Index tests are carried out to enable meaningful comparisons of the properties of different products, provided the same test standard is used.
These “in isolation” tests do not take into account soil-geotextile interaction.
Properties determined by index testing are not generally appropriate for analytical design.
We are capable of conducting tests in accordance with the following standards: South African (SABS), American (ASTM, EPA), Australian (AS), British (BS, TRRL), Dutch (NNI), International (ISO, RILEM), European (EDANA, CEN), German (DIN), French (CFG), Swiss (VSS) and Chinese (CNS).
More detail on tests:
- Mass
- Thickness
- Tensile Strength
- Elongation
- Trapezoidal Tear
- Grab Tensile
- Puncture (CBR)
- Dart (Drop Cone)
Mass
Scope
This document specifies a method for the determination of mass per unit area of geotextiles and geotextile-related products for identification purposes and for use in technical data sheets.
The method is applicable to all geotextiles and geotextile-related products.
Test Method
Test specimens are taken from various locations across the full width of the sample geotextile. Each of the specimens is then weighed. The mean average is then reported as the Nominal Mass and is expressed as grams per square metre (gsm).
Test Standards
Thickness
Scope
This part of EN ISO 9863 specifies a method for the determination of the thickness of geosynthetics at specified pressures and defines the pressure at which the nominal thickness is determined.
The test results are intended for identification purposes and for use in technical data sheets and/or as part of other test methods, e.g. tests of hydraulic properties.
The method is applicable to all geosynthetics.
Note 1: Normally, the thickness of geosynthetics is determined by measuring one layer of the products. When two or more layers are used on top of each other in a design, the test may be made in accordance with this standard with the agreed number of layers instead of one.
Note 2 When testing structured geosynthetics, care should be taken to ensure that the results are meaningful for the particular products.
Test Method
Test specimens are taken from various locations across the full width of the sample geotextile. The specimens are placed on a flat planar surface. A circular presser foot is lowered onto the geotextile for a pre-determined time. The nominal thickness of each geotextile is then recorded and the sum total averaged to determine the mean thickness under the prescribed pressure.
Test Standards
SANS 10221
ASTM D 5199
ISO 9863
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Tensile Strength
Scope
This International Standard describes an index test method for the determination of the tensile properties of geosynthetics, using a wide-width strip. The method is applicable to most geosynthetics, including woven geotextiles, nonwoven geotextiles, geocomposites, knitted geotextiles and felts. The method is also applicable to geogrids and similar open-structure geotextiles, but specimen dimensions may need to be altered. This test is not applicable to polymeric or bituminous geosynthetic barriers, but is applicable to clay geosynthetic barriers.
The tensile test method covers the measurement of load elongation characteristics and includes procedures for the calculation of secant stiffness, maximum load per unit width and strain at maximum load. Singular points on the load-extension curve are also indicated.
Procedures for measuring the tensile properties of both conditioned and wet specimens are included in this International Standard.
Test Method
Wide width test specimens are taken from across the width of a sample roll. The test specimens are gripped in either flat plates or split spool capstan clamps depending on the nature of the geosynthetic material. The required strain rate is applied to the specimen and the maximum force recorded.
Test Standards
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Elongation
Scope
Elongation is a measure of the stretch inherent in a geotextile when exposed to a load.
Test Method
The elongation is determined from the point of slack take-up until the point of rupture.
NOTE: Uses external extensometers or movement of crosshead.
Test Standards
SANS 10221
ASTM D 4595
ISO 10319
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Trapezoidal Tear
Scope
This is an index test used to measure the force required to continue or propagate a tear in woven or nonwoven geotextiles by the trapezoid method. The trapezoidal test is useful for quality control and acceptance testing but is unsuitable for design applications. This test method is suitable for most geotextiles including woven fabrics, nonwoven fabrics, layered fabrics, knitted fabrics and felts that are used for geotextile applications.
Test Method
An isosceles triangle is marked on a 200mm x 76mm rectangular test specimen. The 2 non-parallel sides are gripped in parallel flat faced clamps and the required strain rate applied. A continuous tear is propagated in this way and the maximum force recorded.
Test Standards
ASTM D4533 speed
AS 3706 speed
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Grab tensile
Scope
- This test method covers the measurement of tensile properties of geotextiles using a wide-width strip specimen tensile method. This test method is applicable to most geotextiles including woven fabrics, nonwoven fabrics, layered fabrics, knit fabrics, and felts that are used for geotextile application.
- This test method covers the measurement of tensile strength and elongation of geotextiles and includes directions for the calculation of initial modulus, offset modulus, secant modulus, and breaking toughness.
- Procedures for measuring the tensile properties of both conditioned and wet geotextiles by the wide-width strip method are included.
- The basic distinction between this test method and other test methods for measuring strip tensile properties is the width of the specimen. This width, by contrast, is greater than the length of the specimen. Some fabrics used in geotextile applications have a tendency to contract (neck down) under a force in the gage length area. The greater width of the specimen specified in this test method minimizes the contraction effect of those fabrics and provides a closer relationship to expected geotextile behaviour in the field and a standard comparison.
- This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.
Test Method
A rectangular geotextile specimen is positioned in a tensile test machine and secured using 25mm x 50mm grips. The prescribed strain rate is applied until rupture occurs. The maximum force is recorded as the Grab tensile strength.
Test Standards
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Puncture (CBR)
Scope
- This test method is an index test used to measure the force required to puncture a geotextile and geotextile-related products. The relatively large size of the plunger provides a multidirectional force on the geotextile.
- The values stated in SI units are to be regarded as the standard. The values given in parentheses are for information only.
- This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.
Test Method
The test specimen is clamped, without tension between 2 ring clamps. The clamp is then secured to a suitable compression type machine. A polished steel probe of 50mm diameter is then forced through the centre of the unsupported area of the specimen at a fixed speed until the geotextile ruptures. The rupture force is then recorded.
Test Standards
SANS 10221
ASTM D 6241
ISO 12236
AS 3706
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Dart (Drop Cone)
Scope
This International Standard specifies a method to determine the resistance of geosynthetics to penetration by a steel cone dropped from a fixed height.
The degree of penetration is an indication of the behaviour of the geosynthetic when sharp stones are dropped on its surface.
The method is generally applicable to geosynthetics. However, the validity of this test for some types of products should be considered carefully, as the test principle may not be applicable.
Test Method
A circular geotextile specimen is clamped between 2 ring clamps and subjected to a stainless steel cone being dropped onto its surface from a fixed height. The cone is designed such that it has a 45° angle with a total impact mass of 1000±5 g.
Test Standards
ISO 13433
AS 3706.5
View this test in action below.