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Multi-component geosynthetic clay liner improves barrier applications

Geosynthetics have been used in civil and environmental applications for many decades. Primarily functions include separation, filtration, drainage, reinforcement, protection and sealing.
Beyond the basic awareness of the available products, the marked increased use of geosynthetics as a whole appears to have been driven by the many advantages geosynthetics have over traditional construc-tion methods and materials. Advantages include the direct material cost savings, airspace savings for landfills, the reduction of excavation volumes, faster installation rates, improved performance as well as the possibility of steeper slope applications. However, with the technical advances, greater care must be used to ensure the correct product is selected and just as importantly, that the product is properly installed. Poor selection or installation can have the effect of negating the economic and technical benefits.
This paper will touch mainly used geosynthetic systems but focus mainly on geosynthetic clay liners (GCLs) and the recent development of multicomponent GCLs.
Geosynthetic clay liners (GCLs) are mostly needle-punched, fibre-reinforced composites that combine two durable outer layers and an intermediate uniform core of high swelling powder sodium bentonite clay, which acts as the barrier component. These uniform needle-punched GCLs form a direction inde-pendent shear strength transferring sealing barrier. When the bentonite core hydrates with fresh water, the bentonite swells and forms a low permeability gel layer, which outperforms traditional, thick compacted clay liners, due to the bentonite’s ability to self-seal and re-heal.
GCL improvements, since the invention of needle-punched GCLs in 1987 and contribution to the under-stand-ing and adoption of GCLs in engineering and construction, have been numerous. This paper will discuss the new GCL technology, the advantages of the polymer coating added to the GCL, the current test results, the applications where such GCL products are ideally used and the necessary design consid-erations.