# Using Biopolymers to Control Hydraulic Degradation of Natural Expansive-Clay Liners Due to Fines Migration: Long-Term Performance

## TL;DR

This study shows that adding biopolymers like guar gum and sodium alginate can stabilize natural clay liners and improve their long-term hydraulic performance.

## Contribution

The novel use of biopolymers to prevent fines migration and enhance the long-term stability of natural expansive-clay liners is demonstrated.

## Key findings

- Biopolymers significantly reduce hydraulic degradation in natural clay liners over 360+ days of continuous flow.
- Sodium alginate with EC20 shows superior stabilization of fines and hydraulic performance compared to guar gum.
- Biopolymer-soil interactions form a cementitious gel that stabilizes soil structure and prevents fines migration.

## Abstract

Liners made of natural materials, such as expansive soil with sand, have a wide range of applications, including geotechnical and geoenvironmental applications. Besides being environmentally friendly, these materials are locally available and can be constructed at a low cost. The concern regarding these liners is sustainability and serviceability in the long run. The research conducted revealed significant degradation in hydraulic performance after periods of operation under continuous flow, which was attributed to the migration of fines. This study investigated the stabilization of these liners by using biopolymers as a cementitious agent to prevent the migration of fines and enhance sustainability in the long run. Two different biopolymers were examined in this study, including guar gum (GG) and sodium alginate (SA). The hydraulic conductivity tests were conducted in the laboratory under continuous flow for a long period (i.e., more than 360 days). The results revealed that incorporating biopolymers into these liners is of great significance for enhancing their sustainability and hydraulic performance stability. Further in-depth identification of the interaction mechanisms demonstrates that biopolymer–soil interactions create cross-links between soil particles through adhesive bonding, forming a cementitious gel that stabilizes fines and enhances the stability of the liners’ internal structure. Both examined biopolymers show significant stabilization of fines and stable hydraulic performance within the acceptable range, with high superiority of SA with EC20. The outcomes of this study are valuable for conducting an adequate and sustainable design for liner protection layers as hydraulic barriers or covers.