Self-Healing Concrete (Biocrete) and Self-Sensing Concrete: Innovations in Smart Infrastructure

By Shashikant Nishant Sharma

Concrete is the backbone of modern infrastructure, used in roads, bridges, buildings, and various other structures. However, traditional concrete is prone to cracks and degradation over time due to environmental factors, load-bearing stress, and other wear and tear. This deterioration leads to costly repairs and maintenance, significantly impacting infrastructure longevity and sustainability.

In response to these challenges, two cutting-edge innovations—self-healing concrete (also known as biocrete) and self-sensing concrete—have emerged. These smart materials are designed to enhance the durability and resilience of concrete, thereby reducing maintenance costs, improving safety, and extending the lifespan of infrastructure. This article delves into these revolutionary technologies, their mechanisms, benefits, challenges, and real-world applications.

1. Self-Healing Concrete (Biocrete)

a) What is Self-Healing Concrete?

Self-healing concrete is a type of concrete designed to autonomously repair cracks and micro-cracks as they develop, without the need for external human intervention. Traditional concrete is prone to cracking due to mechanical stress, temperature fluctuations, and water ingress, which eventually weakens the structure. Self-healing concrete addresses this issue by incorporating materials or agents that react to crack formation and “heal” the structure by filling in gaps before they propagate into larger issues.

A prominent form of self-healing concrete, known as biocrete, leverages biological agents (specifically bacteria) to induce self-healing. Biocrete uses bacteria that precipitate calcium carbonate, which seals the cracks in the concrete.

b) Mechanisms of Self-Healing Concrete

Several mechanisms are used to enable concrete to heal itself, including biological, chemical, and encapsulation methods. i) Biological Healing (Bacteria-Based Self-Healing)

Biocrete uses specific strains of bacteria (typically from the genus Bacillus) that remain dormant in the concrete until cracks appear and moisture enters the material. The healing process works as follows:

1. Embedding Bacteria and Nutrients: The concrete mix is embedded with bacterial spores and nutrients (usually calcium lactate). These bacteria are hardy and can remain dormant for years.
2. Crack Formation: When cracks form in the concrete and water penetrates, the dormant bacteria are activated by the moisture.
3. Calcium Carbonate Precipitation: Upon activation, the bacteria consume the calcium lactate and produce calcium carbonate (limestone) as a byproduct. This calcium carbonate fills in the cracks and seals the gap.
4. Healing the Structure: As the calcium carbonate solidifies, it restores the structural integrity of the concrete.

This bio-based healing mechanism is environmentally friendly and helps reduce maintenance costs while extending the lifespan of concrete structures.

ii) Chemical Self-Healing (Polymer-Based)

Another approach to self-healing concrete involves the use of encapsulated healing agents, such as polymers or adhesives. Another approach to self-healing concrete involves the use of encapsulated healing agents, such as polymers or adhesives. These capsules are mixed into the concrete during production:

References

Amjad, H., Zeb, M. S., Khushnood, R. A., & Khan, N. (2023). Impacts of biomimetic self-healing of Lysinibacillus boronitolerans immobilized through recycled fine and coarse brick aggregates in concrete. Journal of Building Engineering, 76, 107327.

Hayakawa, M., Matsuoka, Y., & Shindoh, T. (1993). Development and application of superworkable concrete. In Special Concretes-Workability and Mixing (pp. 185-192). CRC Press.

Sharma, S. N., Prajapati, R., Jaiswal, A., & Dehalwar, K. (2024, June). A Comparative Study of the Applications and Prospects of Self-healing Concrete/Biocrete and Self-Sensing Concrete. In IOP Conference Series: Earth and Environmental Science (Vol. 1326, No. 1, p. 012090). IOP Publishing.