BIO-CONCRETE

Prabhat kumar sahu0901109200Civil engg

SELF HEALING CONCRETE

Concrete is the most widely used material for construction.

It has low tensile strength than compressive strength.

So is most effective when reinforced by steel bars.

Concrete is a brittle material with low tolerance for strain.

INTRODUCTION

So it forms cracks, leading to corrosion water ingress Decrease in durability increasing maintenance cost self healing concrete is a solution to all

above.Here we will induce self healing property

using JC3 (Bacillus subtilis) bacteria.

JC3 is a gram +ve bacteria

Can be cultivated easily in lab with minimum cost

It is non-pathogenic

Bacillus subtilis(JC3)

ObjectivesExperimental procedureChemical reactionsExperimental results

EXPERIMENTAL PROGRAMME

Analysis of compressive strength with varying bacterial con.

Analysis of split tensile strength .Effect of bacterial conc. on different grades of

concrete

OBJECTIVE

JC3 bacteria is added to concrete with Calcium lactate as feeding material.

The conc. of JC3 bacteria is proportional to H2O conc.

Calcium lactate & JC3 mixture is added in form of palates .

Initially JC3 bacteria spores remain in dormant state

These spores germinate when come in contact with H2O in temp around 25deg.

Procedure

When cracks are formed ,the local palates also breaks releasing JC3

Water also seeps through cracksBacterial spores germinates when comes in

contact with H2OJC3 feeds on Calcium lactate forming CaCO3

which precipitates on cracks.This process is known as Microbiologically

Induced Calcium Carbonate precipitation(MICCP)

MICCP involves a complicated chain of reaction.

But can sum up to following two stepsCa2+ + Cell → Cell-Ca2+

Cell-Ca2+ + CO32- → Cell-CaCO3↓

Chemical process

Surface 1 :Concrete surfaceSurface 2 : CaCO3 ptt

PLAIN CONCRETE BACTERIAL CONCRETE

Cell Conc./ml of water

Compressive strength

(28 days)(Mpa)

% increase

NIL 51.81 _

10^4 58.02 11.99

10^5 61.79 16.15

10^6 57.21 10.42

10^7 54.66 5.51

Experimental results

Grade of concrete

Controlled concrete

(Mpa)

Bacterial concrete

(Mpa)

% increase

M 20 28.18 32.74 16.18

M 40 51.19 60.17 17.54

M 60 72.61 94.21 29.75

M 80 93.8 119.2 27.08

Compressive strength (28 days)

No of days Controlled concrete

(Mpa)

Bacterial concrete

(Mpa)

%increase

7 3.78 4.30 13.75

14 4.62 5.28 14.28

28 4.85 5.74 18.35

Spliting tensile strength

The use of Self healing concrete has been very limited world wide .

The concept is still in developing stage & on the way to large scale use.

In India no use of this has been done.A group of professors in JNTU are

researching on bacterial concrete.

Prctical use

Based on the present experimental investigations, the following conclusions are drawn:

decrease of permeability of water and other liquids in concrete.

increases the compressive strength of concrete. The compressive strength

Splitting tensile strength is increasedAll over maintenance cost is minimized

CONCLUSION

From all above results we can consider non pathogenic bacteria as a major material for inducing self healing property in concrete.

Now self healing concrete can be said to be future material.

Wang, J., Van Tittelboom, K., De Belie N., and Verstraete, W.. "Use of Silica Gel or Polyurethane

Immobilized Bacteria for Self-healing Concrete." Construction and Building Materials 26.1 (2012): 532-40.Print.

Li, V., University of Michigan, “Self-healing concrete for safer, more durable infrastructure.” Science Daily,22 Apr. 2009. Web. 28 Feb. 2012.

Jonkers, H. M., A. Thijssen, G. Muyzer, O. Copuroglu, and Schlangen, E. "Application of Bacteria as Selfhealing Agent for the Development of Sustainable Concrete." Elsevier. Elsevier B.V., 30 Dec. 2008. Web. 25Feb. 2012.

Referrence

Brownell, Blaine. "Self-Healing Concrete." Architect, The AIA Magazine (2011): 90-91. Print. O'Driscoll, Cath. "Bacteria Fill in the Gaps in Concrete." Chemistry & Industry (2010). Web. 11 Feb. 2012.

Zwaag, S. Van Der, and Schmets A. J. Self Healing Materials: An Alternative Approach to 20 Centuries of Materials Science. Dordrecht, The Netherlands: Springer, 2007. Print.

Yonkers, H. M., and E. Schlangen. "Crack Repair by Concrete-immobilized Bacteria." Proc. of First International Conference on Self Healing Materials, Delft University of Technology, Noordwijk Aan Zee. Springer, 2007. Print