Potential Recycling of Excavated Tunnel Materials from Grand Paris Express Disposal as a Construction Material

The Grand Paris Express (GPE) is a project that aims to extend the metro network of Paris by creating four new lines, plus extending two existing lines. A total of 200 km of new tracks and 68 new stations are to be added, serving a projected 2 million passengers a day. Since it started, more than 20 Mt of earth is extracted, to which will be added until the end of the project in 2030. It is anticipated that the project will produce 30–40 Mt of excavated materials, which will primarily be transported out of Paris to be stored or buried in suitable areas. A potentially useful resource gets submerged in this process, which comes at a significant financial, economic, and environmental cost. Storage of those enormous, excavated materials is not sustainable, especially in a highly dense area. This paper explores the feasibility of using the excavated materials from the line 15 East as a building material. The detailed characterizations corroborate such a valorization. Expected benefits from recycling excavated disposal of GPE project include reduction of excavation management costs, reducing ultimate storage need, recycling of used materials, reduction of raw material requirements, positive CO2 impact, and a positive societal impact through support for local employment.