From the article:

Self-healing "smart building materials" have the potential to reduce structure repair costs, lower cement-production carbon emissions and even save lives. One barrier that has kept these materials from being commercialized, however, is their potentially labor-intensive and thus expensive production process. Recently, an engineering student from the University of Rhode Island (URI) announced that she has developed a self-healing concrete that would be inexpensive to produce.

Michelle Pelletier, collaborating with URI Chemical Engineering Professor Arijit Bose, created a concrete matrix that was embedded with a micro-encapsulated sodium silicate healing agent. When cracks formed in the concrete, the capsules ruptured and released the agent into the adjacent area. The sodium silicate reacted with the calcium hydroxide already present in the concrete, and formed a calcium-silica-hydrate gel that healed the cracks and blocked the concrete's pores. The gel hardened in about one week.

When Pelletier's concrete was stress-tested to the point of almost breaking, it proceeded to recover 26% of its original strength. By contrast, conventional concrete only recovers 10%.

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