Reflection Cracking

Description

Cracks in a flexible overlay over an existing crack or joint. The cracks occur directly over the underlying cracks or joints. “Joint reflection cracking” specifically refers to reflection cracks arising from underlying PCC pavement joint movement. Reflection cracks can also occur over existing HMA pavement cracks, cement or lime stabilized base, etc.

Figure 1: Joint reflection cracking on an arterial.

Figure 2: Joint reflection cracking on an arterial.

Figure 3: Joint reflection cracking up close.

Problem

Allows moisture infiltration, roughness

Possible Causes

Differential movement across the underlying crack or joint. For joint reflection cracking, this is movement of the PCC slab beneath the HMA surface because of thermal and moisture changes. Generally not load initiated, however loading can hasten deterioration.

Repair

Strategies depend upon the severity and extent of the cracking:

  • Low severity cracks (< 1/2 inch wide and infrequent cracks). Crack seal to prevent (1) entry of moisture into the subgrade through the cracks and (2) further raveling of the crack edges. In general, rigid pavement joints will eventually reflect through an HMA overlay without proper surface preparation.
  • High severity cracks (> 1/2 inch wide and numerous cracks). Remove and replace the cracked pavement layer with an overlay.