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. 2026 Jan 20;18(2):272.
doi: 10.3390/polym18020272.

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

Ahmed M Al-Mahbashi  1 , Abdullah Shaker  1 , Abdullah Almajed  1
Affiliations

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

Ahmed M Al-Mahbashi et al. Polymers (Basel). .

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.

Keywords: biopolymers; expansive-clay liners; fines migration; flow; hydraulic conductivity; long-term performance.

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Conflict of interest statement

The authors declare no conflicts of interest.

Figures

Figure 1
Figure 1
Grain size distribution for (a) sand, and (b) expansive clay.
Figure 2
Figure 2
Schematic diagram of the testing system.
Figure 3
Figure 3
Unstable zone for tested liners: (a) hydraulic conductivity, and (b) introduced flow.
Figure 4
Figure 4
Representative cross-section for (a) EC liner’s initial state, (b) fine migration during flow, and (c) particle rearrangement and skeleton adjustment for final stabilization.
Figure 5
Figure 5
Determination of fine content by the washing technique: (a) specimen soaked in distilled water, (b) materials washed over a #200 sieve, and (c) fines passed after oven-dry.
Figure 6
Figure 6
Measured fines before and after conducting long-term performance in different expansive clay liners.
Figure 7
Figure 7
Effect of biopolymer treatment on (a) hydraulic conductivity; (b) cumulative flow of tested liners.
Figure 7
Figure 7
Effect of biopolymer treatment on (a) hydraulic conductivity; (b) cumulative flow of tested liners.
Figure 8
Figure 8
Comparison of different biopolymers on the long-term performance of (a) hydraulic conductivity, and (b) introduced flow.
Figure 8
Figure 8
Comparison of different biopolymers on the long-term performance of (a) hydraulic conductivity, and (b) introduced flow.
Figure 9
Figure 9
Representative cross-section showing interaction of biopolymer–clay particles in the voids between sand particles.
Figure 10
Figure 10
Microstructural study conducted by SEM for (a) sand particles, (b) clay filling the voids between sand particles, and (c) the presence of amended biopolymer SA.
See this image and copyright information in PMC

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