Another subset of nanoparticles, called quantum dots, combines the tiny quantum power of nanotech with the ability to conduct electricity. The myriad of potential applications for these little guys is almost unimaginable, but early applications include "smart aggregate," a kind of road concrete that can actually report on where it's weakening or broken. By analyzing the low-level electrical field of a structure -- such as a road -- embedded with these tiny guys, you can get a readout on its status; it's not unlike the screen of an old-fashioned calculator. Because nanoparticles naturally align themselves to one another based on their chemical and thermodynamic properties, scientists can manipulate those properties to create roads or buildings made of smart aggregate that can actually repair itself.
Or there's nano-silica, an artificial silicate (SiO2, a classic building material) that, when mixed into concrete, uses the quantum attraction between its particles to increase strength by three to six times without increasing concrete's density. It's like a net of quantum energy, keeping everything bound together. SiO2 is also a useful ingredient or coating for glass or concrete that needs fireproofing -- when heated, it realigns its particles into a much more rigid, fire-retardant structure.