60,000 m² of hollow core slabs for new bol.com building

For the new distribution center of bol.com in Waalwijk, the Netherlands, producer of innovative precast floor systems VBI has produced and supplied almost 60,000 m² of hollow-core slab floors. In total this involved about 3,000 floor elements of about 16 meters long, 40 centimeters thick and weighing 9,000 kg, which were transported to the construction site just in time and in almost 1,000 loads.

"We were involved in the project at an early stage by Bouwbedrijf van de Ven," says Hugo Suppers, technical consultant at VBI. "In the design phase, we contributed ideas on the right floor layouts, couplings and detailing, among other things, with an eye on simple and cost-efficient production and assembly. We then fleshed this out in the engineering phase. We clarified and resolved any bottlenecks with the steel structure. Based on the assembly sequence and in close consultation with the work planner, foreman and project manager of Van den Brink Staalbouw, we also made the logistics and production schedules."

All elements were transported to construction just-in-time.

Great design freedom

With the hollow-core slab floors, spans of up to 16 meters were achieved with an imposed load of 7.5 kN/m², resulting in great design freedom for bol.com, Suppers said. "In addition, the hollow-core slab saves up to 50% of concrete compared to solid floors, resulting in significantly less weight. It also requires less reinforcement. The floor is 100% recyclable and there is no waste in the industrial manufacturing process. Because the hollow-core slabs require no curing time at the construction site and are fully loadable immediately after installation, the shell construction time speeds up by 30%." 

Safe processing

Secondary raw materials, including concrete granulate, were used in the production of the hollow-core slab floors for bol.com. Combined with the channels, this significantly reduces CO2 emissions, Suppers said. "The floor elements were produced according to the so-called long runway system. At the VBI factory in Huissen, there are lanes 150 meters long, on which the prestressing and concrete are applied. This included the use of a slip streamer. Once the concrete was sufficiently cured, the elements were cut and briefly stored on the bag field so that the elements had sufficient strength to be assembled. They were then transported to construction just-in-time." Prior to delivery and assembly, Suppers provided a toolbox meeting for the steel erector, contractor and everyone else involved, helping to ensure safe handling of the hollow-core slabs.