<p><p><strong>Reference(s):</strong></p><p><em>Holtz et al. (2008)</em></p><p><strong>Method Summary</strong></p><p>The most important mechanical properties are the tensile strength and modulus of the reinforcement, seam strength, soil-geosynthetic friction, and system creep resistance. The tensile strength and modulus values should preferably be determined by an in-soil tensile test. In-situ properties of many geosynthetics are markedly different than those from tests conducted in air. However, in-soil tests are not yet routine or standardized, and the proposed test methods need additional work. The practical alternative is to conservatively use a representative (i.e., wide strip) tensile test as a measure of the in-soil strength. Therefore, strength and modulus are based on testing of wide specimens. ASTM D 4595, <em>Standard Test Method for Tensile Properties of Geotextiles by the Wide-Width Strip Method</em>, is used for geotextiles, and ASTM D 6637, <em>Standard Test Method for Determining Tensile Properties of Geogrids by the Single or Multi-Rib Tensile Method, </em>with Method B or C (wide specimen) is used for geogrids. These test standards permit definition of tensile modulus in terms of: (i) initial tensile modulus; (ii) offset tensile modulus; or (iii) secant tensile modulus. Furthermore, the secant modulus may be defined between any two strain points. Geosynthetic modulus for design of embankments should be determined using a secant modulus, defined with the zero strain point and design strain limit (i.e., 2 to 10%) point. For soil-geosynthetic friction values, either direct shear or pullout tests should be utilized.</p><p>Table 2 is intended to provide a list of parameters which could be measured and the specific property to be determined from the test. Each project should define the testing required as part of the Quality Control program and the testing to be completed as part of the Quality Assurance.</p><p><strong>Accuracy and Precision</strong></p><p>Geotextile testing has been standardized by ASTM procedures.</p><p><strong>Adequacy of Coverage</strong></p><p>The specifications typically indicate the frequency of testing.</p><p><strong>Implementation Requirements </strong></p><p>Geotextile testing is generally completed by the product manufacturer. Most transportation departments are not set up to complete the tests, and samples taken during field QC/QA activities must be sent to an off-site laboratory for testing.</p><p><strong>General Comments</strong></p><p>Geotextile testing is an essential part of monitoring materials as part of construction of embankments over weak soils.<br><h3><strong>Table 2. Geosynthetic testing summary (after Holtz et al 2008).</strong></h3><table class='tablepress' id='tablepress-1972'><thead><th><center>Criteria and Parameter </th><th><center>Property</th><th><center>Test Method</th></thead><tbody><tr><td >Design Requirements:
a. Mechanical
Tensile strength
Tensile modulus
Seam strength
Tension creep
Soil-geosynthetic friction
b. Hydraulic
Piping resistance
Permeability
</td><td >
Wide width strength
Wide width strength
Wide width strength
Creep Resistance
Soil-geosynthetic friction angle
Apparent opening size
Permeability
</td><td >ASTM D 45951
ASTM D 4632
ASTM D 45952
ASTM D 4632
ASTM D 4884
ASTM D 5262
ASTM D 5321
ASTM D 4751
ASTM D 4491
</td></tr><tr><td >Constructability Requirements:
Tensile strength
Puncture resistance
Tear resistance
</td><td >Grab strength
Puncture resistance
Trapezoidal tear
</td><td >
ASTM D 4833
ASTM D 4533
</td></tr><tr><td >Longevity:
UV stability (if exposed)
Soil compatibility
</td><td >UV Stability
Chemical; Biological
</td><td >ASTM D 4355
ASTM D 6389
</td></tr></tbody></table><br><p class="disclaimer"><sup>1</sup> For geotextile soil reinforcement</p><p class="disclaimer"><sup>2</sup> For geogrid soil reinforcement</p></p></p>