CCL has been awarded the Structural Concrete Alliance (SCA) Award 2016 for its innovative work in designing a refurbishment solution for a National Grid asset at Isle of Grain in the UK.
The award was presented to CCL’s Chief Operating Officer for Europe, Jon Machin, and Operations Director for CCL GB, Terry Bradley during the Concrete Society Awards dinner.
CCL fought off strong competition from 16 entries and two other shortlisted projects to take home the award, thanks to the ingenuity of the post-tensioning solution used at Isle of Grain, which delivered a fresh approach to the replacement of gas storage tank bund wall restraints.
Comments Jon Machin: “CCL is constantly driving innovation across concrete design and engineering projects to find new approaches to maximising the potential of concrete structures. The Isle of Gain scheme is an example of that commitment and we are delighted that it has been recognised with this award.”
The winning project involved a liquid gas storage tank with a 50,000 m3 capacity. The 19.5m tall reinforced concrete bund wall that surrounds it to provide secondary containment was 35 years old and in need of upgrading. CCL designed a bespoke post-tensioned assisted strap restrainment solution, involving the design of special anchors capable of restricting bursting forces of 223 tonnes per anchor. This enabled the safe de-tensioning of the 14 existing preloaded multi-wire bands around the bund with a purpose-designed man basket used to enable access for release of the load in the existing wire-wrapped tendons.
The wires were then removed and the concrete surfaces prepared. Twenty unbonded strands in special HDPE greased sleeves were then installed in each of the recesses, with three additional bands in the lower section. Anchors were installed on each band of strands and stressed to allow the concentrated forces to be resisted for the full height of the bund wall. With 5,575 tonnes of restrainment stress in place, the CCL team completed the project with an aesthetic weatherproof coating.
Terry Bradley adds: “Health and safety was paramount in the design of this scheme and our approach enabled the existing horizontal bands to be secured vertically to enable de-stressing to be carried out safely.”