JPH0141761B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to improvements in paving materials used for grounds such as athletic fields or outdoor playgrounds. As the surface layer material of conventional Craigland, materials shown in Table 1 below are generally used. These surface materials dry out and become hard when the weather is sunny for a long time. If the surface soil becomes too hard, the impact on the user's knees or the like will be too large and will have a negative impact on the user, or the user will be more likely to be injured if they fall. Also, surface soil that becomes soft or hard depending on the weather, or whose hardness changes too much, is undesirable because it means that the ground condition is constantly changing.

【table】

[Table] Other methods have also been proposed, such as adding zeolite particles to the surface material (Japanese Patent Publication No. 57-50887) and incorporating pulverized coal ash (Japanese Patent Publication No. 40-3224), but the surface material contains a large amount of water. If this is the case, there are problems such as the inability to prevent muddy formation. In view of these circumstances, the present inventors aimed to develop a surface material that does not harden even when the weather continues for a long period of time, can prevent it from becoming muddy even when it contains a large amount of water, and has excellent workability. As a result of intensive studies, we have arrived at the present invention, which has remarkable effects. That is, the present invention provides a Craigland surface paving material comprising 0.5 to 20% by dry weight of silica gel having a particle size of 4 to 200 mesh and 5 to 25% by volume of lime filler whose main component is calcium carbonate. It is something. Silica gel has the property of absorbing and retaining a large amount of water, but this property is reversible; if the surrounding area dries, the water contained in the silica gel will evaporate, and if the surrounding area becomes wet, the silica gel will absorb the surrounding water. absorb. In this way, silica gel repeatedly absorbs and releases moisture depending on the dryness of its surroundings. However, if the rain continues for a long time or the amount of rainfall is large, it is difficult to sufficiently suppress the decline in soil hardness, and the soil tends to become muddy and soft. On the other hand, when lime filler is used together,
The ion-exchange reaction and pozzolanic reaction of the calcium in the lime filler causes the soil to coagulate appropriately, and this coagulated soil aggregates and improves drainage, so even when it rains for a long time, the soil does not become muddy or muddy. It exhibits the effect of not becoming soft and having a small decrease in hardness. In addition, the setting effect of lime filler is moderately small compared to slaked lime and cement, so the soil will not become too hard.
It is most suitable for exhibiting a synergistic effect with the water supply effect of silica gel. In addition, even when the weather is sunny for a long time, the large amount of water contained in silica gel evaporates appropriately, making it difficult to dry and harden. However, lime filler has a negative effect on the effectiveness of silica gel. There isn't. In addition, when it rains, ordinary Craigland forms puddles or contains large amounts of water in the surface soil, so it cannot be used immediately even after the rain has stopped.
Surface soil mixed with silica gel and lime filler is
If there is a small amount of rainfall, the silica gel in the surface soil will quickly absorb water on the ground, and due to the coagulation effect of the lime filler and the resulting improvement in drainage, the ground can be used immediately after rain, preventing it from becoming muddy or soft. figure,
The decrease in hardness is also small. The silica gel used in the present invention has a particle size of 4 to 200 mesh. If the particle size is larger than 4 meshes, there will be drawbacks such as the user being more likely to be injured when falling. Moreover, if it is smaller than 200 mesh, the water absorption effect of silica gel will not be sufficiently exerted. The amount of silica gel used is 0.5 to 20% by dry weight; if it is less than this, no substantial effect can be expected, and if it is more than this, it is difficult to expect a larger effect in practice and it is not economical. Lime filler is also called limestone powder, and its main component is calcium carbonate, which is different from lime, which has calcium oxide or calcium hydroxide as its main component. The lime filler is added in an amount of 5 to 25% by volume based on the surface layer material. If it is less than this, no substantial effect can be expected, and if it is more than this, there is a risk that the soil particles in the surface layer material will coagulate excessively. The silica gel and lime filler may be mixed into the Craigland surface material separately, or may be done at the time of constructing the surface material on the ground. Traditional Craigland construction is sensitive to rainfall. When it rains, the surface soil has a high moisture content, so if construction is carried out in this condition, the surface soil will turn into mud, making construction impossible. Surface soil with a high moisture content must be dried in the sun to a workable state before construction can be carried out. When rain and sunny weather occur in short intervals, the surface soil does not have enough time to dry and construction cannot be carried out. On the other hand, by mixing silica gel and lime filler with the surface soil, it is possible to rapidly bring the surface soil into a workable state. In winter, when a large amount of water is contained between soil particles in the surface soil, frost is likely to occur. However, by mixing silica gel and lime filler, the silica gel absorbs water and the lime filler improves drainage, so there is also the effect that frost is less likely to occur. Generally, when the surface layer of Craigland dries, dust tends to be generated. However, surface soil made of a mixture of silica gel and lime filler does not easily dry out as described above, and also exhibits a dust-proofing effect because it is subjected to a coagulation effect and traps dust sources. Volcanic sand and lightweight aggregate also have the ability to absorb and retain water, so if you mix volcanic sand and lightweight aggregate in place of the sand in Craigland surface material and use it in conjunction with silica gel and lime filler, Even more remarkable effects can be obtained. Here, the Craigland surface material which is a mixture of silica gel and lime filler, which is one of the features of the present invention, will be explained with reference to the experimental results of the present inventors. Generally, the hardness of Craigland surface layer is measured by the Proctor needle test. It is said that the appropriate proctor needle value obtained from the proctor needle test is within the range shown in Table 2. It is desirable for each ground to satisfy the range of proctor needle values shown in Table 2 regardless of the weather, but in reality, if the weather continues for a long time, the upper limit of the range is often exceeded. In addition, in Table 2, the Proctor needle test refers to a cylindrical penetrating rod with a cross-sectional area of 1/20 inch ²
The hardness of the penetrated part is indicated by the maximum value (Lbs) of the penetration resistance value at that time when the penetration speed is 1 inch/sec.

[Table] Next, examples according to the present invention will be described. In the indoor model experiment, as shown in Figure 1, on the roadbed A,
A roadbed made of crushed stone with a thickness of 15 cm was installed.
Furthermore, the surface layer C, which was paved to a thickness of 15 cm, was provided thereon. The manufactured model was kept under normal usage conditions and left outdoors. Example 1 Proctor needle values were compared when only silica gel was mixed into the surface layer material for schoolyards, and when silica gel and lime filler were mixed. Display the results -
Shown in 3.

[Table] From the results in Table 3, the proctor needle value after 15 days of continuous sunny skies is in a preferable range for both silica gel alone and silica gel and lime filler combination, compared to when nothing is added. However, measurements after rain show that only the case where silica gel and lime filler are used in combination falls within the preferable range. Example 2 Proctor needle values were compared when only silica gel was mixed into the surface material for a baseball field, and when silica gel and lime filler were mixed. The results are shown in Table 4.

[Table] From the results in Table 4, it can be seen that only the case where both silica gel and lime filler are mixed shows a preferable Proctor needle value both after 12 days of clear weather and approximately 24 hours after the end of rain.

Claims (1)

[Claims] 1 Silica gel 0.5-20 with a particle size of 4-200 mesh
A paving material for Craigland surface material, characterized in that it contains 5% to 25% by volume of lime filler whose main component is calcium carbonate and dry weight%.