Norock’s ultra-high density stone (~3.2 t/m³) is an ideal material for stabilising immersed tunnels. When tunnel elements are floated into position and filled with air, they naturally tend to rise. The higher the density of the cover and backfill material, the better it holds the tunnel in place.

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Key benefits of Norock stone for tunnel projects

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• Maximum stability – high density reduces uplift and buoyancy risks

• Efficient construction – less volume needed compared to standard rock

• Long-term durability – resistant to erosion, abrasion, and freeze–thaw cycles

• Flexible supply – delivered in required gradings for cover, filter, or backfill layers

 

Our material has been successfully tested and applied in challenging marine environments, ensuring safe and cost-effective installation of underwater tunnels.