Installed under the deck
The lightweight formwork is handled and placed beneath deck structures where access is restricted, and the works above carry on while it goes in.
Solutions
Scour protection · under the deck
Protecting piled revetments.
The slope beneath a piled deck takes both propeller wash and wave action. A fabric-formed concrete mattress protects it for a fraction of the material of rock armour, pump-filled in situ under the completed deck.
The advantage
Less material, off the critical path.
On an open piled structure the mattress earns its place two ways. It uses far less material: a single 220 / 150 mm slab in place of multiple layers of rock armour, at a time when modern propulsion demands larger stone sizes that make rock progressively less cost-effective.
And it is installed under the deck, so the works above continue uninterrupted. Rock layers are difficult to form around piles on slopes; the fabric form is tailored to them, sealed sand-tight at every penetration.
Material comparison
Al Faw Grand Port
Why it suits open piled structures
Much thinner than rock layers
A single 220 / 150 mm slab in place of multiple layers of rock armour, where modern propulsion now demands stone sizes that make rock less cost-effective.
No expensive marine plant
The mattress is pump-filled in situ from the deck, supplied directly from ready-mix wagons. No dredgers, no rock barges.
Formed to the revetment
The form conforms to the tolerances and undulations of the slope and seals sand-tight around each pile, without precise dredging or extensive bed preparation.
Our solution
A single, sealed surface.
One method protects the slope, the bed and the pile penetrations, designed to your structure, your bed and your vessel loading.
A sealed scour apron
A plain slab of uniform thickness laid over the revetment face, 220 mm through the wave zone and 150 mm submerged, with fully interlocking shear joints forming one continuous apron.
Sand-tight pile seals
The form seals sand-tight around each pile group and bonds securely to the quay wall, with the seaward edge protected by embedment or rock armour, so flow cannot track down the pile line.
Works above uninterrupted
Everything is placed by divers beneath the completed deck and pump-filled from above, with our engineers supervising on site.
220/150 mm
Wave zone / submerged section
35 N/mm²
Micro-concrete strength, pumped bottom-up
35+ yr
Proven performance on piled revetments
In situ
Pump-filled by divers, under the deck
Installation
Laid out by divers
Divers lay out the tailored formwork, secure it around the piles and zip-connect it to adjacent panels, forming a continuous interlocked apron.
Filled from the deck
A 2:1 sand-cement micro-concrete, designed for 35 N/mm², is supplied from ready-mix wagons and pumped into the panels from the bottom up through grout hoses.
Conforms to the slope
Bottom-up filling eliminates voids, and the mattress follows the tolerances and undulations of the revetment without precise dredging or extensive bed preparation.
Piled jetty project
Proven under working decks.
Al Faw Grand Port
A 1.75 km piled jetty where the concrete mattress was installed beneath the deck, around the pile clusters, in parallel with the main build, scour protection kept entirely off the critical path.
Puerto Quetzal
A piled jetty protected under the deck while construction continued above, the mattress draped down the slope and sealed around the piles in the confined space below.
The technology behind it
Go deeper on the method.
FAQs
Frequently asked questions
How do you protect the slope under a piled deck?
A fabric-formed concrete mattress is laid over the slope, woven to match the pile grid and placed by divers beneath the deck, then pump-filled in tremie fashion.
Because it goes in empty and is filled in place, the protection can be installed in the restricted headroom under a piled jetty without heavy marine plant.
Why use a concrete mattress instead of rock armour under a jetty?
Access is the first reason: getting graded rock under a piled deck in the required volumes is slow and often impractical. The second is material.
A mattress uses around 16× less material than the equivalent rock section. At Al Faw Grand Port, that saved 405,600 m³ of rock across the 120,000 m² berth.
Does installing the protection delay deck construction?
No, it can be kept off the critical path. The mattress can be installed beneath a piled deck before, during or after deck construction, so the sequence is set by what suits the site rather than by the protection.
It needs no marine plant and no crane time, so it does not compete with piling or deck works for access. The slope can also be protected in sections and connected to the berth mattress later, which lets the work fit around the contractor’s programme.
What thickness is used on a piled revetment?
Typically 220 mm in the wave zone and 150 mm for the submerged slope, set by the exposure at each level rather than a single blanket thickness.
The mattress is a sealed, continuous surface, so the slope is protected without relying on individual units staying stable.
Who installs it, and how are the piles sealed?
Installation is by the contractor’s own divers, with Proserve engineers supporting on site. The form is woven to the pile layout with integral pile seals the diver clips to each pile.
Where the piles are irregular, bespoke cut-outs are fabricated from an as-built survey so the apron seals around every element.
Before construction locks it in
Discuss your revetment protection with our engineers.
Send us the deck layout, the slope and bed conditions and the vessels using the berth. The earlier we are in the design, the more we can keep the protection off your critical path.
or call Martin Hawkswood, Director & Principal Engineer · +44 (0)1926 512 222 · [email protected]