Development of a Long-Duration Layering Method Based on Pressure Bleeding Control Using Ultra-High-Retardation Concrete
By H. Yamaguchi, K. Yukita and H. Nemoto
Concrete Journal, Vol.64, No.8, Aug. 2026
- Synopsis
- In recent years, with the expansion of infrastructure in the Tokyo metropolitan area, the construction of largescale underground structures in urban areas has been increasing. One effective means of addressing the associated construction challenges is a method that uses concrete containing super-retardant as a chemical admixture and achieves a layering interval of half a day or longer. Toward the establishment of this method, this study organized the required performance of ultrahigh- retardation concrete and, through full-scale experiments, identified the issue that bleeding caused by pressure from overlying concrete affects surface quality. In addition, to reduce the effects of pressure bleeding, the study examined an approach for determining the addition rate of the super-retardant required to obtain the target setting retardation time, proposed a construction method for discharging bleeding water outside the formwork, and confirmed its effectiveness.
- Keywords:
- Ultra-high-retardation concrete, Super-retardant, Layering, Pressure bleeding, Setting retardation
