ccf46e02_ction_of_Concrete___InterNACHI__Primary_Cause
[Type of Cracking] Alkali-aggregate reaction [Form of Crack] Pattern cracks; cracks parallel to joints or edges [Time of Appearance] Typically, over five years, but may be much sooner with highly reactive aggregate [Primary Cause] 
Reactive aggregate plus moisture
Visual Inspection of Concrete - InterNACHI
Primary Cause