Research on self-healing concrete has been going on for more than a decade. The quest for self-healing concrete has led researchers to the discovery of different approaches to the problem. In 2010, Michelle Pelletier, an engineering student from the University of Rhode Island, and Professor Arijit Bose discovered a method of healing concrete. This method involves the use of a microencapsulated sodium silicate healing agent with the concrete mixture. At the formation of cracks in the concrete, the capsules break and release the healing agent which reacts with the calcium hydroxide in the concrete mixture. This leads to the formation of a calcium-silica-hydrate gel which heals the concrete by blocking the pores; the gel hardens in a week. The report on New Atlas alleges that when the concrete was stress-tested, it recovered 26 percent of its original strength, 16 percent more than when normal concrete was used.
Researchers have recently used bacteria spores that secrete calcium carbonate or glass capillaries that secrete healing agents to seal cracks. Large cracks in the concrete start as little cracks; this is the view that has motivated the idea of self-healing concrete. The most recent research was inspired by the human body’s ability to heal itself. Congrui Jin, Guangwen Zhou, and David Davies from New York’s Binghamton University and Ning Zhang from Rutgers University collaborated on the project. The researchers used fungus to seal the cracks in concrete, instead of using a calcium-silica-hydrate gel.
The spores of the fungus Trichoderma reesei is incorporated with nutrients and added to the concrete matrix during mixing. The spores become hardened with the concrete and only become activated when tiny cracks begin to appear. The spores are germinated when exposed to water and oxygen through the tiny cracks. The spores grow and precipitate calcium carbonate which seals the cracks. The report states that the spores become dormant again when no water and oxygen can reach the spores but may be reactivated when cracks reappear.
The researchers claim that the material is low-cost, pollution-free, and sustainable, according to Digital Trends. One of the most practical uses of this research is in nuclear power plants because concrete is used for radiation shielding. Self-healing concrete is vital for the construction industry because of its potential. This project is still in its early stages, but it seems the future of infrastructure may belong to self-healing concrete.
A paper on the Binghamton research was recently published in the journal Construction and Building Materials.