The following is from the American Society of Civil Engineers (ASCE)

MINOR DAMAGE

  • Mechanical abrasion or impact spalls up to 1-inch in depth;
  • Occasional corrosion stains or small pop-out corrosion spalls;
  • Surface cracks up to 1/16-inch in width.
The following minor damage reverts to the Moderate Damage rating:

MODERATE DAMAGE

  • Structural cracks up to 1/16-inch in width;
  • Corrosion cracks up to 1/4-inch wide;
  • Chemical deterioration: random cracks up to 1/16-inch oin width;
  • Soft concrete or rounding of corners up to 1-inch deep;
  • Mechanical abrasion or impact spalls greater than 1-inch in depth.
The following moderate damage reverts to the Major Damage rating: 
  • Structural breakage and/or spalls;
  • Exposed rebar;
  • Loss of cross section due to chemical deterioration beyond rounding of corner edges.

MAJOR DAMAGE

  • Structural cracks 1/16-inch to 1/4-inch in width and partial breakage (through section cracking with structural spalls);
  • Corrosion cracks wider than ¼-inch and open or closed corrosion spalls (excluding pop-outs);
  • Multiple cracks and disintegration of the surface layer due to chemical deterioration;
  • Mechanical abrasion or impact spalls exposing the rebar.
The following major damage reverts to the Severe Damage rating:
  • Loss of cross section exceeding 30% due to any cause.

SEVERE DAMAGE

  • Structural cracks wider than 1/4-inch or complete breakage;
  • Complete loss of concrete cover due to corrosion of rebar with more than 30% of loss for any main reinforcing steel (rebar);
  • Loss of bearing and/or displacement at connections;Loss of concrete cover (exposed rebar) due to chemical deterioration;
  • Loss of more than 30% of cross section due to any cause.