moisture and other harmful chemicals such as acids, chlorides and sulfates affect the material and seriously reduce their strength and life. An additive that seals the pores and cracks and thus reduces the permeability of the structure would immensely improve its life. Conventionally, a variety of sealing agents such as latex emulsions and epoxies etc.; and surface treatments with water repellents such as silanes or siloxanes are used to enhance the durability of the concrete structures. However, they suffer from serious limitations of incompatible interfaces, susceptibility to ultraviolet radiations, unstable molecular structure and high cost. They also emanate toxic gases.

In order to overcome the shortcomings of conventional sealing agents, materials with self-healing capability can be used effectively. Use of urease producing microbes addresses these problems effectively, as these continue to survive and grow within the concrete structure after the initial use. Urease helps in mineralization of calcium carbonate, by hydrolyzing urea present in the environment. It releases carbon dioxide from urea that combines with calcium ions resulting in deposition of calcium carbonate in the form of calcite. Due to urease activity, bacteria are able to use urea as a sole nitrogen source and produce ammonia, which increases the pH in the proximal environment, causing Ca2+ and CO32- to precipitate as CaCO3. These unique properties make it particularly suitable for many applications in civil engineering (concrete structures, plasters, mortars, prefabricated elements, refractory elements, bricks, natural stones, etc.)

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A microbial additive that helps in calcite precipitation with urease would enhance durability of building materials as well preserve the cultural heritage.

I am pleased to present herewith my preliminary findings of the effects of microbial additives (where I used Sporosarcina pasteurii, previously known as Bacillus pasteurii, a facultative anaerobic Gram-positive soil bacterium) to enhance the durability of building materials. The significant amount of data, some of which are attached hereto, accumulated to date leads us to the preliminary findings:

1. Microbial additive resulted in improvement in compressive strength of mortar by up to 38%.

2. Microbial additive can remediate cracks in building materials and monumental stones and regain strength within 28 days.

3. To make the process economic, microbial additive can be prepared by growing cells using industrial by products such as lactose mother liquor, corn steep liquor as nutrient sources.

4. Microbial additive can enhance the durability of bricks by reducing their permeability and increasing compressive strength.

5. The reduced permeability rates resulting from the microbial additive will increase the concrete structures’ useful life.

The data accumulated to date are, in my opinion, sufficient in quantity and trend to allow me to draw some preliminary conclusions with a reasonable confidence that in future it will further support the preliminary findings. As previously stated though the study period has not yet run the full course, the data and trends indicate the microbial additive is having the beneficial effect of enhancing the durability of building materials and preservation of cultural heritage.


We are extremely thankful to Varenyam Achal for publishing these research finding on our site and thus helping people who are interested to explore this unknown field.

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Name: Varenyam Achal
Mailing Address: TIFAC-CORE in Biotechnology, Thapar University, Patiala-147004, Punjab (India)

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Comments
  • Sarvesh Dip Dhakal March 22, 2010 at 1:28 pm

    Sir, I liked Your New idea of biocement. I would really like to learn more about your further research outcomes. Moreover i am also intrigued and wonder how the cement would do in an ” environment rich in organic food and water. Also I also wonder what effects this cement has with time duration. I would really like to keep in touch with you about your further findings and experiments.

  • Ajith Kumar April 10, 2010 at 3:13 pm

    this article is quite useful and helpful.

  • C.Ravikumar May 19, 2010 at 3:05 am

    Sir,

    An usual article.How can we get Bacillus pasteruii?

    Is it readily available

  • C. Green May 27, 2010 at 9:53 pm

    Besides repairing concrete, one can make bricks using this bacteria.

    I plan to experiment with this technique in the near future. The Sporosarcina pasteurii bacteria are a common soil bacteria. The problem is to sort out that from other bacteria.

    Or just buy some from a microbiology supplier and incubate them.

    The problem to be solved ow is to find a way to reduce any ammonia/ nitrous oxide off-gassing by this process. I think that problem is solvable with some tweaking of the ingredients in the sand mixture.

    • Varenyam Achal July 14, 2010 at 8:36 am

      Thanks Green for your comment!

      I have already made bricks and enhanced its durability using such bacteria.
      You can isolate S. pasteurii from any extreme environments and even there are many other bacteria which can help in same process. Generally Bacillus group are known to resident of extreme environments.

      To sort out specific bacteria, there are certain molecular tools based on 16 S rRNA sequencing, which help in identification of a particular bacterium, thats not a big issue.

      If you buy strain from any laboratory than also its not guranatee that you are buying that particular species of bacteria due to lack of maintainance there.

      Your further questions are also welcomed.

  • arman August 6, 2010 at 12:31 am

    Is highway road made of R.C.C or P.C.C.

  • Garima September 8, 2010 at 6:05 am

    Good project work. We require ur contact no. on behalf of institute incase intrested for guest lecture

    • Varenyam Achal September 28, 2010 at 8:02 am

      Thanks Garima to acknowledging the work.

  • Komala December 24, 2010 at 5:40 am

    Hai,sir. Did there any work done on B.sphaericus for biocementing?

    • V. Achal January 9, 2011 at 3:31 pm

      Yes Komala, there are some reports available on Biocementation by B. sphaericus. But Sporosarcina/Bacillus pasteurii is the best species reported till so far.

    • R.Shahrokhi April 28, 2012 at 2:47 pm

      biocement is novel useful method for increas streangth of soil and concrete, now i working on my project at university for piping erosion reduction in earth dams.

  • J. Stork May 12, 2011 at 12:05 pm

    I am very interested in exploring affordable housing and roads made of cemented sand. The use of this bacterium could help a lot of people. I am just beginning my research and would like to learn more. Thank you for your research and site.

  • Varenyam Achal May 26, 2011 at 8:46 am

    Best wishes for your research Stork! I am sure that this process would help towards economic housing and roads. For more information you can contact me.

  • Felix Bode June 15, 2011 at 7:43 pm

    good work sir, may i ask can food such as starch improve the property of concrete

  • sanjay September 25, 2011 at 1:24 pm

    nice work sir,
    which other bacteria did u work with, where can i find them and what test did u perform ? pls reply soon!

    • V. Achal October 2, 2011 at 11:33 pm

      Mr. Sanjay, you can use any urease producing bacteria such as Sporosarcina pasteurii, Bacillus megaterium for this purpose. You can isolate such bacteria from environmental sources or may procure from MTCC, IMTech, Chandigarh in India.

  • keerthika October 14, 2011 at 2:40 pm

    Sir ,its a great work. we need your help regarding what is the procedure to mix microbes with cement? help us sir.

    • Varenyam Achal November 12, 2011 at 12:40 am

      Keerthika, you can go through some of my related papers and get information regarding mixing procedure. For detail can contact me. Search my name on science direct and get information

    • V. Achal November 20, 2011 at 12:49 pm

      Keerthika you can search some articles on Microbial concrete or microbial calcite precipitation

  • m.memarian November 17, 2011 at 3:32 am

    Sir, I liked Your New idea of biocement. I would really like to learn more about your further research outcomes. Moreover i am also intrigued and wonder how the cement would do in an ” environment rich in organic food and water. Also I also wonder what effects this cement has with time duration. I would really like to keep in touch with you about your further findings and experiments.

    • V. Achal November 27, 2011 at 6:51 am

      Thanks Memarian, there are many such articles on Microbial Concrete that you can find online to know further information

  • Bharathi November 28, 2011 at 3:05 am

    Great research sir. We wanna experiment this technique through our project. Can i get the mix design procedure?

    • V. Achal December 6, 2011 at 11:23 am

      Bharathi, you may find some papers of mine from where you can get detail procedure

  • ashish February 25, 2012 at 6:52 am

    sir i have to do project work in precipitated calcium carbonate in microbiology .please suggest me any suitable title for my project

    • V. Achal March 4, 2012 at 9:02 am

      Hi!, you can try title such as “Calcium carbonate precipitation by Bacillus species” or like “Bacillus megaterium induced calcium carbonate precipitation”. Here name of bacteria is just example that you can change accordingly. Rest you can get idea from several published related papers. Best wishes

  • Rajesh April 3, 2012 at 7:35 am

    I think the cost of biocement will be approximate double as we have to add some feed material for initiation of growth of bacillus bacteria. How you are adding mixture (bacteria, feed, cement, sand, gravel, etc) uniformly?

    • V. Achal April 24, 2012 at 7:14 am

      Well, Rajesh, it won’t be double, you can go through some recent papers regarding cost analysis. Bacteria one can isolate and to grow the bacterial cells one may replace expensive nutrient media with industrial by-products (such as CSL, LML). these by-products can be obtained even at free of cost (just transportation you need to pay). These are good sources of nutrients. Uniform mixture needs good skills.

  • R.Shahrokhi April 30, 2012 at 3:29 pm

    Biocement is novel useful method for increas strenght of soil and concrete,therefore i want use bacteria for piping erosion reduction in earth dams.

  • Mireia G. August 16, 2012 at 6:52 am

    Hello, I’m a 17 year old student and I’m working on a project based on the use of Sporosarcina Pasteurii in the actual engineering. I have a lot of questions and I would like to keep in touch with you and your team.
    Just a little question, to create the bricks using S. pasteurii, did you use the liquid medium (BHI) of such bacterium or did you apply the solid medium (agar plate) into ringer?

  • Sneha W. September 26, 2012 at 10:32 am

    Hello sir, i am a student, am also working on a project “Biocementation”, but sir i have a problem regarding to the measurement of strength of biocemented column. Can u give me the method for strength measurement other than penetrometer and ultrasound waves?

  • Rajnish Tatiwala October 4, 2012 at 10:17 am

    V. Achal Sir, Can i contact you. I like to make bricks ! can u please send me contact info where i can call or visit you

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