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Omaruru River bridge repair, Namibia (organised by the South African Group of IABSE)
The upgrading and rehabilitating of the Omaruru River Bridge stemmed from the project to upgrade the salt road between Swakopmund and Henties Bay (MR44) to a bituminous paved road. First constructed in 1980, after a mere 12 years, it required comprehensive concrete repairs due to severe concrete damage to the structure. A further 23 years later, in 2015, the bridge was found to have deteriorated again to an extent that greatly compromised its structural integrity.
The deterioration of the Omaruru River Bridge was predominantly the result of the harsh local conditions. Located approximately 2 km from the Atlantic Ocean, its poor condition can be attributed to the extremely harsh environmental conditions impacting the bridge. The climate in this area varies from very warm and dry (when the wind blows from the inland of Namibia) to wet, misty and very cold, virtually marine conditions (when the wind blows from the ocean). This results in temperatures ranging from 0°C to 45°C. In addition to these environmental conditions, the approach road was a salt road, which had been sprayed regularly with salt water. The combination of the harsh environment and salt ingress into the structure created ideal circumstances for the inevitable chloride corrosion of the steel reinforcement and weakening of the concrete.
Various options were evaluated for rehabilitating and upgrading the Omaruru River Bridge. The most sustainable and cost-effective repair solution comprised demolishing and rebuilding elements of the bridge (the deck and pier seating beams), as well as changing the bridge’s structural configuration from simply supported to continuous.
The durability of the original bridge was mainly compromised in those locations where water flowed on the concrete due to the specific detailing at the time. The detailing issues identified included leaking joints, drainage pipes flowing on the deck and piers as well as porous surfacing.

Oct 28, 2022 02:00 PM in Zurich

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