Quicklime generally contains overburnt lime. Overburnt lime slakes slowly, and if slaking occurs after the lime slurry has hardened, the expansion caused by slaking will lead to bulging and cracking. To eliminate this hazard of overburnt lime, it should be allowed to "age" for about two weeks after slaking.
It is white (or gray, brownish-white) in appearance, amorphous, and absorbs water and carbon dioxide from the air. Calcium oxide reacts with water to form calcium hydroxide, releasing heat. It is soluble in acidic water but insoluble in alcohol. It is an inorganic alkaline corrosive substance, classified as hazardous material (National Hazardous Goods Code 95006). Quicklime reacts chemically with water, immediately heating to temperatures exceeding 100°C.
