Surface scaling occurs when the concrete surface breaks off to a depth of 2 inches and keeps peeling away. Causes for scaling vary and are dependent on surface strength, curing procedures, water seepage, air content and air entrainment. Concrete subjected to use of de-icing salts combined with freeze-thaw conditions is prone to scaling. Chemicals such as ammonium nitrate and ammonium sulfate, which are components of most fertilizers, can cause scaling as well.
Solution: All factors have to be taken into account when designing a concrete mix in order to produce concrete with a workable slump. For best results concrete is finished at the right time, once all water has been evaporated. Cure concrete adequately without using salt or other chemicals during winter. Don’t overwork the concrete surface. Avoid using a vibrating screed on high slump concrete.