Effects of compaction on the erodibility of a residual soil of gneiss

Abstract

This work aims to verify the effects of the natural structure of a residual soil on its erodibility and the potential, employing compaction, to restore the erosion resistance. It is a residual soil of gneiss that occurs in the state of Santa Catarina, Southern Brazil. Infrastructure earthworks expose this material to the action of water, which can develop severe erosive features. The erodibility evaluation was made using the MCT methodology based on infiltrability and modified loss of mass by immersion tests. These tests were conducted in undisturbed specimens at natural moisture content and in compacted specimens at optimum moisture content. Such tests were also carried out in specimens air-dried for 24, 48, and 96 hours. This soil is inherently erosive, but the natural macrostructure makes it even more susceptible to erosion. Even compaction under modified energy is not able to recover the erodibility resistance. Drying slightly reduces the soil’s erosive potential when compacted, regardless of the compaction energy, but clearly increases the erosive potential of undisturbed soil.