As the largest infrastructure project in western Europe, London’s Crossrail needs a lot of steel. Last month, the £14.8bn project to create a 118km high speed rail link across London moved into top gear. Five giant tunnel-boring machines (TBMs) are carving out 21km of twin-bore tunnels underneath the UK’s capital city, 24 hours a day – and as the tunnels are being created, ArcelorMittal’s steel is being used to strengthen them.
Our company has been chosen as the largest steel fibres supplier to the Crossrail project. More than 11,000 tonnes of bespoke steel fibres are being supplied from our wire solutions plants in Sheffield, England and Bissen, Luxembourg.
In Crossrail’s eastern tunnels, from the Limmo Peninsula to Farringdon, and from Pudding Mill Lane to Stepney Green, around 4,000 tonnes of ArcelorMittal HE++90/60 steel fibres to reinforce the segments and more than 1,000 tonnes of HE+55/35 fibres in sprayed concrete are being supplied to contractor Dragados Sisk.
The 8.3km Limmo Peninsula to Farringdon will be the longest of the five Crossrail tunnel drives, dug by two TBMS who have been named after two English queens, Elizabeth and Victoria.
Close to Farringdon and the tunnel drive, excavations for Crossrail have unearthed bodies believed to date from the time of the Black Death, in the 1300s. Thirteen bodies have been found so far in the 5.5m-wide shaft at the edge of Charterhouse Square, alongside pottery dated to the mid-14th Century.
A new Thames tunnel
In the 2.6km tunnel from Plumstead to North Woolwich – the only point where the Crossrail route crosses the River Thames – around 1000 tonnes of HE++90/60 steel fibres in segments are being supplied to contractor Hochtief Murphy. TBM Sophia – named after the wife of engineer Marc Isambard Brunel, who built the first tunnel under the Thames – started operations in January.
In addition to the steel fibres being used to strengthen the Crossrail tunnels, 5,000 tonnes of our steel are being used to build new stations, in Liverpool Street and Whitechapel. Contractors Balfour Beatty, Morgan Sindall, Alpine Bemo and Vinci are working together on this major element of Crossrail.
Our WireSolutions fibres sales team, technical support, research and development, and production teams worked together to supply the steel. They also worked with and provided advice to the material engineers and production managers in the three joint ventures involved in the tunnel and stations projects in which our steel is being used.
Steel for concrete
Two new grades of high performance steel fibre with exceptional tensile strength have been developed specifically for Crossrail, which is due to open in 2018. These products, HE +55/35 and HE ++90/60, will reinforce the sprayed concrete and tunnel lining segments.
When used in concrete, steel fibres provide reinforcement while also reducing and controlling concrete shrinkage. The fibres also help to prevent micro-cracks – a common feature in concrete – from becoming major cracks.
The new grades will also be used in mining, pre-cast production, and any applications with high-strength concrete.
inset image top right: crossrail.co.uk
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