Contractor | Farrans |
|---|---|
Designer / Architect | Arup |
Aggregate Supplier: | LKAB Minerals |
Concrete Producer: | Capital Concrete |
The background
The Gull Wing Bridge is a rolling bascule bridge that spans Lake Lothing in the town of Lowestoft, Suffolk, and is the largest bridge of its kind in the world to date. Due to its distance of 12m from the water below, the crossing will allow bigger vessels to pass beneath it without having to open, resulting in fewer traffic delays. The total contract value was around £76M and the total project duration was around 27 months. The single-span rolling bascule bridge’s most striking feature is the dual ‘gull wings’ that act as counterweights.
The challenge
The bridge raises and lowers on one platform, compared with two platforms seen in other bascule bridge designs. This means the single platform is larger and therefore required a higher-density heavyweight concrete in its counterweights. This heavyweight concrete needed to counterbalance was designed to be approximately. 380 tonnes.
Our solution
To achieve the necessary weight for this counterbalance, Master Builders Solutions worked in partnership with Capital Concrete and LKAB Minerals utilising MagnaDense aggregates and MasterGlenium SKY 1966 to produce the high-density concrete that is installed in the upper portions of the gull wings.
Included in the concrete mix was MasterFinish DF 880 which is a highly effective defoamer that reduces the air voids inherent in concrete’s manufacturing process. It also helps reduce the air voids created during placement and compaction, significantly reducing the formation of air voids on the concrete’s surface to produce high-quality architectural concrete.
Several lab and site trials were needed to produce a concrete mix utilising the MagnaDense aggregates to achieve the higher density needed for this project, as well as to ensure the mix remained workable for over 4 hours once batched.
To achieve this consistency, MasterSure 1970 was added as it has been optimised to work in conjunction with the high-performance superplasticiser, MasterGlenium SKY 1966. These admixtures create a two-component system giving high performance concrete with controllable and selectable consistence retention periods needed.
