Concrete for tunnels and underground structures

When building tunnels and underground structures, MagnaDense concrete can be used for controlling buoyancy and overcoming issues with sound, vibration and hydraulic pressure.

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Magnus Johansson

Magnus Johansson

Business Development Manager - Americas Region

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High density concrete aggregate

Worldwide, engineers are seeking new and sophisticated tunnelling and underground solutions to limit ground borne noise and vibration and overcome hydrostatic pressure, in an environment where space is often restricted. Similarly, sub-level structures are looking for solutions to withstand natural ground water pressure. The solution for many projects has included the use of our high density aggregate MagnaDense.

Preventing vibration and noise from tunnels to surface

Crossrail, recently done in the UK, is a perfect example of where MagnaDense is the best fit in an area bound by many limitations. Running beneath central London, the project encountered many constraints including the restricted volume of the tunnel and the proximity of surrounding infrastructure, meaning space was limited.

The solution was the construction of a High Density Floating Track Slab (FTS), utilising MagnaDense concrete. Due to the limited available construction space the concrete, developed to include the heavy aggregate MagnaDense, was the most suitable option to prevent noise and vibration caused by the passing trains. The project also had to overcome many logistical challenges, especially with the pumping site being situated within the city centre.

The Crossrail project saw the world’s first installation of a High Density Floating Track Slab and set a world record for pumping high density concrete. As a result, LKAB Minerals and partners were nominated for four awards at the NCE Tunnelling Awards in 2017.

For more information about the project, or to hear about the technical details of this construction, you can listen to the Crossrail webinar recorded together with our partners.

Overcoming hydraulic pressure with heavy aggregate

The use of high density concrete in situations where there is a need to overcome hydrostatic pressure is not only limited to tunnelling projects but is also in more common constructions such as sites with existing sewer networks, buildings with sub-level floors and underground parking garages.

In a second section of the Crossrail project, high dense concrete was required for the first stage concrete works due to the location’s proximity to the River Thames. Again, due to tunnel bore restrictions, additional weight was required in the concrete to overcome hydrostatic pressure.

Logistics and availability

Mined from our group owned resources in Northern Sweden, MagnaDense, manufactured from the natural iron oxide Magnetite, will always be of constant quality. Via the large harbours of Narvik (Norway) or Lulea (Sweden), ships take the heavy aggregate to our different stock locations around the world, or directly to your project.