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Fronded Concrete Mattresses (FCM’s)

The Bi-flex fronded concrete mattress (FCM)

Effective for stabilisation and scour prevention in areas that are subject to seabed or riverbed material transition.

The flexible concrete mattress consists of high strength concrete segments linked together by polypropylene ropes to form a continuous flexible concrete barrier.

Frond lines are then attached to the mattress, when both products are used in conjunction this gives an instantly self-stable product ensuring the fronds are not swept away in onerous conditions.

The individually profiled concrete segments provide a high degree of flexibility which offer complete protection of subsurface structures.

Useful in many applications, such as cable or pipeline cover; riverbed and riverbank scour prevention and stabilisation; protection and stabilisation for fixed structures such as bridge footings, buildings, ports, quay heading and seawalls. The products are also used to combat coastal erosion.

The UV stabilised fibrillated polypropylene strips (fronds) are secured to polyester webbing and fibrillate under repetitive current action. The fronds are enclosed in a safety net for storage and deployment which is released by ROV or diver post installation.

Shallow Water Study

Fronds Immediately after placement

Fronds 15 days after placement covered by fully formed sediment bank

Key Features and Benefits are:

  • Fronds slow down current and allow sediment to form between fronds, this adds to on bottom stability of the covered object, increasing submerged hold down by at least 800kg/m3.
  • A typical FCM with 1.25m fronds can form a sediment bank over 900mm high, providing outstanding dropped object protection.
  • Fronds will provide a consolidated sand bank which naturally builds up over the mattress, offering an anti- scour solution.

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