JPS5942761B2 - Surface material for playgrounds - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to surface materials for tennis courts, baseball fields, and other track and field or athletic fields.

Outdoor playgrounds that have natural soil on their surface have the disadvantage that they are not immediately ready for use even when the weather changes significantly due to rainfall.

In general, the preferred conditions for a playground are: (1) it should be well compacted and have uniform physical properties over the area; (2) for this reason, it is preferable that the constituent material be as simple as possible; (3)
(4) It maintains its strength even under hot sun and high temperatures;
(5) Good water permeability and water retention.

It is generally said that the composition of the surface layer material satisfying the above conditions should be within the range of the grain size accumulation curve ASB in the figure.

That is, sand content (5.0 mm to 0.05 m) 70 to 80
%, silt content (0.05wn~0.005m) 7~
15%, and the clay content (0,005 wrL or less) is said to be in the range of 2 to 15%.

In addition, in order to improve drainage and water retention, a material called Xingu surface layer, which is a mixture of natural soil, coal grit, volcanic gravel, etc., or so-called Antuca, etc., is also used.

However, since these are expensive porous raw materials, they are susceptible to shock, and the impact and pressure transmitted from the surface cause them to become fine and clogged, resulting in gradual deterioration of drainage performance.

Furthermore, apart from these, a playground using powder of basic minerals such as serpentinite or serpentine as a part has also been proposed.

, (Special Publication No. 42-11252 and Special Publication No. 42-1436
4) However, since these rocks have no viscosity, they have the disadvantage that various binder materials must be added separately.

The present invention deals with 51rr of amphibolite, which is produced in various parts of Japan and currently has no use value! This method uses crushed particles with a particle size of less than IL, and is inexpensive, as well as the fact that the fine particles with a particle size of 0.005 mm or less exhibit clay-like, or plastic, properties in a water-containing state, which gives it a binder effect and improves drainage. Good 5m~1■
It is possible to increase the content of coarse particles of about 0.00
98 to 90% of particles of 5 m or more, preferably 95 to 90
%, the drainage performance, strength, etc. can be maintained within the above-mentioned desirable range, and the dark green color tone that the amphibolite itself has can be utilized.

That is, when amphibolite is crushed to 2 mm or less, the particle size composition is generally as follows.

2m - 1m 35% 1 - 0.05TrrIrL50% 0.05m - 0,005m 10% 0.005m or less 5 out of these, particles of 0.005wn or less exhibit plasticity when they contain water.

The particle size distribution of the above-mentioned pulverized material is similar to the ideal blending ratio for the sports field mentioned above, and together with the above-mentioned expression of plasticity, when this pulverized material is added with moisture and then dried, ultrafine powder of 0.005 mm or less is produced. It acts as a connector for coarse grains (2 to 0.05 mm) and forms a strong surface layer.

A comparative experiment was conducted to examine the strength of the surface layer material of the present invention, and the following results were obtained.

First, dig a 10cm deep hole (ltr?) on the flat ground.
On one side, the ground material of the present invention mixed with 10 parts of water was laid down, and on the other side, the above-mentioned ideal playground surface was laid down, and each was rolled under the same conditions using a 1-ton vibrating roller. The 1-inch vertical penetration value was measured using a broctor needle.

Ideal playground soil Penetration value: 61 lbs. Crushed product of the present invention: 55 lbs. Although the penetration value of the pulverized product of the present invention itself is lower than that of ideal playground soil, it has better drainage, and the pulverized material itself is dark green, making it difficult to see. It has the advantage of being less tiring on tennis courts and the like, and is better than Anzucar.

Even if this pulverized material is mixed with other surface materials, the content will be 70%.
The same effect will be achieved if the level is higher than that.

Example: The entire surface of the court site was dug down 20 cm and quarried stone with a diameter of 3 cfrL or less was laid down to a depth of 18 cm.
Amphibolite crushed to 0 m or less (particles of 0,005 m or less 8
%) and 20 parts of sand sieved to 1.0 to 0.5 - were thoroughly mixed and spread to a thickness of 3 cfrL, and rolled with a 1 ton roller to make a tennis court.

With this court, the white balls were clearly visible, there was less eye fatigue, and drainage was good.

[Brief explanation of drawings]

The figure shows a soil particle size accumulation curve showing the particle size distribution range suitable for the surface material of a playground.

Claims (1)

[Claims] 1 A crushed amphibolite with a diameter of 51rrIrL or less,
98-90% of particles larger than 0.005m++, 0.0
A surface layer material for an outdoor playground, comprising a pulverized material adjusted to have a composition of 2 to 10 particles of 0.05 m or less, as a surface layer material constituting material with a ratio of 70 or more.