Discipline: Technology & Engineering
Subcategory: STEM Research
Joao Machado - California State University, Los Angeles
Co-Author(s): Wing Shun Kwan, Cal State LA, Los Angeles, CA; Matthew S. Gore, Golder Associates, Illinois, MO; Arnaldo Rendon, Cal State LA, Los Angeles, CA; Omar Cojulun, Cal State LA, Los Angeles, CA; Gustavo Menezes, Cal State LA, Los Angeles, CA
Advanced hydraulic characteristic of treated and untreated Bauxite Residue (Red Mud) is studied and compared through the use of a Steady-State Centrifugation (SSC)Unsaturated Flow Apparatus (UFA). Red Mud is the by-product waste from Bayer process during aluminum production that has shown the potential of being reused as fill material in embankment construction. The basic geotechnical engineering properties of the residue have been investigated in recent studies, but there is a limited number of documented studies on its unsaturated hydraulic characteristic. This information is essential for utilizing Red Mud in geotechnical applications such as above-ground embankment. Furthermore, the high pH (>12) and high alkalinity of the bauxite slurry is a challenge for reusing the material. Past studies have shown two effective and economic pH 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 with a salt concentration of 32 g/L, and treated with gypsum. The result will add to the body of knowledge on unsaturated hydraulic characteristic of the Red Mud and can shed light on neutralizing methods, leading to better opportunities for utilizing this widely available mining waste as a civil engineering material.
Funder Acknowledgement(s): This work is supported by the CREST Center for Energy and Sustainability (CEaS) of the National Science Foundation - United States under NSF Award Number HRD 1547723. Any opinions, findings, conclusions or recommendations expressed in this material are those of the authors and do not necessarily reflect those of the National Science Foundation.
Faculty Advisor: None Listed,
NSF Affiliation: CREST