Self-healing Concrete: Feasibility and Future in Construction Industry

Self-healing Concrete
Is self-healing concrete a feasible option to reduce long-term maintenance cost? An evaluation
of construction industry’s future
Reference:
Tittelboom, V.K. and Belie, D.N., 2013. Self-healing in Cementitious Materials – A review. Magnel Laboratory for Concrete research, Department of Structure engineering. Belgium .
Li, C.V., 2012. Robust Self-Healing Concrete for Sustainable Infrastructure - Scientific Figure on ResearchGate. Available through: < https://www.researchgate.net/270188811_fig2_Fig-8-Schematic-illustration-of-a-chemical-
encapsulation-self-healing-approach-b>. [Accessed on 7th September, 2017].
Overview of research
Construction industry across the globe faces an issue of damage that is caused to infrastructure
developed so far. This deterioration of buildings, dams, bridges and other structural designs is caused
due to cracks or gaps that arises in concrete slabs. It is with passage of time that concrete or material
used to develop infrastructure gets eroded; which in turn brings up the cracks into structure constructed.
Lime getting filled in Cracks”
Chemical equation
Ca(C3H5O2)2 + 7O2 → CaCo3+5Co2+5H20
Where,
Ca(C3H5O2) is Calcium lactate; and
CaCo3 is lime
In order to meet up the future demand of construction industry; substance named as self-healing
concrete is developed. This concrete is created by mixing up the bacteria named “Genus Becillus” with
calcium-containing nutrients such as calcium lactate, nitrogen & phosphorous with ingredients of
concrete in particular composition. This mixture would help in producing lime on the surface of concrete
slab when exposed to oxygen and water; which in turn is expected to fill the cracks into structure.
Research Aim and objectives
Research Aim “To assess the future of self-healing concrete within context of decline in the long-
term maintenance cost.”
Objective 1 “To evaluate the mechanism of self-healing concrete & its importance.”
Objective 2 “To identify the impact of self-healing concrete in reducing long term maintenance
cost.”
Objective 3 “To assess the application of self-healing concrete in future of civil engineering.”
Objective 4 “To recommend ways to help self-concrete mechanism emerge as cost-effective
and sustainable technique in future.”
Self healing approaches
Self-healing concrete
Intrinsic Self-healing
concrete
Autogenous Healing
Improved autogenous
healing
Healing in polymer
modified concrete
Biological Based self-
healing
concrete
Aerobic bacteria
Anaerobic bacteria
Chemical Based self-
healing concrete
Capsule based self
healing concrete
Vascular based self-
healing concrete
Self- healing approach Description
Intrinsic Self-healing concrete Under the intrinsic methods, healing agents are
not used and changes are made in the concrete
substance or material
Biological-based self-healing concrete Biological Based is the process in which micro-
organisms such as bacteria are used which help
in making the desired changes
Chemical- based self-healing concrete Under chemical based method, healing or
repairing is done through the application of the
artificial healing chemicals
Intrinsic self-healing approach
Mechanism of Biological based Self-healing concrete
The pictures presented herewith shows way in which self-healing concrete fills the gap when comes
into contact with oxygen and water. It is seen that bacteria comes to surface of crack; and it gets
multiplied with exposure to H2O & O2. Finally, the bacteria generates healing substance that fills up
the cracks or gaps into concrete slabs. This in turn indicates that self-healing mechanism of concrete
not only helps in bridging the gap; but also strengthen the building capacity to last for long.
Diagram shows Improved
autogenous healing by three ways:
A) Restriction of crack width;
B) Water supply; and
C) Improved hydration &
crystallization
Chemical Based self-healing concrete
Capsule based self healing
concrete Diagram presented above
depicts: A, B: Exhibits moisture or air
or due to heating
C, D: Presents cementitious matrix
E, F: small, light colored inclusions
shown in matrix G, H: Additional
capsules
Vascular Based self-healing Concrete
It isolates the healing agent through hollow
tubes that are connected towards interior &
exterior of structural design. Diagram presented
above shows flow of healing agent due to
gravitational & capillary forces through: a) One
channel; and b) Multiple channels
Comparison of cost in self-healing & Ordinary concrete
In Self-healing concrete; initial cost is
higher as compare to ordinary concrete.
The same is depicted from diagram; level
of curve B is above A. However, in long
run, cost of maintenance of infrastructure
is lower in case of Self-healing concrete.
Comparison of Repairs in Ordinary & Self-healing
concrete
Conclusion
The research work has brought forward the fact
that self-healing concrete is an effective
mechanism to ensure sustainability of buildings
and other infrastructure. Different scientific
mechanisms are identified to implement the
process. It helps in controlling cost in long-run.
Finally, it can be considered to lay down
foundation for future growth of construction
industry.
Figure 1: Lime getting filled in Cracks
Figure 2: Self healing approaches
Figure 3: Improved autogenous healing by different ways (Source: Tittelboom and Belie,
2013)
Figure 3: Biological self-healing concrete with
examples (Source: Li, 2012) Figure 4: Biological process of self-healing
Figure 5: Capsule & Vascular based self –healing (Source: Tittelboom and Belie, 2013
Figure 6: Comparison of cost
Figure 7: Comparison of Repairs