Concrete discoloration

[sandman21]

They have pulled some forms from some architecturally exposed wall. Two issues were clearly visible concrete discoloration, appears to be improper curing of the concrete. However, one issue I have not run into, color banding, at about the location of the pour a darker strip of concrete appears for the full length of the pour. My thoughts are that the contractor did not follow proper vibration techniques and held the vibrator in one location causing water to bleed to the top and bring cement with it. Anyone had this happen or have an opinion on the cause?

Thank you

 

[Ron]

Variations in curing cannot usually be detected by visual assessment.

Post a couple of photos so that we can better see what you are describing.