Engineering properties of fine-grained red mud

ABSTRACT Basic engineering parameters of fine-grained red mud tailings were evaluated via laboratory tests; the coupled effect of mineralogy and microstructure was investigated by appraising the stress-deformation characteristics; and the static and seismic liquefaction susceptibilities were evaluated via critical state soil mechanics and empirical equations, respectively. Results indicated the presence of cementitious minerals without swollen clay minerals. The textural and compression properties were similar to those of clays, whereas the strength parameters were similar to those of sand. The stress-deformation curves show overall strain softening with a temporary strain-hardening curve at the beginning, which can be qualitatively explained by the coupled effect of the microstructure and mineral components. Hydroxysodalite precipitated at the contact points among the particles afforded microstructural cementation bonds, allowing the aggregates to resist external loads at the initial loading stage. Red mud presented strong resistance to static liquefaction but was potentially seismically liquefiable.