Permeability testing of synthetic running tracks measures the vertical water infiltration rate of porous plastic track systems, a key indicator of drainage performance, surface safety and long-term durability. This guide explains the applicable GB, EN and ASTM standards, sample preparation requirements, laboratory and field test procedures, calculation methods and typical acceptance criteria used by accredited third-party laboratories for quality control and project acceptance.
Technical Overview
Synthetic running tracks, often referred to as plastic or all-weather tracks, are polymer-based surfacing systems composed of polyurethane binders, EPDM or SBR rubber granules, and layered constructions installed over an asphalt or concrete base. Two principal system families exist: porous (breathable) systems, in which rainwater migrates vertically through the wearing course and base mat into a permeable substrate, and non-porous (dense) systems, in which water is shed laterally toward drainage channels by the designed crossfall of the surface.
Permeability testing applies to porous systems and quantifies the rate at which water passes through the track structure. Adequate permeability prevents surface water accumulation, maintains slip resistance and playability immediately after rainfall, reduces hydroplaning hazards for athletes, limits moisture entrapment that can cause delamination or blistering, and improves freeze-thaw durability in cold climates. Weak or blocked drainage is one of the most common non-conformities observed on aging track installations, which is why infiltration testing is embedded in both factory quality control and site acceptance regimes.
The most widely referenced methods include EN 12616 (determination of water infiltration rate for sports surfaces), EN 14877 (synthetic surfaces for outdoor sports areas), GB 36246-2018 (safety requirements for sports fields in primary and secondary schools, as applicable in China), GB/T 14833 (synthetic material track surfaces for sports), GB/T 22517.6 (requirements and test methods for synthetic track facilities), and ASTM D2434 (constant-head permeability of porous media, adapted in some laboratories for panel testing). Specimen conditioning generally follows ISO 291 (standard atmospheres for conditioning and testing of plastics).
Testing Samples
Laboratory Production Panels
Panels are cast at the production facility or on site using the same material batches, mixing ratio, thickness and laying technique as the actual installation. Typical panel dimensions are 300 mm by 300 mm at the full specified system thickness. Panels must be fully cured, commonly for at least 14 days, and then conditioned for a minimum of 24 hours at 23 ± 2 °C and 50 ± 5 % relative humidity in accordance with ISO 291 before testing.
Full-Depth Field Cores
Drilled cores, typically 100 mm to 150 mm in diameter and extending through the complete track structure, are extracted from representative locations on the finished installation. The core faces are inspected for delamination, voids, thickness deviation and adhesion between layers, since these features strongly influence measured flow. Cores are conditioned to laboratory temperature before the permeability determination.
In-Situ Installed Surface
For acceptance testing on completed tracks, portable infiltration rings are sealed directly onto the installed surface. This non-destructive approach evaluates the real drainage performance of the system as built, including the interaction between the track surface and the underlying base, which cannot be reproduced by a laboratory panel alone.
Testing Items
Typical test parameters assessed in a permeability evaluation program include:
- Vertical water infiltration rate of the track surface, expressed in mm/h or L/m² per minute.
- Saturated permeability coefficient K of the material, expressed in cm/s, derived from Darcy's law.
- Permeability retention after accelerated aging, repeated compression loading or simulated soiling.
- Verification of the declared system type, distinguishing porous (breathable) construction from non-porous construction.
- Uniformity assessment across lanes, low points and high-traffic areas of the facility.
Testing Methods
Constant-Head Method (Laboratory and Field)
A permeameter or infiltration ring is sealed onto the specimen or surface with an impermeable sealing compound. Water is poured into the apparatus and the head is maintained at a prescribed constant height above the surface, commonly on the order of 50 mm. After the flow reaches steady state, the volume of water passing through the test area over a measured time interval is collected and recorded. The general procedure is:
- Seal the apparatus to the surface and verify that no lateral leakage occurs.
- Pre-wet the specimen to saturation before formal measurement.
- Maintain the constant water head throughout the test.
- Collect the permeated water over a defined period once the flow has stabilized.
The infiltration rate is calculated as I = 36,000 × V / (A × t), where V is the collected water volume in cm³, A is the test area in cm², t is the collection time in seconds, and I is the result in mm/h.
Falling-Head Method (Laboratory)
In the falling-head configuration, a standpipe of known cross-sectional area is filled with water and the time required for the water level to drop between two fixed marks is measured. The saturated permeability coefficient is calculated as K = (a × L / (A × t)) × ln(h1 / h2), where a is the standpipe cross-sectional area, L is the specimen thickness, A is the specimen cross-sectional area, t is the elapsed time, and h1 and h2 are the initial and final heads. This method is well suited to materials with relatively low flow rates.
Field Infiltration Ring Method
For on-site testing in the spirit of EN 12616, a single or double infiltration ring is bonded to the cleaned track surface. Water is supplied to maintain a constant head, and the steady-state flow rate is recorded. Testing is normally performed at multiple positions distributed across the facility, commonly at least five points for a standard track, including lane areas, curved sections and any locations where ponding has been observed. Testing is conducted only after the surface is fully cured and cleaned of loose granules and dust.
Data Processing and Reporting
Because water viscosity varies with temperature, measured values are corrected to a reference water temperature using the ratio of viscosities so that results remain comparable between seasons and laboratories. The test report typically includes the test method and standard applied, specimen description and thickness, conditioning details, water temperature, individual results for each measurement point, the arithmetic mean, the reference temperature, and a statement of conformity against the specified limit. Acceptance limits are product- and specification-dependent; porous athletic surfaces are commonly required to achieve infiltration rates in the range of several hundred millimeters per hour, and the applicable limit must always be taken from the governing standard edition or the project specification.
Applications
Permeability testing of synthetic running tracks supports a wide range of engineering, regulatory and commercial purposes:
- Acceptance testing of newly constructed tracks for schools, universities and public stadiums, including compliance demonstration against national school facility safety requirements.
- Factory quality control during track material production, verifying that batch formulations deliver the declared drainage performance.
- Periodic condition surveys of aging facilities to detect clogging, wear of the porous structure, or surface contamination before failure occurs.
- Diagnostic investigations of ponding, blistering or delamination complaints, differentiating surface permeability loss from base construction defects.
- Product development and type testing of new track systems by manufacturers seeking certification of porous system designs.
- Verification after cleaning, re-surfacing or maintenance treatments intended to restore drainage capacity.
FAQ
Why is permeability testing mainly applied to porous (breathable) track systems?
Non-porous tracks are intentionally sealed and rely on surface slope for drainage, so a vertical infiltration measurement is not meaningful for them. Porous systems are engineered to transmit water through their structure, and the infiltration rate is therefore the defining functional property that must be verified.
How many test points are required on a completed track?
Most acceptance regimes require multiple positions distributed across the facility, commonly at least five points for a standard 400 m track, with additional points at suspect areas. Individual and average values are reported so that localized defects are not masked by the mean.
Does permeability change over the service life of a track?
Yes. Pores gradually clog with dust, worn rubber particles, biological growth and surface treatments, and the porous structure can compact under traffic. Periodic testing allows maintenance such as deep cleaning or re-spraying to be scheduled before drainage performance falls below specification.
Can a track that fails the permeability requirement be restored?
In many cases yes, depending on the cause. Contamination-related losses can often be recovered by high-pressure or specialist cleaning, while structural blockage, over-applied seal coats or base defects may require partial removal and re-laying of the affected areas.
What influences the reproducibility of the test?
Key factors include the completeness of saturation before measurement, the quality of sealing between apparatus and surface, water and specimen temperature, head stability, and the cure state of the binder. Following the conditioning and procedural requirements of the applicable GB, EN or ASTM method is essential for comparable results between accredited third-party laboratories.