Spraying limestone – producing bacteria to heal cracks in concrete
Dr. Henk Jonkers, Delft University of Technology
Development of self-healing concrete: towards full-scale application
Since 2006 we are developing in our laboratory a bacteria-based self-healing concrete. In order to substantially improve the concretes self-healing capacity we add a bacteria-based healing agent to the concrete mixture. This two-component agent consists of dormant bacterial spores and a suitable feed. The bacterial spores become activated when concrete cracks and water enters. The active bacteria subsequently convert the feed into limestone thus sealing and waterproofing the concrete.
This system was originally designed for new concrete constructions as the healing agent must be added to the concrete mixture. However, as current (aged) concrete constructions do not feature a specifically inbuilt self-healing system, we also developed a liquid bacteria-based impregnation system. This system enables the transportation of bacteria and feed into porous and cracked concrete surfaces. Once inside the bacteria start forming limestone thereby increasing the density of the porous concrete matrix resulting in a more durable material. In a number of outdoors tests we have applied and tested the bacterial spray system for its waterproofing functionality.
Results show that prior cracks become sealed with limestone effectively waterproofing the structures. We expect that this bio-based system will substantially increase the service life of aged concrete constructions and will considerable save maintenance and repair costs.
First aid emergency post Galder, the Netherlands, first outdoors object treated with the newly developed bacteria-based spray system for waterproofing cracked concrete structures
Henk Jonkers studied Marine Biology at Groningen University, the Netherlands, were he also obtained his PhD in Marine Microbiology in September 1999.
After working for 7 years as research scientist in the Microsensor Research Group at the Max-Planck-Institute for Marine Microbiology, Bremen, Germany, he joined as associate professor the Materials & Environment section of the Faculty Civil Engineering & Geosciences of the Delft University of Technology.
His interests and currently running research projects include the development of both durable and sustainable bio-based materials
for the construction sector.
Delft University of Technology,
Faculty of Civil Engineering and Geosciences, Micolab
Stevinweg 1, 2628 CN Delft, The Netherlands