Maximises clearance levels
A 220–300 mm slab prevents scour and mounding while keeping bed clearance, so the berth keeps the depth it was dredged for.
Solutions
Scour protection · sealing
Protecting quay walls.
Vessel propulsion erodes the bed at the wall, undermining bearing capacity and berth depth. A sealed in situ concrete mattress, typically 220–300 mm, protects the wall and maximises clearance, proven against jet flows to 12.5 m/s over 50 years of use.
The advantage
Sealed protection, 220–300 mm.
An in situ concrete mattress produces a plain concrete slab of uniform thickness with fully interlocking shear joints: one continuous slab that seals against the quay wall, with edges protected by rock, embedment or a collapsing formwork edge.
By distributing the hydrodynamic forces across the slab, it allows low vessel clearance with high propulsion velocity, at a time when larger propellers, reduced bed clearance and new propulsion types are driving scour actions that have caused failures of quay walls and their protection.
Rock armour · Concrete mattress
Same wall, compared
Rock armour
Concretemattress
What the sealed slab gives you
Conforms to the seabed
Cast directly on the bed, the mattress follows undulating ground without precise dredging or underwater levelling to prepare the surface.
Withstands 12.5 m/s jet flows
Sealed protection withstands far greater hydrodynamic forces than open systems, with 50 years of proven usage behind it.
Installed at up to 300 m² a day
Dive teams roll out and pump-fill the panels from the quay side, per team, with no expensive marine plant or heavy lifting equipment.
Our solution
A single, sealed surface.
Fabric-formed concrete does both jobs with one method and one crew, designed to your wall, your bed and your vessel loading.
One interlocked slab
A plain concrete slab of uniform thickness, typically 220–300 mm, cast directly on the seabed so it follows the bed contours. Panels join through grout-tight ball-and-socket shear joints, so the cured apron behaves as one slab, not individual units.
Closed with a wall bolster
A concrete bolster is cast at the base of the quay wall to close the joint between mattress and structure, so propeller flow cannot enter behind the protection and unload the wall.
Protected against under-scour
The seaward edge is designed to the bed material: an embedment trench, hinged edge blocks that settle into local scour, or a rock detail, eliminating the under-scour that defeats open systems.
220–300 mm
Typical slab for vertical quay walls
12.5 m/s
Proven against propeller jet flow
50 yr
Proven usage of the system
Up to 300 m²/day
Installed per dive team, conditions depending
Installation
Rolled out at the toe
Divers roll out the formwork panels on the seabed along the toe of the quay wall and position them against the structure.
Pump-filled from the quay side
A 2:1 sand-cement micro-concrete, designed for 35 N/mm², is pumped into the panels. The formwork protects the mix against washout while it cures.
Joined into an interlocked slab
Divers engage the dual-connection system between panels, zipping them together to form ball-and-socket shear joints. The cured apron acts as one interlocked concrete slab, with continuity across the whole protection area.
Quay wall projects
Proven on working ports.
Ashdod 17 m Berths
New 17 m deep container berths on a combi-wall quay, protected with a sealed 300 mm apron so the largest container vessels afloat can berth with no joints to scour.
Port of Szczecin
Sealed scour protection enabling greater depth capacity from the existing quay structure, for the Port of Szczecin.
The technology behind it
Go deeper on the method.
FAQs
Frequently asked questions
How do you protect a quay wall from propeller scour?
A fabric-formed concrete apron is laid over the bed in front of the wall, 220–300 mm thick, and sealed against the wall face so there is no open joint for flow to enter.
Divers position the empty form on the bed and it is pump-filled with micro concrete from the quay side, curing in place as one continuous slab.
How thick is quay wall scour protection compared with rock armour?
A sealed concrete apron is typically 220 to 300 mm thick. The equivalent graded rock section is 1.5 to 2.5 m, so rock takes up around ten times the depth to do the same job.
On a working wall that depth matters. Rock protection is built up off the bed, which takes water depth away from the berth. A concrete apron adds a few hundred millimetres, so the depth stays available to the vessel.
Can protecting the wall also help gain berth depth?
Yes. A rock section takes up 1.5 to 2.5 m of the depth in front of the wall. A sealed concrete apron takes up 220 to 300 mm, so the bed can be dredged lower while the wall keeps the same protected toe.
At the Port of Szczecin, sealed protection was used to gain depth capacity from the existing quay structure rather than rebuilding it. How much depth can be won is set by the wall and the ground behind it, so it is checked case by case.
Can it be installed while the berth stays in use?
Yes. Installation is by divers from the quay side, with no marine plant, so work can be phased around vessel movements.
The apron is pumped in sections and connected as work proceeds, which lets the team pause and restart between berth occupations.
What flow velocity is the protection designed for?
Sealed fabric-formed protection is proven against propeller jet flows to 12.5 m/s, with over 40 years of in-service usage behind the system.
Design velocities are always confirmed project by project from the vessel classes, propulsion type and seabed conditions.
Before it reaches the surface
Discuss your quay wall protection with our engineers.
Send us the wall type, the bed conditions and the vessels using the berth. Your enquiry goes to our engineers, whether you are specifying the protection or pricing its construction.
or call Martin Hawkswood, Director & Principal Engineer · +44 (0)1926 512 222 · [email protected]