Under the guidance of,

Dr. P.C SABUMON

Effect of “bacterial concrete” on REINFORCED CONCRETE beams

Department of Civil EngineeringSchool of Mechanical and Building Sciences

VIT UniversityChennai Campus

PRESENTED BY,

BALAJI..N

(13MST1028)

Cracks in concrete are inevitable and are one of the inherent weaknesses of concrete. Water and other salts seep through these cracks, corrosion initiates, and thus reduces the life of concrete.

Remediation of already existing cracks has been the subject of research for many years.

The various products such as structural epoxy, resins, epoxy mortar and other synthetic mixtures are used as a filling agents for repairing concrete, but these are neither environment friendly nor safe.

Scope

The materials that are capable of controllable response to the environment are called smart materials.

A dumb material can be made smart by combining them with microorganisms.

In the study microorganism added are, Bacillus pasteurii, common soil bacteria. Since the cracks are remediated by the microorganisms the process is called the microbiologically-enhanced crack remediation (MECR) process.

To repair minor/micro cracks of concrete by bacterial action.

Cast specimen and test for load to crack and treat with bacterial biomass and study the repairing action.

OBJECTIVE

SL NO NAME OF AUTHOR YEAR RESEARCH WORK

1)

2)

3)

4)

Ramakrishnan et al

Barabesi et al

Day J L et al

Muynck et al

2001

2007

2003

2008

microbiologically induced calcite (CaCO3) precipitation. (MICP) is reported by the research group

he has studied calcite formation by Bacillus subtilis, in order to identify genes involved in the biomineralization process.

This paper describes the results of an innovative approach in concrete crack remediation utilizing microbiologically induced calcite .

Shortcomings of conventional surface treatments have drawn the attention to alternative techniques for the improvement of the durability of concrete. .

LITERATURE REVIEW

SL NO NAME OF AUTHOR YEAR RESEARCH WORK

1)

2)

3)

4)

Leuschner et al

Marvasi et al

Patil et al

Nagaraj et al

2001

2009

2008

2004

Research was conducted to examine the effects of dehydration and rehydration on radioactive phosphorous and carbon molecular mobility in dormant Bacillus subtilis spores.

They have chosen Bacillus subtilis 168 as their model to study which physiological aspects are associated with calcium carbonate (calcite) formation during biofilm development when grown on precipitation medium.

Efficiency of Microbiologically Enhanced Crack Remediation was evaluated by comparing the compressive strengthcheck in involvement. of Bacillus pasteurii in calcite precipitation.

He says that for proportioning concrete mixes water cement ratio becomes a dominant factor, when the strength of concrete is lesser than that of aggregate characteristic.

LITERATURE REVIEW

• Bacterial concrete is a self-remediating biomaterial, in which microorganisms, Bacillus pasteruii, a common soil bacterium, are added which can continuously precipitate calcite, which fills the cracks.

• The phenomenon of calcite precipitation is called Microbiologically Induced Calcium Carbonate Precipitation (MICCP).

• Actually bacterial concrete is not a concrete. Bacteria are just introduced either on the hardened concrete or into the concrete before placing.

What is Bacterial Concrete?

• Microorganism - Bacillus pasteuri

• Polymer – Polyurethane

• Medium - Urea-CaCl2

Components of Bacterial concrete

METHODOLOGYReview of literature

Study of bacterial concrete

Comparison of crack before and after injecting bacteria using NDT

Application of load induce hair pin crack find crack

width using NDT

Preparing the reinforced concrete beams

Bacterial injection to beam in medium and curing

Result

MATERIALS AND METHODS Ordinary Portland cement of 53 Grade.Size of beam available in our lab 100*100*500.

BACTERIAL SOURCES Microorganisms Bacillus pasteurii and Bacillus sphaericus

were obtained pure bacterial culture was isolated named as isolate 1 from curing tank at Civil Engineering PG Research lab, M S Ramaiah Institute of Technology Bangalore.

Test procedure

Using the compression testing machine, care should be taken for inducing very minor crack like hair pin crack.

Crack width has to be determined using NDT.

Cracks formation and finding the width of the crack

Medium of Bacterial Concrete•Three different mediums were selected for test.•Water•Phosphate-buffer solution•Urea-CaCl2

The beam specimens after de-molding are immersed in triplicates in respective bacterial solution grown overnight separately for 24hrs. After 24hrs the beam are wiped with a blotting paper to remove any surface bacteria and cured in corresponding calcite precipitation media (Calcium source 49gm/Lt + Urea 20g/Lt) at room temperature (Figure) until compression testing at the intervals of 7, 14 and 28 days. Media were replaced at a regular interval of 7 days. Control samples need to be prepared in similar manner and cured in water. Compression testing is performed in compression testing machine.

Method of bacterial treatment by Immersion method

Dr .sookie bang in 2007Dr.v. ramakrishnan in 2007

References