Geotextile Acid and Alkali Resistance Chamber – QualiGTX™ AA
The QualiGTX™ AA Geotextile Acid and Alkali Resistance Chamber evaluates the chemical durability of geosynthetic
materials by exposing specimens to acidic and alkaline solutions under controlled heating conditions. After
exposure, tensile testing determines the percentage of original strength retained by the material. The system
features two separately operated liquid tanks, allowing acid and alkali resistance assessments to run simultaneously
on specimens cut from the same material. Operating temperatures can be adjusted from ambient conditions to 65 °C,
with temperature accuracy of ±1 °C at the commonly used 60 °C screening temperature.
Chemical compatibility is a critical consideration when selecting geosynthetics for applications involving aggressive
soil and groundwater conditions. Polyester materials are susceptible to strength degradation through alkaline
hydrolysis, while acids can affect the stabilizing additives used in polyolefin products. Laboratory testing
therefore provides essential evidence of material durability under anticipated service conditions. With the
QualiGTX™ AA, specimens undergo controlled chemical immersion for a predetermined period before their tensile
strength is compared with that of untreated reference samples.
Temperature regulation is handled by a digital touchscreen controller, supported by a 2.4 kW heating system that
brings the liquids to the required temperature and keeps conditions stable throughout extended exposure cycles,
which frequently last several days. The chamber provides internal dimensions of 450 × 550 × 550 mm. Weighing 60 kg,
the equipment occupies a footprint of 1150 × 560 mm and operates from a single-phase power supply. Its testing
capabilities support geosynthetic manufacturers, independent certification laboratories, and geotechnical research
organizations conducting product qualification, incoming material inspection, and long-term durability
investigations.
Geotextile Acid and Alkali Resistance Chamber – QualiGTX™ AA Applications
Geosynthetic chemical resistance assessment is important in projects where fabrics, barriers, reinforcement products,
or drainage materials come into contact with groundwater, industrial liquids, or other substances with strongly
acidic or alkaline properties.
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Landfill Leachate Containment: Assesses the chemical durability of protective geotextiles
and drainage components exposed to landfill leachate throughout the post-closure service period.
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Concrete and Cement-Stabilized Structures: Evaluates reinforcement materials installed in
contact with cement-based construction materials, where pore water with a pH of 12 to 13 can cause polyester
degradation through hydrolysis.
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Mine Drainage and Tailings Facilities: Determines the resistance of geosynthetics exposed to
acid rock drainage, which can produce highly acidic conditions with pH levels well below 3 over periods
extending for decades.
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Industrial Waste and Process Water Containment: Examines whether geosynthetic products are
compatible with the actual chemical composition of industrial waste and process liquids at a project site.
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Agricultural and Fertilizer Runoff Applications: Evaluates drainage fabrics installed in
agricultural soils where fertilizer application can increase the concentration of chemicals in the
surrounding environment.
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Geotextile Manufacturing Quality Control: Supports routine production checks by identifying
changes in chemical resistance associated with variations in resin supply or additive formulations.
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Polymer Selection and Product Development: Provides comparative test results for polyester,
polypropylene, and polyethylene materials to help determine which construction is better suited to the
intended chemical exposure.
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Third-Party Certification Laboratories: Generates retained tensile strength measurements
required for product approval programs, certification assessments, and project documentation.
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Failure Investigation: Recreates suspected chemical exposure conditions in the laboratory to
establish whether chemical degradation contributed to strength loss in recovered geosynthetic samples.
Geotextile Acid and Alkali Resistance Chamber – QualiGTX™ AA Key Features
The QualiGTX™ AA combines simultaneous chemical exposure testing with controlled heating, providing consistent
conditions for accelerated geosynthetic durability assessments.
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Two Independent Liquid Tanks: Provides separate environments for acidic and alkaline
exposure, allowing matched specimens to undergo both tests concurrently. This arrangement reduces overall
testing time while limiting differences caused by variations between material samples.
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±1 °C Temperature Accuracy at 60 °C: Keeps the operating temperature within the specified
tolerance, reducing the influence of temperature fluctuations on chemical reaction rates during testing.
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Ambient to 65 °C Operating Range: Supports commonly specified screening temperatures while
providing additional capacity for accelerated chemical exposure investigations.
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2.4 kW Heating System: Supplies the heating capacity required to bring both tanks to their
selected temperatures and sustain those conditions during exposure cycles lasting several days.
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Digital Touchscreen Controller: Allows operators to select the required temperature and
monitor the actual operating value throughout the test.
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Automatic Thermostatic Operation: Regulates heating to preserve the selected temperature
without requiring continuous operator intervention during extended testing.
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450 × 550 × 550 mm Internal Chamber: Provides sufficient working space for batches of
prepared specimens arranged on suitable racks or suspended within the test liquid.
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Uniform Temperature Distribution: Creates consistent thermal conditions throughout each
tank, helping ensure that specimens within the same batch experience comparable exposure.
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Single-Phase Power Supply: Allows installation using a standard single-phase electrical
connection without requiring a dedicated power service.
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Broad Material Compatibility: Accommodates geotextiles, geomembranes, geogrids, and other
geosynthetic materials requiring laboratory chemical resistance assessment.
Theory and Test Method
The way chemical exposure affects a geosynthetic depends largely on its polymer composition and the chemical
structure of its constituent materials. Polyester contains ester bonds along its molecular backbone. In alkaline
environments, hydroxide ions attack these bonds and break them through hydrolysis. As the molecular chains become
shorter, their molecular weight decreases, resulting in a corresponding reduction in tensile strength. This behavior
makes polyester reinforcement particularly important to evaluate when it is installed near concrete or
lime-stabilized soil, where cement-based pore water can reach pH levels of 12 to 13.
Polypropylene and polyethylene have different chemical structures. Their molecular backbones do not contain
hydrolyzable groups, giving these polymers strong resistance to both acidic and alkaline environments. However,
chemical exposure can still affect their stabilizing additives and mineral fillers through leaching or chemical
attack. Consequently, the base polymer alone does not provide sufficient evidence of long-term durability, and the
complete material construction should be assessed.
The test procedure focuses on measuring changes in mechanical performance following chemical exposure. Prepared
specimens are immersed in specified acidic and alkaline solutions at elevated temperatures for a predetermined
duration. Once exposure is complete, the samples are removed, rinsed, conditioned, and subjected to tensile testing.
Their post-exposure strength is then compared with the tensile strength of unexposed reference specimens from the
same material. The resulting retained-strength percentage provides a quantitative indication of chemical durability
and serves as the primary value used for specification compliance.
Testing both chemical environments with specimens obtained from the same production roll is particularly important.
Geosynthetic properties can vary between rolls, potentially creating differences in tensile performance that are
unrelated to chemical exposure. Using matched specimens helps isolate the effects of acidic and alkaline conditions
and makes the comparison more representative.
Elevated temperature accelerates chemical degradation, making it possible to evaluate material performance over
shorter laboratory periods. Hydrolysis and many other degradation reactions approximately double in rate with every
10 °C increase in temperature. Accordingly, exposure at 60 °C can compress degradation that would otherwise develop
over years under ambient conditions into a period of several laboratory days.
Accurate temperature regulation is therefore essential to obtaining meaningful results. If the chamber operates
several degrees above the specified temperature, chemical reactions may proceed faster than intended, potentially
making the material appear less durable than it actually is. Conversely, temperatures below the target can slow
degradation and produce overly favorable results. The QualiGTX™ AA addresses this requirement with ±1 °C temperature
control at 60 °C. Its independently operated tanks also allow acidic and alkaline solutions to reach their
respective operating temperatures without either testing process having to wait for the other.
Geotextile Acid and Alkali Resistance Chamber - QualiGTX™ AA Technical Specifications
| Parameter |
Specification |
| Test Principle |
Immersion exposure in acidic and alkaline liquids at controlled elevated temperature |
| Measured Property |
Retained tensile strength after chemical exposure (tested separately) |
| Number of Liquid Tanks |
2 |
| Maximum Working Temperature |
65 °C |
| Temperature Control Tolerance |
60 °C ± 1 °C |
| Total Heater Power |
2.4 kW |
| Temperature Control |
Digital touchscreen, automatic thermostatic |
| Working Chamber Dimensions |
450 × 550 × 550 mm |
| Applicable Materials |
Geotextiles, geomembranes, geogrids, and other geosynthetic and non-geosynthetic materials |
| Voltage |
220 V (110V is also available) |
| External Dimensions (W × D × H) |
1150 × 560 × 550 mm |
| Weight |
60 kg |
