Self-healing 'living concrete'

Scientists have developed what they call living concrete by using sand, gel and bacteria.

Researchers said this building material has structural load-bearing function,is capable of self-healingand is more environmentally friendly than concrete – which is the second most-consumed material on Earth after water.

The team from the University of Colorado Boulder believe their work paves the way for future building structures that could “heal their own cracks, suck up dangerous toxins from the air or even glow on command

Self-healing 'living concrete' is an innovative building material that integrates biological and concrete technologies to enhance durability and sustainability. This material combines traditional concrete with bacteria that can heal cracks and improve the overall lifespan of structures. Here's a detailed look at how it works and its components:

Components and Mechanism

1. Concrete Matrix:

   • Traditional Concrete: The base material consists of conventional concrete, which includes cement, aggregates (sand and gravel), and water. This provides the structural integrity and strength of the living concrete.

2. Biological Agents:

   • Bacteria: Specially selected strains of bacteria (often from the genus Bacillus) are embedded in the concrete. These bacteria are capable of surviving in harsh conditions and remain dormant until activated.
   • Nutrients: Organic compounds, such as calcium lactate, serve as a nutrient source for the bacteria. These nutrients are mixed into the concrete during the preparation phase.

3. Self-Healing Mechanism:

   • Crack Formation: When cracks form in the concrete due to stress, weathering, or other factors, water can infiltrate these cracks.
   • Bacteria Activation: The presence of water activates the dormant bacteria.
   • Calcite Precipitation: The bacteria metabolize the nutrients (calcium lactate) and produce limestone (calcium carbonate) as a byproduct. This limestone fills and seals the cracks, effectively "healing" the concrete.

Advantages

1. Extended Lifespan: Self-healing concrete can significantly extend the lifespan of structures by reducing the need for repairs and maintenance.
2. Reduced Costs: While the initial cost may be higher, the reduction in maintenance and repair costs over time can lead to overall savings.
3. Environmental Benefits: By reducing the need for frequent repairs and new concrete production, living concrete can lower the carbon footprint associated with construction activities.
4. Enhanced Durability: The self-healing process helps maintain the structural integrity of concrete, preventing the ingress of harmful substances like water and chemicals that can cause further damage.

Challenges and Considerations

1. Cost: The initial cost of self-healing concrete is higher than traditional concrete due to the inclusion of biological agents and nutrients.
2. Performance in Different Environments: The efficiency of the self-healing process can vary depending on environmental conditions such as temperature, humidity, and the presence of water.
3. Scalability: Implementing this technology on a large scale poses logistical and technical challenges that need to be addressed for widespread adoption.

Applications

1. Infrastructure: Bridges, roads, tunnels, and other critical infrastructure can benefit from the enhanced durability and self-repair capabilities of living concrete.
2. Buildings: Residential, commercial, and industrial buildings can use self-healing concrete to reduce maintenance costs and extend the lifespan of the structures.
3. Marine Structures: Structures exposed to harsh marine environments, such as piers and offshore platforms, can significantly benefit from the self-healing properties of living concrete.

Future Directions

Research and development in self-healing concrete are ongoing, with efforts focused on improving the efficiency and cost-effectiveness of the technology. Innovations in microbial engineering, nutrient delivery systems, and material formulations are likely to enhance the performance and applicability of living concrete in various construction scenarios.

In summary, self-healing 'living concrete' represents a significant advancement in building materials, offering the potential for more durable, cost-effective, and environmentally friendly construction practices.