Concrete is the single most widely used construction material in the world [source: Crow]. In fact, it is the second-most consumed substance on Earth, after water [source: Rubenstein]. Think of all the concrete homes, office buildings, churches and bridges built each year. Concrete is cheap and widely adaptable, but it's also susceptible to cracking and deterioration under stresses like extreme heat and cold.
In the past, the only way to fix cracked concrete was to patch it, reinforce it, or knock it down and start from scratch. But not anymore. In 2010, a graduate student and chemical engineering professor at the University of Rhode Island created a new type of "smart" concrete that "heals" its own cracks. The concrete mix is embedded with tiny capsules of sodium silicate. When a crack forms, the capsules rupture and release a gel-like healing agent that hardens to fill the void [source: URI].
This is not the only method of self-healing concrete. Other researchers have used bacteria or embedded glass capillaries or polymer microcapsules to achieve similar results. However, the Rhode Island researchers believe their method is the most cost-effective.
Prolonging the life of concrete could have huge environmental benefits. Worldwide concrete production currently accounts for 5 percent of global carbon dioxide emissions [source: Rubenstein]. Smart concrete would not only make our structures safer, but also cut back on greenhouse gasses.