What are the visual signs of concrete failure?

Concrete failure can manifest in several visual signs, and the presence of cracking, surface scaling, or spalling is particularly indicative of underlying issues with the material.

Cracking occurs when the concrete experiences tension or stress that exceeds its tensile strength. These cracks can vary in size and location, with some forming along joints or as a result of shrinkage during curing. Surface scaling refers to the chipping away of the top layer of concrete, which can be caused by freeze-thaw cycles, inadequate curing, or poor-quality materials. Spalling involves the flaking or chipping off of the surface layer, which may occur due to a combination of water intrusion and freeze-thaw cycles, as well as chemical reactions within the concrete. All these signs are critical indicators of distress and can ultimately lead to structural failure if not addressed.

Other options may include interesting characteristics of concrete, but they do not primarily represent the immediate visual signs of concrete failure.