A major trial of self-healing concrete is underway in the South Wales Valleys - thought to be the first to take place in the UK.
The Materials for Life project is piloting three separate concrete-healing technologies in real-world settings, with a view to incorporating them into a single system that could be used to automatically repair concrete in the built environment.
The Cardiff Universtiy-led team behind the project said about £40bn a year was spent in the UK maintaining, fixing and restoring structures such as bridges, buildings, tunnels and roads, many of which are made from concrete.
It said that the overall aim of the project was to develop a single system that could be embedded into concrete as it is initially set and automatically sense when damage occurs. The team said the system would be able to repair itself autonomously without the need for human intervention.
Cardiff University school of engineering principal investigator Bob Lark said: “Our vision is to create sustainable and resilient systems that continually monitor, regulate, adapt and repair themselves without the need for human intervention.
“These self-healing materials and intelligent structures will significantly enhance durability, improve safety and reduce the extremely high maintenance costs that are spent each year.”
The trial is being undertaken in partnership with contractor Costain, and is taking place on the Heads of the Valleys road improvement scheme in South Wales.
The research team, which also includes academics from the University of Bath and the University of Cambridge, is trialling three separate technologies at the site.
The first technique uses shape-shifting materials, known as shape-memory polymers, to repair large cracks in concrete. The team said that when these materials were heated with a small current, they could transform into a different shape that the material has ‘memorised’. The researchers believe that these materials can be embedded into concrete and used to close cracks or make them smaller.
In the second technique, researchers will pump both organic and inorganic healing agents through a network of thin tunnels in the concrete to help repair damage.
In the third technique, the team will embed tiny capsules, or lightweight aggregates, containing both bacteria and healing agents into the concrete. It is anticipated that once cracks occur, the capsules will release the bacteria and nutrients that will enable them to function and produce calcium carbonate. The researchers envisage this will heal the cracks in the concrete.
Researchers have cast six concrete walls at the test site, each containing the different technologies. Over time the team said that it would load the concrete at specific angles to induce cracks, and then monitor how effective each of the self-healing techniques was.
Costain civil engineer Oliver Teall said: “From this trial we should gain an insight into the feasibility of constructing a full-scale structure using these techniques and their early-stage effects on structural properties. We will be monitoring properties such as stiffness, permeability and the mechanical damage recovery of the trial walls in comparison with conventional reinforced concrete walls.”