The tunnel is part of the A66 Federal Motorway, which leads from the Hessian capital of Wiesbaden to the Fulda motorway junction via Frankfurt.
Cemex says its expertise was required for the project because of the many complexities of an underground pour. A continuous, uninterrupted flow of materials is needed while maintaining uniform quality of concrete and protecting against exsolving. Strict quality control and tailor-made delivery methods using teams of divers are necessary to complete a task of this magnitude.
“The biggest construction stage is the placement of underwater concrete, which can take more than 24 hours,” says Mario Bischof of Cemex distribution in the Fulda/Würzburg region.
“Around 2,500m³ are placed at a time with the aid of divers. The required output per hour is 100-120m³.
Cemex concrete supply supports the installation together with a work group partner, by using large pumps measuring up to 63m in height. Due to the restricted space conditions and the size of the carriers, we use a pump in pump cascade supply.”
The water of the nearby Fliede stream and the ground water is pressed into the foundation pit, which is why underwater concrete is required to build the footwall. Pumping out the pit is not possible, because this would cause the ground water level to sink and considerable damage would occur. The divers are responsible for two tasks: they level the height of the concrete and remove mud from the foundation pit at the same time.
