Dyckerhoff supplied concrete for the floors of the world's largest central warehouse of the automotive industry.

On the 'Isle of Green', in the immediate vicinity of the Dyckerhoff ready-mixed concrete plant in Germersheim in southern Palatinate (Rhine-Main-Taunus branch), the Daimler AG logistics center, which had existed since 1990, was expanded. Three new warehouses were built on a total area of around 70,000 m² – equivalent to about ten standard football pitches.

The executing companies were Klebl GmbH, Neumarkt i.d.OPf. as general contractor and CBL Chemobau Industrieboden GmbH, Leingarten, as subcontractor for the finishing of the industrial floors with high flatness requirements.

Standard and premium concretes from Dyckerhoff
The new buildings contain a total of 28,900 m³ of concrete, including not only concretes for the exterior and waterproof mass concrete but also the premium steel fiber concrete Dyckerhoff FERRODUR; the latter two were produced according to DAfStb guidelines. The compressive strength classes of the concretes ranged from C12/15 to C50/60. They were predominantly produced with Dyckerhoff HOZ Doppel, a blast furnace cement of CEM III/A 42.5 N quality from Dyckerhoff's Amöneburg cement plant. Portland limestone cement (Dyckerhoff PKZ Doppel) and Portland cement (Dyckerhoff PZ Doppel) from the Göllheim and Amöneburg plants were also used.

Delivery at high rates – with consistent concrete quality at all times
At the end of August 2018, the floor area was concreted for a fully automatic high-bay warehouse in steel construction. The challenge was to place a total of 10,000 m³ of concrete of compressive strength class C50/60 during six days. That means 14 truck mixers per hour! The concrete for the six construction segments was supplied by the Germersheim plant; for the large scale concreting, supported by the Rohrbach plant (Saar-Mosel branch) approx. 25 km away – 17 hours per day in a row. With two powerful pumps, it was installed in three layers of 40 cm each "fresh in fresh". The lower two layers mass concrete with a maximum grain size of 32 mm were installed by Klebl. For the surface course, a special recipe was used using chippings (maximum grain size 16 mm). It was installed by CBL Chemobau Industrieboden. The problem was that the concrete was not allowed to harden until the next layer was poured, so that the layers could bond optimally. The experts call this "needling". With the hot temperatures prevailing at that time, rapid installation and a consistently good flowability of the product were essential.

Optimum concrete consistency required
Then the two halls for incoming and outgoing goods were tackled. At the beginning of October 2018, installation of the floor began in the second large construction phase – at a construction height of 30 cm with strong reinforcement, because this area will be always exposed to high loads. The base course had previously been paved with crushed stone and a water-cement mixture. On each of the 4 concreting days, the truck mixers delivered 8 to 10 hours from the Germersheim plant without interruption from 4 o'clock in the morning until the ordered 690 m³ or 860 m³ (two sections each) of normal concrete of compressive strength class C25/30 with flowability F4 covering an area of almost 10,400 m² had been placed. Two pumps were also used here. Only a few hours later the finishing work began. For the last large construction phase Dyckerhoff also supplied 6,700 m³ of FERRODUR C30/37 steel fiber concrete of performance classes 1.5/1.5 in accordance with the DAfStb guideline "steel fiber concrete". In order to take account of the significantly increased load on the ramps and driveways within the halls, a combination of normal reinforcement and Dyckerhoff FERRODUR was used. It was also completely poured using a pump. To achieve this, the concrete had to have the optimum consistency to ensure pumpability at all times.

For the exterior, air-entrained concrete of compressive strength class C 30/37 with chippings of grain sizes 8 to 16 mm was used - a more durable concrete with increased freeze and freeze-thaw with de-icing salt resistance due to enclosed air-entrained pores.

The Mercedes-Benz Global Logistics Center, together with its external locations, is the world's largest parts warehouse in the automotive industry. Service companies all over the world are supplied from here. Thanks to its ideal connection to the A61 motorway and several internationally connected airports, this location is ideally suited for handling logistics processes.

All photos: Dyckerhoff / Christoph Mertens