Loose ballast or heavy concrete for bridges

MagnaDense mixed into heavy concrete or as loose ballast can be used for bridges in need of extra weight in the suspension, legs, pivot or deck.

Bridges are often constructed in existing locations and over existing waters or roads. Consequently the space available for the actual bridge construction is limited by local situations. To make sure the bridge is strong and stable enough, many bridges use high density concrete or loose ballast to provide enough weight or balance for the bridge.

The caissons of the Öresund bridge between Denmark and Sweden are ballasted with high density aggregate from LKAB Minerals

Heavy concrete for balanced bridges

Whether it is a self-anchored suspension bridge, a cable-stayed bridge,  a road connection or a railway bridge these highly engineered constructions require concrete with a high density aggregate to provide enough weight to keep the correct balance.

When MagnaDense, a natural mineral, is added to a concrete mix a density of up to 4.0 t/m3 can be achieved; an increase of up to 60% in comparison with normal concrete. The increased density means that less material is required for the precast items which can provide environmental benefits with less transportation or build space required.

Structurally precast concrete bridge anchors must be sound and extremely reliable throughout their lifetime. MagnaDense can ensure this due to its resilience to weathering and abrasives above and below water. The heavy concrete can also be pumped or pre-cast into various shapes and provides a stable secure bridge anchor.

A detailed and interesting case study about the use of high density concrete for the construction of the Samuel Beckett Bridge in Dublin over the river Liffey is available upon request via our sales team.

MagnaDense for ballast is available in different grades

Loose aggregate as ballast for bridges

Sometimes bridges need a lot of weight but do not allow for the volume that concrete would need. In these cases, the use of MagnaDense as a loose aggregate can be a solution. With a density of up to 5.1 t/m3 MagnaDense often provides the right weight and volume when limited space is available.

LKAB Minerals has supplied loose ballast material for the construction of among others:

  • Öresund Bridge; bridge between Denmark and Sweden
  • Great Belt Bridge; bridge construction in Denmark over the Great Belt

In both examples the high density iron ore aggregate was used as a ballast in the caissons that carry the bridge deck. A detailed case study of both of the above two projects are available upon request via our sales experts which can be contacted through the above expert box (top right).

Application expert

Bo Öhman
Sales Manager Magnetite

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