After the lime has reacted with the water or slaked, it is referred to as slaked lime 4 . Many factors affect the speed of this slaking reaction. Naturally occurring impurities from the limestone generally slow the reaction. Magnesium carbonate intermixed with the calcium carbonate in equal parts can almost completely eliminate slaking. Small additions of clay, or iron oxide, or firing above 2000 degrees F, usually slows the speed of the reaction.
Slaked lime is mixed with sand to produce lime mortar.
Historically, before the development of Portland cement, this mortar held together many masonry structures. The true miracle of slaked lime mortars is that they get stronger with age. Over the span of decades, the mortar slowly reabsorbs carbon dioxide from the atmosphere and again becomes limestone. Slaked lime is the main ingredient in traditional whitewash. On the stucco walls of our house, it repairs cracks, increases water resistance, and kills mold and other growths.