15 March 2001
DISTRESS 47, JOINT-REFLECTION CRACKING FROM PCC
(LONGITUDINAL AND TRANSVERSE)
9.1. Description. This distress occurs only on pavements having an asphalt or tar surface over
a PCC slab. This category does not include reflection cracking from any other type of base (i.e.,
cement stabilized, lime stabilized); such cracks are listed as longitudinal and transverse cracks.
Joint-reflection cracking is caused mainly by movement of the PCC slab beneath the AC surface
because of thermal and moisture changes; it is not load related. However, traffic loading may
cause a breakdown of the AC near the crack, resulting in spalling and FOD potential. If the
pavement is fragmented along a crack, the crack is said to be spalled. A knowledge of slab
dimensions beneath the AC surface will help to identify these cracks. Deduct curves for
joint-reflection cracking from PCC are shown in Figure 9.1.
9.2. Severity Levels.
9.2.1. L. Cracks have only light spalling (little or no FOD potential) or no spalling and can be
filled or nonfilled. If nonfilled, the cracks have a mean width of 1/4 inch (6.4 millimeters) or less.
Filled cracks are of any width, but their filler material is in satisfactory condition (Figure 9.2.).
9.2.2. M. One of the following conditions exists: (1) cracks are moderately spalled (some FOD
potential) and can be either filled or nonfilled of any width; (2) filled cracks are not spalled or are
only lightly spalled, but the filler is in unsatisfactory condition; (3) nonfilled cracks are not spalled
or are only lightly spalled, but the mean crack width is greater than 1/4 inch (6.5 millimeters); or
(4) light random cracking exists near the crack or at the corner of intersecting cracks (Figures 9.3.