Impact Attenuation

1. All the surfaces pass the existing specifications for impact attenuation of playground surfaces. 2. The polyurethanes exhibited higher G values overall (in comparison to EWF, silicone- and latex-stabilized EWF) and only the polyurethanes exceeded 100, but none exceeded the maximum allowed, 200 G. 3. All the surfaces passed the existing HIC specifications (HIC<1000) with the polyurethanes, foaming and non-foaming having the highest HIC of all the surfaces tested. 4. The silicone, latex, and unstabilized EWF have statistically indistinguishable (α=.05) impact performance. 5. We are able to state with confidence α=.05) that the 6 months of aging have significantly changed the impact performance for all systems except the unsurfaced (without an additive) EWF.


1. Firmness

  • One plot of silicone became Not Firm, otherwise the silicones were on the higher end of Moderately Firm .
  • The polyurethane had usual ratings of Firm, though during the heat, and dryness, of summer, the polyurethanes moved into the Moderately Firm ranking.
  • The EWF and latex were consistently rated as Moderately Firm.

2. Stability

  • The polyurethanes were Stable in nearly all tests and conditions.
  • The silicones became Unstable within the first month.
  • EWF and latex were consistently rated as Moderately Firm.

System Durability

1.The EWF under the stabilized surfaces was significantly wetter than unsurfaced


2.Stabilized surface layers are retarding the drying process for the underlying EWF resulting in very saturated EWF.

3.Additional study should focus attention on the moisture levels and rate of decay under these surfaces which seem to exacerbate the EWF wet/saturated conditions.


It is recommended that the next phase of development should be to install larger surfaces in a working playground to evaluate accessibility and durability. The stabilizers that have met the requirements for this next phase include the polyurethanes and latex systems. We believe it best to choose one commercially available binder for each type of adhesive system. From the standpoint of their impact and accessibility performance, the polyurethane Vitriturf and the latex Soil-Sement are the best candidates. The polyurethane ReacTITE produced a hard brittle shell which aged to be even harder and would increase the injury rate for falls on the surface. The silicone AllGuard system is also rejected as it did not maintain its integrity adequately to bond EWF into a contiguous mat.

Before any recommendations for public acceptance of any candidate Resin-EWF System(s) can be made, there is a critical need for a full-scale Phase III Field Assessment to more completely understand the on-going performance and durability of any candidate Resin-EWF System(s). For Phase III a larger pad than that used in Phase II would give a better result and reduce the edge effects on the evaluation. At a minimum, a 3 x 3 meter (10 x 10 ft.) surface should be installed on a working playground being accessed regularly by children. System performance and the moisture and temperature profiles through the depth of the candidate Resin-EWF System(s) during a two-year field exposure should be carefully monitored. To identify two configurations of each of the two binder systems to install in our proposed full-scale Phase III Field Assessment, industry leaders should be consulted.