Three technologies that could lead to self-repairing roads and buildings are being tested in Wales.
As part of the trial underway at a site in the South Wales Valleys, researchers from Cardiff University have built six concrete walls that contain shape-shifting polymers, capsules with bacteria and organic and inorganic healing agents that should keep the walls intact without human intervention.
“Our vision is to create sustainable and resilient systems that continually monitor, regulate, adapt and repair themselves without the need for human intervention,” said Professor Bob Lark, the leader of the project from Cardiff University’s School of Engineering.
“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 researchers envision all three tested technologies will be able to detect damage occurring in the concrete structure and automatically fix it.
The shape-memory polymers have been developed to fill large cracks in the concrete. They need to be heated with a small current to transform into a shape they have been taught previously.
The capsules with bacteria are expected to dissolve when cracks occur, releasing the bacteria that will thus gain access to nutrients and produce calcium carbonate that will heal the cracks.
The third technique involves pumping organic and inorganic healing agents into the concrete through a network of tunnels to help repair damage.
The researchers will first load the concrete walls at specific angles to induce cracks and then monitor how effective each of the self-healing techniques is.
“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,” said Oliver Teall, a civil engineer at Costain, the project’s industrial partner. “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.”
The trial, part of the Materials for Life project, is the first probing of the self-healing technologies in real-world settings and hopes to provide a foundation for their use in future construction projects.
The researchers envision all three technologies should be part of a single self-healing system to be integrated into concrete structures.
At present, billions of pounds are spent every year maintaining, fixing and restoring structures such as bridges, buildings, tunnels and roads.
It is estimated that around £40bn a year is spent in the UK on the repair and maintenance of structures, the majority of which are made from concrete.