Concrete is the most widely used building material in the world, but it has a significant environmental impact, accounting for approximately 8% of global CO₂ emissions. One of the challenges with concrete structures is their susceptibility to cracks, which compromise durability and safety. However, researchers are exploring innovative solutions, including self-healing concrete that incorporates bacteria capable of repairing damage autonomously.

The Role of Bacteria in Self-Healing Concrete
One promising development involves the use of Sporosarcina pasteurii, a bacterium that can induce calcium carbonate precipitation, effectively sealing cracks in concrete. Traditionally, embedding living bacteria into concrete has been challenging, as they require specific conditions to survive and remain active over time. Recent research, however, has shown that freeze-dried Sporosarcina pasteurii retains its self-healing functionality for months, making it a practical and scalable solution for construction applications.

Freeze-Drying for Scalability and Longevity
Recent advancements in freeze-drying techniques have improved the storage and usability of Sporosarcina pasteurii. Scientists have demonstrated that by suspending the bacteria in sucrose-based solutions before freezing, they remain viable for at least three months in resealable plastic bags. This allows construction workers to store and transport the bacteria easily, applying them on-site when needed.

Further experiments tested the bacteria in sand-based environments, including 3D-printed cylindrical moulds. When the freeze-dried bacteria were rehydrated and mixed with urea and calcium chloride, they successfully produced biocement, strengthening the sand structures. Field tests further confirmed that applying the bacteria to soil enhanced its stability within 24 hours, making this approach viable for both structural reinforcement and emergency repairs.

From Laboratory to Construction Site
Laboratory experiments demonstrated that freeze-dried bacteria, once rehydrated, successfully produce the necessary minerals to heal concrete cracks. Scientists confirmed the viability of this method through controlled tests and simulated environmental conditions. The next step is to scale up this technology for real-world applications, where it could significantly extend the lifespan of concrete structures, reduce maintenance costs, and lower overall material consumption.

Sustainability and Circularity in Construction
The potential of self-healing concrete extends beyond durability. By reducing the need for frequent repairs and replacements, this technology contributes to more sustainable building practices. Additionally, using biological processes for material regeneration aligns with the principles of circular design, minimising waste and enhancing resilience in the built environment.

For architects, landscape designers, and product developers focusing on sustainable construction materials, bio-based innovations like self-healing concrete offer exciting opportunities. This advancement could lead to smarter, more durable infrastructure while addressing the carbon footprint of the construction industry.

Sources: Change Inc., ScienceDaily
Photo: wal_172619