The Netherlands with its many waterways and its dense population is home to a countless number of bridges. A bridge is an ideal object to test the properties and possibilities of new biocomposites. Biocomposites combine natural materials with excellent properties for strength, climate resistance, insulation and fire resistance. A biocomposite has different properties than its individual components. Demonstration projects help to increase the knowledge of biocomposites on the one hand, and to proof that biocomposites can play an important role in infrastructural constructions and as an alternative to conventional construction materials such as concrete, steel and fossil-based composites on the other hand.
The new Wildlands Adventure Zoo in Emmen features the first Dutch biocomposite folding bridge. The composite sandwich bridge deck is made of flax, cobalt-free bio-resin, a foam core of recycled PET bottles and a tiny amount of steel. It has a width of 4m and a span of 5m. Finding the best bio-resin was just one of the challenges. It weighs 50% less than a conventional bridge, so the concrete foundation can be lighter and it takes less energy to open it. Check this video (in Dutch) by RTV Drenthe featuring a model of the bridge.
Another pedestrian biocomposite bridge, but with 14m much longer, was built at the Eindhoven University campus. This ‘biobridge’ consists of a long, slender beam and fan-shaped balustrades that remind of blades of grass. Materials used include PLA (poly lactic acid) foam, cork, hemp and flax fibres and a bio-based epoxy resin. Have a look at the video here.
A bridge of similar length is to be realised at Schiphol Logistics Park. Here a unique combination of (strong, light-weight) basalt fibres and bio-based polyester resin will be used for the deck of a bio-basalt-balsa (B3) pedestrian bridge. The materials are selected for strength, light weight, expected lifespan and low maintenance. The bridge is scheduled to be opened for public use in late 2018.
The by far largest biocomposite bridge will be built across the Van Harinxmakanaal near Ritsumasyl (Ritsumazijl) in Fryslân (Friesland) later this year. The asymmetrical swing bridge has a total length of 66m. It will get decks of 32m and 34m with two free spans of 22m. It is slated to become the largest biocomposite bridge in the world that is integral part of the public road network and crosses a canal used for commercial shipping. It is estimated that the materials will last for at least 100 years, and will require less intensive maintenance and repair than conventional materials. You can check progress of bridge construction here.