Self-Healing Concrete May Revolutionize Construction Industry
A new material developed by a microbiologist in the Netherlands could solve the problem of concrete stressing, cracks and collapse in the future. Henk Jonkers, professor at the Delft University of Technology, has been experimenting for several years with a concrete mixture that incorporates self-repairing capabilities.
This self-healing concrete is designed to maintain the structural properties of concrete years after it is poured, reducing costs of repair and maintenance throughout the world. Clearly, Jonker’s development has the potential to revolutionize the construction and contracting industries, if not civilization as we know it.
How Does the Self-Healing Concrete Work?
To engineer a self-healing concrete product, Jonkers turned to Mother Nature. “Nature is supplying us a lot of functionality for free,” he tells CNN. “In this case, limestone-producing bacteria.”
The bacteria Jonkers uses naturally produces limestone as a by-product of its digestion process. Two different strains, Bacillus pseudofirmus or Sporosarcina pasteurii, can be used. In conjunction with some sort of food source embedded within the concrete, the bacteria automatically stimulates digestion and reinserts limestone minerals at the source of cracks and water leaks. While substances like glucose sugar can be used to fuel this process, Jonkers chose calcium lactate because it helps reinforce the concrete mixture rather than weakening it.
Another challenge Jonkers and his team faced was sustaining the repair actions over extremely long periods of time. Similar solutions used algae, but that algae must be kept alive somehow with water, oxygen and a reliable food source. The bacterial strains Jonker uses instead can remain dormant in concrete for as long as 200 years, waiting to activate when cracks and pockets begin to affect the structure.
Best of all, this strategy means that the bacteria activates at just the right time. Each bacterial colony is contained in a capsule, along with the calcium lactate food source. The capsule is made from a biodegradable plastic material. As cracks in the concrete form over time, oxygen and water reaches the capsules and dissolves them. As a result, the bacteria becomes useful just as it is needed, creating fresh limestone deposits that seal up cracks and prevent structural wear.
The Amazing Potential of Self-Healing Concrete
Stress cracks and water intrusion are two of the biggest sources of architectural weakness in concrete structures. Even as the concrete is being poured and dries, tiny air pockets and stress cracks form. Over time, these cracks create uneven weight distribution to the point where collapse becomes possible.
The solution in the past was to lace concrete with internal rebar scaffolds, but even this practice has its limits. When water intrudes into the concrete, it can rust away the rebar and destroy the construction from the inside out.
This type of degradation calls for massive, expensive renovation projects. For underground or underwater structures that are affected the most, repair costs skyrocket astronomically.
Jonkers’ product can significantly cut costs and material use of renewal projects like these, reducing humanity’s carbon footprint in the process. As global demand for concrete increases at an alarming pace, solutions like these help businesses, governments and contractors save resources and prevent disasters.