Control of Early-Age Cracking in Super-Long Mass Concrete Structures

The early-age cracking problem in concrete has long been recognised by civil engineers and scientists because it can jeopardise the intended serviceability of concrete structures. However, the effects of various crack control methods are different. This paper carried out field monitoring on a super-long wall with different crack control measures and compared the temperature and strain development process of the wall. In the middle of the super-long wall, the pipe cooling method reduced the hydration heat of concrete by 13 °C via a vertical pipe arrangement, but the wall could reach the maximum tensile strain earlier than with the other methods. By embedding an I-shaped steel plate in the induced joint method, a structurally stiff mutation zone was generated, and the maximum strain was generated at the induced seam web. By calculating and setting a reasonable construction length, the alternative bay construction method reduced the internal tensile strain of the structure. The early-age cracking of super-long mass concrete structures is affected more by restrained shrinkage than by temperature, so it is difficult to control early-age cracking by addressing only one factor.