Visually inspect the surface of the sidewalk for any hairline cracks, flaking, pitting, scaling or spalling of the concrete. If any of these deficiencies are noted, an evaluation should be made as to the severity to determine if it is best to replace the concrete slab.
In addition, the concrete should be sounded to evaluate its condition for any delaminations. Delamination is a horizontal splitting, cracking, or separation of a slab in a plane roughly parallel to, and generally near, the upper surface.
Sounding is a technique to evaluate the condition of hardened concrete by striking the surface with a hammer. Sound concrete will exhibit a clear ringing sound, whereas dull or hollow sounds indicate delaminated areas. Another procedure to sound concrete would be by dragging a chain over the concrete surface. Again, dull or hollow sounds indicate delaminated areas, whereas solid concrete would exhibit a clear ringing sound. In most cases, if any delamination is detected, the concrete should be replaced.