Waterproofing performance of waterstop with adhesive bonding used at joints of underground concrete structures

Abstract

Waterstop is a typically used waterproofing material to prevent water leakage through the joints where consecutive concrete casting is not possible during the construction of underground concrete structures. A conventional waterstop, however, frequently allows for water passage through the interface between a waterstop and concrete under a high water-pressure environment owing to a deep excavation depth and high groundwater table. An alternative solution proposed in this study is to use artificial adhesive bonding between the waterstop and concrete using double-sided adhesive tape to actively prohibit water leakage through joints under a high hydrostatic pressure. The performance of the proposed waterproofing system was experimentally evaluated and compared with the control system (without adhesive). The results indicated that the adhesive bonding type resisted water migration under the pressure head of 30 m, whereas the conventional waterstop could not effectively waterproof even at the pressure head of 10 m in the soundly constructed cementitious composite structures. In addition, the peel strength, which is the bonding strength between the adhesive tape and cementitious composite, was measured to quantify the effect of surface contamination of the waterstop on the interface bonding strength. The adhesive tape on the surface of the waterstop was “contaminated” by either or both sand and bentonite slurry for the peel strength test. The results indicate that the surface contamination of the waterstop does not induce a meaningful reduction in the bonding strength for the tested conditions.