Impact of third generation synthetic turf athletic field age on surface hardness and infill depth spatial variability

Abstract

The use of synthetic turf (ST) has become a popular option for many athletic fields. Little is known about how surface hardness and infill depth spatial variability changes over time on third generation (3G) ST athletic fields. A research study was conducted to investigate the impact of field age on surface hardness and infill depth spatial variability from 12 3G ST athletic fields in Tennessee and Georgia (USA) between March 5, 2014 and April 8, 2014. The 3G ST athletic fields tested varied in fiber type including monofilament, slit film, and a combination of monofilament with slit film fibers. All 3G ST athletic fields were directly over gravel with no shockpad present. Surface hardness and infill depth were collected in the same location on all fields. Surface hardness was collected with the Toro Mobile Tester (400–450 samples/field) and infill depth was collected manually with a three-prong infill depth gauge (200–225 samples/field). As field age increased, surface hardness and spatial variability of the surface hardness increased significantly. Surface hardness and infill depth also had a significant negative relationship with one another. The increase in mean surface hardness and variability is partially attributed to infill depth loss and compaction of the remaining infill. Infill depth did not have a significant relationship with age, unless plots were outside the manufacturer’s recommendation for infill depth. Considering the nearly 3000 samples collected in this study, maintaining a minimum infill depth between 30 and 35 mm kept 90% of surface hardness data points below the National Football League limit of 100 Gmax. Results from this study highlight how 3G ST athletic fields can change with age, which may indicate the need for targeted infill applications and decompaction to improve field uniformity over time.

The development of mandatory practices for the testing and maintenance of synthetic turf fields in the National Football League

“…This generally agrees with the data presented by Dickson et al. (2021), who indicated that target infill depths are commonly set to about 67% of the pile height. Individual football clubs can request slight alterations in the target depth.…”

“…Athletic play and other activities on the surface can displace the infill and otherwise disrupt constituents of the surface, such that the overall hardness of the surface may change from the as‐designed specification and variability in the localized hardness over the playing surface area may increase (Dickson et al., 2021) . In practice, then, surface hardness testing should be carried out a regular basis at all locations on the surface, and maintenance practices should be used that generate consistent values across the field surface and over time.…”

“Nothing Beats Nature”: Park Visitor Preferences for Natural Turfgrass and Artificial Turf: A Case Study

“…Specifically, participants discussed the hardness of artificial turf. Artificial turf fields can increase in hardness over time without proper maintenance and lead to increased injury rates (Dickson et al 2021;Fleming et al 2020;McMurtry and Fiedler 2019). The thermal comfort of a surface is also a crucial element and was cited by participants often.…”