Widening the scope

Flexmat, a flexible concrete block mattress originally designed for coastal protection, has found a variety of uses in Australia’s infrastructure sector. Today, it is being utilised for a number of large onshore projects.When coastal engineer Jan de Geeter finished a two-year assignment at Woodside Energy’s Rankin project on Australia’s North West Shelf region in the 1980s, he identified the need for more comprehensive pipeline stabilisation and erosion control on similar projects.

Mr. de Geeter came up with the idea for a flexible concrete block mattress that could effectively help protect marine-related infrastructure and environments. The result was the Flexmat system – an alternative to traditional systems such as rip-rap, rock linings, groutfill or reno mattresses and sealed linings, including shotcrete, bitumen, concrete slabs or pavers.

In 1984 he started Marine Environmental and Construction Consultants (Marecon), and has been supplying the wider Australian infrastructure sector with Flexmat solutions as part of the business since.

“The earliest Flexmat applications were all off shore, but we began to shift its emphasis towards coastal protection against foreshore regression and scour prevention in front of wharfs, dams and other coastal structures,” explains Mr. de Geeter.

“We also saw a sharp increase in smaller scale applications, such as boat and barge landing ramps,” he adds.

Its long-term durability in water, broom-finish, anti-slip roughness, and hydraulically smooth lining face have made it ideal for myriad marine and coastal projects.

With a fast installation rate, which Mr. de Geeter says normally exceeds 80 square metres per hour, and the fact it is retrievable and re-deployable in seasonal or temporary applications, has given the Flexmat the flexibility to be employed both off and onshore.

“It’s proved, in a number of instances, to work in the most adverse environmental conditions with a durability of more than 50 years,” he says.

Flexmat is now being used for a number of applications, including waterway embankments, lining of channels and open drains, road and rail embankment lining, temporary roadways, terrain cover in utility areas and walkways and bush tracks.

Today, Mr. de Geeter says the Flexmat has undergone a couple of key developments that are seeing it rolled out in a range of larger onshore, or ‘dry’ applications.

“The installation and pick-up of the mattresses has become quicker and easier by moving away from traditional lifting groups to basic, low-cost tubulars. This means it can be operated safely without any specalised skills. It also makes the mattress ideal for repeated application, such as movable roadways and hardstand areas on mine sites or farms,” he says.

This has helped the company focus on significant onshore applications of the flexmat.

“A key new development has been the large scale rollout of onshore Flexmats. It commenced earlier this year where the system was used as culvert crossings at a large mine project in North Queensland and as service roadways at Sydney Airport,” says Mr. de Geeter.

“The mattresses have been extensively load tested to ensure the block won’t crack under heavy vehicle trafficking, and that service life is very long,” he says.

“Some Flexmat ramps with high traffic density are still in operation 20 years on from installation.”

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