The cable-stayed Samuel Beckett bridge in Dublin has a unique design with heavy concrete in both pivot and bridge deck to maintain the right balance. For boats to pass, the bridge swivels open balancing on a pivot placed out of the centre.
Therefore, the bridge needs extra weight on the short end of the construction to keep the balance perfect. In this case, the best solution for extra weight in the complete design was MagnaDense heavy concrete, as it gives more weight and requires less volume than ordinary concrete.
Heavy concrete balance weight
The Samuel Beckett Bridge is inspired by a harp, the national instrument of Ireland, lying on its side making it a striking appearance. This cable-stayed bridge that joins Macken Street on the south side of the river to Guild Street on the North Wall Quay in the docklands area was designed by Santiago Calatrava who also designed the James Joyce Bridge that is further upstream. The contractor for this project was the Graham Hollandia Joint Venture for whom CEMEX Ireland supplied the heavy concrete.
What makes this bridge unique from many other modern bridges is not only its looks but moreover its engineering design. The bridge has a total length of 123 meters and a weight of 2350 ton for the steel construction. Unlike other bridges that turn to have boats pass, this bridge has its pivot point out of the centre, with 31 meters to one side of it and 92 meters to the other side. As a result, the “short” part of this construction needs extra weight to keep the right balance when swivelling 90 degrees allowing ships to pass.
Flowing high density concrete
For this project, LKAB Minerals was contacted by the company CEMEX Ireland, who was responsible for providing heavy concrete in the construction. They needed 2200 ton concrete ballast weight with a density of 3900 kg/m3 +/- 2.5%. Another requirement was that this concrete had to have high workability of 620mm on the flow table, enabling the concrete to flow around the completely closed steel compartments. Avoiding segregation of the concrete at such high flow rates was an added challenge for this project.
The 470 cubic meter concrete pour was a significant technical challenge that took months of planning. Carried out over four separate days the weight of the MagnaDense concrete ballast ensured that the bridge remained balanced during its placement and final assembly over the river Liffey.
Workable and pumpable dense concrete
To design the special heavyweight concrete CEMEX worked closely with LKAB Minerals to create the most appropriate mix for the project. CEMEX needed to achieve a concrete density of 3.9 mt/m³ to meet the specifications. Achieving a higher weight with the same volume required a high-density aggregate for the concrete. LKAB Minerals markets MagnaDense and has a specific gravity that can exceed 5 mt/m³. Also, it is available in different fractions, making this product ideal for heavy concrete. During the construction phase, CEMEX confirmed with LKAB Minerals that they were pleased with the workability and pumpability of the concrete.
Experience in bridge projects
We supplied our high density MagnaDense to various bridge projects, even more than we currently display on the website. We advise you to contact us for more detailed information. Some exciting projects that we do share online are: