Concrete has had a bad reputation over the years, but what if bacteria could provide a solution?
Imagine introducing green technology that embeds self-activating bacteria into concrete. The result is self-healing concrete, and three UK universities are actively working towards bringing this innovation to life.
In this groundbreaking approach, scientists use a ground-borne bacteria called bacilli megaterium to create calcite, a crystalline form of natural calcium carbonate. This calcite can be used to block the concrete's pores, effectively keeping out water and other damaging substances, ultimately prolonging the life of the concrete.
The concept of self-healing concrete is a fusion of two seemingly unrelated fields: civil engineering and marine biology. This innovative idea arose when a civil engineer with no background in microbiology read about applying limestone-producing bacteria to monuments. This led to the intriguing question: could this be used for buildings? The challenge was to find the right bacteria that could not only survive being mixed into concrete but also actively initiate a self-healing process.
When water seeps into a crack, the bacteria swiftly burst out of their protective cases and begin producing limestone. This process seals the gap before it can widen and turn into a pothole.
The potential of this technique is immense. Scientists believe it could significantly extend the lifespan of concrete, eliminate the need for costly repairs, and reduce costs by up to 50%.
Ironically, water is both the problem and the catalyst that triggers the solution. Bacteria are mixed and evenly distributed throughout the concrete but can remain dormant for up to 200 years as long as there is a food source in the form of particles. It's only when concrete's adversary—rainwater or atmospheric moisture—enters the cracks that the bacteria spring into action, producing the limestone needed to repair the damage. This process is reminiscent of how osteoblast cells in our bodies mend bones.
Repairing cracks the traditional way can be a significant expense. In the UK alone, an estimated £40 billion is spent annually on the repair and maintenance of structures, the majority of which are constructed from concrete.
The project is currently piloting three separate concrete-healing technologies in real-world settings. The goal is to merge these techniques into a single system that can autonomously repair concrete in the built environment.
The first technique involves shape-shifting materials, known as shape-memory polymers, which can repair large cracks in concrete when heated with a small current. The second technique employs a network of thin tunnels through which both organic and inorganic healing agents are pumped into the concrete to facilitate repairs.
The third technique embeds tiny capsules or lightweight aggregates in the concrete, containing both bacteria and healing agents. Once cracks occur, these capsules will discharge, and in the case of the bacteria, nutrients will enable them to produce calcium carbonate, healing the cracks.
The ultimate aim of the project is to develop a single system that can be embedded into concrete during the initial setting process. This system will autonomously detect damage and perform repairs without the need for human intervention.
Self-healing concrete is a remarkable innovation inspired by nature, showing that intelligent design exists throughout the created world. HostRooster is excited to be part of the journey toward more sustainable and efficient construction practices.