Building for the energy transition – Innovative waterproofing for precast concrete elements

The protection of the environment and resources are among the biggest challenges of our time, with the construction industry playing a key role here. An efficient utilization of energy and heat are decisive for the success of the energy transition. Currently, an impressive construction project is being built in the city of Tübingen on the Neckar river, setting the course for a more sustainable future: A 48m-long tunnel was built under the Neckar in order to extent the district heating supply system to the other side of the river. In this way, the heat from the waste water of the city‘s near-by wastewater treatment plant is to reach the other side of the Neckar and to supply the areas of the city there with district heating.

Innovative sealing solutions for a complex construction project

The tunnel for the district heating pipeline terminates in two deep manhole structures which were built on both sides of the Neckar, being the core of the project. Röser Vertriebs GmbH supplied exactly fitting precast concrete elements for the manholes that had to be placed on top of each other in the approx. 8.5m-deep shafts with millimeter precision, being waterproofed in this process. The precision during production was decisive here. Each of the manhole elements weighing about 50 tons had to fit exactly on the structural component below so as to ensure perfect waterproofing. The MultiElast joint tapes of BT innovation, being laid with spacers onto the precast elements, were used as waterproofing system. The weight of the upper structural component provided for the compression needed for the waterproofing effect of the MultiElast joint tapes. The turnbuckles used served as installation aids and to secure the position. Thanks to the exact production and logistics by Röser, the smooth installation by PPR, Peter und Partner Rohrvortrieb, and the innovative waterproofing systems of BT innovation, the project was very successful.

Fast waterproofing of precast elements with MultiElast of up to 10m-deep component joints

MultiElast is a fiber-reinforced waterproofing tape free of bitumen. This tape can be used to seal component joints between precast element connections up to a pressure of 1 bar (10 m pressurized water). Hence, the joint tape allows for the construction of manhole elements down to 10 m deep into the groundwater. Applying of the sealing tape between the precast elements is possible up to a temperature of -5 °C. In case of construction planning with the BT Spannschloss as connection system, MultiElast, similar to the RubberElast, can be combined and processed together with turnbuckles. Even if the Neckar had high water during the construction works, the manhole remained protected from buoyancy and waterproof.

Secured twice: ProElast system for external protection

A second protection and external waterproofing of component joints on the manhole were to be achieved from outside with the aid of the ProElast system. At first, the shaft was gradually backfilled with limestone chippings externally in order to make the joints in the manhole accessible from outside. In this way, the ProElast system consisting of ProElast film and InnoElast type 2 could be installed on the two joints of the component at the exterior of the precast manhole. Apart from the dirt at the manhole wall, the narrowness at parts of the manhole to the sheet pile wall was more challenging. But even at the constriction the installation of the ProElast film could be managed by means of the powerful InnoElast type 2 film adhesive and a board as an extended arm. A dimpled sheet was attached against the ProElast film installed in this way, before backfilling the construction space with limestone chippings had been continued.  

The water-tight ProElast system for consequent joint covering

The high-grade and tested ProElast system is easy to apply and consists of two parts: The resistant ProElast EPDM film and the InnoElast adhesive with its high adhesive force to common construction materials. These strip-shaped waterproofing system allows reliable sealing of construction joints as well as predetermined crack joints in exterior applications.

The ProElast system is resistant to pressurized water and can be applied on damp and ice-free substrates from - 3°C without any primer. Typical applications of the ProElast sealing system are in the field of new construction and renovation works of basements, shafts, underground parking garages, sewerage systems, civil engineering, but also of balconies and roofs.

With waterproofing systems of high quality and a long service life, BT innovations ensures that building structures and the environment are protected in the long run, but also investments will be secured for a long time. In order to meet the increasing requirements of the customers, B.T. innovation GmbH based in Magdeburg is constantly further developing their own waterproofing systems.

The companies involved – Röser GmbH, PPR Peter + Partner Rohrvortrieb Spezialtiefbau GmbH and B.T. innovation GmbH – are proud to have made an important contribution to efficient utilization of thermal energy in Tübingen with their innovative solutions.

The used waterproofing systems of BT at a glance

MultiElast: Joint tape tested by building authorities for precast concrete elements and in-situ concrete, allowing waterproofing of structural components down to a water depth of 10 m.

ProElast system: Sealing system tested by building authorities for waterproof concrete, it consists of film and InnoElast adhesive and can be used for subsequent waterproofing of water pressure up to 20 m.

With these advanced products, BT innovation sets benchmarks in the field of structural sealing and plays an active part in shaping a sustainable future.