Environmental profile of bentonite drilling fluids for civil engineering applications

Bentonite is the commercial name of a class of materials composed mainly of montmorillonite, which may also contain kaolinite, feldspars, micas, cristobalite and quartz. Such product is widely used for different civil engineering applications such as foundations (piles and diaphragm) and tunnel excavations (TBM, Micro-TBM and other no-dig technologies). This paper presents the results of a Research program developed by ITALFERR and GEEG including an experimental investigation based on the analysis of geotechnical and chemical properties of bentonite-based slurries in order to compare and identify the main properties of fluids prepared either with natural or polymer-modified bentonites. The interaction of the drilling fluids with the environment is an extremely delicate issue that must be carefully addressed during the design and construction phases. This study aimed at acquiring knowledge and defining best practices for the proper management of drilling fluids and the sustainable reuse of soils and rocks during and after the excavation.