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We are looking at using a regular liner. Are there any advantages of switching to Hydroclay Geosynthetic Clay Liner?

Yes, see the Comparison Table


Is my project going to be very expensive using Hydroclay Geosynthetic Clay Liner?

No. Usually, even though Hydroclay GCLs have many advantages over regular liner, your project works out substantially cheaper.


Are there any specialist installers of Hydroclay Geosynthetic Clay Liner?

No. Simply because there are no expertise involved in the installation of Hydroclay GCL, its extremely straightforward. Full Installation Guidelines are provided with each order.


What is the lifetime of Hydroclay Geosynthetic Clay Liner?

To the best of our knowledge, the natural and synthetic components of a GCL will uphold far into the future, likely over 50 years under normal confinement conditions. The bentonite in Hydroclay GCLs is already millions of years old and the synthetic geotextiles are made of chemically stable polymers which resist long-term degradation.


What equipment do I need to unload the delivery vehicles?

When GCL rolls arrive the vehicles are best unloaded using the slings provided. Alternative methods include using an forklift truck equipped with a “stinger” which is pushed through the roll core, or a steel core pipe can be inserted manually and the rolls lifted using an excavator, crane or other suitable machinery.


How strong are Hydroclay Geosynthetic Clay Liners?

All HYDROCLAY GCLs are reinforced, in which the fibres of a non-woven geotextile are needle-punched through the bentonite layer into a non-woven geotextile. The needle-punched fibres give HYDROCLAY GCL's excellent internal shear strength for use in sloped applications.


Is the Hydroclay performance impacted by freeze/thaw?

Freeze / thaw cycles have no adverse impact on the Geosynthetic clay liner. Laboratory testing has shown that the hydraulic conductivity of GCLs remains stable after many freeze / thaw cycles.


What is the steepest slope on which Hydroclay Geosynthetic Clay Liner may be used?

HYDROCLAY GCLs have been successfully used on slopes 3H:1V. These designs were based on internal and interface direct shear testing.


The contractor has requested permission to use cover material that contains limestone or chalky substrate. Should I be concerned?

Calcium and magnesium can leach from cover material and exchange with the sodium ions in the sodium bentonite used in Hydroclay GCLs thus reducing its efficiency. As a general guideline, calcium-rich cover materials are NOT recommended.


What is the difference between flux and permeability?

Flux is the actual rate of flow through the GCL and is expressed in units of volume per unit area per unit time e.g. m3/m2/sec. Permeability or hydraulic conductivity is a mathematical constant derived from Darcy’s Law to describe a soil’s ability to convey flow under known hydraulic forces. The benefit of using flux is that this value can be used for a direct comparison to any maximum leakage specifications or requirements for a given project.


Is a Geosynthetic Clay Liner compatible with organic chemicals?

In general, yes. Small concentrations of common organic groundwater contaminants, for example, have no effect on the hydration and function of a GCL. However, we would recommend both soil and water samples be taken for analysis to ensure elements such as Calcium are not present which can inhibit cation exchange and the Sodium Bentonite's ability to seal.


How long do Geosynthetic Clay Liners take to hydrate?

When a geosynthetic clay liner is placed on a soil, it will hydrate through absorption of moisture contained within the adjacent soil. Testing results show that the GCL will even hydrate when placed on a soil with a moisture content well below optimum. Because the Bentonite in Hydroclay GCL's is a powdered form, hydration will commence immediately under suitable conditions.


What is the typical moisture content of the bentonite in Hydroclay Geosynthetic Clay Liners?

During manufacturing of the GCL, water is added to the bentonite to assist GCL needle-punching. The resulting bentonite moisture content in HYDROCLAY is less than 10%, well below that of fully hydrated bentonite, and will have no negative effect on performance. In fact, bentonite with 25% to 40% moisture has the appearance, consistency and strength of a granular soil.


Will HYDROCLAY Geosynthetic Clay Liners shrink in the field upon deployment?

Thiel (2005) found that GCLs can experience shrinkage when subjected to repeated cycles of wetting and drying (full hydration followed by complete desiccation). However, reasonable measures can be implemented to prevent this from occurring.

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