Some tests on concrete made in the early summer with shrinkage-compensating cement showed that they had more shrinkage than concrete made the previous fall from the very same shipment of cement. What could the time of the year have to do with it?
It has been reported that the amount of initial expansion in shrinkage-compensating cements decreases with the length of time they have been stored because of carbonation, hydration or both. This would account for higher apparent shrinkage in concrete made after the cement had been stored a long time. One way to minimize or eliminate this problem would be to purchase ready mixed shrinkage-compensating concrete from a supplier who has a reasonably rapid rate of turnover, rather than stockpiling your own supply of shrinkage-compensating cement.