GB/T 20394-2019Gymnastic artificial turf (English PDF)

3.1 Gymnastic artificial turf

The artificial synthesis paving materials formed by mechanical tufting, weaving, fixing synthetic fiber similar to the appearance of natural grass on […]

3.9 Tuft

The smallest tufted unit of gymnastic artificial turf.

3.10 Vertical rate

The number of tufts per meter of gymnastic artificial turf in the longitudinal direction.

3.11 Horizontal rate

The number of rows of artificial grass per meter horizontally.

3.12 Dtex

The mass (g) of 10000 m long artificial grass filament.

3.13 Tuft density

The number of tufts per square meter of gymnastic artificial turf.

4.1 Product classification

According to the shape of artificial grass filament for sports, it is divided into tape yarn, monofilament, curly.

4.2 Product specifications

The specification of gymnastic artificial turf shall include at least:

a) Longitudinal rate (tufts/m);

b) Horizontal rate (row/m);

c) Pile height (mm);

d) Dtex (g/10000 m).

6.2 Standard environment for specimen conditioning and test

It is performed according to Chapter 4 and Chapter 5 of GB/T 2918-1998; the test temperature is (23 ± 2) °C, the relative humidity is (50 ± 10)%, the specimen state conditioning time is 4 h.

6.3 Appearance quality

Check visually in natural light.

6.4 Tuft density

6.4.1 Specimen preparation

Select the test area on the backing of the gymnastic artificial turf. The longitudinal and cross section sampling length shall not be less than 1100 mm.

6.4.2 Test procedure

6.4.2.1 Vertical rate

Count the number of longitudinal tufts to reach the nominal tuft density. Use a steel ruler which has an accuracy of 1 mm to measure the corresponding length L; it shall be measured at three different positions.

6.4.2.2 Horizontal density

Count the number of rows of tufts to reach the nominal row number of tuft. Use a steel ruler which has an accuracy of 1 mm to measure the corresponding length L; it shall be measured at three different positions.

6.4.2.3 Calculation

The arithmetic mean value rho of the vertical rate and horizontal rate of tuft is calculated according to formula (1):

Where:

rho - The arithmetic mean of the vertical rate and horizontal rate; the unit is tuft per meter (tuft/m) or row per meter (row/m);

N - Nominal vertical rate or horizontal rate of tuft, in units of tuft per meter (tuft/m) or rows per meter (rows/m);

6.9 Alkali resistance test

Take a specimen of 50 mm × 50 mm gymnastic artificial turf. Soak it in a 30% sodium carbonate solution with a concentration of 20% for 48 hours. Take out the specimen. Use distilled water to rinse it. Compare it with the unsoaked specimen through visual inspection in natural light.

6.10 Grass filament breaking force

6.10.1 Specimen preparation

Randomly select 5 tufts of grass filament in different rows. Select one grass filament from each tuft for the tensile test of the grass filament.

6.10.2 Test procedure

Carry out the test on a tensile testing machine which has an accuracy of 1 N or more; the test speed is (250 ± 25) mm/min. Record the value of the tensile force when the specimen breaks. Test 5 specimens. Take the arithmetic mean of the results, accurate to 1 N.

Note: If the difference between the test result of a specimen and the average value exceeds 30%, the test of the specimen is invalid and the test shall be repeated.

6.11 Abrasion resistance of grass filament

The retention rate of grass filament's abrasion resistance shall be carried out in accordance with the method specified in Appendix B.

6.12 Aging performance

6.12.1 Test conditions

After 168 h aging test in accordance with GB/T 8430-1998, carry out the test of the retention rate of grass filament's breaking force and the color fastness to weathering.

6.12.2 Retention rate of grass filament's breaking force after aging test

6.12.2.1 The sampling and test procedures shall be carried out in accordance with 6.10.

6.12.2.2 The retention rate µ of the breaking force of the grass filament is calculated according to formula (8): […]

6.18 Flame retardancy

Intercept 3 pieces of 230 mm × 230 mm specimens of gymnastic artificial grass.

Fill them with appropriate amount of quartz sand and rubber particles (the volume ratio of quartz sand and rubber particles is 1:1); ensure that the height of the exposed grass filaments after filling is 10 mm. Perform test according to Chapter 6 of GB/T 11049-2008. Measure the maximum distance from the center of each specimen to the damaged edge. The result is represented by the maximum value of the three specimens.

7.1 Exit-factory inspection

7.1.1 The product can only be exit-factory after being qualified by the manufacturer.

7.1.2 The exit-factory inspection items shall be inspected in accordance with 5.1 appearance and Table 1 product specifications and dimensions.

7.2 Type test

7.2.1 Type test shall be carried out when one of the following situations occurs

a) When the new product is finalized and appraised;

b) When production is discontinued for six months;

c) When there are major changes in raw materials and production processes that may affect product performance;

d) During normal production, once a year;

e) When the quality department supervises the spot check.

7.2.2 The type inspection shall be carried out by taking samples from the products that have passed the exit-factory inspection.

7.2.3 Type inspection items shall be carried out in accordance with the requirements of Chapter 5.

7.3 Sampling

Randomly take samples in batches. If the batch is within 30 rolls (including 30 rolls), take 1 roll; if the batch is more than 30 rolls, take 2 rolls.

7.4 Judgment rules

A.1 Scope

This method is suitable for sampling and intercepting test samples of gymnastic artificial turf.

A.2 Sampling requirements

Select a batch of products as specimens.

A.3 Procedure

A.3.1 Select samples

Samples shall be selected along the entire width of the product, but do not include any parts that are normally cut off during the production process.

A.3.2 Intercept samples

A.3.2.1 The specimen can be square or rectangular. The truncated edge shall be parallel and perpendicular to the longitudinal and transverse edges of the sample. For the paved site, it shall be parallel or perpendicular to the edge of the site.

A.3.2.2 The cut specimen shall be at least 100 mm away from the edge.

A.3.2.3 If more than one specimen needs to be intercepted on the sample, these specimens shall be evenly and dispersedly arranged, as far as possible from the available sampling area, meanwhile ensure (as the structure allowed) each specimen is distributed in different longitudinal and transverse positions.

A.3.2.4 When cutting specimens on the sample, they shall be widely distributed in the entire available sampling area; when cutting multiple specimens, they shall be evenly distributed on the sample.

A.3.2.5 If it needs to do several tests on the sample, the specimens taken shall be distributed as far as possible on the sample, for example, using a random number table to indicate the position on the network.

A.3.2.6 When sampling on a paved site, it shall take full consideration to sampling in different areas; the relevant parties shall negotiate and decide.

B.1 Scope

This method is suitable for the abrasion resistance test of grass filament in the laboratory.

B.2 Principle

The specimen is worn under the action of a pair of grinding wheels; then the overall damage is measured.

B.3 Test equipment

B.3.1 Rotating platform, double-head grinding machine.

B.3.2 A pair of grinding wheels with newly replaced abrasion plates, with 500 g weight placed on each wheel.

B.3.3 Balance, with an accuracy of ±0.01 g.

B.4 Specimen

Take 3 unused specimens which have a length of at least 100 mm and a width of at least 100 mm; trim the grass filament with a pile height of more than 15 mm to 15 mm; those which has a pile height of less than 15 mm is tested directly.

Or otherwise take one piece of used specimen which has a length of at least 100 mm and a width of at least 100 mm; trim the grass filament with a pile height of more than 15 mm to 15 mm; those which has a pile height of less than 15 mm is tested directly.

B.5 Test procedure

Use a balance to weigh the weight of specimen. Place the specimen on the corresponding position in the abrasion machine. Lower the grinding wheel to place it on the specimen. Turn on the machine. Shutdown the machine after 1000 rotations. Remove the loose debris on the specimen. Use the balance to re-weigh the weight of specimen.

Repeat 5 times, to make the specimen subjected to 5000 rotations in total.

Replace the grinding stone pieces on the grinding wheel after every 1000 rotations. […]