Accounting for 57%, excavated soil accounts for the bulk of waste generated in Austria. Depending on its quality, it is often disposed of in landfill or used for applications such as filling road shoulders or building landfills. “Too little is still being done to reintegrate excavated soil – which intrinsically has great potential – into the material cycle”, says PORR CEO Karl-Heinz Strauss. “This is where PORR comes in: We systematically ensure it is turned into a valuable raw material, especially on large-scale projects”.  

New life for 14,275 tonnes of excavated soil from Favoriten, Vienna

How does this work in practice? PORR subsidiary Koller Erdbau has the answer, together with brick manufacturers. At the Klinik Favoriten construction site in Vienna, for example, excavated soil is being transformed into the building material of the future. PORR was commissioned by Wiener Gesundheitsverbund to excavate the foundation pit for the new central emergency department at Klinik Favoriten, covering an area of around 10,500 m². The works included the demolition of existing pavilions, the relocation and reinstallation of utilities, as well as securing the excavation pit. In the course of these works, 14,275 tonnes of clay-rich material had been recovered by the end of August. Around 13,300 tonnes were delivered to Wienerberger in Hennersdorf, where they were used to produce around 2 million wall bricks. A further 975 tonnes were supplied to brickmaker Ziegelwerk Lizzi GmbH in Bad Erlach.

Another successful example came during the expansion of the Vienna metro. Here too, clay-rich layers were excavated. Following laboratory tests, material analyses and production trials, these proved suitable for brick production. This meant that – in collaboration with Wienerberger and Ziegelwerk Lizzi – PORR was able to give a second life to five-figures worth of tonnage of excavated material.

Circularity begins on the construction site

Circularity is a central feature of PORR’s Sustainability Strategy 2030. And the reuse of excavated material demonstrates how this approach is being implemented in practice. Landfill volumes are reduced, primary raw materials are conserved, and existing material is given a second life as a raw material for new bricks.

“We want to introduce a systematic approach, particularly on large-scale projects, so that recycling demolition material and excavated soil becomes the norm rather than the exception”, says Strauss. A prerequisite for this is collecting materials and sorting them by type directly on the construction site. Circularity can only work if materials of different quality are separated, analysed and directed towards appropriate further uses at an early stage. 

This is exactly where PORR Umwelttechnik and its subsidiaries excel: Earthworks, logistics, processing, recycling, landfill engineering, concrete production and waste management all work together. Depending on its quality, mineral excavated material can then be used as sealing material, recycled construction material, aggregate for concrete or – as in the case of Vienna clay – as a raw material for new bricks.