Used by the Roman Empire to build architectural wonders that have survived the test of time, concrete has proven to be one of the most durable building materials developed by man. Nevertheless, the recipe for this material has evolved and improved over time. But is it reasonable to think that one day it will be possible to use concrete that can repair itself?
Well, that day may not be as far away as we might think. In fact, for some years now, a Dutch research team at the Delft University of Technology has been working on a “living” concrete that contains bacteria that have the ability to seal cracks as they are formed.
Dormant bacteria integrated into the concrete recipe
To manufacture this innovative concrete, Bacillus and/or Sporosarcina bacteria in a dormant state, as well as their food source, calcium lactate, must first be packaged in the form of tiny granules resembling a fine white powder. This powder is then mixed with the wet concrete which can then be poured into the formwork.
When a crack forms and water begins to seep in, the bacteria emerge from their dormant state, become active and begin to eat the food. The bacteria then excrete a hard limestone load that fills the crack and prevents the water from doing more damage.
Although many forms of concrete begin to decompose after 20 to 30 years, these bacteria can remain dormant for 200 years in the absence of food, which can extend the life of a concrete structure for decades after it has exceeded its useful life.
Incidentally, this revolutionary concrete has the potential to significantly reduce costs in terms of monitoring concrete condition, damage detection and maintenance of concrete structures. For the time being, the main factor that could affect the popularity of this material is the cost of biological agents, which increase the price of concrete by about 50%.
Conclusive laboratory tests
Currently, due to the cracks that can form in concrete, it must be strengthened with steel reinforcement. However, if water seeps into the concrete and reaches the steel rods, corrosion can form and threaten the strength of the material.
Moreover, the construction industry currently tolerates the occurrence of cracks of less than 0.2 mm since they do not cause any real loss of strength. Researchers are therefore looking to fill larger cracks by adding bacteria to the concrete. In the laboratory, they were able to repair cracks 0.5 mm wide, two to three times larger than those tolerated by current standards.
While you wait for this concrete to reach the market
Of course, there is still plenty of research to be done before this bacteria-containing concrete can be used on a large scale. However, the day when cracked concrete will repair itself is perhaps not so far away!
In the meantime, you can always leave the repair of your cracked concrete foundations and slabs to the Foundation Crack Expert Group. The 10-year guarantee offered on our crack repairs guarantees the quality of the corrective work performed. Do not hesitate to contact us.