Biopolymer Stabilization/Solidification of Soils: A Rapid, Micro-Macro, Cross-Disciplinary Approach

In this study, we describe a novel high throughput, micro-macro approach for the identification and efficient design of biopolymer stabilized soil systems. At the "microscopic" scale, we propose a rapid Membrane Enabled Bio-Mineral Affinity Screening (MEBAS) approach supported by Mineral Binding Characterization (MBC) (TGA, ATR-FTIR and ζ Potential), while at the "macroscopic" scale, micro scale results are confirmed by Geotechnical Verification (GV) through unconfined compression testing. We illustrate the methodology using an exemplar mine tailings Fe₂O₃-SiO₂ system. Five different biopolymers were tested against Fe₂O₃: locust bean gum, guar gum, gellan gum, xanthan gum, and sodium carboxymethyl cellulose. The screening revealed that locust bean gum and guar gum have the highest affinity for Fe₂O₃, which was confirmed by MBC and in agreement with GV. This affinity is attributed to the biopolymer's ability to form covalent C-O-Fe bonds through β-(1,4)-d-mannan groups. Upon their 1% addition to a "macroscopic" Fe₂O₃ based exemplar MT system, unconfined compressive strengths of 5171 and 3848 kPa were obtained, significantly higher than those for the other biopolymers and non-Fe systems. In the current study, MEBAS gave an approximately 50-fold increase in rate of assessment compared to GV alone. Application of the proposed MEBAS-MBC-GV approach to a broad range of soil/earthwork components and additives is discussed.