How can spalling affect the structural integrity of concrete?

Spalling refers to the flaking or chipping of concrete due to various factors, such as freeze-thaw cycles, corrosion of reinforcing steel, or chemical reactions. When spalling occurs, it compromises the concrete's surface, which can expose the reinforcing rods (rebar) embedded within the concrete. This exposure can lead to the corrosion of the rebar since it is no longer protected by the concrete. As the reinforcing steel weakens, the overall structural integrity of the concrete is diminished. Over time, this deterioration can lead to structural failure or collapse, especially if the spalling is severe or widespread. Thus, option C directly addresses the critical impact spalling has on the safety and stability of concrete structures.