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To minimize inconvenience on through traffic, formwork supplier Construx-Dijkhor B.V. developed a unique prefabricated and largely interchangeable pillar formwork in collaboration with Heijmans.
Construx-Dijkhor is part of the Belgian family business Construx and specializes in the development and production of steel molds for the concrete industry and the infrastructure sector. "Already in the tender phase, we came up with a solution together with Heijmans to build the viaduct as efficiently as possible, zooming in on the pillar walls in particular," says Herry van Houten, General Director of Construx-Dijkhor. "That idea was refined and further developed after being awarded to Heijmans. In the end, a total of 9 concrete pillar walls can be realized with only two steel formworks. Incidentally, these are hefty 'boxes' of 120 tons each, consisting of a large number of composite components."
Construx-Dijkhor's design is based on Heijmans having to assemble as few elements as possible on site. "That costs time and causes unnecessary blockages on the A4," Van Houten states. "Moreover, the space in the intermediate verges of the A4 is extremely limited. The pillar formwork is therefore assembled as much as possible at the pre-construction location next to the future viaduct. A pillar wall is 65 meters long, 5.20 meters high and consists of nine pillars (i.e. nine individual formworks) connected to each other by a beam formwork. In each case, all nine individual pillar formwork was assembled at the preconstruction site, including reinforcement, and placed on site in one move. This saved the contractor a great deal of time. In just one overnight road closure, our assembly team was able to place the complete formwork (including intermediate beam formwork) of the 65-meter-long pillar wall. Consequently, we met all deadlines by a wide margin and were even ahead of schedule. This also gave the 'little train' after us (braiding, placing platforms, etc.) a little more air."
What is quite special about the already substantial formwork is that it is centerless. Van Houten: "Again, this had to do with the short lead time. The contractor does not have to finish the pillar wall after the formwork has been removed. The forces involved here were such that centering would have made the composition of the formwork somewhat simpler and lighter. However, the short lead time and assembly time was the deciding factor here." Moreover, the beauty of the pillar formwork was that Construx-Dijkhor engineered it in such a way that the different parts could be used interchangeably. "The same goes for all 34 landings along the formwork. They are all interchangeable. It significantly reduces the chances of things going wrong during assembly." Van Houten therefore looks back on a fine project. "Turning ideas from the client and inventive solutions from our engineering into concrete solutions and a workable whole. That is our strength, where we emphatically seek cooperation. Like us, Heijmans has a flat organizational structure; decisions are made quickly. A prerequisite for bringing such short construction projects to a successful conclusion."
