1

Done by Pratika Rane

Msc. Biotechnology Part I

Goa university

Bio Cement-An Eco Friendly Construction Material

Shri R. Laxmana Reddy, A.Manjusha and M. Arun kumar

International Journal of Current Engineering and Technology

2

Construction material consumes a large amount of nonrenewable resources.

5% of carbon dioxide emission is caused due to production cement.

For producing 1 tone of cement it requires 1M ETU of energy.

The buildings and traditional structures get deteriorated after a given time.

Introduction

3

Bio cementIt refers to CaCo3 deposit that is formed due to the microorganisms activity in the system which is rich in calcium ions.

4

Bacillus pasteurii with urea hydrolysis mechanism. The cementation process occurs in pipe columns filled with commercial sand contained silica.

Urea/calcium solution and bacteria solution were mixed immediately and put in the pressurized vessel to be injected to the sand core in pipe column for several time until the sand core fully saturated. Bio cementation takes about 24 hours to complete the reaction, after that the bio cement were dried in temperature of 60˚C.

5

It needs a much shorter time for production and the in-situ process raw material of bio cement are produced at low temperature.

It consume less energy and less CO2 emission in the production process as compared to other ordinary cement.

It increases compressive strength of mortar by up to 38%.

Bio cement can remediate cracks in building materials and monumental stones and regain strength within 28 days.

Advantages of Bio cement

6

Bio cementationBio cementation is a process to produce binding material (bio cement) based on microbial induced carbonate precipitation (MICP) mechanism.

7

First ever complete bio-cement building

8

Bio concrete The above is a picture of a construction made of bio concrete. It may be observed that the cracks are self-healed

9

The cracks are formed on the surface of concrete due to many reasons like shrinkage, Inadequate water for hydration …etc,

The water is deliberately forced into the crack and the precursor is activated

Ca(C3H5O2)2 + 7O2 → CaCO3 + 5CO2 + 5H2O

CO2 + Ca(OH)2 → CaCO3 + H2O The activated precursor inturn induces the bacteria to

react with that precursor and form a base of calcium carbonate called as limestone, the chemical equation is given above.

Mechanism of self healing of cracks

10

Eco friendly reduction of Co2This bio concrete absorbs and reduces atmospheric co2.It supports biological growth on its on surface.This are called vertical gardens. The material lends itself to a new concept of vertical garden, not only for newly built constructions, but also for the renovation of existing buildings. Unlike the current vegetated façade and vertical garden systems, the new material supports biological growth on its own surface; therefore, complex supporting structures are not required, and it is possible to choose the area of the façade to which the biological growth is to be applied.

11

This method is more complex than the chemical one as the microbial activity depends on many environmental factors including temperature, pH, concentrations and diffusion rates of nutrients and metabolites etc.

Successful commercialization of the technique requires economical alternatives of the medium ingredients that cost as high as 60% of the total operating costs.

Challenges and issues

12

Comparative studies should be done to check the feasibility of this method with that of the chemical methods which should include environmental impacts as well as cost.

Long term efficacy of these bio minerals should be investigated

Conclusion and future prospects

13

Achal V, Mukherjee A, Reddy MS (2010) Microbial concrete: way to enhance the durability of building structures.JMater,23:730 734.doi: 10.1061/ (ASCE) MT.1943-5533.0000159

Achal V, Mukherjee A, Reddy MS (2011) Effect of calcifying bacteria on permeation properties of concrete structures. J Ind Microbiol Biotechnol 38:1229 1234. doi:10.1007/s10295-010-0901-8

Arunaye FI, Mwasha A (2011) On behavior of limited life geotextile materials for reinforcing embankment on soft ground. World J Eng 8:195 199. doi:10.1260/1708-5284.8.2.195

Bang SS, Galinat JK, Ramakrishnan V (2001) Calcite precipitation induced by polyurethaneimmobilized Bacillus pasteurii. Enzyme Microb Technol 28:404 409

Bang S, Min SH, Bang SS (2011) Application of microbiologically induced soil stabilization technique for dust suppression. Int J Geo-Eng 3:27 37

Barlaz MA, Staley BF, De Los Reyes III FL (2010) Anaerobic biodegradation of solid waste. In: Mitchell R, Gu JD (eds) Environmental microbiology, 2nd edn. Wiley, Hoboken, NJ, USA,pp 281 299

References