Mace is building a new advanced imaging centre, known as the Extreme Photonics Applications Centre (EPAC), at the Harwell science campus in Didcot. The £81m project is for the UK’s Science & Technology Facilities Council (STFC).
A unique concrete mix was designed for the project to support the complex technical building’s requirements.
Mace used 7,500m3 of structural concrete with a composition of 75% ground granulated blast furnace slag (GGBS) instead of traditional Portland cement. A less carbon intensive alternative, this led to a 48% overall carbon reduction and a saving of 1,373 tonnes of carbon, the contractor said.
The composition of concrete mix was guided by specific experimental shielding properties that required the use of high density aggregates and a reduced cement content to minimise the risk of thermal cracks occurring as a result of the heat generated during the concrete curing process.
Due for completion in spring 2022, EPAC will house super-bright lasers that can produce state-of-the-art high-contrast 3D images of the internal structure of complex objects from aircraft wings to bones.
The laser testing process will achieve temperatures of 50 million degrees Celsius, hotter than the centre of the sun. A single flash from the laser is a quadrillion (1015) watts, which makes it 10,000 times more powerful than the whole of the UK national grid output. These extreme conditions meant that the Mace team was facing a number of challenges to deliver a structure able to house them.
Attached to the chamber is a complex arrangement of labyrinths for service and personnel access into the testing chambers. Care had to be taken to ensure that the internal dimensions of both chambers and the labyrinth provide enough shielding and absorption required for future experiments.
Project director Robert Cocks said: “EPAC has one of the most technically challenging and complex concrete structures in Europe in 2020 and the result is testament to the strong commitment and expertise from everyone involved.’’
Professor John Collier, director of STFC’s Central Laser Facility, said: “EPAC will drive the development and application of a completely new class of compact accelerators and advanced sources of radiation based on lasers. We expect this to lead to a step change in a number of fields, for example the rapid, 3D imaging of complex or moving structures, or systems under load like engines or turbines.
“We’ve reached a very significant milestone for EPAC. I am delighted that this has been achieved on schedule whilst adhering to the necessary coronavirus controls, such as social distancing. This is a great credit to our construction partners, Mace.”
Mace is building three new science and technology facilities at Harwell – The Rosalind Franklin Institute, the National Satellite Test Facility and the Extreme Photonics Applications Centre. Appointed through the Southern Construction Framework, the projects have a total construction value of more than £133.5m.