Neighbouring the legendary Gherkin tower, the £135m office development, known for its strikingly unique curved appearance, will offer 300,000 sq ft of prime office space at the heart of London’s business district. When completed later this year, the iconic structure will stand at an impressive 96 metres tall and 23 storeys high, with its unique shape specifically designed to allow for breathtaking views over the City.
For concrete sub-contractors AJ Morrisroe, a key requirement of the project was to source a concrete solution that would enable larger floor spans to be cast without compromising the dead load of the overall structure. Key to ensuring that the building is constructed in an environmentally-friendly manner, it was also important that all materials were as sustainable as possible.
The natural choice proved to be Lytag from Aggregate industries, a highly innovative lightweight concrete solution with unrivalled credentials when it comes to the construction of high rise structures. Up to 40% lighter than conventional concrete, during the development Lytag was able to effectively reduce the composite deck concrete slab load by approximately 25% over normal weight control, while offering the same level of structural performance.
Furthermore, as a concrete made from secondary aggregate, Lytag has unique properties that can help to significantly reduce the amount of natural quarried material required on a project – making it a much more environmentally friendly option than standard concrete.
In total, Aggregate Industries has supplied 2000m3 of Lytag to the project, which was instrumental in helping the tower recently receive an Excellent rating in BREEAM by conforming to clause WST 02 in relation to recycled aggregate.
What’s more, Aggregate Industries’ on-site inspector, who was present throughout the project, was always on hand to make sure the concrete pour ran smoothly and was successfully delivered on time.
Steve Curley, general manager for Lytag at Aggregate Industries, said: “As a modern skyscraper pushing the boundaries of construction and design, the 70 St Mary Axe project required equally innovative construction materials to achieve the building’s iconic vision. From the start it was clear there was no contender to Lytag and its unrivalled capabilities when it comes to building complex, high rise structures of this nature, especially for buildings looking to achieve a superior sustainable BREEAM rating.”
Anthony Blair, project manager at AJ Morrisroe said: “As one of the most high-profile developments in the Capital, it was important that the 70 St Mary Axe project used a sustainable concrete solution that would not only reduce the dead load bearing on the city’s foundation but also help the structure achieve its BREEAM targets.
“We were delighted with the exceptional properties of Lytag, without which this project might not have been technically and architecturally possible. We were also impressed with the solution’s sustainable credentials and would like to thank Aggregate Industries for their excellent service, on-time deliveries and support throughout this development.”