Elastocoast pilots in the Netherlands, storm season 2007/2008

Abstract

In September 2007 two prototype pilot tests were constructed along the Dutch coast with an experimental, polymer based revetment. An area of 490 m2 was put on a dike slope in the Eastern-Scheldt basin, and another 385 m2 on the horizontal surface of a beach groyne near the Pettemer Zeewering along the North-Sea coast. The revetment consists of polyurethane bonded aggregate. A two-component polyurethane adhesive is added to and mixed with narrow graded mineral aggregate. The mixture is then cast in-situ on the dike surface, where hardening takes place. The individual rocks are fixed together only at their contact points, so that the natural porosity of the aggregate is maintained. During the storm season of 2007-2008 the two pilot locations were inspected on a regular basis. Damage observations were done visually and material loss out of several control areas was quantified. Though the storm season counted several periods with strong winds and high waves, both pilots survived with only negligible and superficial damage. During the most extreme conditions, the Eastern-Scheldt pilot was persistently subjected to high flow velocities and the most unfavourable form of wave loading on a dike slope, namely plunging and collapsing waves. The pilot along the North-Sea coast was mostly submerged, resulting in attack by strong bed flow velocities, with water containing high concentrations of abrasive material (sand and shell fragments). With the pilots, the polymer revetment proved able to withstand typical Dutch storm conditions and also valuable experience in constructing with this new material was gained.