15 March 2001
DISTRESS 63, CRACKS (LONGITUDINAL, TRANSVERSE, AND DIAGONAL)
5.1. Description. These cracks, which divide the slab into two or three pieces, are usually
caused by a combination of load repetition, curling stresses, and shrinkage stresses. (For slabs
divided into four or more pieces, see Shattered Slab/Intersecting Cracks.) Low-severity cracks
are usually warping- or friction-related and are not considered major structural distresses.
Medium- or high-severity cracks are usually working cracks and are considered major structural
distresses. Deduct curves for cracking are shown in Figure 5.1.
(Note: Hairline cracks that are only a few feet long and do not extend across the entire slab
are rated as shrinkage cracks.)
5.2. Unreinforced PCC Severity Levels.
5.2.1. L. Crack has no spalling or minor spalling (no FOD potential). If nonfilled, it is less than
1/8 inch (3.2 millimeters) wide; a filled crack can be of any width, but its filler material must be in
satisfactory condition (Figures 5.2., 5.3., and 5.4.).
5.2.2. M. One of the following conditions exists: (1) a filled or nonfilled crack is moderately
spalled (some FOD potential); (2) a nonfilled crack has a mean width between 1/8 inch (3.2
millimeters) and 1 inch (25.4 millimeters); (3) a filled crack has no spalling or minor spalling, but
the filler is in unsatisfactory condition; or (4) the slab is divided into three pieces by two or more
cracks (Figures 5.5., 5.6., and 5.7.).
5.2.3. H. One of the following conditions exists: (1) a filled or nonfilled crack is severely spalled
(definite FOD potential); (2) a nonfilled crack has a mean width approximately greater than 1 inch
(25.4 millimeters), creating tire damage potential, or (3) the slab is divided into three pieces by
two or more cracks, one of which is at least medium severity (Figures 5.8., 5.9., and 5.10.).