The strength of masonry depends upon the strength of masonry units, mortar and the bond between them.
The strength of the component materials is defined by standardized tests, which don’t necessarily reflect the state of stress in the
component material in brickwork, but serve as index values in the selection of design stresses. This is only an empirical
approach, which provides an acceptable basis for the structural design of brickwork. The approach is not altogether satisfactory
as it gives little insight into the behavior of the brick mortar composite.