Despite being susceptible to degradation, concrete is still the most used construction material worldwide. It is a critical component of our infrastructure, from flood defences and tunnels to hospitals, bridges and dams.
As worldwide concern increases over climate change, the building sector is seeking alternative sustainable building materials and innovative construction solutions. This is vital to reduce the UK's eco footprint and mitigate the projected doubling of cement-based CO2 emissions by 2050.
Reducing concrete-based pollution
Instead of using more concrete to repair existing structural damage, our researchers are developing healing technologies that will enable concrete to repair and maintain itself without human intervention.
This self-healing concrete comes with major benefits. It could prolong the life of our core infrastructure which will have a big impact on construction supply chains. It has the potential to change the way we manage and maintain our built environment in the future.
The research builds on new approaches to repair concrete discovered in the Resilient Materials for Life (RM4L) project. Led by Professor Kevin Paine and Dr Susanne Gebhard, our civil engineers and microbiologists have found bacteria in natural habitats that reflect the conditions found in the built environment. They are using this to create novel bacteria-based self-healing and self-sensing concrete that can adapt to its environment. It has the ability to develop immunity to harmful actions, self-diagnose the onset of deterioration and self-heal in response to damage.
Taking advantage of nature in construction
Bacteria are found in almost any habitat on Earth, and one key to their success is their extraordinary ability to monitor their environment and respond to changes and stresses they might encounter.
Our researchers add bacterial spores to a concrete mix, along with growth media. If the concrete cracks, the bacteria are released and exposed to oxygen and water. They feed on the growth media, they multiply, and as a result of metabolic actions, calcium carbonate, or limestone, forms to seal the crack before it has a chance to enlarge.
The team based in our Departments of Architecture & Civil Engineering, and Biology & Biochemistry, have also been carrying out trials using the bacteria at different temperatures. So far, they have mainly tested the bacteria in concrete at around 20 degrees.
As a further technological advancement, they have designed concrete mixes with dormant bacteria proven to survive extreme conditions. They are using psychrotrophic bacteria which are isolated from local limestone caves and can grow at low temperatures to initiate crack healing.
Professor Kevin Paine explains:
This is truly ground-breaking stuff. What we know about bacteria tends to come from medicine, so we know plenty about how they behave at body temperature. How they operate at, say, five degrees, we just have to find out for ourselves.