A concrete floor on piles, reinforced only with steel fibers

Floors on piles are increasingly seen in Belgium. The choice for this specific construction method is not only dictated by the increasing requirements in terms of differential settlements and allowable loads. The growing scarcity of good quality building land is also contributing to the fact that concrete floors are increasingly being constructed in combination with foundation piles. Such as in the construction of the new distribution center of the sanitary group Van Marcke in Rekkem. Here no less than 40,000 m² floor surface founded on piles. Only steel fibers were used for its reinforcement. Supplied by Bekaert, world market leader in steel wire transformation and coating technologies.

Installation of the floor in full swing.

The construction of the new DC, located in the LAR-South industrial park, is one of the largest projects of its kind realized within Belgium in recent years. The fact that the low-joint and load-transfer profile work floor rests entirely on foundation piles is already remarkable. But what also makes the building special has everything to do with the reinforcement of the spacious floor area. "The floor has no traditional mesh reinforcement, but is reinforced solely with the Dramix^® steel fibers," says Ben Vanheuverzwijn, sales engineer Dramix^® at Bekaert. "A so-called fiber only solution that was possible mainly due to the unique properties of the Dramix^® 5D steel fibers. In addition to 24 tons of Dramix^® 4D steel fiber is about 260 tons of this incorporated into the floor."

Unique combination

The Dramix^® 5D steel fibers are revolutionizing the world of steel fiber concrete. The combination of an ultra-high tensile strength (2,200 N/mm²), perfect anchoring and a highly deformable steel wire (more than 6% extension before rupture) ensures that a bending-hardening behavior is obtained. "This means that when a bending test is performed, after the formation of the first crack, a force greater than force required to form this first crack can be absorbed," Vanheuverzwijn explains the uniqueness of the product. "This distinguishes Dramix^® 5D clearly distinguishes itself in terms of behavior from classic steel fiber concrete, which exhibits a certain decline in the absorbable strength after the initial crack strength is reached. It therefore makes our product extremely suitable for implementing fiber-only solutions in structural applications."

Collaboration

Van Marcke's new DC.

A perfect interaction between foundation piles and floor is crucial to achieving a sound and, above all, cost-efficient solution. This was demonstrated once again during the project completed for Van Marcke, which used 5,215 foundation piles (diameter 34 centimeters) placed in the ground in 2.9 x 2.9 meter grids. "When the piles are placed further apart, fewer are required, but the floor has to be thicker," Vanheuverzwijn explains. "When you put the piles closer together, although you need more of them, the floor can be considerably thinner. And you see that back under the line. In addition, the diameter of the piles plays a big role in the final cost. For example, piles with a larger diameter or a widened pile head have a positive impact on the thickness of the floor and thus also on the amount of concrete needed to get the job done." 

Text | Chris Elbers    Image | Bekaert