# Additional Criteria for Playground Impact Attenuating Sand
## 6 Conclusions  
This paper proposed an additional IAS test to eliminate sands that degraded above an established threshold rate after installation due to normal usage. IAS degradation properties of fifteen sands were tested including sand particle shape, sand particle distribution, percentage fines and sand particle degradation. This accelerated ageing test method would apply only to sands and not rubber and wood fibre IAS products. It is recommended that for sand to be used for impact attenuation within children's playgrounds, the following criteria must be satisfied:  
1. The coefficient of uniformity must not exceed 2.70. 2. The percentage of material passing a 0.075 mm sieve aperture must not exceed 3.1% when compared to the value ascertained for percentage fines. 3. The percentage fine material passing a 0.075 mm sieve is less than 4.5%. Nevertheless, a coefficient of uniformity less than 2.00 together with percentage fines approaching 0.00 is preferred. The following conclusions are drawn from this study:  
* Selected sand can possess excellent long-term impact attenuation properties that make it ideal for usage within children's playgrounds. * Sand with a particle shape that is rounded to well-rounded has excellent impact attenuation properties which makes it ideal for usage in children's playgrounds where it enables the energy to flow and disperse away from the point of impact. * High levels of fines and clay within playground sand are correlated with poor impact attenuation as these tend to bind the sand particles and reduce the flow and dispersion of energy away from the point of impact. * IAS sand used within children's playgrounds can and does degrade with usage and this can be dramatically reduced by better material selection. * The playground sand particle size is not particularly important. * The grading coefficient of playground sand is important and the coefficient of uniformity should be kept below 2.75. * The early identification of playground sand types that exhibit robust resistance to degradation during usage should be encouraged. * The installation of playground sand types that exhibit non-robust stability to degradation (generation of clay and fines) during usage should be discouraged and/or eliminated. In addition to these conclusions, it was noted that the best IAS sands were sourced from quarries located on rivers that had eroded volcanic outcrops. These sands were shown \begin{table}
\begin{tabular}{l c c c c c} \hline \hline
**Sand** & **Coefficient of** & **Fineness** & **\% Fines** & **Degradation** & **Degradation** \\  & **Uniformity** & **Modulus** & **\%** & **0 Impacts** & **1500 Impacts** \\ \hline
01 & 2.45 & 2.87 & 2.5 & 2.45 & 2.60 \\
02 & 2.40 & 2.87 & 1.3 & 2.40 & 2.51 \\
03A & 2.36 & 2.80 & 1.2 & 2.36 & 2.50 \\
03B & 2.33 & 2.71 & 1.6 & 2.33 & 2.38 \\
03C & 2.31 & 2.72 & 1.3 & 2.31 & 2.34 \\
04 & 2.10 & 2.20 & 0.4 & 2.10 & 2.47 * \\
05 & 2.75 & 2.93 & 0.1 & 2.37 & 2.80 * \\
06 & 2.03 & 2.53 & 0.2 & 2.03 & 1.98 \\
07 & 2.09 & 2.70 & 0.4 & 2.09 & 2.19 \\
08 & 1.97 & 1.91 & 1.2 & 1.97 & 3.57 \\
09 & 3.47 & 3.39 & 0.8 & 3.47 & 2.48 \\
10 & 3.55 & 3.16 & 4.6 & 3.55 & 7.04 \\
11 & 10.39 & 4.24 & 4.4 & 10.39 & 20.00 \\
12A & 8.22 & 2.66 & 14.2 & - & - \\
12B & 5.68 & 2.69 & 8.8 & - & - \\ \hline \hline \end{tabular}
\end{table} 
Table 3: Summary table for all 15 sands analysed (* 1000 impacts). to degrade the least and their particle shape was rounded to well-rounded. The most reliable location for good quality IAS sands on these rivers was on specific bends. The sand mined at these locations consistently had a tight particle size distribution. Sand classified as unsuitable for use as IAS sand for children's playgrounds was sourced from calcareous rock, coral and seashell middens. All authors contributed equally to this publication. All authors have read and agreed to the published version of the manuscript. This research was internally funded by the University of Technology Sydney. Not applicable. Not applicable. Not applicable. Not applicable.