Improving the engineering performance of coarse-grained soils with direct current electric fields

Soils are continuously affected by environmental and anthropogenic loads, with detrimental effects on their properties, behavior, and interconnected engineering performance. These effects lead to many catastrophic events every year, including landslides, sinkholes, and subsidence, and hamper the conservation and development of constructions. Therefore, the ability to “engineer” geomaterials in situ, i.e., enhance or control their properties and behavior (e.g., hydro-mechanical), is critical to support human activity in natural and built environments. Currently, grouting is the most widely used method to engineer soils. This method involves the injection of cementitious fluids that, once solidified, serve as binding agents for the solid particles of such porous materials, providing an enhanced particle contact surface, a greater material strength, and a reduced permeability. However, grouting has the drawbacks of requiring tremendous energy, high injection pressures, and cumbersome equipment, making its application challenging or infeasible in unstable or hardly accessible target zones, and when effectiveness or discretion are necessary to treat soils. This research aims to shed light on the potentially revolutionary path of using direct current (DC) electric fields to electrokinetically precipitate over seconds binding mineral crystals that would naturally form over centuries in soils due to the migration and reaction of ions in their pores.