Commissioned by Rijkswaterstaat, IXAS (a combination of Ballast Nedam, Fluor and Heijmans) widened the A9 Gaasperdammerweg motorway. Part of the project involved building a 3 km long land tunnel. Trisoplast was used to repair a leak in one of the tunnel floor joints. Trisoplast was applied on the roof of the tunnel over the joint and compacted after which an LDPE film was applied as a separation and signalling layer over a length of about 70 x 4 metres.

The applied flexible Trisoplast layer sealed the leaking joint. The swelling clay gel (bentonite/polymer) in the Trisoplast mixture created a watertight connection to the underlying concrete deck. A simple and robust solution with an environmentally friendly material. A soil cover layer was applied on the Trisoplast on the tunnel roof to create a large park where people from the surrounding area can recreate.

In 2017, Trisoplast was also applied on this project under the tunnel box to restore the Pleistocene layer, which was damaged during the construction of the tunnel box. The sealing Pleistocene layer had been excavated unintentionally. As a result, if the drainage of the tunnel would have been ceased, water would start to seep up from the Pleistocene sand. To prevent this seapage, Trisoplast was applied as a fluid-impermeable repair layer. Because Trisoplast is much more impermeable than for instance clay or sand-bentonite layers, this could be carried out with a thin layer of only 11 cm. This use of Trisoplast successfully precented the risk of seapage.

This is another fine example of the versatile application possibilities of Trisoplast.