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Heal thyself! Scientists have been developing smart materials that can heal themselves. These substances have the potential to make everything from bridges to bicycles more durable by repairing damage as it occurs. Last week, we learned that self-healing materials were engineered and used by the ancient Romans.
For years, scientists have marveled at the durability of Roman concrete. It was used to build the Pantheon Dome, harbors, and other structures, and proved to be more robust than modern concrete. The Pantheon was built two thousand years ago, and it remains the world’s largest unreinforced concrete dome.
Scientists recently discovered that Roman concrete included lime clasts, a material that contains calcium oxide. When damage occurred in Roman concrete, cracks would form through the lime clasts. Then, as water traveled through the crack, a calcium-saturated solution would form and crystalize, repairing the crack.
Knowing the secret to the durability of Roman concrete is likely to improve modern concrete and extend the lifespan of many types of infrastructure. Concrete isn’t the only material that has the potential to repair itself, though. Scientists are engineering other smart materials to fight the effects of age, wear-and-tear, and defects in all kinds of products. Typically, these substances contain microcapsules filled with some type of repair material. When damage occurs, the microcapsules rupture, releasing their contents to combine with a catalyst and repair the damage. In some cases, the catalyst is water, light, or another environmental factor. In other cases, the catalyst is engineered into the material, too.
Self-healing materials could have many interesting applications. Imagine airplanes that can repair wing and fuselage cracks. The same might be possible for spaceships, satellites, automobiles, motorcycles, and bikes. Already, there is a coating that mends scratches in automobile paint. All you need is a self-healing clearcoat and some sunshine.
The global market for self-healing materials is expected to grow rapidly.
Weekly Focus – Think About It
“We live in a society exquisitely dependent on science and technology, in which hardly anyone knows anything about science and technology.”
—Carl Sagan, astronomer and astrophysicist
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