What are typical signs of concrete substructure distress?

• A. Cracking and surface discoloration.
• B. Cracking, spalling, scaling, efflorescence, exposed rebar, settlement, and movement.
• C. Only color changes in concrete.
• D. Increased deck load capacity.

Answer: (B)

Recognizing concrete substructure distress comes down to identifying a range of signs that reflect moisture, reinforcement condition, and movement affecting the foundation. The most complete set includes cracking, spalling, scaling, efflorescence, exposed rebar, and settlement or movement. Cracking shows where concrete tensile stresses or shrinkage have exceeded what the material can handle. Spalling and scaling are surface forms of deterioration from freeze–thaw cycles, deicing salts, or corrosion that progressively expose deeper material. Efflorescence indicates moisture carrying salts to the surface, signaling ongoing moisture movement through the substrate. Exposed rebar is a clear warning that reinforcement is deteriorating due to corrosion, which weakens the member. Settlement and movement reveal underlying foundation or bearing issues that can alter load paths and lead to further damage. Color changes by themselves aren’t reliable indicators of distress, and simply noting an increased deck load capacity doesn’t reflect substructure problems.