Spalling, Joint

Joint spalling is the breakdown of the slab edges within 1.5 ft (0.5 m) 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 caused by traffic loading or by infiltration of incompressible materials; weak concrete at the joint caused by overworking; or water accumulation in the joint and freeze-thaw action.

The following table shows the severity levels of joint spalling. A frayed joint where the concrete has been worn away along the entire joint is rated as low severity.

Spall Pieces Width of Spall Spall length:  < 1.5 ft (0.5 m) Spall length:  > 1.5 ft (0.5 m)
Tight: Cannot be removed easliy (maybe a few pieces missing). Any L L
Loose – can be removed and some pieces are missing; if most or all pieces are missing, spall is shallow, less than 1 in (25 mm). Any L M
Missing – most or all pieced have been removed.  < 4 in (100 mm) L M
Missing – most or all pieced have been removed.  > 4 in (100 mm) M H