No Magic Number: Coating Concrete After 28 Days

From JPCL, September 2018

By R. A. Nixon, Corrosion Probe, Inc.

Historically, the coatings industry has specified 28 days of cure time for concrete before coatings are applied. This 28-day curing period was designated to address two key concerns: cement paste shrinkage continuing after coating application resulting in the formation of cracks and excess moisture unnecessary for cement hydration escaping from the substrate and causing problems at the coating/concrete interface. The author examines this “magic” number and presents real-world cases. ...