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Testing Methods for Geotextiles    (Educational Research)

     

Education

  The Educational information in this section has been graciously donated to the Apparel Search Company by Professor Kermit Duckett.
 

 

Praveen Jana, Rammohan Nanjundappa & Hong Yin

INTRODUCTION

A geotextile is (as given in the terminology used for geosynthetics in ASTM Standard D 4439-87) "any permeable textile material used with foundation, soil, rock, earth, or any other geotechnical engineering material, as an integral part of manmade product, structure or system."

The various standards for testing the geotextiles are listed in Annual Book of ASTM Standards, volume 4.08 (geosynthetics) and volume 4.09 (geotextiles and geomembranes). A few important test methods are described in this paper and the rest are listed with the test number at the end of this paper.

TEST METHODS

1. Standard Test Method for Deterioration of Geotextiles from Exposure to Ultraviolet Light and Water (Xenon-Arc Type Apparatus) : ASTM Test Method D 4355-84.
This method determines the deterioration in tensile strength of geotextiles by exposure to ultraviolet light and water using an apparatus that employs a xenon-arc light source. This procedure compares five specimens (2 x 6 in.) of geotextiles in MD and CD under a standard set of conditions of humidity and temperature for three exposure times (0, 150, 300 and 500 hours), against unexposed specimens. The exposure consists of 120 min of light only, followed by 18 min or water spray and light. After being exposed to UV light, the specimens are subjected to cut or ravel strip tensile test. These results are compared to test results of unexposed specimens to give an indication of the deterioration in tensile strength of geotextiles by exposure to ultraviolet light and water. This method is not recommended for acceptance testing of commercial shipments.

2. Standard Test Method for Effects of Temperature on Stability of Geotextiles : ASTM Test Method D 4594-86.
This method measures the effects of temperature on the tensile strength and elongation properties of geotextiles. In this test, specimens of geotextile are conditioned at selected temperatures (typical of temperature that geotextiles are exposed to in actual usage) in an environmental chamber (capable of maintaining a temperature range from -40 to +100
C and able to regulate the test temperature within
2
C). While the selected temperatures are being maintained, two-inch cut or ravel strip tensile tests of five specimens (in MD and CD) are carried out. The same tests are carried out as control under the standard laboratory test conditions. Changes in strength and elongation as a result of exposure to different temperatures are thus determined. This test method is capable of evaluating the effects of temperature on geotextiles made from different polymers, different manufacturing processes, or both. This method can be used to test geotextiles made from nonwoven, woven, and composite fabrics (up to fabric strength of less than 1000 lb/in. width). But it cannot be used for knitted fabrics. This method is not recommended for testing of commercial shipments.

3. Standard Test Method for Tensile Properties of Geotexitles by Wide-width Strip Method : ASTM Test Method D 4595-86.
This method measures the tensile properties of geotextiles using a wide-width (8 x 8 in.) strip specimen tensile method. The width (which is greater than the length) of the specimen is the basic distinction between this method and other methods determining tensile properties. The greater width is to minimized the tendency of geotextiles to contract and also to provide a closer relationship to the expected behavior of geotextiles in actual usage. The dimensions of jaw faces need to be wider than 200 mm (8 in.) and the length needs to be a minimum of 50 mm (2 in.) in the direction of the applied force.

This procedure provides parameters for reinforcement applications. This method can be used for acceptance testing of commercial shipments.

4. Standard Test Method for Breaking Load and Elongation of Geotextiles (Grab Method): ASTM Test Method D 4632-86.
This method determines the breaking load (grab) and elongation (grab) of geotextiles using the grab method (only a part of the width of the specimen is gripped by the clamps). A continually increasing load is applied longitudinally to the test specimen until it ruptures. This method can be used if the effective strength of the fabric in use (that is, the strength of the material in a specific width together with the additional strength contributed by adjacent material) needs to be determined. Rectangular specimens (4 x 8 in.) must be cut in taking care that the longer dimension is parallel to the machine direction or cross machine direction depending on whether it is a MD or CD sample, respectively.

This method can be used for acceptance testing of commercial shipments. This procedure cannot be used for knitted geotextile materials.

5. Standard Test Method for Determining Apparent Opening Size of a Geotextile: ASTM Test Method D 4751-87.
Apparent Opening Size (AOS) for a geotextile is a property "which indicates the approximate largest particle that would effectively pass through the geotextile."

This method determines the AOS of a geotextile by sieving glass beads through a geotextile. A specimen is placed by sieve frame with sized glass beads on top of it. The frame with the geotextile is shaken laterally so that the jarring motion induces the beads to pass through the geotextile test specimen. This procedure is repeated with varius size glass beads on the same test specimen until the AOS of the geotextile is determined.

This method is useful because a geotextile and the adjacent soil need to be compatible. The apparent opening size (AOS) of a geotextile is a reflection of the approximate largest opening dimension testing of commercial shipments

6. Standard Test Method for Index Puncture Resistance of Geotextiles, Geomembranes, and Related Products: ASTM Test Method D 4833 - 88
Geomembranes are "very low permeability synthetic membrane liners or barriers used with any geotechnical engineering related material so as to control fluid migration in a man-made project, structure, or system.

Puncture resistance is "a test procedure which may contain a known bias but which may be used to establish an order for a set of specimens with respect to the property of interest."

The Index Puncture Resistance test is "a test procedure which may contain a known bias but which may be used to establish an order of a set of specimens with respect to the property of interest."

A test specimen (minimum specimen diameter is 100 mm) is clamped between circular plates of a ring clamp attachment secured in a tensile testing machine. A solid steel rod attached to the load indicator exerts force against the center of the specimen until it ruptures. The maximum force recorded is the puncture resistance of the specimen.

This method can be used for acceptance testing of commercial shipments.

7. Standard Test Method for Abrasion Resistance of Geotextiles (Sand Paper/Sliding Block Method): ASTM Test Method D 4833 - 88. This test method determines the resistance of geotextiles to abrasion using an abrasion tester.

In this procedure, an abradant (with specified surface characteristics) is used to rub a test specimen (five specimens in MD and CD, 3 x 8
1/16 in.) that is mounted on a stationary surface. Under controlled conditions of pressure and abrasive action, the abradant is rubbed on a horizontal axis using a uniaxial motion. Resistance to abrasions is expressed as a percentage of original strength before abrading.

This method can be used for acceptance testing of commercial shipments, but cannot be used for geomembranes and grids.

Following are the listed test methods in the Annual Book of ASTM Standards: * the number in the brackets indicate the Volume number

 

GEOSYNTHETICS

 

  • Apparent opening size - geotextiles, by sieving glass beads, test, - D 4751 (04.09)
  • Biological clogging - geotextile or soil/geotextile filters, test, - D 1987 (04.09)
  • Carbon black dispersion - polyolefin (PO) geosynthetics, microscopic evaluation, test, D 5596 (04.09)
  • Coefficient of friction-geosynthetic/soil combinations, by direct shear test, D 5321 (04.09)
  • Constant head hydraulic transmissivity- geotextiles/related products, in-plane flow, test, D 4716 (04.09)
  • Design of liner system for containment of wastes, guide, D1973 (11.04)
  • Filtering efficiency/flow rate of a geotextile for silt fence application, using site specific soil, test, D 5141 (04.09)
  • Geosynthetic durability-experimental evaluation, selecting test methods, guide, D 5819 (04.09)
  • Geosynthetics-field immersion testing, practice, D 5496 (04.09)
  • Geosynthetics-sampling, practice, D 4354 (04.09)
  • Geosynthetics-unconfined tension creep behavior at constant temperature subjected to sustained tensile loading, test, D 5262 (04.09)
  • Geosynthetics, terminology, D 4439 (04.09)
  • Geotextiles-mass per unit area, test, D 5261(04.09)
  • Geotextiles-deterioration from ultraviolet light exposure/water, by xenon-arc apparatus, test, D 4355 (04.09)
  • Geotextiles-mass per unit area, test, D 5261 (04.09)
  • Geotextile stability-effect of temperature, test, D 4594 (04.09)
  • Grab breaking load/elongation-geotextiles, test, D 4632 (04.09)
  • Hydraulic conductivity ratio (HCR)-soil (compacted/ undisturbed) geotextile systems, test, D 5567 (04.09)
  • Identification/storage/handling-geotextiles, guide, D 4873 (04.09)
  • Immersion procedures (laboratory)-evaluating chemical resistance of geosynthetics to liquids, practice, D 5322 (04.09)
  • Index puncture resistance-geotextiles/geomembranes/related products, test, D 4833 (04.09)
  • Large scale hydrostatic puncture testing-geosynthetics, test D 5514 (04.09)
  • Multi-axial tension test-geosynthetics, test, D 5617 (04.09)
  • Nominal thickness-geotextiles/geomembranes, test D 5199 (04.09)
  • Obtaining geosynthetic samples-from test section, for assessment of installation damage, practice, D 5818 (04.09)
  • Seam strength-sewn geotextiles, test, D4884 (04.09)
  • Soil-geotextile system clogging potential (under unidirectional flow), by gradient ratio, test, D 5101 (04.09)
  • Specification conformance-geosynthetics, practice, D4759 (04.09)
  • Subsurface liquid levels in a borehole/monitoring (observation) well, test, D 4750 (04.08)
  • Tensile properties-geotextiles, by wide-width strip method, test, D 4595 (04.09)
  • Trapezoid tearing strength-geotextiles, test, D 4533 (04.09)
  • Water permeability-geotextiles, by permittivity method, test, D 4491 (04.09)

GEOTEXTILES

  • Permittivity-geotextiles under load, test, D 5493 (04.09)
  • Pyramid puncrture resistance-unprotected/protected geomembranes, test, D 5494 (04.09)

GEOMEMBRANES

  • Air-oven aging of polyolefin (PO) geomembranes, practice, D 5721 (04.09)
  • Chemcial resistance-geomembranes to liquids, practice, D 5747 (04.09)
  • Chemical resistance-geomembranes to liquids, selecting test, practice, D 5747 (04.09)
  • Geomembrane seam evaluation, by vacuum chamber, practice, D 5641 (04.09)
  • Geomembranes (polyethylene)-2% secant modulus (using d 638, v 08.01), practice, D 5323 (04.09)
  • Index puncture resistance-geotextiles/geomembranes/related products, test, D 4833 (04.09)
  • Integrity of factory seams used in joining flexible sheet geomembranes, summary of test procedure, practice D 4545 (04.09)
  • Integirity of field seams (used in joining flexible polmeric sheet geomembranes), selecting test procedures, practice, D 4437 (04.09)
  • Nominal thickness-geotextiles/geomembranes, test, D 5199 (04.09)
  • Performance strength of synthetic geomembranes, by wide strip tensile method, test, D 4885 (04.09)
  • Polyolefin (PO) geomembranes-stress-crack resistance, using notched constant tensile load, test, D 5397 (04.09)
  • Pressurized air channel evaluation-dual seamed geomembranes, practice, D 5820 (04.09)
  • Pyramid puncture resistance-unprotected/protected geomembranes, test D 5494 (04.09).

 

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