Ships use concrete to avoid sinking

A lightweight concrete filling injected into a ship’s bulkhead will make vessels more resistant to collisions, fatigue and corrosion, according to its Norwegian developers.

Risk management agency Det Norske Veritas, in partnership with Aker Kvaerner Yards, claims the steel-concrete sandwich structure will add extra strength and fire resistance, plus help dampen noise and vibration.

The announcement of the composite for ships follows a collision in the Channel last month when the 55,000-tonne carrier Tricolor hit another vessel and sank. Luxury cars worth around £30m were lost.

Prof Paal Bergan , vice president of strategic research at DNV, said his original idea was to weld steel plates on either side of the corrugated steel bulkheads in old ships, then fill the gaps with concrete. This led him to design a whole new ship around the concrete sandwich concept.

The team then developed a lightweight concrete with a specific weight below one – or lighter than water. This was achieved with ordinary cements and chemical additives. Bergan said that, like steel, the material could resist crushing of up to 15 megapascals and he hoped to raise this to 20. He compared the sandwich idea to car bumpers with a composite that absorbs the shock of collisions.

In the event of fire, concrete would act as an insulator preventing it from spreading, he said. Other benefits are that, as the structures would have less surface area than corrugated steel, it would require less painting, be easier to clean and less prone to corrosion.

The next stage of the project aims to test the properties of the sandwich construction, and design processes for building ships to include it. He estimated that within five years it could be possible to try out the idea in a restricted segment of a vessel.

Another firm, Intelligent Engineering, has developed a similar material. This uses elastomers as a filling rather than concrete but is used mainly for reinstating ships’ decks rather than bulkheads.