Aggregates from tunnel muck treatments. Properties and uses

Tunnel muck should be considered as a valuable resource: if it is managed and treated correctly, it can be used for different purposes. This would lead not only to environmental benefits but also those of an economic nature. This work is part of the REMUCK project and it has the purpose of evaluating the effects of different treatments on different types of excavated rock. Five case studies have been selected and, of these, two were excavated with TBM (the Torrent-La Thuile tunnel and the Brennero tunnel), one with EPB (the Turin underground railway) and two using traditional excavation methods (Turin underground railway station and the Omegna tunnel). Tests have been carried out in the laboratory on both the muck in its natural state and on muck treated in two different plants (a mobile plant and a fixed plant) in order to characterise the aggregates from the shape and mechanical resistance points of view (according to EN 933-3 and EN 1097-2, respectively). The results of these tests have been compared with the threshold values foreseen in a muck management plan for a tunnel in Switzerland in order to verify the quality of the treatments the recycled aggregates were subjected to. This has made it possible to evaluate the suitability of the treatments, on the basis of the foreseen types of use, and to propose alternative working schemes for the nonconforming cases.