The green technology embeds self-activating bacteria into concrete to make it self-healing, but will it win over a risk-averse construction industry?
Hendrik Jonkers, a microbiologist at Delft University and a finalist at the recent 10th annual European Inventor Awards, has a plan to increase the lifespan of concrete. His innovation, which embeds self-activating limestone-producing bacteria into building material, is designed to decrease the amount of new concrete produced and lower maintenance and repair costs for city officials, building owners and homeowners.
Jonkers’ self-healing concrete marries two fields: civil engineering and marine biology.
“One of my colleagues, a civil engineer with no knowledge of microbiology, read about applying limestone-producing bacteria to monuments [to preserve them],” Jonkers said. “He asked me: ‘Is it possible for buildings?’ Then my task was to find the right bacteria that could not only survive being mixed into concrete, but also actively start a self-healing process.”
When it comes to Jonkers’ concrete, water is both the problem and the catalyst that activates the solution. Bacteria (Bacillus pseudofirmus or Sporosarcina pasteurii) are mixed and distributed evenly throughout the concrete, but can lie dormant for up to 200 years as long as there is food in the form of particles. It is only with the arrival of concrete’s nemesis itself – rainwater or atmospheric moisture seeping into cracks – that the bacteria starts to produce the limestone that eventually repairs the cracks. It’s a similar process to that carried out by osteoplast cells in our body which make bones.
The invention comes in three forms: a spray that can be applied to existing construction for small cracks that need repairing, a repair mortar for structural repair of large damage and self-healing concrete itself, which can be mixed in quantities as needed. While the spray is commercially available, the latter two are currently in field tests. One application that Jonkers predicts will be widely useful for urban planners is highway infrastructure, where the use of de-icing salts is notoriously detrimental to concrete-paved roads.
Encouraging as it sounds, Jonkers’ self-healing concrete can’t cure very wide cracks or potholes on roads just yet; the technology is currently able to mend cracks up to 0.8mm wide.
More Reading: http://edition.cnn.com/2015/05/14/tech/bioconc