Pop-outs are conical fragments that break out of the surface of the concrete leaving holes.

• A. False
• B. Not Applicable
• C. True
• D. Both

Answer: (C)

Pop-outs are a surface defect where a piece of concrete around a near-surface aggregate separates and is ejected, leaving a conical fragment and a hole. The cone shape comes from the way the weakened paste and aggregate fracture at the surface, often where the aggregate–paste bond is compromised. This weakening is typically caused by moisture ingress and freeze–thaw action, or other reactions at the aggregate interface, which build up pressure and cause the superficial layer to pop out rather than crack uniformly. Seeing pop-outs on a deck or exposed concrete signals that the surface has degraded and could invite further deterioration if water and temperature cycles continue. In practice, spotting them means the defect is present and needs surface repair and protective sealing to slow progression.