Cologne’s peripheral drain completely renovated

Cologne’s peripheral drain (Randkanal) is part of the municipal drainage system and performs an important function in keeping the city free from surface water.Its paving was renovated in the summer of 2017 in a project that involved the complete replacement of the surface wear coat, together with some impressive logistical achievements along the way.

Cologne’s peripheral drain is around 20 km long and serves to remove sump water from the nearby open cast mine, directing it into the river Rhine in order to compensate for high water in its tributary, the river Erft. The drain is consolidated by means of a concrete composite pavement, combined with an asphalt concrete layer below and a bituminous surface seal. The latter was heavily weathered and perforated by heavy biogenic growth, resulting in underflow erosion and spalling. In some places, the surface of the underlying interlocking paving was also extensively exposed. The client, Zweckverband Kölner Randkanal, followed the recommendation of Moers-based planners Marc Achterberg (IMA) to implement a total renewal of the surface coating using Expert Proof eco and Oxal RM-L, a system that IMA had developed together with its partners at MC.

 

Impressive results

The work was carried out from mid-May to the end of July 2017 by Weiss GmbH of Duisburg, under the management of Daniel Debbelt and Markus Lessmann. The coating system had to be UV-proof and offer durable resistance to the mechanical stress and chemical attack of the fast-flowing water. In addition, the repaired watercourse had to be ready quickly to receive water again in order to avoid major downtimes and additional water storage costs, with water having to be redirected at great expense during the work.

 

The bitumen-free sealant Expert Proof eco was applied by spraying. As well as being flexible, crack-bridging and highly economical, it offers the advantage of exceptionally fast, virtually temperature-independent curability, together with outstanding adhesion to the substrate and quick and easy overworkability. It is also harmless in terms of water hygiene and meets the strict criteria of the AgBB, the German committee for the health-related evaluation of building products. As IMA also identified the need for a mechanical wear layer, Expert Proof eco was fully scattered with sand as it was laid and was overcoated with Oxal RM-L after it had completely cured. This single-component, microsilica-modified mortar offers outstanding workability and is highly resistant to sulphates, wear, temperature and frost. Both products proved their outstanding strength of adhesion to the substrate during the application work, which took place under adverse weather conditions alternating between continuous rain and unusually high temperatures above 30 degrees Celsius. Ultimately, this multi-product solution ensured that the drain could be quickly returned to service and exposed to the wear and tear of flowing water.

 

 

Exceptional logistical Achievement

The extent of the refurbishment can be seen from the volume of building materials that had to be delivered. Approximately 200 metric tons of construction products were distributed along the length of the repair site using a sophisticated logistical plan which included unloading by crane to enable rapid application and placement. The client was delighted at the speed of the working cycles and the associated reduction in costs for water storage. The durability of the coating solution met the project specifications in full, much to the satisfaction of all.