Spalling

Description

Cracking, breaking or chipping of joint/crack edges. Usually occurs within about 0.6 m (2 ft.) of joint/crack edge.

Figure 1: Spalling along a linear (panel) crack.

Figure 2: Onset of spalling up close.

Figure 3: Bad construction joint spalling.

Problem

Loose debris on the pavement, roughness, generally an indicator of advanced joint/crack deterioration

Possible Causes

Possible causes are (AASHTO, 1993[1]):

  • Excessive stresses at the joint/crack caused by infiltration of incompressible materials and subsequent expansion (can also cause blowups).
  • Disintegration of the PCC from freeze-thaw action or “D” cracking.
  • Weak PCC at a joint caused by inadequate consolidation during construction. This can sometimes occur at a construction joint if (1) low quality PCC is used to fill in the last bit of slab volume or (2) dowels are improperly inserted.
  • Misalignment or corroded dowel.
  • Heavy traffic loading.

Repair

Spalling less than 75 mm (3 inches) from the crack face can generally be repaired with a partial-depth patch. Spalling greater than about 75 mm (3 inches) from the crack face may indicated possible spalling at the joint bottom and should be repaired with a full-depth patch.



Footnotes    (↵ returns to text)
  1. AASHTO Guide for Design of Pavement Structures.  American Association of State Highway and Transportation Officials.  Washington, D.C.