TM 5-803-11/AFJMAN 32-10139
Table 11-4. Sieve Analysis of Sand and Gravel.
f. Cost. Wood products have a low initial cost and
a high maintenance cost.
11-6. Inorganic Loose-Fill Surfacing.
Sand, gravel, and chopped tire are popular inor-
ganic loose-fill surfaces. These materials absorb im-
pacts by changing shape upon impact. Chopped tire
also traps air between the particles to provide a
cushioning effect. The primary advantage of sand,
gravel, and chopped tire surfacing is that the mate-
rials are easy to install, and readily available. The
materials are not ideal for microbial growth. Sand
and gravel are nonflammable and initially inexpen-
sive. The primary disadvantage of these materials
is that continuous maintenance is required to pre-
serve impact attenuation.
a. Design Considerations.
(1) Sand. The natural appearance of sand and
its importance as a play material makes it a popular
safety surface. Sand is an excellent manipulative
play material, especially if provided in conjunction
titles a maximum of 12 mm (1/2-inch) in size; and
with water. However, separate sand play areas
free of metal, harmful chemical, and foreign mate-
should be provided away from play equipment use
rial.
zones. The impact-attenuating ability of sand is
(4) Selection Considerations.
greatly reduced when wet. Therefore, it is not rec-
ommended for use as a safety surface in regions
(a) Appearance. It should be determined
with wet climates, such as the Pacific Northwest.
whether the material will look attractive and will
Sand is abrasive to floors when tracked indoors.
complement the appearance of playground equip-
Sand used as a safety surface will meet the follow-
ment.
ing specification: Sand will be rounded naturally or
(b) Maintenance. It should be determined
by mechanical means; washed; free of dust, clay,
whether a high level of maintenance can be pro-
soil, hazardous substances, or foreign objects; and
vided to maintain impact attenuation.
sieved as shown in table 114.
(c) Installation Requirements. Sand or gravel
(2) Gravel. Gravel drains well and does not
should be installed over a compacted subgrade.
easily freeze or compact. It is popular in cold and
Chopped tire should be installed over a subgrade of
wet climates. It should not be used as a safety sur-
compacted gravel covered with geotextile fabric.
face in play areas designed for children under 3
Barriers should be provided to contain these loose-
years because of the potential for choking. Gravel
fill materials.
used as safety surfacing will meet the following
specification: Gravel particles will be rounded natu-
provided. Many play areas may require subsurface
rally or by mechanical means; washed; free of dust,
drainage under inorganic loose-fill surfaces.
clay, soil, hazardous substances, or foreign objects;
(e) Chopped Tire. Test results should be ob-
and sieved as shown in table 114.
tained from the manufacturer verifying that a fall
(3) Chopped Tire. Chopped tire safety surfacing
onto this surface from the height specified by the
is highly effective, trapping air between particles to
purchaser results in a g-force rating of no more than
provide an impact-attenuating effect. Chopped tire
200 g's and a HIC value of no more than 1,000.
is nonabrasive. It does not absorb moisture or at-
Photos of tested samples should be obtained from
tract cats, dogs, rodents, or insects. Select chopped
the manufacturer to compare with the purchased
tire manufactured specifically for safety surfacing.
material. A copy of the warranty for the material
The results of impact attenuation tests should be
and an estimate of the anticipated durability of the
obtained from the manufacturer. Chopped tire
material should be obtained.
safety surfacing that is manufactured from steel
belted tires will not be used. Chopped tire used as
Pests and Vandalism. It should be deter-
safety surfacing will meet the following specifica-
mined whether pests, such as fleas, or high vandal-
tion: Chopped tire will be asymmetrical rubber par-
ism will increase maintenance requirements,
11-6
Previous Page
