Geotechnical Characterization of Compacted Bauxite Residue for Use in Levees: Fid-Bau Portal

Geotechnical Characterization of Compacted Bauxite Residue for Use in Levees

Gore, Matthew S. / Gilbert, Robert B. / McMillan, Ian / Isovitsch Parks, Shannon L.

This paper describes the results from a laboratory test program developed to characterize and evaluate the geotechnical properties of compacted bauxite residue, a byproduct from the production of alumina. Demand for suitable fill materials to construct flood-protection levees, particularly along the U.S. Gulf Coast, prompted this study to determine if bauxite residue could be a feasible solution. The laboratory test program consisted of characterization tests and performance tests including shear strength, hydraulic conductivity, erosion resistance and compressibility. Samples of both untreated bauxite residue and alkalinity-adjusted bauxite residue were tested. The results provide several conclusions. The characterization tests show that bauxite residue behaves like a fine-grained, plastic soil. Oven-drying the material before testing affects its geotechnical behavior and provides impractical results. In a compacted state, bauxite residue has a low hydraulic conductivity that is resistant to internal erosion and suitable for the core of a flood-protection levee. Compacted bauxite residue has a shear strength that is greater than fine-grained soils typically used in levees, potentially reducing the necessary footprint and volume required for a levee constructed with this material. The high alkalinity of untreated bauxite residue makes it necessary for neutralization or encapsulation to minimize its impact on the environment.