JPH05214708A - Pavement body - Google Patents

Abstract

PURPOSE:To exhibit effect for both low noise and drainage by constituting a surface layer with porous asphalt in which aggregate is mixed to asphalt to which rubber and/or resin is added. CONSTITUTION:The surface layer 5 of a pavement body 1 to be constructed on a roadbed 2 is constituted of porous asphalt in which aggregate 8 is mixed in asphalt 7 to which either rubber or resin, or both of them are added. Thickness H of the surface layer 5 is made 4.5cm or more and void ratio is made above 20%. Maximum particle size of crushed stone to be used as the aggregate is made under 20mm and above 7mm. In this way, noise to be generated by vehicles running on road is absorbed by the surface layer 5 of the pavement body 1 and traffic noise can be reduced adequately without using sound insulating wall and so on.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION This invention relates to reducing road traffic noise.

[0002]

2. Description of the Related Art Conventionally, as a noise reduction measure for preventing noises emitted from tires, engines, etc. of vehicles traveling on a road from being radiated to the neighborhood, it has been customary to provide a soundproof wall beside the road. ..

[0003]

[Problems to be Solved] However, although the countermeasures using the soundproof wall can be taken on the motorway, they cannot be carried out on the general city road. Further, the countermeasures by the soundproof wall have to raise the wall in order to obtain a sufficient effect, and there are problems that the view of the vehicle driver is squeezed, the landscape is damaged, and the cost is high.

[0004]

Therefore, the present inventors have come to the idea that the road surface is made of a sound-absorbing pavement made of a porous material so that noise can be absorbed and reduced in the road surface. Invented the pavement of.

In this pavement, the surface layer is made of porous asphalt having a thickness of 4.5 cm or more and a porosity of 20% or more, which is obtained by mixing aggregates with asphalt to which rubber or resin or both are added. It is characterized by

A pavement having a surface layer made of porous asphalt is conventionally known as a drainage pavement. Such a conventional drainage pavement has a thickness of 3 to 4 mm and a porosity of about 15 to 20%. Therefore, a sufficient noise reduction effect cannot be obtained. By setting the thickness to 4.5 mm or more and the porosity to 20% or more as described above, sound absorption due to the voids is exhibited for the first time, and an excellent noise reduction effect is obtained.

Moreover, since this porous asphalt uses asphalt containing rubber or resin or both as a binder, it has excellent durability despite its large porosity.

Further, in the above pavement, by setting the maximum particle size of the crushed stone used as an aggregate to be 20 mm or less and 7 mm or more, both drainage and low noise can be achieved. The maximum particle size referred to in this specification is 85% in terms of weight percentage.
The above is what goes through a sieve of that size.

[0009]

[Examples] FIG. 1 is a cross-sectional view showing an example of a pavement body to which the present invention is applied, where 1 is a pavement body and 2 is a roadbed. The pavement body 1 includes a roadbed 3 including a lower roadbed 3a and an upper roadbed 3b, and an asphalt pavement portion 6 including a base layer 4 and a surface layer 5.
It is formed by and.

The asphalt pavement portion 6 is formed of an asphalt mixture produced by combining an asphalt 7 as a binder with an aggregate 8 such as crushed stone and mixing the mixture in an appropriate manner and heating and mixing the mixture under a predetermined temperature condition. However, the present invention particularly relates to the surface layer 5.

That is, the surface layer 5 is based on the present invention and has an asphalt having a thickness H of 4.5 cm or more, a porosity of 20% or more, and rubber (SBR) as a modifier in an amount of about 5% by weight. Is used.

Because of its thickness and porosity, this surface layer 5 is
Traffic noise is reduced by absorbing the frictional noise between the tire and the road surface generated when the vehicle is running, and the sound reflected on the road surface and radiated to the four sides. Further, since SBR is contained in the asphalt, the durability of the road surface is improved.

FIG. 2 shows the result of an experiment conducted to confirm the influence of the thickness H of the surface layer 5 on the noise reduction effect. In this experiment, No. 6 crushed stone (maximum particle size: 13 mm) was used as the aggregate and the surface layer 5 with a porosity of 22%
The thickness H was changed variously, a small car was run at 60 Km / h in a steady state, and the noise level was measured according to JIS D1024. The curve A of FIG. 2 shows the value of the noise level measured about each thickness H, and the broken line B shows the noise level in the normal asphalt concrete pavement with a small porosity (dense-grained ascon pavement). From this, it can be seen that the thickness H of the surface layer 5 must be 4.5 cm or more in order to obtain a sufficient noise reduction effect.

FIG. 3 shows the results of the relationship between the porosity of the surface layer 5 and the noise level obtained by the same experiment. In addition,
At this time, the thickness H of the surface layer 5 is 5 cm, and the aggregate is No. 6 crushed stone. From now on, to obtain a sufficient noise reduction effect, 20%
It can be seen that the above porosity is required.

FIG. 4 shows the relationship between the maximum particle size of crushed stone used as an aggregate of porous asphalt and the noise level. At this time, the thickness H is 5 cm, the porosity is 22%, and the broken line in the figure is the noise level in the dense grain Ascon pavement. As can be seen from FIG. 4, in order to obtain a sufficient noise reduction effect,
The maximum particle size of the aggregate must be 20 mm or less.

FIG. 5 shows the relationship between the maximum particle size of crushed stone used as an aggregate and the water permeability of the surface layer 5. The water permeability is measured by storing water with a head of hcm on the surface layer 5 with a thickness of dcm, obtaining the velocity Vcm / sec at which this water flows down in the surface layer 5, and using the formula kh / d = V, the permeability coefficient k (cm / sec). The larger the water permeability coefficient k, the better the water permeability. As can be seen from FIG. 5, in order to obtain sufficient water permeability, the maximum particle size of the aggregate needs to be 7 mm or more.

Therefore, the maximum particle size of the crushed stone used as the aggregate must be in the range of 7 mm to 20 mm in order to give the surface layer 5 a large noise reduction property and a sufficient drainage property.

In the above embodiment, SBR is added as a modifier in the asphalt in order to modify the asphalt to improve the durability, but other rubber or resin such as CR, EVA, SBS is used. Etc. or a mixture thereof may be added to the asphalt as a modifier.

[0019]

According to the present invention, the noise generated by the vehicle traveling on the road is absorbed by the surface layer of the pavement, so that the traffic noise can be sufficiently reduced without using a soundproof wall or the like.

Further, a pavement having both drainage property and low noise property can be obtained.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing an example of a pavement body to which the present invention is applied.

FIG. 2 is a graph showing the relationship between the surface layer thickness and the noise level.

FIG. 3 is a graph showing the relationship between the porosity of the surface layer and the noise level.

FIG. 4 is a graph showing the relationship between the maximum particle size of crushed stone used as an aggregate and the noise level.

FIG. 5 is a graph showing the relationship between the maximum particle size of crushed stone used as an aggregate and water permeability.

[Explanation of symbols]

1 ... Pavement, 2 ... Roadbed, 3 ... Roadbed, 4 ... Base layer, 5 ... Surface layer, 6 ... Asphalt pavement section, 7 ... Asphalt, 8 ...
aggregate.

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[Procedure amendment]

[Submission date] August 26, 1992

[Procedure Amendment 1]

[Document name to be amended] Statement

[Correction target item name] 0006

[Correction method] Change

[Correction content]

A pavement having a surface layer made of porous asphalt is conventionally known as a drainage pavement. Such a conventional drainage pavement has a thickness of 3 to 4 cm and a porosity of about 15 to 20%. However, a sufficient noise reduction effect cannot be obtained. By setting the thickness to 4.5 cm or more and the porosity to 20% or more as described above, the sound absorption due to the voids is exhibited for the first time, and the excellent noise reduction effect is obtained.

Claims (2)

[Claims] 1. The surface layer has a thickness of 4.5 cm or more and a porosity of 20.
% Or more of a porous asphalt obtained by mixing aggregates with asphalt to which rubber or resin or both have been added. 2. The maximum particle size of crushed stone used as the aggregate is
The pavement according to claim 1, which is 20 mm or less and 7 mm or more.