Investigating the Role of Biopolymer Associations in Soil Mechanics and Stability

To mitigate climate change, researchers are increasingly exploring the use of biopolymers in soil treatment. Various types of biopolymers have been reported, but their performance can vary significantly. The mechanisms underlying the strength of biopolymer-treated soils remain poorly understood. Xanthan gum is known to interact with galactomannans, such as guar gum and locust bean gum, to form a firm gel even at low concentrations, with the gel's elasticity depending on the polymer ratios used.
In this study, we prepared a xanthan gum/locust bean gum mixed gel that exhibits significantly higher storage modulus (G') than a pure xanthan gum solution. This gel was then incorporated into sand particles. We aim to investigate the relationship between the viscoelastic properties of the biopolymer blend and soil mechanics through rheological measurements and unconfined soil compression tests. The compression strength of xanthan gum/locust bean gum-treated samples showed a significant increase compared to samples treated with individual polymers; however, the results were only partially aligned with the viscoelastic properties of the polymer blend. Additionally, we assessed the effects of moisture and drying cycles on biopolymer-treated sand. The surface tension of different biopolymer solutions was measured using a contact angle goniometer, and the interactions between the biopolymer and sand were analyzed using SEM-EDS.
We gratefully acknowledge support from the US Army Corps of Engineers (ERDC) grant numbers W912HZ2120034 and under subcontract 45085319245.