Technical
Reference 213
THE WATER COMPATIBILITY TEST
A VITAL STEP IN THE WATERPROOFING DESIGN PROCESS
Introduction. CETCO offers a wide range of below-grade waterproofing technologies and
materials, including spray-applied asphaltic emulsions, swellable bentonite-based membranes,
and even a bentonite-polymer alloy (BPA). These materials have varying chemical resistance
properties, and so special testing is required to ensure that the site water is compatible with the
waterproofing membrane. This is especially important in “brownfield” sites where existing soil
and/or groundwater contaminants are present. This Technical Reference provides a detailed
discussion of the water/soil compatibility test and its importance in the design of any belowgrade waterproofing system.
Water Sampling. The water analysis starts with the project
specification. In a proper specification, the contractor or applicator
will be required to furnish a “representative” site water sample to the
waterproofing manufacturer. Ideally, the sample can be obtained
very early in the project, such as during the hydrogeological
investigation.
More typically, however, the water sample is
submitted during construction from a site de-watering system or
sump. It is important that the water collected is representative of
actual groundwater conditions at the site. This means it should not be
mixed with surface water runoff or precipitation. If the site covers a
large area and there is the potential for water quality variability, then
a composite sample should be provided in which two or more
samples from different locations within the site are mixed together.
Water samples should be placed in two 1-quart (1-L) plastic bottles, furnished by CETCO. Strict
adherence to EPA sampling protocol is not required, because CETCO does not perform tests that
quantify contaminant concentrations. The samples are used for compatibility assessments which
are not sensitive to minute changes in water chemistry that may occur during sampling or in
transit. The sample must be submitted with an information form that can be obtained from
CETCO or downloaded from the Building Materials group website.
Soil Sampling. In cases where no water is present, a soil sample may be submitted instead.
CETCO will then “wash” the soil to create a water specimen for use in compatibility tests. The
objective of this procedure is to generate a liquid that is somewhat representative of site water
chemistry. CETCO's washing procedure requires 3 pounds (1.5 Kg) of soil. Samples should be
submitted in a sealed and durable plastic container.
Page 1 of 3
TR-213
Revised 04/05
1500 W. Shure Drive • Arlington Heights, IL 60004 • USA • (800) 527-9948 • FAX (847) 506-6195
A wholly owned subsidiary of AMCOL International
The information and data contained herein are believed to be accurate and reliable. CETCO makes no warranty of any kind and accepts
no responsibility for the results obtained through application of this information.
Technical
Reference 213
The Compatibility Test Procedure. When a
water sample is received at the CETCO
laboratory, four screening tests are performed
to assess compatibility. Two of the tests, pH
and conductivity, measure water quality from
instantaneous instrument readouts. The other
two tests, fluid loss and free swell, measure the
relative swelling and sealing ability of the
active component of the Volclay waterproofing
product specified for use. Each of the four test
parameters is evaluated as follows:
► pH: Indicates if any strong acids or bases are present; these chemicals can damage bentonite
clay. It would be unusual to measure pH that is not close to neutrality (7.0).
► Conductivity: Indicates strength of dissolved salts in the water. Because salts can hamper the
swelling and sealing properties of bentonite, this is a very useful indicator parameter and is
used to determine whether standard or contaminant-resistant products are evaluated in the test
program.
► Fluid Loss: Indicates the sealing performance of bentonite or BPA. A good indicator test
that return results in a short time (2 days) compared to a hydraulic conductivity test which
requires 5 days.
► Free Swell: Assesses volumetric swelling ability of bentonite. Swelling relates to the ability
of the clay to transform from a loose granular material into a monolithic sealing layer.
Testing is performed on clean, de-ionized or “DI” water to develop baseline data, and duplicate
data is obtained using the site water sample. CETCO uses each of these test results to develop
project-specific guidance as to which Volclay Waterproofing products will perform effectively
when in long-term contact with the site water. Of key importance is the free swell and fluid loss
difference between the results performed in DI water and site water. The larger the difference,
the greater the effect that the site water will potentially have on the waterproofing membrane.
Test Results. The pH and conductivity test results serve as indicators of key water quality
parameters but do not measure waterproofing performance. If the pH is outside the 5-8 range or
if the conductivity exceeds 1,000 µmhos/cm, contaminant-resistant (CR) materials will be added
to the testing regime.
Page 2 of 3
TR-213
Revised 04/05
1500 W. Shure Drive • Arlington Heights, IL 60004 • USA • (800) 527-9948 • FAX (847) 506-6195
A wholly owned subsidiary of AMCOL International
The information and data contained herein are believed to be accurate and reliable. CETCO makes no warranty of any kind and accepts
no responsibility for the results obtained through application of this information.
Technical
Reference 213
By performing duplicate tests in fresh water and site water, CETCO can quantify the decrease in
performance, if any, caused by contaminants in the site water. This decrease is called the water
contamination index or “WCI” on the compatibility test report. When the WCI for free swell or
fluid loss exceeds 15%, the product in question is not recommended. Depending on the severity
of the difference and other project-specific considerations, an alternative recommendation may
be made. For example, CETCO may test a standard bentonite membrane and find it
incompatible with a certain site water, although a more robust contaminant-resistant (CR) grade
of product may be found compatible. In such cases, CETCO will recommend the CR version of
the product.
It should also be noted that in exceptionally contaminated (saline) waters, it is possible that
neither the standard nor the CR products would perform sufficiently. CETCO will not hesitate to
make a recommendation that eliminates Volclay waterproofing as a potential solution.
Commercial considerations will not influence the objective recommendations made in these
tests.
Conclusion. While some may view the water test as an inconvenience, it provides vital
information on the suitability of Volclay Waterproofing products on a site-specific basis. For
this reason, it is a required test for all projects proposed to be covered by CETCO's
comprehensive system warranty.
Page 3 of 3
TR-213
Revised 04/05
1500 W. Shure Drive • Arlington Heights, IL 60004 • USA • (800) 527-9948 • FAX (847) 506-6195
A wholly owned subsidiary of AMCOL International
The information and data contained herein are believed to be accurate and reliable. CETCO makes no warranty of any kind and accepts
no responsibility for the results obtained through application of this information.