Compact Geosynthetic Clay Liner Permeameter – QualiGTX™ CLP C
Permeability Coefficient Testing of Geosynthetic Clay Liners and Sodium Bentonite Waterproofing Blankets
The QualiGTX™ CLP C is designed to measure the hydraulic permeability of geosynthetic clay liners (GCLs) by
monitoring water movement through sodium bentonite waterproofing blankets under a controlled hydraulic differential.
During testing, the laboratory measures the volume of water passing through a specimen over a defined period and
uses this information, together with the specimen thickness, to determine its permeability coefficient. The
instrument accommodates specimens with a diameter of ø70 mm and supports applied pressures up to 50 kPa. Its
high-strength aluminum alloy specimen holder maintains secure clamping throughout the test.
Obtaining consistent permeability measurements requires careful temperature management. As hydrated bentonite
restricts water movement, testing can continue for extended periods, making the results particularly sensitive to
changes in water viscosity. Even minor temperature fluctuations can influence the measured flow rate and introduce
inconsistencies between tests. To address this issue, the QualiGTX™ CLP C incorporates a water-conditioning system
with both heating and cooling capabilities. This arrangement maintains the permeant at a predetermined temperature
before it reaches the specimen, rather than allowing its temperature to fluctuate with laboratory conditions. The
water supply and reservoir tank are provided in a custom configuration, making this system particularly suitable for
laboratories that report permeability results at a standardized reference temperature.
The instrument also features a large-format color touchscreen for configuring test parameters, monitoring operating
conditions, and managing automatic timing. This integrated interface simplifies operation during lengthy permeation
tests and minimizes the need for continuous technician involvement. Its vertical column construction brings the
water circuit, specimen cell, and control components together within a compact floor area of 720 × 700 mm. Qualitest
North America offers the QualiGTX™ CLP C to geosynthetic manufacturers, independent testing facilities, and
engineering consultancies conducting GCL permeability and containment liner conformance evaluations.
Compact Geosynthetic Clay Liner Permeameter – QualiGTX™ CLP C Applications
Permeability testing establishes whether geosynthetic clay liners provide the hydraulic barrier performance required
for their intended applications. The QualiGTX™ CLP C supports this evaluation at different stages, from
manufacturing quality checks and incoming material inspection to construction verification and engineering research.
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GCL Manufacturing Quality Assurance: Provides routine permeability measurements across production batches,
helping manufacturers monitor water transmission characteristics between rolls and identify inconsistencies
in bentonite distribution before products leave the facility.
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Landfill Cell and Cap Projects: Verifies that supplied GCL materials achieve the permeability requirements
established in landfill containment designs, supporting barrier performance throughout construction.
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Incoming Material Inspection: Enables independent laboratories and project quality teams to assess delivered
GCL rolls against specified permeability limits before installation begins.
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Mining and Tailings Containment Systems: Evaluates sodium bentonite barriers intended for use beneath heap
leach pads, tailings storage facilities, and process water containment ponds.
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Reservoirs, Canals, and Retention Basins: Measures the seepage resistance of GCL materials used in water
storage facilities and water conveyance infrastructure.
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Secondary Containment Installations: Supports the assessment of barrier materials specified for areas beneath
storage tanks, fuel distribution facilities, and chemical containment bunds.
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Wastewater Treatment and Agricultural Lagoons: Determines the suitability of GCL products for manure storage
facilities, aeration basins, and industrial wastewater process ponds.
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Academic and Scientific Research: Provides testing capabilities for investigations into bentonite hydration
behavior, cation exchange processes, and the long-term performance of geosynthetic clay barriers.
Compact Geosynthetic Clay Liner Permeameter – QualiGTX™ CLP C Key Features
The QualiGTX™ CLP C brings together controlled water conditioning, reliable specimen containment, and automated
measurement functions in a compact vertical configuration. Its features address the practical requirements of
laboratories conducting extended permeability tests on sodium bentonite liners.
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Integrated Water Heating and Cooling: Regulates permeant temperature through both heating and cooling,
maintaining the selected setting and limiting viscosity-related variations that could affect comparisons
between test results.
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High-Strength Aluminum Alloy Specimen Holder: Provides firm, consistent specimen restraint while keeping the
holder assembly relatively lightweight. Its construction also makes specimen replacement easier and reduces
operator fatigue during repeated testing.
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Large-Format Color Touchscreen: Provides a centralized interface for entering test conditions, viewing live
operating information, and accessing results, making routine operation and operator training more
straightforward.
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Automatic Digital Timing: Controls the measurement interval without requiring manual stopwatch operation,
reducing timing inconsistencies during water collection and permeability calculations.
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Dedicated Water Reservoir: Supplies the permeation circuit from an integrated reservoir, allowing the test
arrangement to operate independently of direct laboratory water supply connections.
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Pressure Capacity up to 50 kPa: Accommodates the applied hydraulic pressure differentials required for
measuring water transmission through sodium bentonite waterproofing blankets.
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ø70 mm Specimen Compatibility: Uses a defined specimen diameter to maintain consistent flow area across tests
and simplify sample preparation.
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Space-Efficient Vertical Construction: Arranges the reservoir, specimen cell, and operating controls within a
vertical frame measuring 720 × 700 mm in floor footprint.
Theory and Method
The permeability coefficient of a geosynthetic clay liner is determined by examining the relationship between water
flow through the specimen and the hydraulic conditions under which that flow occurs. Four measurements form the
basis of the calculation: the volume of water collected, the duration of collection, the hydraulic head difference
across the specimen, and the specimen thickness.
Darcy's relationship provides the basis for calculating the coefficient:
k = QL / (A · Δh · t)
Where:
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k = Permeability coefficient
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Q = Volume of water passing through the specimen
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L = Specimen thickness
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A = Cross-sectional flow area
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Δh = Hydraulic head difference across the specimen
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t = Water collection period
Each measurement directly affects the calculated result. Inaccurate thickness measurements, inconsistent collection
intervals, or errors in determining the hydraulic differential can therefore compromise the reported permeability
coefficient. Reliable testing depends on controlling these variables throughout the measurement process.
Temperature control is another important consideration because the measured hydraulic conductivity reflects both the
properties of the specimen and the behavior of the fluid passing through it. Water viscosity decreases as
temperature rises, with an approximate reduction of two percent per degree Celsius near room temperature.
Consequently, even modest temperature changes during an extended test can alter the measured flow rate without any
corresponding change in the GCL itself.
Maintaining the permeant at a consistent temperature helps separate actual specimen performance from variations
caused by fluid properties. When results must be compared under standardized conditions, measurements can also be
corrected to a designated reference temperature, such as 20 °C. Combining temperature-controlled water supply with
reference-temperature correction improves the consistency of reported results across different operators and testing
laboratories.
The extremely low flow rates encountered during GCL testing are closely related to the hydration and swelling
behavior of sodium bentonite. When exposed to water, montmorillonite mineral layers attract water molecules and
hydrated sodium ions into the spaces between their layers. This process causes the bentonite particles to expand. As
the material swells within its confined structure, the interconnected voids between particles become progressively
smaller, leaving narrow and increasingly tortuous pathways for water movement.
The degree of swelling and the resulting restriction of water flow depend not only on hydration but also on the
compressive stress applied to the material. Confinement influences how much the bentonite can expand and,
consequently, how effectively it closes the available flow paths. For this reason, maintaining secure specimen
containment is essential to obtaining meaningful permeability measurements. The clamping assembly must prevent water
from bypassing the specimen along its perimeter, ensuring that the collected permeant represents water that has
passed through the bentonite rather than leakage around its edges.
Compact Geosynthetic Clay Liner Permeameter - QualiGTX™ CLP C Technical Specifications
| Parameter |
Specification |
| Test Method |
Permeability coefficient of sodium bentonite GCL under specified hydraulic differential |
| Specimen Diameter |
ø70 mm |
| Maximum Applied Pressure |
50 kPa |
| Specimen Holder Material |
High-strength aluminum alloy |
| Control System |
Large-format color touchscreen |
| Timing |
Digital, automatic |
| Water Supply |
Temperature-controlled with heating and cooling, plus reservoir tank (custom configuration) |
| Dimensions (W × D × H) |
720 × 700 × 1910 mm |
| Weight |
110 kg |
Configuration
| Item |
Description |
| Specimen Holder |
High-strength aluminum alloy clamping assembly for ø70 mm specimens |
| Control System |
Large-format color touchscreen with automatic digital timing |
| Water Conditioning Unit |
Temperature-controlled supply with heating and cooling, custom order |
| Water Reservoir |
Permeant supply tank, custom order |
| Support Frame |
Floor-standing vertical column structure |
