Self Healing concrete is the future in construction industry. This concrete technique will help improving building/infrastructure life span.

1. Presentation
on
Advance Concrete Technology – “Self Healing Concrete”
By
Ravichandra G

2.  Introduction about Cement
 Introduction about Concrete & Concrete Technology
 Classification of Concrete
 Advancement in Concrete
 Classification of Advance or Special Concrete
 Introduction to Self Healing Concrete
 Need of Self Healing Concrete
 Production of Self Healing Concrete
 Advantages & Disadvantages with Cost Analysis
 Feasibility & References
Contents

3. Introduction on Cement and Concrete
What is Cement ?
“A cement is a binder, an inorganic substance used for construction that sets, hardens, and adheres to
other materials to bind them together”
“ Various trials and tests were done by Romans and Egyptians for binding materials using lime
combinations but first portland cement was invented and patented by Joseph Aspdin in 1824 in
England”
What is Concrete?
“ There are various definitions for the concrete but in simple terms, it can be defined as an artificial
hardened stone formed over time by the combination of binder, aggregates, water and with or without
use of admixtures and additives in proportions is called Concrete”
 Cement Concrete is the only second material which is extensively consumed in quantity wise, first
place being taken by food by the human beings.

4. Concrete Technology
What is Concrete Technology ?
“Can be defined as that branch of Civil Engineering which deals with the study of concrete, its design,
practical applications and properties is called Concrete Technology”

5. Classification of Concrete
Concrete is classified as per IS 456-2000
 Ordinary Concrete
 Standard Concrete
 High Strength Concrete

6. Advancement in Concrete
The last two decades have seen an enormous advances in concrete technology especially in High
strength concrete, durable concrete using Flyash, PPC, GGBS, Fibres, Polymers etc.
A wide range of research and innovations have been done all over the world in concrete technology to
meet the demands of the human society. Some of the new age concrete is as follows.
 Light weight concrete
 Fibre reinforced concrete
 Polymer concrete
 Self compacting concrete
 Self curing concrete
 Self Healing Concrete

7. Introduction to Self Healing Concrete
 This next-generation concrete does not break off like conventional concrete does. However, it
usually bends due to overuse or under stressful conditions and at the most develops minute fissures.
 Nevertheless, these cracks are easily taken care of by the reaction that takes place between the
exposed material and natural elements which are mixed while producing concrete.
Calcium carbonate, a strong substance, is automatically created when the open surfaces of these
tiny crevices come in contact with rainwater or high moisture and with carbon dioxide present in the
air.
 Once it is created, calcium carbonate fills and effectively seals of the cracked areas of the concrete
making it as sturdy as before.
 The applications of this new type of concrete are immense and it is bound to leave its mark on the
construction industry across the globe.

8. Why Self Healing Concrete Needed ?
 Cracks in concrete are inevitable and are one of the inherent weaknesses of concrete due to loading
and unloading cycles repeatedly.
 Water and other salts seep through these cracks, corrosion initiates, and thus reduces the life of
concrete.
 The cracks repairs are time consuming, expensive affair and has accessibility issues.
 So there was a need to develop an inherent biomaterial, a self-repairing material which can
remediate the cracks and fissures in concrete. Bacterial concrete is a material, which can successfully
remediate cracks in concrete.
 This technique is highly desirable because the mineral precipitation induced as a result of microbial
activities is pollution free and natural.

9. Self Healing Concrete – Research Initiation
Jonkers, a microbiologist, began working on it in 2006, when a concrete technologist asked him if it
would be possible to use bacteria to make self-healing concrete. It took Jonkers three years to crack the
problem - but there were some tricky challenges to overcome. "You need bacteria that can survive the
harsh environment of concrete," says Jonkers. "It's a rock-like, stone-like material, very dry." Concrete is
extremely alkaline and the "healing" bacteria must wait dormant for years before being activated by
water. Jonkers chose bacillus bacteria for the job, because they thrive in alkaline conditions and produce
spores that can survive for decades without food or oxygen.
"The next challenge was not only to have the bacteria active in concrete, but also to make them
produce repair material for the concrete -- and that is limestone," Jonkers explains. In order to
produce limestone, the bacilli need a food source. Sugar was one option, but adding sugar to the mix
would create soft, weak, concrete. In the end, Jonkers chose calcium lactate, setting the bacteria and
calcium lactate into capsules made from biodegradable plastic and adding the capsules to the wet
concrete mix. When cracks eventually begin to form in the concrete, water enters and open the
capsules. The bacteria then germinate, multiply and feed on the lactate, and in doing so they combine
the calcium with carbonate ions to form calcite, or limestone, which closes up the cracks

10. Properties of Self Healing Concrete
Self healing bacterial concrete Autogenously crack-healing capacity of concrete has been recognized in
several recent studies. Mainly micro cracks with widths typically in the range of 0.05 to 0.1 mm have
been observed to become completely sealed particularly under repetitive dry/wet cycles.
The mechanism of this autogenously healing is chiefly due to secondary hydration of non- or partially
reacted cement particles (about 15 to 20%) present in the concrete matrix. Due to capillary forces water
is repeatedly drawn into micro cracks under changing wet and dry cycles, resulting in expansion of
hydrated cement particles due to the formation of calcium silicate hydrates and calcium hydroxide in
turn calcium carbonate.
On the crack surface of control concrete, some calcium carbonate will be formed due to the reaction of
CO2 present in the crack ingress water with Portlandite (calcium hydroxide) present in the concrete
mixture according to the following reaction: CO2 + Ca(OH)2 → CaCO3 + H2O

11. Microbial Class Used in Self Healing Concrete
Types of Bacillus Bacterial Family
 Bacillus Alkalinitrulicus
 Bacillus Pasterurii
 Bacillus Sphaericus
 Bacillus Subtilis
 Bacillus Cohnii
 Bacillus Balodurans
 Bacillus Pseudofirmus
 Escherichia Coli

12. Typical Bacillus Microscopic Picture
Bacteria in Action

13. Self Healing Concrete – Healing Process
When the concrete is mixed with bacteria (bacillus subtilus), the bacteria go into a dormant state, a lot
like seeds. All the bacteria need is exposure to the air to activate their functions. Any cracks that should
occur provide the necessary exposure.

14. Self Healing Concrete – Healing Process
When the cracks form, bacteria very close proximity to the crack, starts precipitating calcite crystals.
When a concrete structure is damaged and water starts to seep through the cracks that appear in the
concrete, the spores of the bacteria germinate on contact with the water and nutrients. Having been
activated, the bacteria start to feed on the calcium lactate nutrient. Such spores have extremely thick
cell walls that enable them to remain intact for up to 200 years while waiting for a better environment
to germinate.

15. Self Healing Concrete – Healing Process
In the bacterial self healing process, as the bacteria feeds oxygen is consumed and the soluble calcium
lactate is converted to insoluble limestone. The limestone solidifies on the cracked surface, thereby
sealing it up the gap around the bacteria and in turn crack is sealed.

16. Self Healing Concrete – Chemical Reactions Involved
On the crack surface of concrete, some calcium carbonate will be formed due to the reaction of CO2
present in the crack ingress water with Portlandite (calcium hydroxide) present in the concrete mixture
according to the following reaction:
CO2 + Ca(OH)2 → CaCO3 + H2O
The self healing process in bacterial concrete is much more efficient due to the active metabolic
conversion of calcium lactate by the present bacteria:
Ca(C3H5O2)2 + 7O2 → CaCO3 + 5CO2 + 5H2O
This process does not only produce calcium carbonate directly but also indirectly via the reaction of on
site produced CO2 with Portlandite present on the crack surface. In the latter case, Portlandite does not
dissolve and diffuse away from the crack surface, but instead reacts directly on the spot with local
bacterially produced CO2 to additional calcium carbonate.

17. Self Healing Concrete – Practical Applications
 Nuclear Reactors – Where there is no space for any cracks resulting in hazardous radiation pollution
 Concrete Road Works – Repairs can be mitigated to avoid traffic jams
 Oil and Gas Industries – Where air and water tightness is prime importance
 Strengthening of building – Existing & New
 Extreme Temperature Zones – Where thermal expansion and contracting is more
 Irrigation Projects – Like Dams and other water bodies where even the minutest cracks can lead to
disaster
 Complex Structure – Where accessibility and human interference becomes extremely difficult.

18. Self Healing Concrete – Advantages
 Self healing concrete is very less permeable compared to ordinary concrete over time
 It is an eco friendly technique and non hazardous to the environment
 Even the minutest cracks will be attended by self healing process, there by protecting even steel
reinforcement.
 Relief to the engineers, who cannot access the fine fissure area in a complex structures
 Un-hydrated cement particles, which is in the concrete mass will be automatically utilized for
providing strength at the fissured area in the self healing process
 Increased durability of the structure

19. Self Healing Concrete – Disadvantages
 The volume occupied by the bacteria in the concrete replaces the cementitious part, hence there
will be slight reduction in strength.
 Preparation of self healing concrete needs the requirement of bacteria and calcium lactate.
Preparation of calcium lactate from milk is costlier. Hence preparation of self healing concrete costs
considerable high.
 Full technological utilization of the concrete cannot be used, as it is costlier and because of that, only
in very important structure or at highly in accessible area, it can be utilized.
 Still under research and easily not produced in any local RMC’s.
 Skilled supervision is required in production of concrete

20. Self Healing Concrete – Cost Analysis
 The cost of using microbial concrete compared to conventional concrete is critical in determining the
economic feasibility of the technology. The cost analysis showed an increase in cost of 2.3 to 3.9
times between microbial concrete and conventional concrete with slight decrease of grade.
 The major contributor to the cost of the bacterial mix is the nutrient broth, amounting to over 60-
75% of the cost per cubic meter of concrete. Therefore, further research needs to be devoted to
decrease the amount of the nutrient broth used or to find a cheaper alternative source for bacteria
nutrition in order to make the technology financially feasible. Nevertheless, it is believed that
microbial concrete will yield cost reductions on the long run.
 In the market bacteria is available is lyophilized state. So cost depends on the surface treatment area
or volume of concrete used. Nutrients used for this study are laboratory nutrients which are quite
expensive so other inexpensive nutrient sources can also be tried to reduce the commercial
production cost of bacterial concrete.
 The cost of 500 grams of HIMEDIA M002 nutrient broth powder costs about 2300 rupees so to
prepare one litre of nutrients mixed bacterial culture costs Rs 60. In this project nearly 125 liters of
nutrients mixed bacterial culture was used costing nearly 7500 rupees.

21. Self Healing Concrete – Cost Analysis

22. Self Healing Concrete – Feasibility
 Since the cost of using microbial concrete compared to conventional concrete is 2.3 to 3.9 times
more expensive than the conventional concrete with slight decrease of grade. So other inexpensive
nutrient sources can also be tried and tested to reduce the commercial production cost of bacterial
concrete.
 Though there is absolute no doubt that the self healing concrete is another landmark in concrete
research and as a result there will be milestones achieved in the construction industry in terms of
durable structures and great value for money saying “Built to last and not to repair”.
 It just needs another research step towards economy and practical production in the local RMC’s
with further improvements that can be brought.
“Concrete is marvelous, handle with Care and it will care you for lifetime”

23. References
 Antonopoulou, S. Self healing in ECC materials with high content of different microfibers and micro particles, MSc Thesis, Delft
University of Technology, 2009
 De Muynck, W., Debrouwer, D., De Belie, N., Verstraete, W., 2008. Bacterial carbonate precipitation improves the durability of
cementations materials. Cement & Concrete Res. 38, 1005–1014.
 Bang, S.S., Galinat, J.K., Ramakrishnan, V., 2001. Calcite precipitation induced by polyurethane-immobilized Bacillus pasteurii.
Enzyme Microb. Technol. 28, 404-409
 Jonkers, HM & Schlangen, E. (2009a). Bacteria-based self healing concrete. International journal of restoration of buildings
and monuments, 15(4), 255- 265.
 Jonkers, HM, Thijssen, A, Muijzer, G, Copuroglu, O & Schlangen, E. (2009b). Application of bacteria as self healing agent for the
development of sustainable concrete. Ecological engineering, 1-6.
 International Journal of Modern Trends in Engineering and Research (IJMTER), Volume 2, Issue 7, [July-2015] Special Issue of
ICRTET’2015
 J. Wang K.Van Tittelboom N. De Belie, W.Verstraete 2012 – Construction Building Materials 26(1) (2012) 532-540 – Use of silica
gel or polyurethane immobilized bacteria for self-healing concrete.
 M. Luo, C.x. Qian, R.-y. Li, 2014 – Construction Building Materials 87 (2015) 1-7. – Factors affecting crack repairing capacity of
bacteria based self healing concrete.
Contd………..

24. References
 F.Hammes, W.Verstraete – Rev.Environ. Sci. Biotechnology 1(1)(2002) 3-7. – Key roles of pH and calcium metabolism in microbial carbonate
precipitation.
 Gupta Souradeep Pang Sze Dai, Kua Harn Wei a – Construction and Building Materials 146 (2017) 419-428 – Autonomous healing in concrete by
bio-based healing agents – A review
 Potential application of Bacteria to improve the strength of cement concrete. C. C. Gavimath*, B. M. Mali1, V. R. Hooli2, J.D.Mallpur3, A. B.
Patil4, D. P. Gaddi5, C.R.Ternikar6 and B.E.ravishankera7.
 Aldea, C.-M.; Song, W.-J.; Popovics, J.S.; Shah, S.P. Extent of healing of cracked normal strength concrete. J. Mater. Civ. Eng. 2000, 12, 92–96.
 Edvardsen, C. Water permeability and autogenous healing of cracks in concrete. ACI Mater. J. 1999, 96, 448–454

25. Thank you
“Research never sleeps”