Some claim that bond strength between mortar and masonry units is the most important physical property of masonry. Low bond, it is said, is responsible for nearly every conceivable problem with masonry. BOND ISN'T THE ONLY FACTOR It's not irrefutably clear that mortars that develop higher bond always produce superior masonry. A preoccupation with bond may come at the expense of durability, shrinkage, and other important properties. According to available literature, no consistent correlation can be found between unit-mortar bond strength and compressive strength of mortar, water retentivity of mortar, water-cement ratio of mortar, consistency of mortar in terms of cone penetration, fineness of masonry cement in mortar, or brick IRA. OTHER MORTAR PROPERTIES Though important, bond strength is not always the most important mortar property, and low bond strength is definitely not the cause of all masonry problems. Other mortar properties that are often overlooked but are nonetheless important are durability, sulfate resistance, water absorption, drying shrinkage, workability, and board life.