This standard specifies the method for measuring the tensile properties of geotextiles and related products using wide strip samples. This standard applies to woven geotextiles, non-woven geotextiles, composite geotextiles, knitted geotextiles and felt mats, but not to geocells. GB/T 15788-1995 Geotextile tensile test method Wide strip method GB/T15788-1995 standard download decompression password: www.bzxz.net

National Standard of the People's Republic of China
Geotextiles-Wide-width tensile test method
Geotextiles-Wide-width tensile testGB/T 15788—1995
This standard is equivalent to the international standard ISO10319-1993 "Geotextiles-Wide-width tensile test". 1 Subject content and scope of application
This standard specifies the method for determining the tensile properties of geotextiles and related products using wide-strip samples. This standard is applicable to woven geotextiles, non-woven geotextiles, composite geotextiles, knitted geotextiles and felt mats, but not to geogrids. 2 Reference standards
GB6529 Standard atmospheres for conditioning and testing textiles GB13760 Sampling and specimen preparation for geotextiles 3 Definitions
3.1 Clamping length
The initial distance between the clamps in the tensile test is generally 100mm. 3.2 Maximum load
The maximum tensile force obtained in the test (kN). 3.3 Elongation
The ratio of the increase in specimen length to the clamping length in the tensile test, expressed as a percentage. 3.4 Elongation at maximum load
The elongation corresponding to the maximum load (%).
3.5 Secant modulus
The ratio of the change in load per unit width of the specimen (kN/m) to the specific elongation value (as shown in Figure 2, the secant modulus at point B is BC/CA). 3.6 Tensile strength
The maximum resistance to deformation per unit width generated when the specimen is stretched to break by an external force (kN/m). 4 Principle
The specimen is clamped across its entire width in the grip of the tensile tester and stretched until it breaks. The tensile properties of the specimen are recorded and calculated from the recording device of the tester. For all geotextiles and related products, the elongation rate is fixed at 20 mm/min. This method uses a 200 mm wide and 100 mm long specimen. The specimen width is greater than the length, which is the fundamental difference between this method and other methods for determining the tensile properties of fabrics. This is because some geotextiles have a tendency to shrink ("neck") within the clamping length range under load. The wide specimen reduces the shrinkage effect of these geotextiles and can provide an indicator that is more related to the expected field performance characteristics of the geotextile. 5 Equipment and Materials
5.1 Tensile Testing Machine
Approved by the State Administration of Technical Supervision on December 8, 1995 and implemented on May 1, 1996
GB/T 15788—1995
Constant rate of extension (CRE) tensile testing machine should have an elongation rate of 20 mm/min. The clamp should be wide enough to clamp the entire width of the specimen and can appropriately limit the slippage or damage of the specimen. For most materials, compression clamps should be used. The compression serrated wedge block clamp shown in Figure 1 is recommended. For high-strength woven geotextiles, other clamps that can limit the slippage and rupture of the specimen at the jaws can also be used. tI cloth
Figure 1 Sawtooth wedge block clamp
5.2 Distilled water, for wet specimens. bzxZ.net
5.3. Non-ionic neutral wetting agent, for wet specimens. 6 Specimens
6.1 Number of specimens
Cut at least 5 specimens in the longitudinal and transverse directions of the sample. 6.2 Selection of specimens
Select specimens in accordance with GB13760.
6.3 Size of specimens
6.3.1 Cut each specimen to a final width of 200mm. The specimen length should be sufficient to ensure that the clamp gauge is 100mm, and its length direction is parallel to the direction of the maximum load to be measured. To control slippage, two marking lines with an interval of 100mm can be drawn perpendicular to the length direction of the specimen across the entire width of the specimen to indicate the gauge length.
6.3.2 For woven geotextiles, cut each specimen to 220 mm wide and then remove approximately equal numbers of edges from both sides of the specimen to obtain a specimen width of 200 mm. This helps maintain the integrity of the specimen during the test. When the integrity of the specimen is not affected, it can be cut directly to the final width.
6.3.3 For knitted fabrics, composite geotextiles or other geotextiles, cutting the specimens with a knife may affect the fabric structure. In this case, hot cutting is allowed, but it should be stated in the test report.
6.3.4 When both the wet maximum load and the dry maximum load are required, the length of the cut specimen should be at least twice the normal requirement. Each specimen is numbered and folded in half and cut into two pieces, one for determining the dry maximum load and the other for determining the wet maximum load. Each part of the specimen should be marked with the specimen number. This ensures that each pair of breaking tests is performed on specimens containing the same yarn. Note: For geotextiles with excessive shrinkage after setting, the specimen used to measure wet tensile properties must be slightly longer than the specimen used to measure dry tensile properties, but the width of the specimen should not be changed.
7 Humidity conditioning
7.1 The standard atmosphere for humidity conditioning and testing shall comply with the requirements of the third-level atmospheric conditions specified in GB6529: temperature 20±2℃ and relative humidity 65%±5%.
GB/T.15788—1995
7.2 The specimen shall be humidified under standard atmospheric conditions for at least 24 hours; or when the mass change of the specimen in two consecutive weighings at least 2 hours apart does not exceed 0.25% of the mass of the specimen, the specimen can be considered to have been humidified. Note: If it can be shown that the test results are not affected by relative humidity, humidity conditioning and testing may not be carried out under the specified relative humidity conditions. 7.3 The specimen used for wet testing shall be immersed in distilled water at a temperature of 20±2℃. The soaking time should be sufficient to completely wet the specimen or at least 24 h so that there is no significant difference in the maximum load and elongation after further soaking. In order to completely wet the specimen, not more than 0.05% of a non-ionic neutral wetting agent can also be added to the water. 8 Test Procedure
8.1 Setting up the tensile testing machine
Before stretching, adjust the clamp spacing to 100 ± 3 mm. Select the load range so that the tensile force is between 30% and 90% of the full load range. Set the tensile rate of the testing machine to 20 mm/min. 8.2 Clamping the specimen
Clamp the specimen centrally in the clamp. Note that the length of the specimen for longitudinal and transverse tests should be parallel to the direction of the tensile force. Two pre-marked lines (see 6.3.1) spaced 100 mm apart and perpendicular to the length of the specimen should coincide as closely as possible with the edges of the upper and lower clamp jaws.
The test of the conditioned specimen is carried out under the atmospheric conditions specified in Chapter 7. For wet specimens, the test is to be carried out within 3 min after the specimen is removed from the water.
8.3 Measurement of tensile properties
Start the testing machine and continue running until the specimen breaks. Stop the machine and return to the initial gauge position. Record the maximum load to three significant figures and the elongation to 0.1%. The elongation of the specimen under any given load is measured by a suitable automatic recording device. If the specimen slips in the clamp or jaws during the test, or if the specimen breaks within 5 mm of the jaws and the result is less than 50% of the average of all other results, the test result shall be rejected and another specimen shall be tested. Note: The rejection of broken results shall be based on the observation of the specimen during the test and on the variability of the geotextile itself. Results that are only due to rupture near the jaws due to randomly distributed weak points should not be excluded. If the specimen slips in the fixture or if more than one quarter of the specimens break within 5 mm of the edge of the fixture jaws, the following measures may be taken: ① Add padding to the fixture; ② Coat the specimen clamped in the jaws; ③ Improve the surface of the fixture jaws. Whatever modification is adopted, the method of modification should be stated in the test report. 9 Calculation
9.1 Tensile strength
The tensile strength is directly obtained from formula (1):
W——specimen width, m.
9.2 Elongation at maximum load
Determine the elongation at maximum load (%) from the load-elongation curve (see Figure 2). 1
：127
9.3 Secant modulus
Load.kN
GB/T 15788
Figure 2 Typical load-elongation curve
Determine the load at a specific elongation (point B in Figure 2), and then use formula (2) to calculate the secant modulus: Jaee
F×100
Where: Jsec--secant modulus at a specific elongation c, kN/m; F---measured load at elongation c, kN; c-corresponding elongation, %,
w-sample width, m.
9.4 Mean values ​​and coefficients of variation
Elongation, %
(2)
Calculate the mean values ​​and coefficients of variation of the tensile strength, elongation at maximum load and secant modulus for the longitudinal and transverse groups of specimens, respectively. 10 Test report
The test report shall include the following:
Code and year of this standard,
Name and code of the specimens tested,
Mean tensile strength and coefficient of variation in the longitudinal and transverse directions; Mean elongation at maximum load and coefficient of variation in the longitudinal and transverse directions; If necessary, the mean secant modulus and coefficient of variation corresponding to 2%, 5% and 10% elongation, respectively; The condition of the specimens, whether dry or wet, and the number of specimens tested in each direction; Type of testing machine and test range;
Type of fixture, including fixture dimensions and jaw surface type, initial fixture gauge, and, if necessary, a typical load-elongation curve; Details of any deviations from the provisions of this standard.
Additional Notes:
This standard is proposed by China National Textile and Apparel Council.
GB/T15788--1995
This standard is under the jurisdiction of the Standardization Research Institute of China National Textile and Apparel Council. This standard was drafted by the Standardization Research Institute of China National Textile and Apparel Council, Shanghai Textile Science Research Institute and China Textile University. The main drafters of this standard are Guan Zeqing, Chen Wei, Wei Hong, Mai Jiajun, Zhou Yefang and Wang Ying. 129
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