Workability is generally a characteristic defined by the mason. There is no textbook defintion of workability because there are no standardized tests for it. A
"workable" mortar has a smooth, plastic quality, is easily spread with a trowel, and readily sticks to vertical surfaces.
Ingredients which can increase workability are:
Well-graded, smooth aggregates
proper amounts of mixing water
The lime imparts plasticity and increases the water carrying capablity of the mortar.
Air entrainment is an addative that creates tiny air bubbles in the mix. These air bubbles help the ingredients of the mortar move more freely. These air bubbles can reduce the strength of bond as they reduce the density and
surface area of the bonding surface of the masonry unit. Air contents should be kept below 12-15% if not lower. Mortar requires a maximum amount of water for workability. Retempering should be allowed within the first 2.5 hours