Rosmalen Bicycle Bridge
The curved bicycle bridge in Rosmalen, Netherlands, is no ordinary bicycle bridge: it is an aesthetically eye-catching piece of concrete work. The bridge is 280 metres long and 4-5 metres wide, and meets another important requirement of the client: namely, the bicycle bridge had to attract attention.
The concrete specified for the floating bridge comprised a combination of different exposure classes (XD3 and XF4) in the strength class C45/55. The main technological challenge in the mix design was to limit the development of heat originating from the mass, in combination with the choice of binder and additional requirements. The dimensions of the large spans and the use of pre-stressed steel required a dense array of reinforcing steel, which limited the maximum grain size (Dmax) of the concrete to 16 mm. The combination of traditional cements with a low Dmax resulted in a considerable amount of cement (kg/m³). It was therefore important to quickly generate strength after pouring the concrete, so that the pre-stress could be applied in time.
In addition, the concrete had to meet the requirements of the government guidelines for infrastructural artwork design (Richtlijnen Ontwerp Kunstwerken – ROK), especially in terms of long-term sustainability. This requirement stipulates that the slag content of the concrete must be more than 50%, meaning that only a limited amount of Portland cement CEM I could be used compared to slow-hardening CEM III / B. Because the colour of the concrete surface is influenced by shifting in the ratio of CEM III / B to CEM I, it was necessary to search for a binder sufficient to meet the strength class C45/55. The ROK guidelines specified an aesthetically smooth colour of the uncovered concrete surface and limited the total amount of cement (kg/m³) – the choice thus fell on ENCI CEM III / A 52.5 N, a product of HeidelbergCement’s subsidiary ENCI.
This project was nominated for the Betonprijs 2015 in the category bridges and viaducts. The Betonprijs awards projects that exemplify creative, unique, and meaningful application of the concrete.
