Mixing quicklime with water produces slaked lime, or calcium hydroxide: a slightly less reactive, less caustic paste.

Although aqueous solutions of 'slaked' lime are alkaline, its solubility in water is so low that the solution would not be a caustic hazard (causing chemical burns) used in a hand warmer.

For decades, researchers believed that pozzolanic concrete was made by mixing slaked lime—a product of quicklime (calcium oxide) and water—with volcanic ash. This reaction created a tough ...