Cracking up over BioFibre: self-healing concrete is no joke

This approach could transform the construction industry as well as have profound implications for environmental sustainability.

Concrete is one of the most extensively used construction materials worldwide, but it faces challenges such as degradation and cracking over time, and it is these issues often lead to costly repairs or replacements, contributing to environmental concerns due to the carbon footprint associated with concrete production.

An introduction to BioFibre

Led by Amir Farnam, PhD., Drexel University's College of Engineering researchers have pioneered the development of BioFibre – a polymer fibre coated with a hydrogel containing bacteria, encapsulated within a protective, damage-responsive shell.

This design is inspired by the self-healing capabilities of human skin, where a multilayer fibrous structure infused with blood naturally repairs tissue damage​​.

Mechanism of self-healing

When a crack forms in the concrete, water infiltrates and reaches the BioFibre, triggering the hydrogel to expand. This expansion causes the hydrogel to emerge from the shell and reach the crack's surface.

Concurrently, the bacteria, which remain dormant in the form of endospores within the harsh concrete environment, become activated. These bacteria, specifically a strain of Lysinibacillus sphaericus, are known for their ability to initiate a process known as microbial induced calcium carbonate precipitation. This process results in the formation of a stone-like material that fills and stabilises the cracks​​​​.

Environmental and economic benefits

The environmental impact of this technology is noteworthy as the standard production of concrete is a huge contributor to global greenhouse gas emissions.

By enhancing the lifespan of concrete structures and minimising the need for frequent repairs or replacements, BioFibre can reduce the overall carbon footprint associated with concrete. This is an innovation that aligns with global efforts to curb greenhouse gas emissions and addresses the demand for more sustainable building materials​​​​.

Despite the technology showing promise, further research is needed to fully understand the kinetics of the self-repair process and its long-term effectiveness; however, the early indications are positive, suggesting that the bacteria could repair cracks in as little as one to two days. This development opens the door to the possibility of a 'living' concrete infrastructure that can extend its lifespan and reduce maintenance costs​​.

Collaborative effort

The success of the BioFibre project is attributed to the collaborative effort of a multidisciplinary team at Drexel University. Integrating expertise from civil engineering, biology, chemistry, and materials science, the team has set new standards in the development of sustainable construction materials​​.

By harnessing the power of biomineralizing bacteria and innovative material design, this self-healing concrete could lead to longer-lasting, more environmentally friendly infrastructure, addressing some of the most pressing challenges faced by the construction industry today.