Sustainability in construction works: Reuse of sludge from tunnel boring in lime mortars

• Sludge from TBM is reused for mortars’ application on construction works.
• Geotechnical and mineralogical characterization determine the material type.
• Inorganic clay of low plasticity is treated with limestone and silica sand.
• Flexural and compression strength tests show its possible use as mortar.

This study is based on reuse of sludge from tunnel boring for the manufacture of mortars with calcium hydroxide and their possible application in construction. Three samples have been tested with different percentages of sludge from tunnel boring obtaining high consistency. This percentage was used to produce two types of mortars, one with limestone-type aggregates and the other with siliceous-type material, which were then subjected to compression and flexural tests.The analysis shows that the use of these sludge, with calcium hydroxide and siliceous-type aggregates, helps to improve the mortars’ properties and increase their flexural strength to values above 4 MPa, which could be reused as a coating for underground work and road construction as long as its complies with the standard.