Innovative Self-Healing Concrete Technology for Sustainable Construction

SELF HEALING CONCRETE BIO-CONCRETE Prabhat kumar sahu 0901109200 Civil engg

INTRODUCTION 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.

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.

Bacillus subtilis(JC3) JC3 is a gram +ve bacteria Can be cultivated easily in lab with minimum cost It is non- pathogenic

EXPERIMENTAL PROGRAMME Objectives Experimental procedure Chemical reactions Experimental results

OBJECTIVE Analysis of compressive strength with varying bacterial con. Analysis of split tensile strength . Effect of bacterial conc. on different grades of concrete

Procedure 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.

When cracks are formed ,the local palates also breaks releasing JC3 Water also seeps through cracks Bacterial spores germinates when comes in contact with H2O JC3 feeds on Calcium lactate forming CaCO3 which precipitates on cracks. This process is known as Microbiologically Induced Calcium Carbonate precipitation(MICCP)

Chemical process MICCP involves a complicated chain of reaction. But can sum up to following two steps Ca2+ + Cell Cell-Ca2+ Cell-Ca2+ + CO32- Cell-CaCO3

Surface 1 :Concrete surface Surface 2 : CaCO3 ptt

PLAIN CONCRETE BACTERIAL CONCRETE

Experimental results Cell Conc./ml of water Compressive strength (28 days)(Mpa) 51.81 % increase _ NIL 58.02 11.99 10^4 61.79 10^5 16.15 57.21 10.42 10^6 54.66 5.51 10^7

Compressive strength (28 days) Grade of concrete Controlled concrete (Mpa) Bacterial concrete (Mpa) % increase 28.18 32.74 16.18 M 20 51.19 60.17 17.54 M 40 72.61 94.21 M 60 29.75 93.8 119.2 M 80 27.08

Spliting tensile strength No of days Controlled concrete (Mpa) 3.78 Bacterial concrete (Mpa) 4.30 %increase 13.75 7 4.62 5.28 14.28 14 4.85 5.74 18.35 28

Prctical use 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.

CONCLUSION 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 increased All over maintenance cost is minimized

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.

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