Waco produces first lock gate made of ultra-high strength concrete

BERGEN OP ZOOM, March 6, 2024 – A milestone in the Dutch engineering and concrete industry: FDN Group, in collaboration with Waco, has successfully produced the first maintenance-free lock gate made of ultra-high strength concrete (UHSB). This groundbreaking achievement opens the door to a whole new generation of sustainable infrastructure, including locks, flood defenses and offshore wind turbines.

Traditionally, lock doors are made of wood or steel, materials that require significant maintenance and have a limited lifespan compared to concrete. Wood doors, for example, must be replaced every 25 years or so, while steel doors require a new, often dirty, coating against rust after 10 to 15 years. In contrast, concrete structures offer a maintenance-free lifespan of at least 100 years.


The development of this innovation began in 2018, when FDN Group, in collaboration with the Province of Groningen, designed a lock gate made of ultra-high-strength concrete with a core of EPS (expanded polystyrene). This lightweight core saves weight while providing exceptional pressure resistance similar to steel. Although material research and design went smoothly, pouring a UHSB sluice gate proved complex. After three previous failed attempts, Waco, part of Concrete Valley, did manage to successfully produce the lock doors in February and March of this year.


The ultra high-strength concrete doors, including their buoyancy thanks to the polystyrene core, are as heavy as the steel and wood variants and have a strength class of C200, unprecedentedly high compared to traditional concrete. Due to a higher density concrete mix, the use of steel fibers and special fillers, UHSB is as much as 10 times stronger than traditional concrete. The province of Friesland financed the concrete lock gates, measuring 7.3 by 5.3 meters, which will be installed in the Robbengat lock at Lauwersoog after the sailing season on behalf of the province of Groningen. This will replace the existing wooden lock gates with this considerably more durable variant.