Researchers at Drexel University in Pennsylvania have advanced concrete durability by embedding live microorganisms within the material. The team reports their findings in the peer review journal Construction and Building Materials (CBM), shedding light on a novel approach to reinforcing concrete from within.
To achieve this, the scientists employed a hydrogel rich in bacteria paired with a sturdy polymer fiber that is encased in a protective shell. This combination creates a living reinforcing system, enabling concrete to better resist cracking and to respond dynamically to damage rather than merely bearing load at the moment of construction.
According to the researchers, this microbial reinforcement slows crack growth and can promote repair through a self-healing process. When a fissure forms, the embedded microorganisms become active participants in restoring integrity, reducing the need for exterior interventions and extending the service life of the material in structural applications.
The team isolated the bacterial strain Lysinibacillus sphaericus as the bioremediation agent. These hardy microorganisms are commonly found in soil and have the capacity to initiate microbial calcium carbonate precipitation. This biological reaction yields a mineral-like substance that can fill and solidify cracks, effectively patching damaged zones inside the concrete matrix.
Lysinibacillus sphaericus is capable of surviving the harsh interior environment of cured concrete and remains dormant until moisture becomes available. When water infiltrates a crack, the hydrogel expands and pushes through the protective shell toward the defect. At the same time, the bacteria react with calcium ions present in the concrete to precipitate calcium carbonate, which serves to seal cracks and restore surface continuity. The researchers report that, on average, the microorganisms recover activity within one to two days, resuming the healing process as conditions permit.
Earlier research explored materials for bone regeneration, but the current study demonstrates how living microstructures can play a direct role in the longevity and resilience of civil infrastructure by transforming how concrete heals itself after damage.