“CONCRETE has been a high-tech material since Roman times, when it was discovered that adding volcanic ash to the mix allowed it to set under water. Similarly, the Romans knew that adding horsehair made concrete less liable to shrink while it hardened, and adding blood made it more frost-resistant. In modern times, researchers have added other materials to create concrete that is capable of conducting electricity. It heats up when a voltage is applied, making it possible to build runways and drives that clear themselves of snow. Bill Price of the University of Houston now has an ambitious plan to make concrete with an even more unusual property: he wants it to be transparent.”
More Here