Use of recycled material for segments and inner lining – first experience of on‐site processing on KAT 2 / Verwendung von Tunnelausbruchmaterial – von der TBM bis zum Tübbing, erste Erfahrungen mit der Materialaufbereitung vor Ort im Baulos KAT 2

Abstract

In order to preserve the environment and save resources, Austrian Railways ÖBB have decided to recycle material excavated from contract KAT 2 of the 32.9 km long Koralm Tunnel and process it as aggregates for concrete production. This leads to a saving of gravel resources, reduction of transport routes and reduction of the required landfill areas. The rock mass, which is predominantly formed of schistose gneisses and gneisses with inclusions of mica schist, amphibolites and marbles, is being bored by tunnel boring machines. The material excavated from the tunnel is being recycled on site by processing for concrete aggregates.

The Potential of Recycling and Reusing Waste Materials in Underground Construction: A Review of Sustainable Practices and Challenges

“…This concept, illustrated in Figure 12 Several studies have explored the feasibility of recycling TEM and utilizing it as aggregates in structural concrete, shotcrete, and tunnel lining concrete, provided rock properties and processing methods are appropriately evaluated [37,[60][61][62][63][64][65]. Extensive laboratory and field testing has demonstrated the viability of using recycled TEM aggregates from various tunneling projects, such as the Götschka Tunnel, Koralm Tunnel, Brenner Base Tunnel, Torrent-La Thuile Tunnel, the Turin underground railway, Gotthard Tunnel, and Loetschberg Base Tunnel, and the Omegna Tunnel effectively recycled spoil as concrete aggregates [8,14,17,66,67]. For example, laboratory tests on quartz phyllite and schist rocks from excavation material of the Brenner Base Tunnel showed potential for recycling though variations in properties, especially for concrete mixtures, were addressed [62].…”

“…Testing of a mobile (Figure 13a) and fixed (Figure 13b) treatment plant showed the fixed plant optimized particle size distributions when fractions were well proportioned (Figure 14), whereas the mobile plant was insufficient [69]. In summary, the fixed plant offers a suitable product for concrete, if the different size fractions obtained in the plant are mixed appropriately [14,67]. Several studies have explored the feasibility of recycling TEM and utilizing it as aggregates in structural concrete, shotcrete, and tunnel lining concrete, provided rock properties and processing methods are appropriately evaluated [37,[60][61][62][63][64][65].…”

“…As the construction industry places increasing importance on sustainability, innovative approaches are being explored to diminish the environmental consequences of underground infrastructure development. Several case studies from various geographical contexts have demonstrated the successful implementation of sustainable practices [8,[13][14][15][16][17]. This paper comprehensively reviews sustainable practices applicable throughout underground project lifecycles.…”

Recycling of tunnel excavation using the example of the Koralm Tunnel, contract KAT2 – Status April 2015 / Verwertung von Tunnelausbruch am Beispiel des Koralmtunnels, Baulos KAT2 – Stand April 2015

“…For this purpose, a conveyor about 6 km long was installed in the south bore from the construction shaft through the east portal to a discharge point at the site of the future Western Styria station. About 3 m. t of material excavated from the tunnel were used on site as fill material under the open-air line [3]. Part of this is processed by screening and/or crushing for use in capillary break and frost protection layers.…”

“…Rund 3 Mio. t des anfallenden Tunnelausbruchmaterials werden vor Ort als Schüttmaterial auf der Freistrecke verwendet [3]. Ein Teil wird einer Behandlung durch Siebung und/oder Brechung für den Einsatz als kapillarbrechende Schichten und Frostkoffermaterial unterzogen.…”