Environmentally friendly and lightweight decking

De Hoop Pekso has been supplying a lightweight floor since 2012. This Airdeck floor offers the user many advantages. It is lightweight and because of the application of Airboxes, less concrete has to be used. This also makes the floor a lot more environmentally friendly than traditional wide slab floors. 

"Lightweight floors have many advantages. The biggest advantage is the weight savings. In addition, less concrete needs to be used and larger spans are possible. And because no beams have to be placed under the floors, more flexibility in layout is possible." Frits Simons, director of De Hoop Pekso, sums up the advantages of Airdeck, De Hoop Pekso's lightweight floors. The floors are mainly used in the utility sector, he says. "Because of the column structure of these buildings and the desire not to use beams under the floors, you are more likely to end up with this type of floor."

Plastic Airboxes

Airdeck is a two-way reinforced wide slab floor on which Airboxes made of recycled plastic are installed. Because of the Airboxes, up to 30% can be saved on concrete and support structures and foundations can be made lighter. Another important advantage of the Airdeck floors is that they are more environmentally friendly than other wide slab floors. Simons: "It not only results in less weight, but also less use of materials. As a result, fewer scarce and increasingly expensive raw materials are needed."

Large spans

Lightweight storey floors are well suited for larger spans, emphasizes Jan Versteegen, construction consultant and partner at Pieters Bouwtechniek. "As the span increases, the floor thickness also increases and thus the weight of the floor. The weight of the concrete takes an increasing share of the total load due to increasing thickness. With Airdeck floors, this disadvantage is smaller. You do have a thick floor which is beneficial for strength and stiffness, but it is less heavy due to the application of the Airboxes." The hollow floor leads to a lower total load, resulting in less reinforcement than with a solid floor of the same thickness. The floor is as strong and flexurally rigid as other floors, Versteegen emphasizes. "The client specifies a certain variable floor load in the Program of Requirements and we calculate the floor thickness and reinforcement based on that. The condition is that the specified load is equal to or higher than the minimum loads specified in the Eurocode that apply to a function. Despite using less material for the Airdeck floor, you can achieve the same strength and stiffness with a lighter floor."

Concrete, rebar and saving time

An Airdeck floor has a prefabricated lower shell of 6 to 7 inches with the Airboxes on top. These are available in five different heights and are fully anchored in the element. This is because the Airboxes are placed on the broad plates in a grid of 300 x 300 mm and are vibrated in at exactly the right height. Simons: "This is done with robots in the factory. These can very precisely position the Airboxes in the right place and ensure that they are vibrated in properly." Installation of the floor is easy because the elements can be lifted on the lattice girders after which two people can place it on the temporary underpinning. Then, on site, the torque reinforcement is placed on the wide plate and top reinforcement. The reinforcement mesh can be installed directly on the Airboxes and the pouring of the floor is done in the traditional way. This method saves concrete, rebar and time.

Standards and detailing tightened up

The collapse of a lightweight floor in 2017, in a parking garage at Eindhoven Airport, has unfairly put lightweight floors in a bad light. But there is no reason for this, according to both men. Says Versteegen, "We have designed many such floors and, as a result of investigations after the accident in Eindhoven, we have not yet had to modify or reinforce one. Recommendations were drawn up as a result of the investigation. The detailing and calculation rules were tightened after Eindhoven and we have adjusted our production process accordingly." This is confirmed by Simons. "For example, we have applied solid edge reinforcement (suspension reinforcement) in the floors and we use roughened traditional concrete. We fully comply with all the tightened structural safety requirements."

Accurately detailed

Versteegen emphasizes that lightweight floors are still in wide use. "We include these floors in the different floor variants we consider for projects. In utility construction projects with a column structure where flexibility in layout is required, this floor type is very suitable. Of course, you have to make sure that the floors are accurately detailed and that all measures have been taken to eliminate structural risks. It would be a waste not to use this floor. It is a flat floor that allows you to create a lot of flexibility in a building. Moreover, they are not more expensive than other wide slab floors." By now, tens of thousands of square meters of Airdeck floors have been used in the Netherlands, Simons says. "We recently delivered another nice project at the Leiden Bio Science Park. You notice that the beamless structure in particular is appreciated by the client here."