Inventive cocoa silos in Westzaan

Construction company Vrolijk uses a precast hollow wall system in a format unique by European standards of as much as 10 meters high and 3.5 meters wide, which is filled with wet concrete. 

Amsterdam is the largest cocoa port in the world, transhipping more than 20 percent of the international cocoa crop. Vollers Holland has been active in the storage and transshipment of cocoa beans and coffee, among other things, for more than eighty years. For the construction of the three new warehouses, the cocoa expert has a plot at business park Hoogtij that is accessible by road, inland waterway and sea. The new location therefore has its own quay on the North Sea Canal. Construction company Vrolijk is currently building three warehouses, each with an area of 6,000 m2 and 25,000 tons of capacity. There is room to expand with a possible fourth warehouse.

Foundation

The three warehouses have an identical structure, consisting of concrete walls according to a hollow wall concept. "We used this methodology for both the exterior walls and the partition walls, since the warehouse is divided into different compartments," says Menno Vrolijk of Bouwbedrijf Vrolijk. "Incidentally, we are responsible for the complete shell, including the foundations. That took quite a bit of effort, especially for the warehouse closest to the quay. We ended up using three different pile types that could be installed vibration-free: Vibro-piles, VSP displacement screw piles and VSP-C displacement screw piles with a permanent casing. The latter were applied at the quay. They were fully digitally measured and installed between the grout anchors of the quay structure. A precision job. In total, some 5,000 piles were installed for both the floor and the foundation construction."

30,000 plug anchors

In order to set the hollow walls, as well as the steel structure for the façade finish and roof, Bouwbedrijf Vrolijk incorporated cuttings anchors of around 25 in the floors. Says Vrolijk, "It was therefore important that those cuttings anchors - a total of 30,000 (!) - were all positioned in the right location to the nearest half-centimeter. The hollow wall system consists of two shells of precast concrete 7 centimeters thick that are connected by support beams. The spacing of 23 centimeters is provided with coupling baskets and filled with wet concrete in several pouring stages to a height of 10 meters. It results in a moment-proof connection where the hollow wall is effectively considered lost formwork. This method of construction is lightning fast. We placed all 735 hollow walls in just 15 weeks. You're easily talking about a total of about 22,000 m2 of wall."

Construction company Vrolijk began construction in June 2020 and expects the first silo to be commissioned on schedule by the end of July so that the first ships can be unloaded.