JPH06146205A - Water permeable pavement - Google Patents

Abstract

PURPOSE:To improve performance of water permeability and sound absorbing property by providing a water permeable elastic layer which contains cavities below water permeable pavement consisting of aggregate and clearance related to aggregate and providing a sound absorbing layer which has adjusted sound absorbing property below it as required. CONSTITUTION:A water permeable elastic layer 3 which consists of old tire chips bonded by asphalt and has cavities is provided below a water permeable pavement layer 1 of open grading asphalt. Next, a sound absorbing layer 5 of vitreous particle aggregate is provided below it as required, or the layers 1, 5, 3 are accumulated in this order from above sequentially. Then, when a vehicle passes, the layer 3 is compressed and restored, and the layer 1 oscillates up and down to discharge sand dust among aggregate so as to suppress clogging. Rise of air pressure between tire and road surface is relaxed owing to elasticity of the layer 3, reducing pumping sound. Further, particle diameter, layer pressure, and cavity rate of the layers 3, 5 are adjusted to optimize sound absorbing performance for noise frequency characteristics of vehicle. Consequently, it is possible to ensure water permeability performance for a long time and suppress noise of vehicle effectively.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a water-permeable pavement, and more particularly to a water-permeable pavement that is less likely to be clogged and has elasticity or sound absorption.

[0002]

BACKGROUND OF THE INVENTION A commonly used road pavement is asphalt pavement. Asphalt pavement is roughly classified into dense-grained asphalt pavement and open-grained asphalt pavement. Dense-grained asphalt pavement aggregates have a maximum particle size of 15 to 15
It is composed of gravel, sand, etc. mixed in a wide range up to about mm in almost the same proportion. Aggregate of open-grained asphalt pavement has a majority of gravel with a grain size of 5 to 13 mm (eg 85
%). These aggregates form a pavement structure by the arching action of the aggregates and the gripping force of the binder (asphalt), and water can flow down through the gaps between the aggregates. Therefore, the open particle size asphalt pavement has water permeability. The water-permeable pavement having such a structure is also called porous pavement or drainage pavement.

[0003]

The conventional water-permeable pavement represented by the open-grain size asphalt pavement has the following three problems or problems. Deterioration of water permeability The gaps between aggregates are clogged with dust and abrasion dust on the pavement. As a result, it becomes difficult for water to pass through the gap,
Water permeability deteriorates. In that case, at present, the road surface must be dug up and the pavement must be redone (renovation).

Need for further noise reduction The problem of noise in urban road traffic is extremely serious due to the overcrowding of cities, the increase in traffic volume, and the increase in size of vehicles. In order to alleviate this problem, various measures have been taken such as improvement of vehicles and tires (groove shape, etc.), installation of soundproof walls, improvement of road structure. The water-permeable pavement has been recently adopted mainly for the purpose of preventing slip due to a pool of ruts, but it is recognized that the surface structure has a sound absorbing property and has a certain noise reducing effect. However, there is a demand for further reduction of pumping noise (a noise caused by compression / expansion of gas in a small space composed of a road surface and a tire tread), which is one of the causes of noise in high-speed vehicles.

Control of sound absorption frequency characteristics on pavement Vehicle speeds are different between highways and general roads, and therefore the frequency spectrum of noise emitted by vehicles is also different. It is said that when the speed is slower than 60 km / h, engine sound such as engine sound is excellent, and when the speed is faster than 60 km / h, the tire noise corresponding to the tire tread (groove) is excellent.
In general, noise in the high frequency region is large in the high speed region, and noise in the low frequency region is large at the low speed region. Thus, there is a demand for a pavement having a sound absorbing mechanism that matches noise with different frequency characteristics.

[0006] The present invention makes it possible to prolong the water permeability, further reduce the pumping sound when the vehicle is running, and further exhibit a sound absorbing effect corresponding to the vehicle noise frequency characteristic which changes under the influence of the vehicle speed. The object is to provide a water-permeable pavement that can be made.

[0007]

In order to achieve the above object, the water-permeable pavement according to the first aspect of the present invention is a water-permeable pavement including pores under a water-permeable pavement composed of aggregates and inter-aggregate communication gaps. A characteristic elastic layer is provided.

In order to control the sound absorption frequency characteristics of the pavement,
The water-permeable pavement of the second aspect of the present invention further comprises, under the water-permeable elastic layer, a sound-absorbing layer formed of a laminate of particles having a particle size configuration and a layer thickness adjusted according to the sound waves to be absorbed. Has been.

All the objects of the present invention are also solved by the water-permeable pavement of the third aspect of the present invention. That is, the water-permeable pavement of the third aspect is a water-permeable pavement layer consisting of aggregates and inter-aggregate communication pores; the particle size configuration and layer thickness provided under the water-permeable pavement layer correspond to the sound waves to be absorbed. A sound-absorbing layer composed of a laminated body of adjusted particles; and a water-permeable elastic layer provided thereunder;
It is characterized by consisting of.

[0010]

The function of preventing the clogging of the gap between the aggregates, which is the cause of the deterioration of the water permeability, will be described. The elastic layer below the water-permeable pavement layer is compressed by the weight of the vehicle when passing through the vehicle, and expands and restores after passing through. At this time, the pavement layer swings up and down, and along with this, the sand dust that has accumulated in the aggregate gap is discharged to the outside of the pavement surface or falls into the void in the elastic layer. By stacking such actions, clogging of the water-permeable pavement is suppressed. The elastic layer is preferably composed of particles made of an elastic material and voids between the particles. This is because it has excellent storage and passage of dust. Furthermore, it is more preferable that the above-mentioned sound absorbing layer is provided below the elastic layer, because the sand dust will be stored between the particles in the sound absorbing layer.

Regarding the pumping sound, the presence of the elastic layer alleviates the increase in the pressure of the air compressed in the space formed between the tire tread and the road surface (the road surface is dented), and when the compressed air expands. The noise, which is the bursting sound of the noise, is reduced.

The operation of controlling the sound absorption frequency characteristic of the pavement will be described. The sound absorption characteristics depend on the particle size in the sound absorption layer, the thickness of the sound absorption layer, the porosity of the elastic layer, the thickness of the elastic layer, and the like. Regarding the influence of the particle size, generally, the peak of the sound absorption coefficient becomes clear as the particle size increases. When the thickness of the sound absorbing layer is increased, the frequency at the peak position shifts to the low sound range and the frequency band of sound absorption is widened. In addition, when there is an air layer behind (lower side) the sound absorbing layer, the peak of the sound absorbing coefficient tends to move to the low frequency region as the thickness increases. Their properties are summarized in Table 1. By combining these, it corresponds to the frequency characteristics of vehicle noise,
The sound absorption performance can be optimized. The dominant frequency of the pumping sound changes to a higher frequency range as the tire rotation speed (vehicle speed) increases. From this, the highway
It can be said that a sound absorbing layer structure having a high sound absorbing coefficient in the high frequency range should be adopted. Which of the first, second and third aspects of the present invention is selected depends on which of drainage and sound absorption is to be emphasized.

[0013]

[Table 1]

[0014]

Embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a diagram showing a structure of a water-permeable pavement according to an embodiment of each aspect of the present invention. (A) is an example of the water-permeable pavement according to the first aspect of the present invention, and is characterized in that the water-permeable elastic layer 3 is provided below the water-permeable pavement layer 1.
The water-permeable pavement 1 of this embodiment is a general open-grain size asphalt pavement, and its thickness is preferably 30 mm or more. Other types of water permeable pavements can also be used.

The water-permeable elastic layer 3 of the present embodiment is formed by asphalt-adhering a rubber tire portion of an old tire into granular chips of about 5 to 20 mm. 20 to 4 thickness
0 mm is preferred. There is no asphalt between the chips and there are voids. Due to this void, sand dust or the like can fall from the water-permeable pavement 1 into or through the water-permeable elastic layer 3. Moreover, the elasticity of this layer becomes appropriate when appropriate voids are present.

In addition, as an example of the structure of the water-permeable elastic layer 3, a structure in which a chip-like elastic substance is mixed with aggregate such as crushed stone and the elasticity can be adjusted by the mixing ratio is also preferable. Alternatively, a crushed stone coated with a rubber-like material may be deposited.

The ground 7 may be ordinary concrete or asphalt pavement. When it is necessary to discharge the permeate into the ditch of the road, it is particularly desirable as the foundation structure of the water-permeable pavement of the present invention that a surface treatment and a slope are provided so that the permeate can be discharged to the left or right of the road. It is a non-permeable pavement attached. If there is a groove with a width and depth of several mm along the gradient direction, drainage can be done more effectively. An example of the groove shape is shown in FIG.
It shows in (A). The shape of the groove may be a rectangular drain groove 21, a triangular drain groove 23, a semicircular drain groove 25, or the like. It is preferable to select the dimensions of the grooves and the particles so that the particles constituting the water-permeable elastic layer 3 and the sound absorbing layer 5 bridge the grooves. Instead of the groove, as shown in (B), a water-permeable drain pipe 3
1, 33, 35 may be laid. As the pipe, unglazed ceramic pipe or porous plastic pipe can be used. To make a groove on the roadbed, the roller of the road roller may be provided with a protrusion and pressured.

FIG. 1B shows an embodiment of the water-permeable pavement according to the second aspect of the present invention. The feature of this embodiment is that the sound absorbing layer 5 is further provided under the water-permeable pavement of the first embodiment. In this embodiment, the sound absorbing layer 5 is formed by depositing a granular aggregate having a size of about 10 to 20 mm and made of a glassy granular material remaining after the dust incineration process to a thickness of 20 to 40 mm.
Besides, granules of appropriate size such as granular perlite, gravel, and smelting slag can be used.

FIG. 1C shows an embodiment of the water-permeable pavement according to the third aspect of the present invention. The feature of this embodiment is that the water-permeable pavement layer 1, the sound-absorbing layer 5, and the water-permeable elastic layer 3 are layered in this order from the top. In this aspect, the sound absorbing layer 5
However, it is directly below the water-permeable pavement layer 1 and accepts dust falling from the water-permeable pavement layer 1. Further, since the sound absorbing layer 5 is near the road surface, the sound absorbing effect is high. The water-permeable elastic layer 3 of this embodiment may not have a void for receiving dust. Therefore, it may be a sheet-shaped or belt-shaped rubber band or waste plastic band. Further, such a sheet or belt may be provided with a cut for allowing water to flow down.

FIG. 2 is a conceptual diagram showing a situation in which a tire of a vehicle passes on the water-permeable pavement of the second embodiment. The water permeable elastic layer 3 is dented by the load from the tire 11. Tire 11
When the water-permeable elastic layer 3 is restored (springback) after passing, the dust 13 or the like that was about to be trapped in the air-permeable pavement layer 1 is discharged to the air gap on the road surface or in the sound absorbing layer 5. For this reason, clogging in the water-permeable pavement layer 1 is prevented (suppressed).
To be done.

FIG. 3 is a graph showing the relationship between the thickness of the sound absorbing layer and the sound absorption coefficient frequency characteristic. It is shown that as the sound absorption layer becomes thicker, the peak of the sound absorption coefficient broadens and sound can be absorbed in a wide band. On a general road, the predominant frequency of noise is about 300 to 800 Hz, so the thickness of the sound absorbing layer is preferably around 20 to 80 (particularly 40 to 60) mm. On highways, the dominant frequency of noise is approximately 800-
Since it is 1,200 Hz, it is suitable that the thickness of the sound absorbing layer is 60 mm or more. Regarding the total thickness of the sound absorbing layer, the water permeable pavement layer, and the elastic layer with voids, it has been shown that the peak of the sound absorbing characteristic becomes gentler, that is, the band becomes broader, as the whole becomes thicker. . A wide band is preferable for absorbing noise of a wide frequency.

FIG. 4 shows the thickness (mm) of the space L behind the sound absorbing layer.
It is a graph showing the relationship between the sound absorption coefficient frequency characteristics. In the present invention, when the elastic layer 3 of FIG. 1C has a structure with a high porosity, this layer acts as a back space. It is shown that the sound absorption peak shifts to the lower frequency side as L becomes thicker.

[0023]

As is clear from the above description, the water-permeable pavement of the present invention exhibits the following effects. Since the water-permeable pavement is less likely to be clogged, the water-permeable performance of the water-permeable pavement can be prolonged. Since the elasticity of the road surface is increased and the air compression between the tire and the road surface is reduced, the pumping noise of the tire is reduced.

When a sound absorbing layer is provided, vehicle noise is reduced.
It can absorb sound in a place near the sound source and with a wide sound absorbing area, and exhibits a better sound absorbing effect than sound barriers around roads. The application of the present invention is a serious problem in a part of an urban highway where an expressway and an ordinary road are provided (especially an elevated expressway on the ordinary road), such as a sound reverberation and a standing wave under the elevated road. Is highly effective. By appropriately selecting the particle size, thickness, aggregate used, etc. of the sound absorbing layer, it is possible to effectively suppress noise having a wide variety of frequency characteristics. Contributing to solving various problems related to roads, such as preventing traffic accidents due to long-lasting road permeability, smoothing traffic by extending road repair cycles, improving the environment by absorbing road noise, preventing landscape deterioration due to the existence of unpretentious soundproof walls, etc. Is large.

[Brief description of drawings]

FIG. 1 is a diagram showing a structure of a water-permeable pavement according to an embodiment of each aspect of the present invention.

FIG. 2 is a conceptual diagram showing a situation in which a tire of a vehicle passes through a water-permeable pavement of a second aspect.

FIG. 3 is a graph showing the relationship between the thickness of the sound absorbing layer and the sound absorption coefficient frequency characteristic.

FIG. 4 is a graph showing the relationship between the thickness (mm) of the back space L and the sound absorption frequency characteristics.

FIG. 5 is a diagram showing an embodiment in which various drainage grooves and drainage pipes are provided in the ground.

[Explanation of symbols]

 1 Water-permeable pavement layer 3 Water-permeable elastic layer 5 Sound absorption layer 7 Ground 11 Tire 13 Sand dust 21, 23, 25 Drainage channel 31, 33, 35 Drain pipe

Claims (3)

[Claims] 1. A water-permeable pavement characterized in that a water-permeable elastic layer including voids is provided under the water-permeable pavement composed of aggregates and inter-aggregate communication gaps. 2. The sound-absorbing layer comprising a laminated body of particles, the particle size composition and layer thickness of which are adjusted in accordance with the sound wave to be absorbed, under the water-permeable elastic layer. Permeable pavement. 3. A water-permeable pavement layer composed of aggregates and inter-aggregate communication pores; and a layer of particles having a particle size constitution and layer thickness adjusted corresponding to the sound waves to be absorbed A sound absorbing layer composed of a body; and a water-permeable elastic layer provided thereunder;
A water-permeable pavement characterized by being made of.