15 March 2001
DISTRESS 74, SPALLING (TRANSVERSE AND LONGITUDINAL JOINTS)
16.1. Description. Joint spalling is the breakdown of the slab edges within 2 feet (0.6 meter) of
the side of the joint. A joint spall usually does not extend vertically through the slab but intersects
the joint at an angle. Spalling results from excessive stresses at the joint or crack caused by
infiltration of incompressible materials or traffic loads. Weak concrete at the joint (caused by
overworking) combined with traffic loads is another cause of spalling. Deduct curves for spalling
joints are shown in Figure 16.1.
16.2. Severity Levels.
16.2.1. L. Spall over 2 feet (0.6 meter) long: (a) spall is broken into no more than three pieces
defined by low- or medium-severity cracks; little or no FOD potential exists; or (b) joint is lightly
frayed; little or no FOD potential exists (Figure 16.2.).
16.2.2. L. Spall less than 2 feet (0.6 meter) long: spall is broken into pieces or fragmented,
little FOD or tire damage potential exists (Figure 16.3.).
16.2.3. M. Spall over 2 feet (0.6 meter) long: (a) spall is broken into more than three pieces
defined by light or medium cracks; (b) spall is broken into no more than three pieces with one or
more of the cracks being severe with some FOD potential existing; or (c) joint is moderately
frayed, with some FOD potential (Figure 16.4.).
16.2.4. M. Spall less than 2 feet (0.6 meter) long: spall is broken into pieces or fragmented,
with some of the pieces loose or absent, causing considerable FOD or tire damage potential