Artificial Turf Backing Breakage Force Testing: Methods, Standards, and Applications

Artificial turf backing breakage force testing is a critical quality control procedure that measures the tensile strength of the primary and secondary backing layers that anchor synthetic turf fibers. By evaluating breaking force and elongation in both machine and cross-machine directions, manufacturers, third-party laboratories, and buyers can verify product durability, compliance with international textile standards, and long-term performance under installation and playing loads.

Technical Overview

Artificial turf is a multi-layer engineered product consisting of synthetic fibers (typically polyethylene or polypropylene) tufted into a primary backing cloth and locked in place by a secondary coating of latex or polyurethane. The backing cloth, usually a woven or nonwoven polypropylene fabric, serves as the structural skeleton of the entire turf system: it holds the tufted fibers in position, resists the mechanical stresses of rolling, transport, installation, and seam joining, and maintains dimensional stability throughout the service life of the field.

Breakage force testing, also referred to as tensile breaking strength testing, quantifies the maximum force the backing material can withstand before failure when stretched to rupture. This test is essential because backing failure is one of the most common and costly modes of artificial turf degradation. A backing with insufficient breaking strength may split during installation, tear at seam lines, delaminate under cleat traction, or lose fiber retention prematurely. Systematic testing of backing breakage force therefore supports incoming material inspection, production quality control, product certification against specifications from bodies such as FIFA and World Rugby, and dispute resolution between suppliers and purchasers.

Testing Samples

Primary Backing Fabric

The primary backing is the fabric into which the turf fibers are tufted. Samples are usually collected before coating to verify the intrinsic strength of the base textile. Typical primary backings are woven polypropylene or polyethylene fabrics, sometimes multi-layered constructions combining woven and nonwoven components. Specimens are cut in both the machine direction (MD, parallel to fiber tufting rows) and the cross-machine direction (CD, perpendicular to tufting rows), because woven backings exhibit distinctly different strength characteristics along the warp and weft.

Coated Finished Backing

Finished turf samples include the applied latex or polyurethane coating, which significantly influences overall breaking force. Testing the coated backing reflects the real-world performance of the delivered product. Specimens must be cut from positions free of visible defects, away from seam edges, and with fibers trimmed or removed if required by the applicable standard so that the measured force corresponds to the backing structure rather than the fiber bundle.

Sample Preparation and Conditioning

Specimens are generally prepared as rectangular strips of adequate length with a working width defined by the test method. Raveled strip specimens are prepared by removing edge yarns until the effective nominal width, commonly 50 mm, is achieved, ensuring that force is carried by a precise number of yarns. All specimens must be conditioned in a standard laboratory atmosphere before testing, typically 20 ± 2 °C and 65 ± 4 % relative humidity for a minimum of 24 hours, or until moisture equilibrium is reached, so that results are comparable between laboratories.

Testing Items

A comprehensive backing breakage force evaluation typically covers the following measured and derived parameters:

• Maximum breaking force (N) in the machine direction
• Maximum breaking force (N) in the cross-machine direction
• Elongation at break (%) for both directions
• Breaking strength normalized to width (N/5 cm or N/cm)
• Breaking tenacity where yarn linear density data are available
• Coefficient of variation and statistical validity of replicate results
• Failure mode description, such as yarn rupture, slippage, or coating delamination

Depending on the specification, supplementary items such as seam strength, tear strength, and tuft withdrawal force may be evaluated alongside breakage force to give a complete picture of backing mechanical performance.

Testing Methods

Strip Method

The strip method, standardized in ISO 13934-1, ASTM D5035, and equivalent national standards, is the most widely used procedure for backing breakage force. A full-width strip specimen is clamped between two jaws of a tensile testing machine and extended to rupture at a constant rate. Under ISO 13934-1, the gauge length is normally 200 mm with a test speed of 20 mm/min for fabrics of low elongation, and an appropriate pretension is applied depending on fabric mass. The strip method measures the strength of the full fabric construction and is well suited to woven polypropylene primary backings.

Grab Method

The grab method, standardized in ISO 13934-2 and ASTM D5034, clamps only the central portion of a wider specimen using reduced-size jaw faces, typically 25 mm by 50 mm, at a gauge length of 75 mm with a test speed of 300 mm/min per ASTM D5034. Because the grab test concentrates stress in a narrow zone, it is less affected by edge yarn damage and better reflects localized strength, making it useful for coated fabrics and finished turf where cutting individual strips is impractical.

Equipment Requirements

Testing is performed on a constant-rate-of-extension (CRE) universal tensile testing machine meeting the accuracy requirements of ISO 7500-1, typically force class 0.5 or better. Suitable force capacity ranges from 1 kN to 10 kN depending on product strength. The machine must be equipped with pneumatic or mechanical clamps lined with resilient faces to prevent specimen slippage without causing premature jaw breaks. Force and extension data are captured by computerized acquisition, and calibration of load cells and extension measurement must be traceable to national standards.

Test Procedure

• Condition specimens in the standard atmosphere until equilibrium
• Verify specimen width, length, and alignment before clamping
• Apply the specified pretension and set the gauge length
• Run the test at the prescribed speed until specimen rupture
• Reject results involving jaw breaks or slippage and repeat as required
• Calculate mean breaking force, elongation at break, and variability
• Report the method used, test direction, and all conditioning details

Applications

Backing breakage force testing is applied throughout the artificial turf value chain for multiple purposes:

• Incoming quality inspection of primary backing fabric at turf tufting factories
• Production quality control of coated finished turf before roll release
• Certification testing for sports governing bodies and international tenders
• Football, rugby, hockey, tennis, and multi-sport field product qualification
• Landscape, playground, rooftop, and pet turf durability verification
• Research and development of new backing constructions and coating formulations
• Failure analysis and after-sales dispute resolution on installed fields
• Procurement verification by contractors, sports clubs, and government buyers

Typical product specifications require finished backing breaking strength of several hundred newtons per 5 cm width in both directions, with exact thresholds defined by the manufacturer specification, the certification scheme, or the project contract. Backings intended for high-traffic professional sports installations are generally specified with higher breaking force and lower elongation tolerances than landscape-grade products.

FAQ

What is the difference between the strip method and the grab method?

The strip method tests the entire width of a narrow raveled or cut specimen and measures the collective strength of all yarns across the width, providing a true fabric strength value. The grab method tests only a central gripped region of a wider specimen and reflects localized strength with less sensitivity to edge effects. Standards and product specifications dictate which method applies.

Why are both machine direction and cross-machine direction tested?

Woven backings are anisotropic, meaning warp and weft yarns differ in count, denier, and crimp. Machine direction strength governs resistance to stretching during installation and in-use tension, while cross-machine direction strength governs resistance to splitting, seam opening, and cleat-induced tearing. Both directions must meet specification independently.

How does the latex or polyurethane coating affect test results?

The secondary coating bonds yarn intersections and generally increases measured breaking force while reducing elongation. Coating quality issues, such as insufficient penetration or uneven application, are often exposed by low breaking force results or abnormal failure modes such as interlayer delamination during testing.

What sample quantity is required for a reliable test?

Most standards require a minimum of five valid specimens per direction, with additional replicates if jaw breaks or slippage occur. Statistical validity improves with more specimens, and certification programs typically specify the exact number of specimens and the acceptance criteria for the mean value.

Which laboratories can perform backing breakage force testing?

Testing should be conducted by laboratories accredited to ISO/IEC 17025 with validated procedures under ISO 13934-1, ISO 13934-2, ASTM D5035, or ASTM D5034. Accredited reports are accepted for product certification, tender compliance, and international trade documentation.