As a contribution to the Dutch climate objectives, Rijkswaterstaat wants to emit zero CO2 by 2030. To achieve this, we must build with materials with a lower CO2 footprint. We also want to make concrete, a widely used construction material, more sustainable. The Netherlands is leading the way in developing sustainable concrete mixtures. For example, by recycling old concrete debris, by using alternatives for the cement binding agent or by adjusting the production process. In the Afsluitdijk testing ground, we give parties from the entire concrete sector the opportunity to test their innovative mixtures in practice.
The Afsluitdijk is an ideal location to test various concrete mixtures in practice at the same time. By making so-called Levvel-blocs. Construction consortium Levvel (BAM, Van Oord and Rebel) is using no less than 75,000 of these specially developed concrete blocks to reinforce the Afsluitdijk. The test site consists of 32 Levvel-blocs; each time two blocks of 16 different mixtures. The innovative Levvel-blocs are thus really part of the dyke reinforcement and have to meet the same requirements as the other Levvel-blocs. For example, they have to be heavy enough not to be lifted by the enormous forces of the waves hitting this main water barrier.
In a good cooperation, Levvel and Rijkswaterstaat together determined the performance requirements for the concrete blocks. Several durability tests had to be done in the laboratory. For instance, to see to what extent the concrete is affected when water freezes in the concrete and thus expands. And how it reacts to the interaction with CO2 in the air: does that make the concrete denser or more open? We do not compare the blocks with each other – it is not a competition – but they do have to meet the set requirements. Moreover, the various parties now have to scale up their test mixtures to practical requirements. For example, only a limited amount of alternative binder is needed for the small-scale tests in the laboratory. In order to produce the Levvel-blocs, the parties have to achieve this in larger quantities.
Production in green concrete plant
To make the Levvel-blocs with their special shape, a special mould is needed: steel formwork. In order not to move it too often, we produce the blocks of all participants at the same unique location in Zaandam: the only green concrete plant of the Netherlands. This means that not only the composition of the concrete is sustainable, but also production. The plant generates the necessary energy with solar panels and collects rainwater for use in the concrete. Moreover, the plant is designed to create the ideal conditions for a high-quality concrete product.
The Afsluitdijk pilot project started in October 2020.
Tracking in time
As long as the sustainable Levvel-blocs meet the requirements, they remain on the Afsluitdijk. This means that Levvel will monitor them the coming 20 years. Also after that, the Rijkswaterstaat administrator will continue to inspect the blocks. During the first 10 years, we will also regularly take samples with a drill to examine the blocks. In this way, we can follow the quality of the various types of concrete over time. Blocks that turn out not to be suitable for the heavy conditions on the Afsluitdijk can be replaced outside the storm season. Another advantage is that it is modular, which makes it easy to replace.