Multifunctional geocomposite forms unique dilatation between diaphragm wall and permanent concrete wall

Contractor combination Sassevaart is building the two lock heads of the New Terneuzen Lock in a cofferdam. The concrete outer structures of the lock heads will be poured "directly" against the cofferdam walls (diaphragm wall panels). To separate the two structures and allow them to move independently of each other, the unique properties of EnkaDrain CK20 are being used. A multifunctional geocomposite and in this application rightfully a world-leading solution.

Enka Solutions has a broad portfolio of EnkaDrain geocomposites for vertical and horizontal applications, such as drainage, vibration damping and, in this case, dilatation. These products are applicable in both construction and civil engineering projects, for example along basement walls, at bridge abutments and in tunnel construction. "The specific construction methodology of the lock heads required a unique product," begins Kennard van Malenstein, Sales Manager Enka Solutions at Low & Bonar. "There was relatively little space to build. Traditional methods between the two structures were therefore not an option. The alternative solution had to provide for a long functional life due to the expected long-term settlement period and deformation. Consideration had to be given to the bending of the building pit walls after drying, and to a pressure of 50 kN/m² when pouring the 24-m-high concrete structure." 

Stable, but flexible

"In consultation with the contractor consortium and after extensive calculations and tests to simulate operation in this unique application, EnkaDrain CK20 was chosen as the right solution," continued Van Malenstein. "EnkaDrain CK20 is extremely versatile in terms of application possibilities and met the client's needs. This type of EnkaDrain consists of a 20 mm very stable core of our Enka technology, which has a water-permeable geotextile on one side and a special PVC film on the other. EnkaDrain is lightweight and therefore quick and easy to install against walls reaching up to 24 meters in height. Here it acts as lost formwork and guarantees permanent dilation. During installation, the PVC film is directed inward. The PVC layer prevents penetration of concrete slurry during the pouring of the concrete structures of the lock heads, preventing "hard" contact between them. Due to its stable, yet flexible core structure, the geocomposite allows for deformation (z-direction). At the same time, it is compression resistant and able to withstand the expected pressure of 50 kN/m² absorb, so the outer and inner wall construction will not come into contact with each other even during settlement and deformation."

Custom rolls in partial deliveries

In total, Low and Bonar now has over 12,000 m² delivered to EnkaDrain CK20 for the New Lock Terneuzen. "At the request of the contractor consortium, we delivered custom rolls in partial deliveries to minimize cutting losses." Incidentally, Low and Bonar has also been involved in the other mega lock complex recently completed in the Netherlands. "For the Sea Lock at IJmuiden, in close cooperation with Geopex, engineers from the Dredging Company and project managers from OpenIJ, we developed special sinks into which our EnkaDrain ZB 350 was integrated to be able to transport the rising groundwater under the colloidal concrete to the outlets intended for this purpose in the event of any extreme underpressure. Here, too, custom dimensions were supplied. We are always happy to think along and provide appropriate solutions for every project," Van Malenstein concludes.