Trinity provides high-quality precast concrete construction

The structure is the result of a close, strategic collaboration between Mammoet Nederland BV, Lincon BV and Holcon BV and is largely constructed of columns, beams, TT slabs and solid floor slabs in precast concrete.

"Bouwend Nederland knows Mammoet Nederland BV in particular as a specialist in horizontal and vertical transport, but we are also a valued partner in other areas," says Director of Projects Benelux Frank Melse. "We prove this, for example, at the Lely Campus, where we are responsible for the engineering, delivery and assembly of the precast concrete structure of the production hall on behalf of and in close cooperation with Dura Vermeer Bouw Zuid West. We also assemble the hollow-core hollow core slabs (production: VBI), stairs and landings (production: Waco) in the steel structure of the office wings."

In this project, Mammoet Nederland BV is working in a strategic trinity with Lincon BV and Holcon BV. Together, the three parties can fall back on years of very close partnership, particularly in civil engineering and utility construction. "We fully understand and trust each other and can switch gears very quickly, which benefits both the execution and the end result," Melse said. "In this project, too, execution is going exactly as conceived beforehand."

Special ramp

Mammoet Nederland BV was awarded the overall contract for the concrete structure based on past experience. "In January 2014, the production facility and headquarters (phase 1) of Lely Maassluis were officially opened," Melse says. "The successful cooperation in phase 1, in which we were part of an enthusiastic and expert construction team, was the starting point for phase 2. Again, we are working with an expert team towards an optimal result. Both in terms of execution and BREEAM certification." Compared to phase 1, phase 2 includes different floor loads, he says. "Moreover, the Eurocode is now in force, which meant that other (heavier) requirements were imposed on the calculations and connection details. Moreover, a special feature in this phase is the ramp to the parking floor, which was designed as a staircase at the request of the chief structural engineer. Where prefabricated beams serve as stair stringers, horizontally laid channel plates form the steps. The complete ramp staircase will be insulated and poured with a compression layer by Dura Vermeer Bouw Zuid West. In order to best fulfill the structural design, careful engineering was essential."

Technically feasible design

Responsible for the engineering is Lincon BV, an engineering firm with roots in the world of concrete and concrete structures. "In collaboration with Mammoet Nederland BV and Holcon BV, we translated the aesthetic design of ConverseArchitects and the structural design of IMd Raadgevende Ingenieurs into a technically feasible design," says director Joost Kooiman. "Based on the wishes of the building user, main contractor, installers, concrete manufacturer and concrete assembly specialist, we took care of the complete detailed engineering. We translated the basic 3D model into clear production and assembly drawings. Thus the structure was cut up by us into elements, which are excellent to produce, transport, hoist and assemble."

730 precast concrete elements

A total of 730 precast concrete elements are involved, which were produced on behalf of Mammoet Nederland BV and delivered by Holcon BV. The concrete manufacturer from Markelo was actively involved in the technical development of the concrete skeleton, says project manager Bas van Oosterhout. "We then accepted the work as a category 1 project. This means that we performed the precast concrete production exactly according to Lincon BV's production drawings. All of our precast elements were produced in our production facilities in Germany. Eighty percent of the elements, including our precast columns, beams, TT slabs and solid floor slabs, were transported by ship to the port of Amsterdam, from where they were shuttled just-in-time and 'by axis' to the construction site in Maassluis.      

The remaining elements were delivered to the construction site just-in-time and by axle from the factory. Here Mammoet Nederland BV was responsible for the assembly of all precast concrete. In addition to efficient construction and empty/clean construction site, this approach resulted in a very favorable CO2 footprint."

Attention to logistics

Production in Germany placed special demands on logistics, for example, Kooijman says. "We expressly took this into account during the engineering phase by matching the maximum weights of the elements to transport. In the preparatory phase, we inventoried, among other things, which factories will make the elements, where the factories are located and how the elements will be transported. What requirements are involved? We also paid attention to the logistics on the construction site. For example, where will the construction crane be located? And how heavy can this crane lift? But also: what is the most efficient construction sequence? We combined all these ingredients into a sustainable, efficient and constructively safe design for all parties involved."

Smooth progress

"As an organization, we have a great affinity with concrete producers and assembly parties, Kooiman emphasizes. "This knowledge and expertise also came in very handy in this project. In order to meet the short lead time, we continuously focused on possibilities. Even when data were not yet (fully) known. Instead of stagnating, we continued where we could. A good example of this is the roof of the production hall. Here we chose common TT plates, so that Holcon BV's factory could start production in advance. The specials were added later."

Optimal efficiency

A particular challenge in this project was to produce and load all the elements on time and in the right order, says Van Oosterhout. "But also to always have a full ship sailing to the Netherlands, so that optimum efficiency and minimum transport movements were guaranteed. Thanks to good communication and coordination, this process went splendidly." Each full ship always carried a weight of about 2,000 to 2,200 tons of concrete, he says. The vast majority of the elements were TT slabs, of which Holcon BV produced more than 420. In addition, the concrete specialist supplied a good number of beams with prestressing.

At the end of June, the precast concrete structure was completed. The structure was realized on the precast foundation from Vroom Funderingstechnieken. "In the grid of foundation beams and foundation piles, we completed the channel plates," Melse said. "Then we placed the columns on the piers, casted and/or injected them and installed the beams and TT plates. During the assembly we used, among other things, a 250-ton crawler crane, which rode on special bulkheads in the construction pit and guaranteed sufficient space above the piles. This prevented damage to the foundation piles during lifting and the concrete structure was brought to the very highest level efficiently and quickly."