What term describes the mortar's resistance to separation from a masonry unit?

The term that describes the mortar's resistance to separation from a masonry unit is bond strength. This property is crucial in masonry construction because it dictates how well the mortar adheres to the bricks or blocks, ensuring that the structure remains stable and durable under various loads and environmental conditions. An adequate bond strength allows the mortar to effectively transfer loads between the masonry units, preventing issues such as cracking or delamination over time.

Other strengths, such as flexural strength and tensile strength, refer to the material's ability to withstand bending and pulling forces, respectively, but they do not specifically address the adhesive properties necessary for mortar to bond effectively with masonry units. Adhesive strength is a more general term that may apply to a variety of materials and their ability to stick together; however, in the context of masonry, bond strength is the precise term used to describe this specific interaction between mortar and masonry units.