Early-Stage Strength Growth of High-Strength Concrete in Outer Freezing Shaft Walls

The early-stage strength growth of concrete in outer freezing shaft wall was studied by laboratory and field experiment.The results show that the strength growth at early stages proceeds rapidly due to heat of hydration in the mass of concrete.The strength measured at one,three or seven days exceeded the strength of the test article by 40,70 and 90 percent,respectively.Strength growth in the outer shaft wall significantly exceeds the rate of strength growth in the standard test block.At short times,the closer the sample is to the center of the wall,the higher the strength compared to the test sample.This effect is most noticeable within three days after pouring.The safety of the outer shaft wall can be guaranteed if high-strength cast-in-place concrete is used.