Gmax is the standard test, set forth by the American Society for Testing & Materials (ASTM), to certify that a synthetic turf field is suitable and safe for play. It is recommended that all synthetic turf fields be tested at least annually to determine safety and playability.
ASTM F355 Procedure A and ASTM F1936 describe the equipment and test methods used to measure the impact attenuation properties of synthetic turf playing systems. The test procedure involves dropping a 20 lb impacting missile from a height of 24 inches, three times at each of ten locations. Infill depths and turf temperature at each location are also reported.
A Gmax of 200 or more is considered unplayable (too high). The Synthetic Turf Council recommends all Gmax locations be below 165. The only way to know the Gmax of your field is to have it tested. Knowing your synthetic turf field is properly maintained and safe is an important responsibility of field ownership.
Although not required by ASTM, I also include HIC (Head Injury Criteria) results with your Gmax report.
My location in the Midwest makes it economical for me to travel. In most cases if you are located in the Midwest OR have two or more fields needing tested I don't charge travel fees.
Midwest Gmax and Turf Maintenance
The standard test set forth by the ASTM to measure the impact attenuation of a natural or synthetic turf field.
The ASTM recommends at least annual testing. Depending on the use of your field you may need more frequent testing.
ASTM F1936 Triax Data Acquisition equipment as well as ASTM F1936-10 and ASTM F355 Procedure-A testing method will be utilized and adhered to, to measure the impact attenuation of your turf playing fields. All efforts will be made to keep your testing cost-effective and in almost all cases you will receive your three page report within 24 hours.
The #1 reason for performing annual Gmax testing is to assure a safe playing surface for your athletes. Annual testing along with regular maintenance and grooming assure due diligence in putting your athlete's safety first. ALWAYS keep annual Gmax reports and all maintenance/grooming records!
Regular Gmax testing, along with your manufacturer's recommendations, will assist in determining the best maintenance program for your field. By getting Gmax results and infill depths from various locations on your field, you can adjust your maintenance and grooming routine to easily increase the life of your turf field. Increasing the life of your turf field by two years is a value of tens of thousands of dollars!
As a retired Athletic Director, I know it's nice to be able to put your head on the pillow at night knowing you've done everything possible to keep your athletes safe. Gmax testing and field maintenance should be a part of everyone's comprehensive safety plan.