FAIR particle accelerator, Darmstadt

ne of the largest and most complex construction projects in cutting-edge international research is currently underway at the GSI Helmholtzzentrum für Schwerionenforschung in Darmstadt, a centre for heavy ion research: FAIR – the new Facility for Antiproton and Ion Research. 

The state-of-the-art particle accelerator will be used to generate and study matter that usually only exists in the depths of space. Scientists from all over the world expect that being able to study this matter under laboratory conditions will yield new insights into the structure of matter and the evolution of the universe from the Big Bang until today.

Several buildings are being constructed on the 20-hectare site for the purpose of operating the particle accelerator. PORR is responsible for the extended structural work in the northern part of the facility.

PORR’s contract includes construction of a 1.1km accelerator tunnel and the building elements above it, a transfer building where an underground transfer hall will direct the ray into the accelerator ring and the connected main supply building. 

Solid reinforced concrete structures and concrete recipe developed in-house

In order to meet the demanding requirements, the structures are largely being built as solid reinforced concrete structures up to 6m thick. The complex superstructure and jointless construction require a sophisticated reinforcement structure with a very high rebar density in the individual building elements.

The concrete used must also have some very particular properties. To achieve the required bulk density of 2.35kg/dm³ with a residual water content of 4.5%, PORR had to develop its own concrete recipe. Production, transport and processing presented significant challenges for people and machines.

Watch our video about the project in Vimeo:  PORR Germany . Particle accelerator FAIR, Darmstadt - Project video

Complex construction site logistics: up to 250 lorry trips per day

The concrete is produced directly on site with a mobile mixing plant to ensure a continuous supply of 150m³ per hour – up to 3,000m³ per day. Over the construction period, PORR will handle over 100 large-scale concreting operations with an average of 1,500m³ of concrete each. Given that the excavation and backfilling of the construction pit are being carried out simultaneously, 250 lorry trips per day are not uncommon.

The pipeline construction also matches the other dimensions of this project: the team has installed 10km of steel and HDPE pipelines with diameters up to 2m, and 25km of cable conduits. As this work had to be completed in parallel with the backfilling work, it was no mean logistic feat.

Working shoulder-to-shoulder: from planning to implementation

The experienced PORR team, comprising pde Integrale Planung GmbH’s Structural Planning and Work Preparation departments and the on-site construction team, is working shoulder-to-shoulder to guarantee smooth execution of the project.

PORR Spezialtiefbau was also involved in the preparatory work as a member of the consortium working on the northern construction pit. Stump-Franki was tasked with the specialist civil engineering measures for improving the soil conditions. This included creating the construction pit, including anchored soldier pile walls and pile walls, dewatering and earthworks.