27/08/2026
Why Fiberglass Reinforced Polymer (FRP) Jackets Are the Premier Choice for Bridge Pier and Deepwater Pile Foundation Repair?
I. Background and Pain Points
Bridge piers and quay pile foundations in deep-water and splash zones are subject to long-term chloride ion ingress, current scouring, and wet-dry/freeze-thaw cycles, which commonly lead to concrete spalling, exposed and corroded rebar, necking, and cross-section loss. Traditional repair methods (cofferdam dewatering, steel jacket reinforcement) suffer from prolonged construction periods, high costs, disruption to navigation and traffic, and susceptibility to recurrent corrosion.
II. Core Advantages of the FRP Jacket Reinforcement System
The system consists of custom high-strength FRP (Fiber Reinforced Polymer) jackets combined with underwater-specific epoxy grout. Its main advantages include:
Underwater Operations Without Cofferdams: Divers can install, seal, and grout the jackets entirely underwater, without disrupting bridge traffic or waterway navigation, significantly reducing coordination complexity and temporary works costs.
Corrosion Resistance and Durability: FRP jackets are made of polymer composite materials resistant to acids, alkalis, and salt spray. A dual-barrier system (jacket isolation + grout infill) effectively blocks chloride ion pe*******on.
Long-Term Maintenance-Free Performance: The system withstands tidal action, freeze-thaw cycles, and current scouring. Unlike steel jackets that corrode within a few years, FRP jackets deliver a one-time repair with long-term protection.
Short Construction Cycle: By eliminating cofferdams, formwork removal, and similar processes, the system enables prefabricated assembly-style construction with outstanding overall cost-effectiveness.
Broad Applicability: Suitable for circular and rectangular concrete piles, steel piles, and timber piles. Lightweight design adds no extra load to the pile foundation, and jackets can be custom-manufactured on site.
III. Key Material Properties
Xinchor FRP Jacket (synthetic resin + glass fiber composite):
All tested indicators exceed national standards. For example: tensile strength ≥ 170 MPa (actual: 455 MPa); flexural strength ≥ 200 MPa (actual: 267 MPa); water absorption ≤ 0.7% (actual: 0.22%); water resistance (30-day flexural strength retention ≥ 75%, actual: 93.3%).
Xinchor Underwater Epoxy Grout (modified epoxy resin, etc.):
Features early strength development, high ultimate strength, non-dispersibility underwater, self-leveling properties, and strong adhesion. Direct tensile bond strength with concrete ≥ 3.0 MPa; shrinkage rate (28 days) ≤ 0.1%; excellent resistance to freeze-thaw and hygrothermal aging.
IV. Construction Procedure
Step 1 - Surface Preparation: Underwater cleaning of the pile surface; removal of loose concrete, corrosion products, and sediment.
Step 2 - Jacket Installation and Positioning: Wrapping the jacket around the pile, locking the interlocking seams, and installing elastic sealant strips at the bottom to prevent grout leakage.
Step 3 - Bottom Sealing and Grouting: Injecting epoxy grout to seal the bottom, then allowing it to cure.
Step 4 - Full-Height Grouting: Layer-by-layer injection of underwater epoxy grout to displace internal water and fully fill all voids.
Step 5 - Top Sealing: Applying underwater sealing adhesive at the top and allowing natural curing to form a finished seal.
V. Application Scenarios
Repair of bridge piers and deep-water pile foundations in splash zones of cross-sea and cross-river bridges; underwater reinforcement and anti-corrosion protection of port and wharf pile columns; remediation of defects in bridge piers at inland rivers, reservoirs, and lake areas; durability enhancement of aging pile foundations; underwater repair and reinforcement of concrete, steel, and timber piles.
VI. Conclusion
The underwater FRP jacket reinforcement technology is distinguished by its core competitive advantages: "no cofferdam required, underwater construction, long-term corrosion protection, and low overall cost." With excellent material properties and adaptability to complex working conditions, it has become the preferred solution for numerous bridge pier and pile foundation reinforcement projects.
