You add water to slake its thirst. I'm not sure that's correct though. The lime you slake is quicklime, calcium oxide. If you add water you then get calcium hydroxide, and apparently that's what builders' lime is. It's too alkaline for garden use. Garden lime is calcium carbonate, made by ginding limestone. It's a lot less alkaline, so it's more controllable, and won't burn plants or damage soil.
