Summary Characteristics of Organic and Inorganic Loose-Fill Materials, and Unitary Synthetic Materials INORGANIC LOOSE MATERIAL sand and gravel Installation/Maintenance Should not be installed over existing hard surfaces (e.g.,asphalt, concrete). Method of containment needed (e.g., retaining barrier, excavated pit). Good drainage required underneath material. Requires periodic renewal or replacement and continuous maintenance (e.g., leveling, grading, sifting, raking) to maintain appropriate depth and remove foreign matter. Compacted sand should periodically be turned over, loosened, and cleaned. Gravel may require periodic break up and removal of hard pan. Advantages Low initial cost. Ease of installation. Does not pulverize. Not ideal for microbial growth. Nonflammable. Materials are readily available. Not susceptible to vandalism except by contamination. Gravel is less attractive to animals than sand. Disadvantages The following conditions may reduce cushioning potential: Rainy weather, high humidity, freezing temperatures. With normal use, combines with dirt and other foreign materials. Depth may be reduced due to displacement by children's activities and sand may be blown by wind. May be blown or thrown into children's eyes. May be swallowed. Conceals animal excrement and trash (e.g., broken glass, nails, pencils, and other sharp objects that can cause cut and puncture wounds). Sand Spreads easily outside of containment area. Small particles bind together and become less cushioning when wet; when thoroughly wet, sand reacts as a rigid material. May be tracked out of play area on shoes; abrasive to floor surfaces when tracked indoors; abrasive to plastic materials. Adheres to clothing. Susceptible to fouling by animals. Gravel Difficult to walk on. If displaced onto nearby hard surface pathways, could present a fall hazard. Hard pan may form under heavily traveled areas. |
