What is the most likely cause of scaling on a concrete surface in a cold climate?

The most likely cause of scaling on a concrete surface in a cold climate is freeze-thaw damage, often exacerbated by the use of deicing salts. Scaling is the flaking or peeling away of the concrete surface, resulting in a loss of material and exposure of the underlying concrete. In cold climates, concrete is subjected to repeated cycles of freezing and thawing. When water within the concrete pores freezes, it expands by approximately 9%. This expansion creates internal pressure that can exceed the tensile strength of the concrete, leading to micro-cracking and ultimately, scaling. The use of deicing salts, such as sodium chloride or calcium chloride, further exacerbates the problem. These salts increase the osmotic pressure within the concrete, drawing more water into the pores and increasing the amount of ice that forms during freezing. The salts also disrupt the cement paste structure, making it more susceptible to damage. Concrete surfaces exposed to frequent freeze-thaw cycles and deicing salts, such as pavements and sidewalks, are particularly vulnerable. To mitigate scaling, air entrainment, which introduces microscopic air bubbles into the concrete mix, is crucial. These air bubbles provide space for the expanding water to relieve pressure, preventing damage to the concrete matrix. Proper curing and the use of sealers can also help to reduce water absorption and improve durability.