The American Concrete Institute defines scaling as "local flaking or peeling away of the near-surface portion of hardened concrete or mortar." Scaling is caused by several factors, with deicing chemicals and severe freeze-thaw cycles being the best known. Concrete that is inadequately air-entrained or non-air-entrained is particularly aggravated by deicing chemicals. Improper finishing, perhaps by finishing before bleedwater has stopped or by spraying water on the surface, will also make scaling more likely. Aggregates with high percentages of unsound particles will cause popouts and lead to progressive scaling. Also, concrete that is not properly cured will tend to dry out quickly and hydrate slowly, making the concrete more susceptible to scaling.
prevent scaling, concrete should be adequately air-entrained. The air-void system should have a spacing factor of less than 0.008 inches and a specific surface of at least 600 square inches per cubic inch of air-void volume. Even with proper air content, ACI 201 recommends a maximum water-cementititous materials ratio of 0.45 for concrete exposed to deicing chemicals. To improve all the desirable qualities of concrete, begin curing immediately after final finishing and cure as long as possible. Also, laboratory studies have shown that air-drying concrete for a period after curing will increase the concrete's durability when exposed to freezing and thawing.