Working faster, cleaner and safer thanks to integrated project approach

One coordination partner, one supplier and one warranty party for the concrete floors and concrete walls

A new residential building with 51 apartments is rising in the bustling Leerpark in Dordrecht. De Hoop Pekso not only produces and delivers 3,900 m2 wide slab floors and 600 m2 hollow core slabs for this building, but also 2,300 m2 precast hollow core concrete walls. As a result, construction company Heijmans benefits from one coordination partner, one supplier and one guarantee party for the concrete floors and concrete walls.

Leerpark is an innovative urban district in the making where living, business and learning come together. The project includes an ideal mix of housing, schools, learning companies, a fire station, retail, sports buildings and related facilities, which will be realized in phases. Heijmans signed for several utility and residential buildings, of which Leerpark Block 6B is the beautiful capstone. This apartment building provides space for 51 apartments measuring approximately 55 m², which will be built in a U-shape. Heijmans is responsible for the complete realization. From the first earthwork to the last tile. 

“The piling work was completed in early September,” says Roy den Dubbelden, project manager at Heijmans. “We put prefabricated piles of about seventeen to eighteen meters in length into the ground, on which we are making a traditional foundation with wet concrete. Then various housing installations will be installed, after which De Hoop Pekso will deliver the hollow-core slab first floors starting in November. From here, the new building will continue to be constructed with precast hollow concrete walls and wide slab floors. HSB elements will make the building wind and watertight, while a masonry facade will provide a nice finishing touch.”

Integrated collaboration

The choice of De Hoop Pekso was a logical one, according to Den Dubbelden. “As an organization, we are actively looking for subcontractors who can take various disciplines off our hands. In the case of De Hoop Pekso, these are the first floor floors, storey floors and hollow concrete walls. Our integrated cooperation started in project Kraaihoek in Papendrecht and is constantly being refined, based on our ‘lessons learned’. As a result, we will soon benefit from one contact person, one supplier and one warranty party for all concrete products. This cleverly eliminates noise, coordination errors and failure costs.”

Working faster and cleaner

“In the preparatory phase, we discussed all three disciplines and determined the right product types and floor and wall thicknesses,” explains Rayon Manager Ron van Beusekom of De Hoop Pekso. “For example, to facilitate less slump or just more space for the installations. In addition, we tuned the amount of reinforcement, recesses and spar positions. The biggest optimization in this project, however, is in the hollow walls; a relatively new construction method for Heijmans that enables faster, cleaner and safer work.” 

Saving time and crane hours

“From Heijmans, there is a growing commitment to prefabrication,” Den Dubbelden explains. “Partly because of the great shortage of carpenters and other skilled workers on the construction site. The precast hollow concrete walls of De Hoop Pekso are a nice stepping stone for this, with which we save a lot of labor and crane hours. Thanks to the system, several walls can be placed in one day, which can immediately also be used as formwork. Installations and reinforcement are also already pre-assembled.” Van Beusekom: “The precast walls for Leerpark Block 6B are partly 220 mm and mostly 250 mm thick and are delivered standing, making them even easier to place. The walls consist of an inner shell and outer shell of 60 mm including reinforcement, between which lattice girders are mounted that hold the shells together. Once poured, a ready-to-use wall is created in one go. Simple, fast and without wasting raw materials.”

All reinforcement on one drawing

The wide slab floors are reinforced system floors poured with traditional gravel concrete. “The floors are constructed from a 60 mm concrete shell, which is provided with constructively required plate reinforcement and continuous lattice girders,” explains Van Beusekom, who highlights another major advantage of the integrated approach. “Because we supply both the wide slab floors and precast hollow concrete walls, Heijmans” braiders have all the reinforcement clearly laid out on a single drawing. This allows them to work even more efficiently and prevents failure costs." 

The wide slab floors have a thickness of 250 mm and meet the latest fire safety requirements, he says. “The hollow-core slabs are 200 and 250 mm thick, depending on the span. An Rc value of 3.7 is achieved with these floors.”

Special safety system

A special safety system, developed jointly by Heijmans and De Hoop Pekso, is being used to install the concrete floors. “We have provided trestles to Heijmans, allowing the crane to easily lift a complete load from the truck,” Van Beusekom says. “Then the mechanics can attach the floor slabs at a normal working height.” Another unique feature is that even before hoisting in, guardrails are slid between the lattice girders of the wide slab floors, allowing the mechanics to work safely at height. Den Dubbelden: “We are enormously satisfied with how De Hoop Pekso has also proactively thought along with us in this area. Integral really is integral in this project.”