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

Abstract

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.