Artificial turf shock absorption testing determines the force reduction capability of synthetic sports surfaces in accordance with EN 14808, EN 15330-1, and FIFA Quality Programme requirements. This technical article explains the testing principle, sample preparation, apparatus, procedure, acceptance criteria, and practical applications of shock absorption determination for artificial turf systems. It serves as a professional reference for manufacturers, testing laboratories, facility owners, and certification bodies.
Technical Overview
Shock absorption, also known as force reduction, is a core biomechanical performance indicator for artificial turf systems. It quantifies the ability of the turf carpet, infill, and any optional elastic base layer to attenuate the impact load generated when a player's foot strikes the surface. Higher shock absorption values indicate a softer surface that transmits less force back to the athlete, which is widely associated with reduced stress on ankles, knees, hips, and the spine.
The determination is internationally standardized. In Europe, EN 14808 specifies the laboratory and field method for measuring shock absorption on surfaces for sports areas, while EN 15330-1 establishes performance requirements for artificial turf used for football, rugby, and other sports. The FIFA Quality Programme, World Athletics, and the International Hockey Federation incorporate equivalent impact attenuation criteria into their certification schemes. In North America, related procedures such as ASTM F355 and ASTM F1292 are applied to shock pads and playground systems.
- Results are expressed as a percentage of force reduction relative to a rigid concrete reference.
- Shock absorption is typically evaluated together with vertical deformation and energy restitution to fully characterize surface behavior.
- The property is influenced by pile height, infill type and depth, shock pad thickness and density, and the age and maintenance condition of the installation.
Testing Samples
Laboratory Specimens
Laboratory testing is performed on complete system builds that replicate the installed construction. A turf specimen, commonly at least 500 mm by 500 mm, is mounted on a rigid steel or concrete base, dressed with the specified type and mass of infill such as sand and performance granules, and combined with the designated shock pad where applicable. Specimens are conditioned at a controlled laboratory temperature, typically 23 degrees Celsius plus or minus 2 degrees, before testing.
Aged and Worn Specimens
To assess long-term durability, shock absorption is remeasured after accelerated procedures such as simulated mechanical wear, UV and climatic ageing, water immersion, and freeze-thaw exposure. This verifies that the system retains adequate impact attenuation throughout its intended service life.
In-Situ Field Samples
For field testing, the installed pitch itself serves as the test sample. Measurements are taken at representative and high-stress locations, including goal mouths, penalty spots, corner arcs, the center circle, and points along a defined grid across the playing area. Infill is groomed and leveled to its normal playing condition, and the surface temperature is recorded at the time of each measurement.
Reference Surfaces
A rigid concrete or steel reference surface is used to establish the baseline impact force for the apparatus. Regular verification of this reference value, together with documented load cell calibration, ensures the traceability and comparability of results between laboratories and test campaigns.
Testing Items
The primary testing item is shock absorption (force reduction) expressed in percent. In most certification programs it is determined alongside a complementary set of player-surface interaction parameters:
- Shock absorption in percent, determined in accordance with EN 14808 or the equivalent FIFA test method.
- Vertical deformation in millimeters, determined in accordance with EN 14809.
- Energy restitution in percent, indicating the portion of impact energy returned to the player.
- Vertical ball rebound, ball roll distance, and rotational resistance (torque) for ball behavior and traction assessment.
- Retention of shock absorption after simulated wear, ageing, and moisture exposure.
Testing Methods
Principle of the Method
The determination uses an impact device known as the Berlin Athlete or Advanced Artificial Athlete. A falling mass of 20 kg is dropped from a height of 55 mm onto a spring assembly that transmits the load through a cylindrical test foot resting on the surface. A precision force sensor records the peak force transmitted through the specimen, and an identical impact is performed on a rigid reference surface. Shock absorption is calculated as SA = (1 - F sample / F concrete) × 100 percent, where F sample is the peak force recorded on the turf system and F concrete is the peak force recorded on the rigid reference.
Apparatus and Calibration
The test rig comprises a guided vertical drop column, a 20 kg falling mass, a calibrated spring element, a cylindrical test foot of approximately 70 mm diameter, a high-accuracy load cell, and data acquisition electronics capable of capturing the complete force-time curve at high sampling rates. Before each test series, the apparatus is verified against its reference force on a rigid base, and the force measurement chain is calibrated at documented intervals.
Test Procedure
- Condition the specimen to the specified laboratory temperature, or record the surface temperature for on-site tests.
- Prepare the infill depth, distribution, and moisture condition to the specified state.
- Perform the prescribed number of conditioning impacts at each test position to seat the system.
- Carry out the recorded impacts and capture the peak transmitted force for each impact.
- Repeat the measurement at the required number of positions across the specimen or pitch and compute the mean value at each position.
- Report individual results, mean values, test temperature, system construction details, and any deviations from the standard.
Expression and Evaluation of Results
The force reduction value is calculated from the recorded peak forces and rounded, commonly to the nearest whole percent. Acceptance criteria depend on the sport and the certification scheme. Football turf systems under EN 15330-1 and the FIFA Quality Programme are generally required to achieve shock absorption within an approximate range of 55 to 70 percent, ensuring the surface is neither dangerously hard nor excessively soft. The complete system, including infill and shock pad, rather than the turf carpet alone, must satisfy the requirement.
Applications
- Certification of new artificial turf pitches for football, rugby, American football, hockey, and multi-sport use prior to handover.
- Factory quality control of turf products, infill materials, and shock pads during production and batch release.
- Research and development of yarns, backings, elastic layers, and organic or recycled infill systems.
- Durability assessment through retesting after simulated wear, UV ageing, and freeze-thaw exposure.
- Periodic condition monitoring of existing fields and verification after infill top-ups or renovation works.
- Technical due diligence for procurement tenders, insurance assessments, and dispute resolution.
FAQ
What does shock absorption mean for artificial turf?
It is the percentage by which the peak impact force on the turf is reduced compared with the same impact on rigid concrete. A value of 60 percent means the surface absorbs 60 percent of the measurable impact force, leaving only 40 percent to be transmitted to the player's body.
Which standard defines the test method?
EN 14808, Surfaces for sports areas - Determination of shock absorption, is the principal method standard. It is adopted by the FIFA Quality Programme, the EN 15330-1 product specifications, and most national certification schemes for synthetic sports surfaces.
What shock absorption level is required?
Requirements are sport specific. Football systems are typically required to fall between roughly 55 and 70 percent, while hockey, athletics, and multi-use surfaces may have different limits. The current regulations of the applicable certification body always govern.
Can the test be performed on an installed pitch?
Yes. The same apparatus is deployed on site, and measurements are taken at multiple positions across the installed field, with surface temperature and infill condition recorded. Field results confirm that the as-built construction meets the specified performance targets.
How do infill and shock pads influence the result?
Infill depth, granule type, and compaction level strongly affect force reduction, as do the thickness and stiffness of any elastic shock pad. Loss, contamination, or hardening of infill over time typically reduces shock absorption, which is why periodic retesting is recommended.
How often should shock absorption be tested?
A full determination is normally performed at product type approval, at pitch handover, and then at annual or biennial intervals as part of field maintenance programs and re-certification cycles.