JP4599233B2 - Substructure of water retention pavement - Google Patents

Description

  The present invention relates to a substructure of a water-retaining pavement, and more specifically, to form the surface of a water-retaining pavement in order to always exhibit the effect of alleviating the heat island phenomenon of the water-retaining pavement, particularly the water-retaining pavement, regardless of the weather. The present invention relates to a lower structure of water retention pavement having a function of supplying water toward the inside of the water retention pavement layer.

  In recent years, the heat island phenomenon has become a problem. The main causes are that the evaporation of water from the natural ground is hindered by asphalt pavement and concrete structures, etc., the increase in radiant heat due to their heat storage and reflection, the increase in exhaust heat due to air conditioning of buildings etc., and The effect of exhaust gas heat from vehicles. Here, road pavement made of asphalt, etc., has a black color tone, so it easily absorbs sunlight and rises in surface temperature, and is one of the causes of the heat island phenomenon, especially in urban areas where the road pavement ratio is high. Yes.

  As efforts in the field of road pavement to alleviate this heat island phenomenon, it has been proved that it is effective to lower the pavement surface temperature by water retentive pavement through verification by a public institution. The pavement that has been made is adopted. Here, the water-retaining pavement is a pavement having a function of absorbing and retaining water in the pavement. For example, the heat island mitigating action of a water retentive pavement is carried out by keeping rainwater or the like inside the pavement and evaporating the rainwater during clear weather to take away the heat of vaporization and thereby reducing the pavement surface temperature.

  However, water-retaining pavements generally have limited water retention capacity, while the water supply by rainwater depends on the weather. For example, in midsummer, if it does not rain for a few days, it evaporates immediately. The water retention status is zero. For this reason, in order to always have the function of lowering the road surface temperature on the paved road surface, water must be periodically supplied by a watering vehicle, and a large cost is required for its maintenance and management. It had been.

  As a solution to this, for example, a water-absorbing pavement structure that absorbs water from a rainwater storage facility that stores rainwater buried underground and supplies the water into the surface water-retaining pavement layer (see, for example, Patent Document 1), roads. A water retention mixture layer constituting the surface layer, a water supply channel board provided under the water retention mixture layer for supplying moisture to the water retention mixture layer, a water supply material capable of impregnating moisture provided under the water supply channel board, A water storage unit for storing water to be supplied to the water supply material, and a water supply type water retention pavement for cooling the road surface by supplying the water supplied from the water storage unit to the water supply material to the water retention mixture layer through the water supply channel (for example, , See Patent Document 2), and comprises an open particle size mixture layer having continuous voids inside and a filler having water retention and hygroscopicity filled in the continuous voids, and moisture in the outside air is absorbed by the hygroscopic material. Along with its moisture Retentive pavement structure so as to water retention with water agent (for example, see. Patent Document 3) have been proposed.

However, in these proposals, if rainwater storage facilities are installed at the lower part of the water-retaining pavement and measures are taken to supply water, equipment costs and maintenance costs are incurred. In the case of a filler having a hygroscopic agent, the hygroscopicity is limited and the cost is high, so neither proposal is economically advantageous.
From the above situation, there is a demand for means capable of supplying water at a low cost toward the water-retaining pavement, in particular, the inside of the water-retaining pavement layer of the water-retaining pavement.

JP 2004-293098 A (first page, second page) Japanese Patent Laying-Open No. 2005-2575 (first page, second page) Japanese Patent Laying-Open No. 2005-68900 (first page, second page)

  In view of the above-mentioned problems of the prior art, the object of the present invention is to form the surface of the water-retaining pavement, in order to always exert the effect of alleviating the heat island phenomenon of the water-retaining pavement, especially the water-retaining pavement, regardless of the weather. An object of the present invention is to provide a lower structure of a water-retaining pavement having a function of supplying water toward the inside of the water-retaining pavement layer.

  In order to achieve the above-mentioned object, the present inventors conducted extensive research on the roadbed structure of the water-retaining pavement. As a result, the present inventors have found that a substructure having a function of supplying water into the water-retaining pavement layer forming the surface of the water-retaining pavement can be obtained.

That is, according to the first invention of the present invention, by adding hemihydrate gypsum as a solidifying agent to earth and sand between the water-retaining pavement layer (A) and the foundation ground (C), and mixing and stirring and rolling the mixture. the resulting, Ru is composed of two layers of sand and crushed stone layer, by installing the lower structure (B) having a coefficient of permeability (k) satisfying the equation (1) below, (a) / (B) / With the layer configuration of (C), the lower structure of the water-retaining pavement is provided, which sucks up water in the foundation ground and has a function of supplying water to the water-retaining pavement layer.
5 × 10 ⁻³ >k> 10 ⁻⁶ (1)
(Here, the unit of k is cm / sec.)

  According to a second aspect of the present invention, there is provided the lower structure of the water-retaining pavement according to the first aspect, wherein the earth and sand is at least one selected from sand, crushed stone, and locally generated soil. Provided.

According to the lower structure of the water-retaining pavement of the present invention, in the first invention, it is not necessary to install a separate water supply facility for the water-retaining pavement, and the water-retaining pavement layer is highly energy efficient. The water in the ground can be supplied to the inside, and this makes it possible to always demonstrate the effect of mitigating the heat island phenomenon of water retention pavement, especially water retention pavement, regardless of the weather. The economic value is extremely high. In addition, by measuring the water permeability coefficient of the substructure and adjusting it to a predetermined value, it is possible to manage the water permeability to be favorable, so the type and amount of the solidifying material for the earth and sand to be used are optimized. Useful means can be obtained, for example, for determination of the blending ratio by pre-measurement. Moreover, since it can guarantee the cushion function and the function of retaining the earth strength with appropriate water permeability, it can be used for a wide range of applications such as a water-retaining pavement.

Moreover, according to 2nd invention, a suitable thing can be selected as earth and sand and a solidification material, and according to the use of a water retention pavement, an effect can be exhibited more.

Hereinafter, the lower structure of the water-retaining pavement of the present invention will be described in detail.
The substructure of the water-retaining pavement of the present invention is obtained by adding hemihydrate gypsum as a solidifying material to the earth and sand, mixing and stirring and rolling between the water-retaining pavement layer (A) and the foundation ground (C). , Ru is composed of two layers of sand and crushed stone layer, by installing the lower structure (B) having a coefficient of permeability (k) satisfying the equation (1) below, (a) / (B) / (C ), The water in the foundation ground is sucked up and the water supply function to the water-retaining pavement layer is given.
5 × 10 ⁻³ >k> 10 ⁻⁶ (1)
(Here, the unit of k is cm / sec.)

  In the present invention, it is important to use soil and sand imparted with water permeability by capillary action by adding a solidifying material to the soil and mixing and agitating and rolling it as the lower structure of the water-retaining pavement. In other words, by installing this substructure between the water-retaining pavement layer and the foundation ground, it has the function of supplying underground water to the inside of the water-retaining pavement layer that forms the surface of the water-retaining pavement by capillary action. The substructure having is obtained. Therefore, the effect of relieving the heat island phenomenon caused by the water-retaining pavement can always be exhibited regardless of the weather. At the same time, it is possible to improve the workability of the lower structure and to impart a function of maintaining the earth strength to the lower structure.

First, the outline of the present invention will be described with reference to the drawings. FIG. 1 shows a conceptual diagram of water supply in a water retention pavement using a lower structure including a lower structure having a capillary action according to the present invention.
In FIG. 1, a lower structure 3 is installed between a water-retaining pavement layer 1 such as a water-retaining pavement material and a water-retained block material, and a foundation ground 2 in which natural soil is leveled. Here, water is supplied from the foundation ground 2 to the water-retaining pavement layer 1 through the lower structure 3. That is, when the water in the water retention part 4 in the water retention pavement layer 1 is evaporated, the water retention part 5 is formed from the water storage part 5 formed in the foundation ground 2 in a natural state via the water supply path 6 by capillary action. Water is sucked up by the part 4. In addition, the water of the water storage part 5 is replenished by the rain water or the underground water vein which oozed into the ground.

  By the way, in the lower structure of the conventional water retention pavement, various roadbed structures are taken according to the use of the road surface to be paved, such as a sidewalk, a plaza, and a roadway. For example, a sand cushion (sand) layer, a water-permeable bitumen stabilization treatment layer, a crusher run (crushed stone) layer, a filter layer, and the like are appropriately provided between the water-retaining pavement layer and the foundation ground. Here, the purpose of the sand layer is to finish the pavement smoothly, and the purpose of the crushed stone layer is to disperse the strength. Usually, the sand or crushed stone used in these layers has a coarse particle size. For this reason, the conventional sand layer and crushed stone layer are suitable for the purpose of passing water from the water-retaining pavement layer to the lower part, but do not have a function of sucking water from the lower foundation ground. Therefore, even if there is water in the foundation ground below them, if these layers are provided, the water supply to the inside of the water-retaining pavement layer will be cut off, and the water in the ground can be used effectively. could not.

  On the other hand, in the pavement using the lower structure of the water-retaining pavement of the present invention, the lower structure prepared so as to have a water permeability by capillary action by adding a solidifying material is effective from the lower foundation ground. It can absorb water well and make effective use of underground water.

The lower structure of the present invention is composed of a lower structure having water permeability by capillary action in contact with the water-retaining pavement layer and a foundation ground prepared by leveling soil in a natural state.
As the above-mentioned substructure, in addition to the single-layer structure of locally generated soil, sand, crushed stone, or a mixture thereof, the function of maintaining a cushion function and earth resistance appropriate for road surfaces such as sidewalks, plazas, and roadways Therefore, a roadbed structure composed of a plurality of layers having a predetermined earth bearing strength, thickness, etc. can be taken. For example, a sand layer, a crushed stone layer, a mixed layer thereof, and a combination thereof, which have water permeability by capillary action, and a combination thereof are appropriately used. In particular, a two-layer structure of a sand layer and a crushed stone layer made of locally generated soil or procured sand, crushed stone, and the like is selected depending on the characteristics of the locally generated soil, easily available earth, and the use of a paved road surface.

  Further, if necessary, water permeability having a desired water permeability between the water-retaining pavement layer and the lower structure, between the layers constituting the lower structure, or between the lower structure and the foundation ground. A water-absorbing sheet such as a non-woven fabric having a desired water-absorbing property or a desired water-absorbing property can be provided.

  As the sand layer, the crushed stone layer, and the mixed layer thereof, those in which the void diameter inside the earth and sand is adjusted by adding a solidifying material, mixing, stirring and rolling it are used. As a result, the desired water permeability is maintained by providing a capillary action inside the sand layer, the crushed stone layer, and their mixed layer, and the underground water is supplied from the soil of the lower foundation ground to the upper water-retaining pavement layer. The function can be maintained.

  The lower structure is prepared by adding a solidification material to the earth and sand, mixing and agitating and rolling it so that water permeability due to capillary action is maintained. That is, the water permeability by the capillary action is achieved by changing the kind and blending amount of the solidifying material, the mixing method, etc., and adjusting the pore diameter of the earth and sand to give the lower structure the desired water permeability. . And since the preparation prepared by the said method has favorable workability | operativity, a lower structure is formed by laying | laying the said preparation on the foundation ground leveled.

  The mixing and stirring is not particularly limited, and for example, using a mixing device such as a stabilizer, the solidification material is dispersed in the earth and sand and has a desired water permeability. Further, the rolling pressure is performed using a compacting machine such as a vibrating roller so that the solidified material dispersed in the earth and sand is in close contact with the earth and sand and has a desired water permeability.

  The earth and sand are not particularly limited, and examples thereof include at least one selected from sand, crushed stone, and locally generated earth that can be easily procured. In general, the locally generated soil includes cohesive soil that is substantially impermeable, silt with low permeability, sand-silt-clay mixed soil, such as coarse sand with high permeability, gravel, and the like. Among these, for example, it is economically preferable to use locally generated soil as a main material according to the use of the above-described paved road surface, and to mix and use sand, crushed stone, etc. in consideration of ground strength.

  The solidifying material is not particularly limited, and at least one selected from gypsum, cement, lime, or clay mineral having an action of improving the water permeability of the earth and sand is used. Here, as the gypsum-based solidifying material, hemihydrate gypsum having a property of setting and hardening, for example, commercially available calcined gypsum is preferable. The cement-based solidifying material is appropriately selected from commercially available cements such as super fast hard cement, ordinary Portland cement, ultra-high strength cement, early strength cement, and blast furnace cement. Examples of the lime-based solidifying material include powders such as quick lime, slaked lime, and calcium carbonate. Examples of the clay mineral include powders such as kaolinite and bentonite.

  In the selection of the solidifying material, it is desirable to perform the appropriate water permeability depending on the degree of water permeability inherent in the earth and sand to be used. For example, in the case of clay soil that is substantially impermeable to water, the soil is aggregated by using a coagulating and hardening solidifying material such as lime and hemihydrate gypsum so that the water permeability is improved. Moreover, in the case of gravel with high water permeability, it modifies so that water permeability may be reduced using the said solidification material. Further, in the case of sand having a medium water permeability, the water is raised to a more appropriate water permeability using any of the above solidifying materials.

  The blending amount of the solidifying material is not particularly limited, so that the desired water permeability can be obtained in the lower structure depending on the type of earth and sand used, and the workability and the earth strength of the obtained lower structure. However, usually 3 to 20% by weight is used with respect to earth and sand.

  The water permeability coefficient (k) of the lower structure used in the present invention is not particularly limited, but it is possible to adjust the type, blending amount, etc. of the solidifying material so as to satisfy the following formula (1). In order to obtain a desired water permeability, it is preferable. Furthermore, it is more preferable to adjust so as to satisfy the following formula (2).

5 × 10 ⁻³ >k> 10 ⁻⁶ (1)
10 ⁻³ >k> 10 ⁻⁵ (2)
(Here, the unit of k is cm / sec.)

That is, when the water permeability coefficient (k) is less than 10 ⁻⁶ , the water permeability is very low, so that the adsorption is excellent and the water supply function by capillary action is hardly exhibited. On the other hand, when the water permeability coefficient (k) exceeds 5 × 10 ⁻³ , the water permeability is high and the water permeability is superior, so that the water supply function by capillary action is hardly exhibited.

  Moreover, the kind of solidification material with respect to the earth and sand to be used, and the compounding quantity can be optimized by measuring the water permeability coefficient of the prepared lower structure. In particular, in selecting a solidifying material, the blending ratio can be determined by prior measurement with a test specimen, which is a useful means for design and construction.

The water-retaining pavement layer used in the present invention is not particularly limited, and is constructed using a commonly used water-retaining pavement material, or a water-retaining block material such as a water retentive inter, a water retentive flat plate. It is. In particular, those having continuous voids connected to the water retaining portion inside and not impeding water permeability from the lower portion are used.
Examples of the water-retaining pavement material include composite materials in which a water-retaining filler is added to voids in porous materials such as water-permeable asphalt mixture, cement concrete, cement mortar, and petroleum resin mixture. Examples of the water-retaining block material include a porous molded block made of the composite material and a ceramic sintered body. For example, a space formed between a coarse aggregate such as asphalt pavement, a fine aggregate or the like is filled with a water retention material, a moisture absorption material or the like. Here, as the aggregate, for example, crushed stone, gravel, slag, sand, recycled aggregate and the like are used as appropriate, and rocks such as slaked lime, cement, fly ash, limestone and the like are pulverized as a filler and a hardener. Stone powder etc. can be used.

  The water-retaining material is not particularly limited, and those having properties that prevent volume change and expansion during water absorption and sufficient suction capacity are used, but coal ash clinker, ceramic tile, brick crushing A thing etc. are preferable. The hygroscopic material is not particularly limited, and calcium chloride, silica gel, activated alumina, zeolite and the like are used. These are usually poured into the voids in the form of milk after the asphalt pavement or the like is cured.

Hereinafter, the present invention will be described in more detail by way of examples and comparative examples of the present invention, but the present invention is not limited to these examples. In addition, the evaluation method of the hydraulic conductivity used by the Example and the comparative example is as follows.
(1) Measurement of water permeability coefficient: Conducted by a constant water level permeability test.

Example 1
Using sand with a permeability coefficient (k) of 2 × 10 ^-1 cm / sec as earth and sand, solidifying material is mixed with it to obtain a lower structure material, which is used for the lower structure of water-retaining pavement The water supply function by capillary action was investigated.
Mix and stir and compact 3 parts by weight of hemihydrate gypsum as a solidifying material for 100 parts by weight of the above sand to create a lower structural material, and after curing in air for 4 days, measure its water permeability. did. As a result, the water permeability coefficient (k) of the lower structural member was 2 × 10 ⁻³ cm / sec, and the desired water permeability was obtained.
Next, the lower structure material was laid with a thickness of 5 cm on a normal foundation ground, and a 5 cm water-retaining pavement material was further laid thereon. After that, in order to investigate the water supply function, the surface of the water-retaining pavement layer was heated at 900 W / m ² corresponding to a sunny day in summer for 4 hours to evaporate the water in the water-retaining pavement, and the amount of water contained Remeasured. As a result, it was confirmed that there was no change in the amount of water before and after, and that it had a water supply function by capillary action.

(Example 2)
As the solidifying material, except that 4 parts by weight of a mixture obtained by blending hemihydrate gypsum and blast furnace cement at a weight ratio of 80:20 was used, the same operation as in Example 1 was performed to obtain a lower structure material, The hydraulic conductivity was measured. As a result, the water permeability coefficient (k) of the lower structure material was 7 × 10 ⁻⁴ cm / sec, and a desired water permeability was obtained.
Next, the lower structure material was laid with a thickness of 5 cm on a normal foundation ground, and a water-retaining pavement material was laid with a thickness of 5 cm thereon. After that, in order to investigate the water supply function, the surface of the water-retaining pavement layer was heated at 900 W / m ² corresponding to a sunny day in summer for 4 hours to evaporate the water in the water-retaining pavement, and the amount of water contained Remeasured. As a result, it was confirmed that there was no change in the amount of water before and after, and that it had a water supply function by capillary action.

(Example 3)
Capillary action when using gravel with a water permeability coefficient (k) of 5 cm / sec as earth and sand to obtain a substructure material by blending it with a solidifying material and using it for the substructure of a water-retaining pavement The water supply function was investigated.
To 100 parts by weight of the above gravel, 10 parts by weight of a mixture obtained by blending hemihydrate gypsum and powdered clay as a solidifying material in a weight ratio of 50:50 is added, and the lower part is mixed and stirred and compacted. A structural material was obtained and the hydraulic conductivity was measured. As a result, the water permeability coefficient (k) of the lower structure material was 3 × 10 ⁻⁴ cm / sec, and a desired water permeability was obtained.
Next, the lower structure material was laid on a normal foundation ground with a thickness of 15 cm, and a water-retaining pavement material was further laid thereon with a thickness of 5 cm. After that, in order to investigate the water supply function, the surface of the water-retaining pavement layer was heated at 900 W / m ² corresponding to a sunny day in summer for 4 hours to evaporate the water in the water-retaining pavement, and the amount of water contained Remeasured. As a result, it was confirmed that there was no change in the amount of water before and after, and that it had a water supply function by capillary action.

Example 4
Using clay soil with a permeability coefficient (k) of 2 × 10 ⁻⁶ cm / sec as the earth and sand, solidifying material is blended into it to obtain the substructure material, which is used as the substructure of the water-retaining pavement material The water supply function by capillary action when used was investigated.
10 parts by weight of a mixture obtained by blending hemihydrate gypsum and lime at a weight ratio of 50:50 as a solidifying material is added to 100 parts by weight of the clay, and the mixture is stirred and stirred to form a lower structure material. And the hydraulic conductivity was measured. As a result, the water permeability coefficient (k) of the lower structure material was 5 × 10 ⁻⁵ cm / sec, and a desired water permeability was obtained.
Next, the lower structural body material was laid on a normal foundation ground with a thickness of 15 cm, and a water-retaining pavement material was further laid thereon with a thickness of 5 cm. After that, in order to investigate the water supply function, the surface of the water-retaining pavement layer was heated at 900 W / m ² corresponding to a sunny day in summer for 4 hours to evaporate the water in the water-retaining pavement, and the amount of water contained Remeasured. As a result, it was confirmed that 80% of the water content was recovered and had a water supply function by capillary action.

(Comparative Example 1)
On a normal foundation ground, sand having a hydraulic conductivity (k) of 2 × 10 ⁻¹ cm / sec is laid in a thickness of 5 cm as a substructure material, and a 5 cm water-retaining pavement material is further formed thereon. Laid. After that, in order to investigate the water supply function, the surface of the water-retaining pavement layer was heated at 900 W / m ² corresponding to a sunny day in summer for 4 hours to evaporate the water in the water-retaining pavement, and the amount of water contained Remeasured. As a result, the water content was not recovered, and the water supply function by capillary action was not confirmed.

  As is clear from the above, the lower structure of the water-retaining pavement of the present invention is a water-retaining pavement, in particular, Since the effect of alleviating the heat island phenomenon of a pavement can always be exerted without being influenced by the weather, it is suitable as a substructure of a water-retaining pavement. In addition, by measuring the hydraulic conductivity of the substructure, it is possible to adjust and optimize the type and amount of solidification material for the earth and sand to be used, and in particular, the blending ratio can be determined by preliminary measurement with a test specimen Therefore, it becomes a useful means in design and construction.

It is a figure showing the conceptual diagram of the water supply in the water retention pavement using the lower structure containing the lower structure which has a capillary action of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Water retention pavement layer 2 Foundation ground 3 Substructure 4 Water retention part 5 Water storage part 6 Water supply route by capillary action

Claims (2)

It is obtained by adding hemihydrate gypsum as a solidifying agent to the soil between the water-retaining pavement layer (A) and the foundation ground (C), mixing and agitating and rolling it, and it consists of two layers: a sand layer and a crushed stone layer. By installing a lower structure (B) having a water permeability coefficient (k) that satisfies the following formula (1) and forming a layer structure of (A) / (B) / (C), The substructure of water-retaining pavement, which sucks up the water inside and has the function of supplying water to the water-retaining pavement layer.
5 × 10 ⁻³ >k> 10 ⁻⁶ (1)
(Here, the unit of k is cm / sec.)   The substructure of the water-retaining pavement according to claim 1, wherein the earth and sand is at least one selected from sand, crushed stone, and locally generated soil.

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