Revolutionising bridge construction: The rising dominance of aluminium

The construction industry is transforming with the rising dominance of aluminium in bridge construction. Traditionally, steel and concrete have been the primary materials for bridge infrastructure, but aluminium is now emerging as a game-changer. Its lightweight yet robust properties make it an ideal alternative for constructing bridges, offering numerous advantages. Aluminium bridges are more durable and resistant to corrosion, but they also require less maintenance and can be erected more rapidly, reducing construction time and costs. This shift towards aluminium revolutionises bridge engineering, providing innovative solutions for sustainable, cost-effective, and long-lasting infrastructure projects.

The interest in aluminium is explained by its unique properties. They include low specific gravity, high corrosion resistance and durability: for example, the service life of a bridge with aluminium structures exceeds 70 years. At the same time, aluminium bridge structures mustn't require constant anti-corrosion treatment, unlike steel ones. Recently, with the growing attention to sustainable development – environment and conservation of climate, in particular, with the introduction of the principles of 'green' construction, the possibility of aluminium processing has become of great importance. About 80 per cent of the world's aluminium continues to be used after processing.

An aluminium bridge does not corrode because the oxide coating of aluminium protects against corrosion. Paint is therefore not needed. Aluminium in the bridge can contain up to 100% recycled material, so aluminium is both a climate-friendly and cost-reducing material choice. Aluminium bridges have a historical legacy, and their modern applications continue to shape infrastructure as they forge ahead. Listed below are some of the aluminium bridges that have been in the news:

Schwansbell Bridge: In 1956, the first aluminium road bridge in Germany was opened to traffic over the Datteln-Hamm Canal near Lünen. It is a truss construction made of extruded profiles and sheets made of the AlMgSi 1 alloy (today: EN AW-6082). The Schwansbell Bridge spans 44.20 m and, with a dead weight of 25 tonnes, is approved for a vehicle weight of up to 12 tonnes. The design of a comparable steel bridge resulted in a finished weight of 60 tonnes. The weight saving through aluminium was 58 per cent. Aluminium rivets, made from AlMgSi 1, were used almost exclusively as fasteners. The rivet shape was previously determined and optimized in tests.

Grødola Bridge: The Grødola River bridge in Sunndal, measuring 18 meters in length, represents a significant advancement over the previous stone bridge it replaced. By incorporating recycled aluminium reinforcements and employing thinner concrete slabs, this bridge has achieved an impressive reduction of up to 80 per cent in emissions. Adopting aluminium instead of steel reinforcement in concrete construction marks a remarkable technological breakthrough.

Grøtta Bridge: This bridge in Rauma, Norway, will be the country's inaugural project to utilize extruded aluminium profiles in its construction and will be completed in 25/26. This choice of aluminium is anticipated to yield reduced greenhouse gas emissions throughout the bridge's life cycle compared to alternatives like concrete and steel. Additionally, it is expected to lead to decreased operational and maintenance expenses, making it a more cost-effective option than the alternatives examined.

Hangar Bridge:  In Trondheim, a suspension bridge measuring 55 meters in length and 9 meters in width is slated for construction in 2024/25. This bridge will accommodate maintenance vehicles and snowploughs, with the deck and superstructure being crafted from aluminium. The choice of aluminium allows for creating a single-span bridge that is not only sleeker but also lighter than the traditional steel bridge option.

Langenuen Bridge: the use of aluminium can be a game-changer for bridge-building. For the proposed Langenuen bridge project in Norway, Hydro is focusing on exploring whether using aluminium for all the relevant design criteria for bridge girders would be feasible. The company’s dream is to make the longest aluminium bridge in the world. It could potentially be a game-changer for bridge building and the use of aluminium in new ways in the future. It focused on what could be the longest aluminium bridge in the world: 1,720 meters, 1,250 meters of which would be aluminium, equivalent to 8,000 to 10,000 tonnes.

Rene (pedestrian and bicycle bridge): Austria's latest pedestrian and bicycle bridge, situated in the heart of the country, showcases the extensive use of aluminium in its construction. The bridge spans nearly 55 meters in length, offers a generous passage width of 3.5 meters, and boasts a weight of 21 tonnes. This innovative bridge is composed primarily of aluminium profiles sourced from Hydro, accounting for almost 100 per cent of its materials.

(Source: Hydro)

Verdun Marina mill-finish aluminium bridge: In the year 2002, Technomarine constructed the Verdun Marina Bridge, a robust 25-meter-long and 3-meter-wide arched pony truss bridge compliant with the Canadian Highway Bridge Design Code CAN/CSA-S6-00. This impressive structure boasts a Cumaru wood deck and is designed to withstand a live load of 4.8 kPa. Notably, only the vertical pickets have a powder-coated finish, with the remainder featuring a natural mill finish in aluminium. Remarkably, according to the Borough of Verdun, this bridge has not required any repairs or maintenance throughout its 18-year existence. Furthermore, this bridge is anticipated to remain virtually maintenance-free for several more decades.

Qingchun Bridge: China's first aluminium pedestrian bridge was built on Qingchun Road, Hangzhou in 2006.

The innovation of aluminium bridges stands as a testament to human ingenuity and engineering excellence. These lightweight structures not only offer cost-effective and environmentally friendly alternatives but also provide enhanced durability and aesthetics. With their adaptability and resilience, aluminium bridges promise a brighter future for infrastructure development, meeting the ever-evolving needs of our modern world.