Quay Wall Scour Protection
Quay walls can be structurally undermined by the erosion of bed material caused by vessel propulsion leading to ground loss, loss of bearing capacity, and even structural failure. Such damage not only results in costly repairs but also disrupts port operations and compromises navigational safety.
The displacement of bed material can also produce mounding, effecting clearance levels for vessels.
The size of conventional vessels is continually increasing creating a reduction in bottom clearnces and a demand for deeper berths. The combination of larger propellers with greater power and a reduction in bed clearance has created higher levels of bed scour action affecting berthing structures.
New types of vessels are now also in operation with a wider range of propulsion types.
These new propulsion types can also create increaseing scour actions. In many cases the new actions have not been well understood and failures to quay walls and scour protection have occured.
Concrete Mattress Solution
In situ concrete mattress prevents vessel scour and maximises clearance levels. The system produces a plain concrete slab of uniform thickness with fully interlocking shear joints. This creates a continuous concrete slab that seals against the quay wall and is protected at the edges with rock, embedment, or a formwork collapsing edge.
The plain concrete slab enables low vessel clearance with high propulsion velocity by effectively distributing the hydrodynamic forces across the slab produced by the vessel. As a result, in situ concrete mattresses provide a robust, long-term scour protection system that ensures structural stability of quay walls, reduces maintenance requirements, and supports safe and efficient berthing operations even under demanding marine conditions.
The in situ concrete mattress system has 50 years of proven usage and has a performance record of withstanding extreme action from jet flows of up to 12.5m/s. The system is typically 220 to 300mm in thickness for the protection of vertical quay walls.
Design
Proserve engineers undertake design of berth scour protection and support other engineers as required. Research scale model testing is undertaken in our in-house testing facility.
Installation for Quay Walls
The installation of concrete mattress aprons for quay wall scour protection is carried out by specialist dive teams using an in situ casting method. The process begins with divers rolling out mattress formwork panels on the seabed along the toe of the quay wall. Once correctly positioned, the formwork is pump-filled from the quay side with a 2:1 sand–cement micro-concrete mix, designed to achieve a compressive strength of 35 N/mm². The fluid concrete is contained and protected against washout during curing by the enclosing formwork, ensuring uniform strength development and durability in the marine environment.
Connection between adjacent mattress panels is achieved by divers engaging a dual-connection system that zips together to form ball-and-socket shear joints. This produces an interlocked concrete slab with continuity across the apron, enhancing overall stability and resistance to hydraulic loading. The system offers significant advantages over traditional scour protection methods, as it does not require expensive marine plant, heavy lifting equipment, or precise seabed levelling. Its ability to conform to undulating beds makes it suitable for a wide range of site conditions, while ensuring a close seal against the quay wall.
In practice, typical installation rates range between 125–300 m² per day for each dive team, depending on working conditions such as water depth, visibility, currents, and site access. This combination of speed, adaptability, and robustness makes in situ concrete mattresses a cost-effective and long-term solution for protecting quay walls from scour, maintaining berth depths, and extending the operational life of critical port infrastructure.
Advantages for Quay Walls
Sealed Protection
With effective joints creating a continuous concrete apron, the system seals against propeller-induced flows. Sealed protection can withstand far greater hydrodynamic forces than open systems.
New Berths
In new construction, in situ mattresses can reduce dredging requirements and lower quay wall height.
Berth Deepening
For existing ports, sealed scour protection enables greater depth capacity from the existing quay structure.