Pour strip

I knew that any pour strip should be left opened for 28 or 56 or 60 days, some papers recommends 120 days! What all of this for? Shrinkage! In BS8007 and CIRIA, both say it can be eliminated by designing the section for the early thermal cracks or by checking the designed reinforcement for the early thermal cracks. Some engineers say the reinforcement due to early thermal crack analysis is independent and this reinforcement should be added to the section as the section will be stressed already! I disagree with them because the section will be stressed at the initial stage only for 28 days as major and then stresses will be reliefed.