Improvement of plastic pipe–concrete interface impermeability

Concrete structures, such as bridge piers and pile foundations, in tidal/splash zones and soil–air transition zones in saline environments often suffer more severe structural corrosion and reinforcement corrosion than the structures completely in water, soil, or air. The application of plastic-pipe concrete can effectively solve this problem. Plastic-pipe concrete is formed by pouring concrete into a large-diameter plastic pipe with a certain structural size. Plastic pipes can protect the bridge piers and eliminate the water level change area and the soil–air junction area in structural design, to realize the integrated anti-corrosion protection of the bridge piers in the saline environment. The anti-corrosion protection effect of the plastic-pipe–concrete system depends on the impermeability of the plastic pipe–concrete interface. The difference in linear expansion coefficient between the plastic pipe and concrete and the shrinkage of the core concrete will damage the bonding layer between the plastic pipe and concrete, consequently affecting the interface impermeability. To improve the impermeability of the plastic pipe–concrete interface, the effect of a pressure-sensitive adhesive tape (Preprufe double-sided tape) attached to the plastic pipe–concrete interface was studied. Experiments were conducted to determine the interfacial bond strength, interfacial water penetration height, and interfacial air permeability, and the gas pressure–time decay curve was measured, and the interface permeability index was deduced. The experiment results show that the relationship between the interfacial bond strength and the adhesive tape width can be preliminarily considered as a power function distribution. The bond strength formed between the pressure-sensitive adhesive layer and the liquid concrete during the hardening process is much greater than that between the ordinary adhesive tape and the plastic pipe. Pasting the Preprufe tapes can significantly improve the impermeability of the plastic pipe–concrete interface. The interfacial permeability index decreases with the increase in the adhesive tape width, and the interfacial permeability index coefficient of plastic pipe–concrete specimens with 220 mm–wide tape is only 2.86% of that of the specimens without tape. The Preprufe double-sided pressure-sensitive tape has good performance in improving the impermeability of plastic pipe–concrete interfaces. In engineering applications, the adhesive tape width can be selected based on the required effect and cost.