Currently, numerous admixtures are used in masonry mortar, mainly for economical reasons. None, however, match the properties of lime. Lime's superb properties can be shown in both phases of mortar: the plastic or putty side; and the hardened state. THE PUTTY PHASE The workability of mortar depends on the amount of lubricant or water in the putty. This is where lime plays a role. Lime allows the mortar to hold more water. Today, hydrated lime used in masonry mortars must meet the requirements specified in ASTM C 207 for Type S hydrated lime. Made from dolomitic quicklime, most Type S hydrated limes used in mortar contain about equal amounts of magnesium hydroxide and calcium hydroxide. Type S hydrated lime holds water for a long time. The hexagonal platelet shape of the hydroxide particles also helps make the mortar more workable. THE HARDENED PHASE In the hardened state the most important property of mortar is its bonding ability. Dolomitic Type S lime increases the density of mortar, enabling the mortar to achieve more intimate contact with the brick units. Lime also makes mortar less rigid, which helps mortar accommodate movements in masonry walls.