Service life of columns and bridges extended by 50 years

The 3.500 columns of the vital pipe network on the Chemelot site are over 50 years old and require annual maintenance. The outdoor climate and the environment lead to corrosion of the reinforcement in the concrete structures, which may reduce their strength. Peter Brabers, Senior Project Manager and consultant at Sitech Services, devised a unique solution to extend their service life by 50 years.

Various solution pathways investigated
The concrete pipeways, which are over 50 years old, support the vital network of product and utility pipelines for site users. In 2018, Sitech Infra conducted a study of their failure mechanisms in collaboration with Royal HaskoningDHV to extend the service life of these aging columns by 25 years. It was not easy to find a generic solution, because of differences in the dimensions of the columns due to misalignment and deformation. Various solution pathways were considered, but none of them struck gold. Peter joined us in 2019. “Together with the team we first conducted a thorough analysis,” he explains. “My experience with prestressed concrete structures gave me the idea to use an external prestressing solution.”

Reinforcement from the outside
Peter had gained experience with such a solution when he worked in Italy as a chief structural engineer for concrete and steel structures at a plant where the roof’s concrete structure had been damaged by fire. “At that time we used an external prestressing system to restore the original strength of the concrete structure. I wondered if we could also use this principle to reinforce the pipeways. One option would be to install stainless-steel end plates at the ends of the concrete crossbeams, which are connected and prestressed using threaded rods. This prestressing, combined with external preservation of the concrete, ensures that the supports will remain in one piece for at least another 50 years.” With assistance from the chief structural engineer of Royal HaskoningDHV and his team, Peter worked out the idea in more detail. In turn, contractors SPIE from Elsloo and Frijns Industrial Group from Valkenburg ensured that the construction was feasible and safe.

Economic solution that lasts for 50 years
"The external stainless-steel structure provides the required strength for the concrete, replacing the function of the reinforcement,” he continues. “This makes the risk of corrosion less important. The material is also light, easy to install and maintenance-free, so that lowers the costs. And the good thing is that the service life of the columns can be extended by up to 50 years. That is much longer than a conventional solution using hot-dip galvanized steel with a coating.”

Proud to be the first
RHDHV, SPIE and Frijns have now started the execution of this service life extension project. “As the stainless steel does not have to be preserved, we do not have to wait until spring and can simply get on with the work,” concludes the Senior Project Manager. “The solution has never been applied in this way, so this is a first for our team and the Chemelot site – something we are very proud of!”

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