A corner break is a crack that intersects the joints at a distance less than or equal
to one-half the slab length on both sides, measured from the corner of the
slab. For example, a slab with dimensions of 12 by 20 feet that has a crack 5
feet on one side and 12 feet on the other side is not considered a corner
break; it is a diagonal crack. However, a crack that intersects 4 feet on one
side and 8 feet on the other is considered a corner break. A corner break
differs from a corner spall in that the crack extends vertically through the
entire slab thickness, while a corner spall intersects the joint at an angle.
Load repetition combined with loss of support and curling stresses usually
causes corner breaks.
L*--Break is defined by a low-severity crack and the area between the break and
the joints is not cracked or may be lightly cracked (figs B-76 and B-77).
Figure B-76. Low-severity corner break.
Figure B-77. Low-severity corner break.
M*-Break is defined by medium-severity crack and/or the area between the break
and the joint is mediumly cracked (fig B-78).
H*--Break is defined by a high-severity crack and/or the area between the break
and the joints is highly cracked (fig B-79).
*See linear cracking for a definition of low-, medium, and high-severity cracks.