This problem needs to start with the determination of concrete strength. At present, the evaluation of concrete strength is based on the compressive strength of specimens after 28 days of standard curing. The strength of most concrete increases within 28 days, but there is still a certain strength increase after 28 days. The so-called full use of the middle and late strength of concrete refers to the use of this part of strength. In other words, whether the strength of mass concrete meets the design strength is evaluated by the compressive strength of long age, such as the strength of 60 days and 90 days. In this way, the strength of concrete in 28 days can be lower than the design strength. It can also reduce the amount of cement.