Water-Retention Behavior of Geosynthetic Clay Liners

TLDR

Geosynthetic clay liners’ hydraulic performance depends on their water‑retention curve, yet few studies have measured these curves. This study quantified the water‑retention behavior of four GCL products differing in geotextile type and fabrication (thermal treatment, needle‑punching) using high‑capacity tensiometers and capacitance humidity sensors. The authors examined wetting and drying paths, reporting gravimetric and volumetric moisture contents and bulk void ratios, and fitted theoretical equations to the data to derive parameters for numerical modeling. The resulting WRCs varied markedly between products and between wetting and drying, demonstrating that needle‑punching and thermal treatment substantially influence GCL swelling and water‑retention.

Abstract

The hydration and subsequent hydraulic performance of geosynthetic clay liners (GCLs) depend on the water-retention curve (WRC) of the GCL. Because of the inherent difficulty in obtaining the WRC for these materials, limited data exists regarding the WRCs of GCLs in the literature. In this study, high-capacity tensiometers and capacitance relative humidity sensors were used to quantify the water-retention behavior of GCLs for four different GCL products that vary both in materials (woven and nonwoven geotextiles) and in fabrication detail (thermal treatment and needle-punching). The water-retention behavior was investigated under wetting and drying paths; we present results in terms of gravimetric and volumetric moisture content and bulk GCL void ratio. The WRCs of the different GCL products showed significant variation among wetting and drying curves, indicating that both needle-punching and thermal treatment have a significant effect on the swelling behavior of the GCL and its WRC. Theoretical equations were fit to the experimental data, establishing the parameters that can be used for numerical modeling of these four GCL products.