Bio-Concrete Designed to Self-Repair

TUESDAY, MAY 19, 2015

DELFT, NETHERLANDS—Materials scientists are putting the finishing touches on a decade-long project to make a self-healing concrete infused with bacteria.

The concrete and repair materials are embedded with limestone-producing bacteria capable of repairing cracks, the researchers say.

The new version of the world's most popular building material is set to reach the market this year, courtesy of a team led by microbiologist Hendrick Jonkers at the Delft University of Technology’s Center for Materials.

The concrete will extend the service life of buildings, bridges, tunnels, ushering in a new era for concrete safety,  according to the university.

Jonkers is a finalist for the European Inventor Award 2015, the university notes. This video nomination produced by the European Patent Office offers a detailed explanation of the technology.

How It Works

Development of the “bio-concrete” has been underway for a decade, the university reports.

The scientists found limestone-producing bacteria, naturally occurring near volcanoes and high alkaline lakes, perfect for the concrete repair job, according to research details.

"What makes this limestone-producing bacteria so special is that they are able to survive in concrete for more than 200 years and come into play when the concrete is damaged," Jonkers said in a statement.

The bacteria, along with nitrogen, phosphorus and a calcium-based nutrient known as calcium lactate, are added to the ingredients of the concrete as it is being mixed.

Later, when a crack begins in the concrete, air and moisture awaken the bacteria and it begins to feed on the calcium lactate.

During this process, the bacteria consume oxygen, and the soluble calcium lactate is converted to insoluble limestone that can seal the cracks, the details note.

The technology can seal cracks up to any length provided they have a width of no more than 0.8 millimeters, according to the research details.

The team also says its technology can work on existing concrete structures.

New Products, Pricing Obstacle

Three products that use the technology are expected to hit the market in 2015: self-healing concrete, repair mortar, and a liquid repair variant, according to the university.

However, cost continues to be an obstacle for the material, according to the European Patent Office.

Three Gorges Dam - China
Rehman / Wikimedia Commons

The world's largest power station in installed capacity, China's Three Gorges Dam used 27.2 million cubic meters of concrete—mainly for the wall, which rises 594 feet above its rock base. Researchers say stronger concrete would mean less steel in structures.

The current method’s production cost is twice the cost of regular concrete manufacturing (€ 80/m3 or $90/m3).

The primary cost issue is with the bacteria’s food—calcium lactate nutrient.

However, Jonkers and his team are working to develop a sugar-based nutrient that would reduce the cost to a level closer to that for regular concrete, making it a viable additive and sustainable prevention method, the patent office said.

The European Inventor Award, now in its 10th year, will be presented in June.


Tagged categories: Concrete; Concrete coatings and treatments; Concrete defects; Concrete repair; Europe; Maintenance + Renovation; Research; Surface preparation

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