The enclosure dam between the Wadden Sea and the Ijsselmeer has protected large parts of the Netherlands against flooding since 1932. Meanwhile, the building structure is in need of refurbishment and modernization owing to permanent environmental impacts. In a multi-annual project, the stability of the dam is to be improved by innovative concrete blocks: „Levvel-blocs“ especially developed for this purpose by the Dutch project company Levvel are used on the lower embankment and special basalt quattro blocks made by Holcim Coastal B.V. are used for the upper bank.
Innovative concrete elements for highest demands
The Dutch company Holcim Coastal B.V. is a specialist in hydraulic construction and coastal protection. Jean-Pierre Quartaert, general manager at Holcim Coastal B.V., explains the procedure for selecting appropriate concrete elements for this project and similar ones: „We were aiming at high stability in conjunction with durability and a minimum input of material.”
„Now, we needed the adequate technology for the production of the concrete elements,“ explains project manager Jörg Switala. „In view of the large quantity and the most demanding end use, highest operational safety and perfect mixture homogeneity were key factors for us here.“ Thus, we chose BHS-Sonthofen, the expert in mixing technology, being most familiar with demanding major projects. The Dutch Holcim plant located in Alphen aan den Rijn, where the elements are manufactured and shipped, required two mixers with a daily capacity of 520 m³ at the start of the project in 2019. The company will supply concrete for 700,000 m² of dam area in total until the project completion in 2023.
BHS technology for the required homogeneity
For this field of application, André Däschlein, sales manager mixing and crushing technology at BHS, recommended the twin-shaft batch mixer of type DKX, having already proven its worth in the concrete industry. „Due to several decades of extensive know-how in the field of concrete, we are able to draw on experiences from a large number of similar projects,“ Däschlein says. „Therefore, we were quite sure that the twin-shaft batch mixer provides the required high mixture homogeneity“