TM 5-826-6/AFR 93-5
Figure A-68. High severity blowup.
(3) Counting procedure. A blowup usually occurs at a transverse crack or joint. At a crack, it is counted as
being in one slab, but at a joint two slabs are affected and the distress should be recorded as occurring in two slabs.
r. Corner break, distress 62.
(1) A corner break is a crack that intersects the joints at a distance less than or equal to one-half of the slab
length on both sides, measured from the corner of the slab. For example, a slab with dimensions of 25 by 25 feet that has
a crack intersecting the joint 5 feet from the corner on one side and 17 feet on the other side is not considered a corner
break; it is a diagonal crack. However, a crack that intersects 7 feet on one side and 10 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, and a corner spall interesects the joint at an angle. Load repetition combined with loss of support and curling
stresses usually cause corner breaks.
(2) Severity levels.
(a) Low severity level (L). Crack has either no spalling or minor spalling with no loose particles (no FOD
potential). If nonfilled, it has a mean width less than approximately 1/8 in. A filled crack can be of any width, but the filler
material must be in satisfactory condition. The area between the corner break and the joints is not cracked (figs. A-69
Figure A-69. Low severity corner break, case 1.