Crossrail project benefits from heavyweight aggregate solution

London Concrete, part of Aggregate Industries, has supplied a heavyweight concrete solution to London’s Crossrail project, from Bond Street station through to Farringdon station. Specified by ATC JV, the solution will minimise the noise and vibration generated by the Elizabeth line.

A total 4,000m³ of the heavyweight concrete track slab, manufactured using MagnaDense, which boasts double the density of normal aggregate, was used for the Crossrail project. Formed of black ferrimagnetic natural iron oxide (Magnetite), MagnaDense from LKAB Minerals is mined in northern Sweden before being shipped to the UK via Norway.

A total of three grades of heavyweight aggregate were used, in addition to normal sharp sand, to achieve the required density.

Heavyweight aggregate solution

The aggregate mix used was the result of an extensive 12 month trial process undertaken before any concrete was supplied to the site. Due to the complexity of the concrete mix and its components, London Concrete established a dedicated site plant in Battersea to meet the requirements of the contract. 

The bespoke mix included pulverised fuel ash (PFA) to aid pump ability and meet the durability requirements of the specification.

Luke Smith, London Concrete Managing Director, commented: “Our unique plant offering at Battersea gives us the ability to handle a multitude of aggregate types, which meant we were able to work collaboratively with ATC and provide a bespoke concrete mix that hasn’t been used in this type of rail application before – typically this type of concrete is used in land-based applications focusing on radiation shielding for medical or nuclear environments.”

The delivery of the concrete was carried out entirely at night time and required an innovative approach due to the need for long distance pumping, as the requirements of the project meant that a distance of over one kilometre horizontally needed to be achieved.

Pumping was carried out by Camfaud Concrete Pumps using a Putzmeister BSA2110HP static pump. The concrete has been pumped through 1,100m of pipeline, during which time there is approximately 40 tonnes of material contained in the line.

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