Advanced hydraulic characteristics of treated and untreated Bauxite Residue (Red Mud) are studied and compared using a Steady-State Centrifugation (SSC) Unsaturated Flow Apparatus (UFA). Red Mud is the by-product waste from the Bayer process during aluminum production that has shown the potential of being reused as fill material in embankment construction, which can reduce the energy consumption of disposing the minging waste and producing fill materials. There is a limited number of documented studies on unsaturated hydraulic characteristics of RM. Furthermore, the high alkalinity (pH > 12) of the bauxite slurry is a challenge for reusing the material. Past studies have shown two effective and economic neutralization methods: (i) mixing with seawater and (ii) addition of gypsum. This study utilizes Cal State LA centrifuge facilities to characterize the unsaturated hydraulic properties of the treated and untreated Red Mud. The experimental results are used to develop the Soil Water Retention Curve (SWRC) for the three types of Bauxite Residue: untreated, treated with saline solution, and treated with gypsum. The results show that adding gypsum is more effective than mixing with saline solution in reducing the pH value of RM, and the samples treated with saline solution provide the lowest range of unsaturated hydraulic conductivity values compared with the other two types.

This paper describes four data sets of cyclic simple shear (CSS) tests under modulated harmonic and transient loadings. The CSS tests were performed on reconstituted Nevada Sand specimens prepared by the wet sedimentation method at target relative densities of 40% and 70%. The data sets are freely available through the George E. Brown, Jr. Network for Earthquake Engineering Simulation data repository ( NEEShub.org ; database DOIs: 10.4231/D3W66991S, 10.4231/D30Z70X6F, 10.4231/D34Q7QR0T, 10.4231/D3RJ48W0Z). This paper describes the experimental apparatus, documentation of the specimen preparation procedures, loading histories, and summarizes the available CSS test data. The database includes 106 CSS tests and provides valuable information that can systematically illustrate the response of sand subjected to transient loadings before and after initiation of liquefaction; such a public database had been virtually non-existent until now.

The cyclic simple shear test (CSS) is widely regarded as the preferred element test for liquefaction because it best simulates vertically propagating shear waves. The CSS test provides reliable, high-quality laboratory data for model development and calibration in Geotechnical Earthquake Engineering design. Direct simple shear (DSS) tests can be performed by using the same apparatus to measure the shear strength and define the failure envelope. The consolidation and shearing are performed under K 0 conditions. The K 0 conditions are maintained through lateral confinement that prevents lateral deformations. Wire-reinforced membranes (WR) and stacked rings (SR) have been the two major techniques used to achieve the no lateral strain condition. The motivation for this work was to study the effect of using a WR versus SR on the stress-strain behavior and shear strength of clean sand. The paper presents results from DSS tests performed on Monterey #0/30 and Washed Mortar sands. The tests were performed under a constant vertical stress instead of constant volume to monitor effect of the confinement systems on the contractive and dilative response of the sand samples. The results show that there is general agreement between the measured shear strength and volumetric response with SR and WR confinement systems.

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