SportsTurf provides current, practical and technical content on issues relevant to sports turf managers, including facilities managers. Most readers are athletic field managers from the professional level through parks and recreation, universities.
Issue link: https://read.dmtmag.com/i/32290
Facility&Operations | Tom Serensits Is there any way to cool synthetic turf? W HEN WALKING ACROSS A SYN- THETIC TURF FIELD on a sunny sum- mer day, it does not take long to notice the heat emanating from the surface. While synthetic turf has undergone design changes that have improved overall field conditions, the issue of high surface temperature remains. Should I irrigate my field to cool it off? Do alternatives to black crumb rubber infill really lower surface tem- perature as they claim? At Penn State’s Cen- ter for Sports Surface Research, our studies are beginning to answer these questions. Before we get into the results of our test- ing, it is useful to have an understanding of when and why these surfaces get hot. Sur- face temperatures reach their peak during bright, clear sunny days with little humidity and haze. The temperature of a field on an 82° F clear, sunny day will be higher than on a hazy, humid day with an air temperature in the 90’s. How hot can synthetic turf really get? The highest recorded temperature was 200° F dur- ing a summer day on the campus of Brigham Young University in Provo, UT. While this may be an extreme case, it is not uncommon for temperatures to surpass 150° F. In fact, during Penn State’s Turfgrass Field Days this past summer, we recorded temperatures as high as 175° F on our research plots. For a comparison, natural turf rarely reaches 100° F, even on the hottest, clearest days. 20 SportsTurf | June 2011 Irrigation is the most common method used to try to reduce the surface temperature of synthetic fields. Pumping water onto syn- thetic turf may garner some odd looks, but the application of water can rapidly cool the surface of the field. The problem is that cooling effect is short-lived. Our research shows temperatures quickly rebound 20 minutes after irrigation stops and the irri- gated surface is only slightly cooler than a non-irrigated surface three hours after water- ing (less than 10 degree difference). Another issue with irrigation is the potential for in- creased humidity directly above the turf ’s surface. Rising temperatures coupled with high humidity may expose athletes to even more heat stress. The reason we have not been successful in significantly reducing the temperature of these surfaces through irrigation is that these systems have been designed to rapidly drain water. They simply do not hold onto much water and thus the evaporative cooling is short-lived. We have attempted to increase water holding capacity of the systems and thus increase the duration of the cooling ef- fect by adding water-holding particles to the crumb rubber infill. In our testing, we mixed a substantial amount of calcined clay with crumb rubber (1 to 1 on a volume basis). While successful in prolonging the duration of cooling ini- tially, the calcined clay particles were re- duced to dust when subjected to simulated field use. Not surprisingly, the cooling effect >> Figure 1. INFILLS TESTED included (left to right) Ecofill, TPE, green crumb rubber, tan crumb rubber, and black crumb rubber. was lost as the particles broke down. Addi- tionally, such a high amount of calcined clay may affect the playability of the field and the dust could impact drainage, al- though this was not measured in our study. Although it is common to blame the sunlight’s interaction with the black crumb rubber for the hot surface, the fibers also significantly contribute to a field’s temperature. Anyone who has spent time working with traditional (non-in- filled) Astroturf-type surfaces can tell you that those fields also got extremely hot and they do not contain any crumb rub- ber. In fact, results from our research plots show that the surface temperature of tra- ditional Astroturf is higher than infilled synthetic turf when no irrigation is ap- plied. Surface temperature reduction has been attempted through modifications to both the infill material and changes in the fiber. Marketers of crumb rubber infill alterna- tives claim their products reduce surface temperature. Some have proposed chang- >> Figure 2. EXPERIMENTAL SETUP to evalu- ate surface temperature of synthetic turf. www.sportsturfonline.com By