SYSTEM DESCRIPTION CONCRETE PILES

Piles installed using in De Waal system are of the highest quality. The soil, compressed during drilling, provides an ideal hole for concrete piles. This improves the efficiency of concrete usage, which is not much different from the theoretical pile volume calculated using the exterior diameter of the auger.

The tube is pumped with a sufficient amount of concrete mix for the pile. 
The column of concrete mix in the tube causes the pressure at the tip of the auger to exceed the soil pressure at a given depth. During lifting of the auger, the concrete mix fills the hole providing support for the soil. The differences in pressure occur naturally and preclude any differences in the usage of concrete mix, which often happens with ordinary CFA piles. Full control of concrete usage is achieved by pre filling the hollow interior of the tube with the required amount of concrete mix.

Piles of all sizes can be reinforced along the entire length. In order to ensure appropriate rigidity during transport the main rebars are welded to a spiral coil. The thick cover used for the main rebars provides excellent corrosion protection even in aggressive environments.

The mix, at the right consistency, will easily flow down through the reinforcement, covering it properly and filling the entire hole made by the retracted auger.

During testing a number of piles were excavated and were shown to be of regular shape, the concrete was of the highest quality and excellent uniformity. The compression strengths were between 25 and 30 Mpa.

Quality tests of installed piles were carried out in Maldegem, Belgium. A 6.7 m test pile was installed using a 360 mm auger and a prototype rig with a torque of only 120 kNm. Prior to excavation the pile was test loaded using two adjacent anchor piles. Under a 1,000 kN load, the pile toe did not settle by more than 20 mm. Then the pile was pulled out (in the presence of a SECO representative). The pile was of regular shape, with an almost uniform diameter of 0.36 m.