JP5492589B2 - Water retention rooftop structure - Google Patents

Description

  The present invention relates to a water-retaining rooftop structure that is disposed on a waterproof layer constituting a rooftop and can maintain the water-retaining capacity of the rooftop.

  In recent years, problems peculiar to cities where man-made concentration has become obvious and have become social problems. For example, there is a phenomenon called heat island where the temperature in urban areas where population is concentrated is abnormally high compared to the surrounding non-urban areas. Various problems have been pointed out. For example, urban torrential rain is one of them, and it is thought that the heat island phenomenon, which is progressing rapidly, is partly responsible. By the way, most of the urban ground is paved with asphalt and concrete that cannot absorb water, and it is based on the flow of rainwater through sewers and rainwater pipes. It is a problem. In particular, in the case of the urban torrential rain described above, sewage pipes and rainwater pipes cannot handle rainwater, which often causes frequent urban flood damage in recent years. These issues are particularly noticeable in large cities with dense populations.

  Causes of the heat island phenomenon include a decrease in green spaces, watersides and bare land caused by development, a decrease in the amount of rainfall penetrating into the ground, a decrease in water retention capacity in the soil, and a decrease in evaporation and transpiration. Are listed. In addition, it has been pointed out that there is a vicious cycle in which as the heat island progresses, the cooling demand increases, which leads to an increase in exhaust heat and further promotes the heat island.

  As one of the means for solving the above-mentioned problems, many paving materials having water permeability and water retention and materials with high reflectivity have been developed (see Patent Document 1, Patent Document 2, etc.). The used water-permeable pavement, water-retaining pavement, and heat-shielding pavement have been widely adopted (see Patent Document 3). For example, Patent Document 1 proposes a permeability control material using a hardened material such as cement as a recycled aggregate using waste material such as glass waste. Concrete (hereinafter also abbreviated as ALC) is mentioned. Moreover, in patent document 2, the water retention block containing cement, an aggregate, and water retention materials, such as aerated concrete, is proposed, By controlling the average particle diameter of a water retention material, it becomes a water retention block simply. It is described that a communication hole can be provided. Patent Document 3 describes a water-retaining pavement structure having a pavement block on the surface layer and a cushion layer below the surface layer, and it is proposed to use cellular concrete particles as a water retentive material. .

  On the other hand, greening of cities has been promoted as a measure to alleviate the above-mentioned heat island phenomenon, and greening of rooftops of buildings and wall surfaces (green curtains) is often adopted. So far, it has been confirmed that buildings with rooftop greening can reduce reflected heat and reduce cooling in the summer due to the thermal effects of greening, which is expected as a measure to mitigate the heat island phenomenon. Has been. For this reason, some local governments may require rooftop greening under certain conditions. In addition, in recent years, the effects of water spraying and water spraying have been reviewed, and various measures have been attempted, such as a method in which local residents spray water at the same time, and a lawn is laid on the track of a tramway. Among these, rooftop greening is expected to have an effect on the mitigation of the heat island phenomenon as described above, and there is no complication such as watering or water spraying that forces local residents to move together. It is expected to be an effective policy that can contribute to the beautification of the city. There is also a proposal about making the rooftop structure excellent in external heat insulation as a floating floor system (see Patent Document 4).

JP-A-10-59756 JP 2003-252673 A Japanese Patent No. 3754693 JP-A-57-197348

  However, rooftop greening is not only costly when planting plants, but also requires subsequent management to maintain a greening state comfortably. There is a problem of forcing. Also, it requires a considerable amount of soil, and placing it on the roof is a heavy burden on the building, and it is necessary to make the structure of the building itself robust enough to withstand its weight while reducing the labor and cost. There is. For this reason, rooftop greening is not a simple measure that can be adopted in all buildings, and the development of a simpler measure that contributes to the mitigation of the heat island phenomenon is awaited.

  Accordingly, the object of the present invention is to contribute to the mitigation of the heat island phenomenon as well as rooftop greening, and in addition, high water retention is ensured by a simple means that can be adopted in all buildings, The goal is to develop a rooftop structure that can insulate and reduce the cost of air conditioning.

  The above object is achieved by the present invention described below. That is, the present invention is a water-retaining floor structure that is disposed on a waterproof layer constituting the roof and maintains the water retention of the roof, wherein the air layer, the substrate layer, The water-retaining material layer is laminated in this order, and the water-retaining material layer is mainly composed of two components of the lightweight cellular concrete and cement, and the ratio of the two components is the granularity of the lightweight cellular concrete. A water-retaining rooftop structure characterized by being a water-retaining panel having a large number of voids in which cement is 18 to 70 parts by mass with respect to 100 parts by mass of an object (surface dry state).

The following are mentioned as a preferable form of the said invention.
(1) Further, the above water-retaining rooftop structure in which a space layer of 3 to 5 mm is provided between the substrate layer and the water retention material layer.
(2) The water-retaining rooftop structure according to any one of the above, wherein a plurality of fine irregularities are formed on the surface of the substrate layer, and intermittent space layers are provided between the water-retaining material layers.
(3) The water-retaining rooftop structure according to any one of the above, wherein the water retention amount of the water retention panel is 0.35 g / cm ³ or more.
(4) The water-retaining rooftop structure according to any one of the above, wherein an absolute dry mass per unit area in the water-retaining panel is 25 kg / m ² or less.

  Thus, according to the present invention, like rooftop greening, high water retention can be ensured by a simple means that can contribute to alleviation of the heat island phenomenon and can be adopted in all buildings. Provided is a rooftop structure that can insulate the interior and reduce the cost of air conditioning.

It is sectional drawing which shows a preferable example of the rooftop floor structure of this invention. It is a schematic perspective view which shows a preferable example of the rooftop floor structure of this invention.

  Hereinafter, the present invention will be described in detail by giving preferred forms of the water-retaining rooftop structure of the present invention. As a result of intensive studies to solve the problems of the prior art described above, the present inventors have reached the present invention as follows. The rooftops of buildings concentrated in large cities have a waterproof layer that is exposed to the atmosphere, and a large amount of rainwater that falls on the rooftop and accumulates on the rooftop, especially when the rooftop is not greened. Flows into sewers and rainwater pipes through rain gutters. For this reason, in the event of the above-described urban torrential rain, etc., rainwater from the roof overflows from the sewer pipes and rainwater pipes and flows out in large quantities, which is a cause of urban flood damage. In view of this, the present inventors reduced the amount of rainwater that flows from the roof to the sewage pipes and rainwater pipes at once if the rooftop structure can retain and maintain as much rainwater as possible on the rooftop. It was possible to effectively prevent the occurrence of urban floods. In addition, if a water retention layer can be formed on the roof, temperature fluctuations inside and outside the building can be suppressed by the heat of vaporization required when water evaporates, and if the structure can be further improved in thermal insulation, it is necessary for indoor temperature adjustment. We thought that it was possible to further reduce the heating and cooling costs.

  In view of the above findings, the present inventors have conducted further studies. As a result, conventional materials having water permeability and water retention are mainly intended to be applied to paved roads. In addition, there is soil with excellent water permeability and water retention at the lower part of the paved road, and the basic structure is different. It was concluded that the structure should be developed. First, unlike the road, the rooftop structure of the building is not premised on walking. From this, it was considered that a material more suitable for the rooftop structure should have water retention first, satisfy a certain level of strength, and be desired to be lighter. As a result, it is sufficient for the water retention panel to have a strength of about 0.3 MPa as the bending strength, and for that purpose, it does not contain aggregates like conventional paved road materials, and lightweight lightweight concrete It has been found that the two components of granular material and cement can be constituted as main components. Furthermore, if such a water retention panel is used so that the relationship with the waterproof layer constituting the floor of the roof is a specific relationship, not only the water retention on the roof but also a high thermal insulation effect on the building. As a result, the present invention was found. Hereinafter, first, the water retention panel used in the present invention will be described.

<Water retention panel constituting the water retention material layer>
The water retention panel used in the present invention is composed mainly of two components of lightweight cellular concrete and cement, and the ratio of the two components is 100 parts by weight of lightweight cellular concrete (surface dry state). The cement is 18 to 70 parts by mass and has a large number of voids. More specifically, the bending strength may be about 0.3 MPa. The water retention panel used in the present invention does not use a general aggregate having a density of about 2.5 g / cm ³ that is usually used for concrete, and uses an ALC crushed product having a high water absorption rate. It is excellent in being lighter and more lightweight. The porosity is preferably 20% or more, more preferably high water retention and light weight by adjusting the composition ratio of the two components as described above so that the porosity is 30% or more. Can be made into a water retaining panel. Moreover, it is good to adjust so that the water retention amount may be 0.35 g / cm < ³ > or more, and the siphoning height may be 40% or more. Furthermore, the absolute dry density may be 1 g / cm ³ or less, more preferably 0.8 g / cm ³ or less. Furthermore, the absolute dry mass per unit area is preferably 25 kg / m ² or less in order to reduce the weight burden on the roof.

In the present invention, the water retention amount, wicking height, absolute dry density, bending strength and freeze-thaw of the water retention panel (water retention block) are values measured by the following methods, respectively. Each of these values has the following meaning.
(1) Water retention amount Interlocking block water retention test method (JIPEA-TM-7 (Interlocking Block Pavement Technology Association)), specimen size: 227 mm x 112 mm x thickness 60 mm. It is a property related to the water retention amount in the block product property, and is preferably 0.35 g / cm ³ or more.
(2) Suction height Interlocking block water absorption test method (JIPEA-TM-8 (Interlocking Block Pavement Technology Association)), specimen size: 227 mm × 112 mm × thickness 60 mm. It is a characteristic related to the evaporation performance of the block product characteristic, and is preferably 40% or more.
(3) Absolute dry density In the interlocking block water retention test method (JIPEA-TM-7 (Interlocking Block Pavement Technology Association)), the value obtained by dividing the absolute dry mass by the volume of the specimen, specimen size: 227 mm × 112 mm x thickness 60 mm. It is a property related to the absolute dry density of the block product property, and it is preferably 1 g / cm ³ or less, more preferably 0.8 g / cm ³ or less.
(4) Bending strength (durability index)
Interlocking block bending strength test method (JIS A-5371 precast unreinforced concrete product appendix 2 (regulation) pavement / boundary block recommended specification 2-3 interlocking block), specimen size: 227 mm x 112 mm x thickness 60 mm . Withstands light walks at 0.30 Mpa or higher.
(5) Freeze-thaw cycle conditions: −8 ° C. in air for 7 hours → + 20 ° C. in air for 15 hours → + 20 ° C. in water for 2 hours, specimen size: 200 mm × 200 mm × thickness 60 mm. And it was confirmed visually whether it was normal by repeating 100 cycles.

In order to obtain a water retaining panel satisfying the above characteristics, it is preferable to use lightweight cellular concrete particles having a size of 3 to 10 mm. Then, the composition ratio of the two components of lightweight cellular concrete and cement is 18 to 70 parts by mass of cement with respect to 100 parts by mass of lightweight cellular concrete particles (surface dry state). More preferably, the cement should be 25 to 35 parts by mass with respect to 100 parts by mass of the lightweight cellular concrete particles (surface dry state). If the cement is less than 18 parts by mass, the bending strength may not be 0.3 MPa, and cracks may occur during transportation and construction. On the other hand, when it exceeds 70 parts by mass, not only the weight of the water retention panel increases, but also a sufficient porosity cannot be obtained, resulting in poor water retention.
The surface dry state refers to a state in which the gap inside the aggregate is filled with water, but no water is attached to the surface.
The cement used in the present invention may be an ordinary hydraulic cement such as ordinary Portland cement. And, for example, at a blending ratio as described above, lightweight cellular concrete granules and cement are mixed to form a 500 mm square block with a thickness of about 30 to 50 mm, which is used as a water retention panel. To do. The sizes listed above are merely examples, and may be appropriately determined for manufacturing, transport, or construction reasons.

The lightweight cellular concrete (ALC) granules used to form the water-retaining panel are made by adding water, foaming agent, and other ingredients blended as necessary to the porous material. Can be used, for example, by curing by autoclave curing and then crushing. As a specific example of ALC, for example, concrete defined in JIS A 5416 (lightweight cellular concrete product cured by autoclave) can be mentioned. The concrete is obtained by mixing a calcareous raw material and a siliceous raw material in a powder state, and adding an appropriate amount of water, a foaming agent, and an admixture to make it porous, and then curing the autoclave [normally a gauge pressure of about 10 kgf / cm ² (temperature It is manufactured by being cured by saturated steam curing at about 180 ° C.). The size is about 3 to 10 mm.

<Substrate layer>
The board | substrate layer which comprises the floor structure of the roof of this invention is demonstrated. In the present invention, a so-called floating floor structure in which a substrate layer is provided via an air layer on a waterproof layer that maintains water retention on the roof, and further, the water retention panel described above is laminated thereon. Thus, the initial object of the present invention is achieved. In particular, in the present invention, the substrate layer is provided on the air layer in the floating floor structure. However, since the substrate layer is excellent in mechanical strength, damage due to the application of load is small and thin even in the floating floor structure. However, sufficient strength can be obtained. As a result, it is possible to provide a floor structure that is excellent in lightness and that has sufficient strength to withstand light walking. That is, as described above, the water retention panel constituting the water retention material layer can achieve higher water retention by using no aggregate, but on the other hand, it is lightweight and its strength is minimized. It will be fastened. Therefore, in the present invention, it is possible to maintain the surface strength of the floor by the substrate layer laminated on the lower side of the water retention material layer, thereby exhibiting high water retention and capable of withstanding light walking. Can be achieved.

Specific examples of the substrate layer constituting the roof structure of the roof of the present invention include reinforced mortar boards, precast concrete boards, GRC (glass fiber reinforced cement), inorganic composite building materials, and extrusion-molded boards. Inorganic materials that are lightweight and have high strength and that have high water resistance, corrosion, wear, chemicals, and frost damage are preferably employed. Among them, it is more preferable to use a GRC or a reinforced mortar board from the viewpoint of strength and light weight, and it is most preferable to use a reinforced mortar board from the viewpoint of economy and productivity.
The reinforced mortar plate is obtained by impregnating mesh fibers with mortar. The mortar contains cement and sand, and preferably contains 1% by mass or less of glass fiber in order to cope with fine cracks. Molded by the method.

<Floor structure>
The present invention relates to a water-retaining floor structure that maintains rooftop water retention, and an air layer and a substrate on a waterproof layer that maintains rooftop water retention that is also provided in a conventional rooftop structure of a building. The layer and the water retention material layer are laminated in this order. This point will be described in detail with reference to the drawings.

  Although a preferable example is shown in FIGS. 1 and 2, as a method of forming an air layer on the waterproof layer, for example, a mounting bracket having a support having a structure as shown in FIGS. 1 and 2 is used. Can be easily formed. That is, by using a mounting bracket having a structure as shown in FIGS. 1 and 2, the above-described substrate layer and water retention material layer (water retention panel) are integrated in a laminated state, such as By arranging a plurality of in a grid pattern, a laminate composed of a substrate layer and a water retention panel can be arranged over a wide area, and a rooftop floor structure can be formed. In addition, about the above-mentioned mounting bracket, it can obtain easily by referring to Unexamined-Japanese-Patent No. 57-197348 regarding a rooftop heat insulation structure, for example.

  At this time, the substrate layer and the water retention material layer (water retention panel) may be laminated in close contact with each other. However, according to the study by the present inventors, the substrate layer and the water retention material layer (water retention panel) are substantially between them as shown in FIG. It is more preferable to laminate in a state where a space layer (gap) of about 3 to 5 mm is provided. If it does in this way, it has the effect that water can be hold | maintained between a board | substrate layer and a water retention panel by the surface tension of water. Here, “substantially providing a space layer (gap)” is intended to have, for example, the following form. When the surface of the substrate layer is processed into a plurality of fine irregularities and contacted with the water retention material layer, a space layer of about 3 to 5 mm is partially provided, or rubber is interposed between the substrate layer and the water retention material layer. Or an adhesive is partially disposed, and a space layer is provided by providing a gap on the upper and lower surfaces.

The present invention will be described in more detail with reference to examples and comparative examples of the present invention.
Example 1
Water retaining panels 1 to 6 were prepared with the formulation shown in Table 1-1. Specifically, by using ordinary Portland cement as a binder, mixing ALC crushed product with a particle size of 3 to 10 mm and water, putting the mixture into a mold, demolding, and solidifying by cement hydration reaction Formed. The amount of water blended was the amount of water required for cement hydration and immediate demolding. The water retention panels 1 to 6 produced as described above were measured for porosity, water retention, suction height, absolute dry density, bending strength, and freeze-thaw, and are shown in Table 1-2. The void amount is a value of the void amount designed with the unit amount of the ALC crushed product being 604 kg / m ³ .

  The water retention amount per unit area, the block dry mass, and the like due to the difference in thickness of the water retention panel (water retention block) having the blending ratio as described above were tested, and the results are shown in Table 1-3. Three types of blocks having a block size of 500 mm square and thicknesses of 30 mm, 35 mm, and 40 mm were produced.

A test for indoor temperature reduction performance and evaporation performance was conducted when a water retention panel (water retention block) was laminated with a substrate layer, constructed as shown in FIGS. 1 and 2, and placed on the roof. Furthermore, a comprehensive evaluation is made by conforming to the selection conditions of block strength (kg / m ² ) and block water retention (L / m ² ) per unit area according to bending strength and set thickness. The results are shown in Table 1-3. As a result, in the water retention panels 3 to 6 satisfying the blending ratio defined in the present invention, good results were obtained. However, in the water retaining panels 1 and 2 where the blending ratio deviates, the water retention amount is not sufficient. It was found that indoor and outdoor temperature reduction performance is inferior.

The substrate layer used in the above uses mesh streaks in which iron wires processed into a corrugated shape with a height of a mountain for reinforcement of 6 mm are assembled in a 27 mm grid, and 0.4% of cement, sand, and glass fiber are added thereto. % Mortar mixed and molded into a size of 500 mm in length and width and 21 mm in thickness by a pressure press method was used.

Claims (5)

  It is a water-retaining floor structure that is disposed on a waterproof layer constituting the roof and maintains the water retention of the roof, and an air layer, a substrate layer, and a water retentive material layer are provided on the waterproof layer. The water-retaining material layer is composed mainly of two components of lightweight aerated concrete and cement, and the ratio of the two components is a lightweight aerated concrete granule (surface dry state). A water-retaining rooftop structure characterized by being a water-retaining panel having a large number of voids in which cement is 18 to 70 parts by mass with respect to 100 parts by mass.   Further, the water-retaining rooftop structure according to claim 1, wherein a space layer of 3 to 5 mm is provided between the substrate layer and the water retention material layer. Water retention roof floor structure according to claim 1 or 2 plurality of fine irregularities on the surface of the substrate layer is made form. The water-retaining rooftop structure according to any one of claims 1 to ³ , wherein the water-retaining amount of the water-retaining panel is 0.35 g / cm ³ or more. The water-retaining rooftop structure according to any one of claims 1 to 4, wherein an absolute dry mass per unit area in the water-retaining panel is 25 kg / m ² or less.

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