JP2024014168A - Water-permeable block - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a water-permeable block having high permeability, sufficient strength and light weight by focusing on calcined pumice.

SOLUTION: A frame part formed to surround an inner water-permeable part is provided, and the water-permeable part contains calcined pumice and a binder and is fixed to the frame part.

SELECTED DRAWING: Figure 1

COPYRIGHT: (C)2024,JPO&INPIT

Description

Application for application of Article 30, Paragraph 2 of the Patent Act Publication date: February 20, 2020, “Reiwa 3 Japan Society of Civil Engineers Western Branch Research Presentation Summaries” (CD-ROM), pp. 695-696, Japan Society of Civil Engineers Western Branch Public Interest Incorporated Association [Publications, etc.] Date: March 5, 2020, Conference name: ``2021 Society of Civil Engineers Western Branch Research Presentation'', Real-time presentation using the web conference system ZOOM

The present invention relates to water-permeable blocks laid on sidewalks and plazas.

Conventionally, instead of paving with asphalt, concrete blocks have been laid for sidewalks and plazas, depending on the landscape and desired functionality. Among concrete blocks, permeable blocks have the effect of reducing flooding on the ground surface and protecting and growing street trees and vegetation by allowing rainwater that falls on the ground to permeate underground.

On the other hand, in recent years, river gravel, river sand, sea sand, etc. used as aggregates for concrete have become difficult to obtain due to regulations and bans on their collection due to environmental considerations. Therefore, there is a need to secure alternative aggregate resources.

As such a technique, for example, a water retention controlled concrete product as shown in Patent Document 1 has been developed. The water retention controlled concrete product shown in Patent Document 1 is characterized by adding at least one slag selected from molten slag, electric furnace slag, and slowly cooled blast furnace slag to particles obtained by crushing waste concrete as an aggregate, and further adding cement to the particles obtained by crushing waste concrete. It is obtained by adding and mixing water, molding, and steam curing.

Japanese Patent Application Publication No. 2007-8733 (pages 4 to 5, Figure 1)

The water retention controlled concrete product shown in Patent Document 1 uses waste concrete and slag as alternative aggregates for river gravel, etc., and changes the mixing ratio of particles obtained by crushing waste concrete and slag. This is effective in that water permeability and bending strength can be changed by doing so. However, although the water retention control concrete products mentioned above meet the standard value of the permeability coefficient of the permeable block, 1.0×10 ^-2 cm/s, they cannot withstand the localized heavy rains that have been increasing in recent years. In addition, since particles of crushed waste concrete and slag are used as aggregate, the weight is heavy, making transportation, handling, and construction inconvenient.

The present invention was made with attention to such problems, and by focusing on calcined pumice, it is an object of the present invention to provide a water permeable block that has high water permeability, sufficient strength, and is lightweight. purpose.

In order to solve the above problems, the water permeable block of the present invention has the following features:
It has a frame portion formed to surround an inner water-permeable portion, and the water-permeable portion includes calcined pumice and a binder and is fixed to the frame portion.
According to this feature, the load applied from the outside is mainly borne by the frame part, and rainwater can pass through the permeable part, so the water permeable block can be made to have high strength, light weight, and high water permeability.

The calcined pumice stone is characterized in that it is calcined bora having a density of 1.2 to 2.0 g/cm ³ .
According to this feature, the strength of the water-permeable block can be increased because fired mulch, which has become denser and stronger due to compaction through firing, is used in the water-permeable portion.

The frame portion is characterized in that it includes the fired pumice and cement or mixed cement.
According to this feature, since mortar or concrete using calcined pumice and cement or mixed cement is used for the frame portion, the weight of the water permeable block can be reduced.

A particle size of the fired pumice included in the frame portion is smaller than a particle size of the fired pumice included in the water permeable portion.
According to this feature, the strength of the permeable block can be made even higher than that of an unfired block because fired pumice, which has become denser and stronger due to compaction through firing, is used for the permeable part and the frame part. can. Moreover, water permeability can be increased by making the particle size of the calcined pumice used in the water permeable part larger than that of the calcined pumice used in the frame part. Furthermore, since both the frame portion and the water-permeable portion contain calcined pumice and have the same properties, the calcined pumice stones are strongly bonded to each other, and the water-permeable portion can be firmly fixed to the frame portion.

It is characterized in that the binder is cement or mixed cement.
According to this feature, since the bondability with cement or mixed cement is good, the fixing strength between the water permeable part and the frame part is high, and the strength of the water permeable block can be increased.

The present invention is characterized in that the binder is a sintering aid.
According to this feature, by reducing the number of joints between calcined pumice stones, it is possible to form a water permeable part that has the same bending strength as a water permeable part using cement or mixed cement as a binder, and to increase the porosity. It is possible to form a water permeable part with high water permeability.

The sintering aid is characterized by having SiO ₂ as a main component and further containing 5 to 30 wt% of CaO.
According to this feature, by containing more CaO than the calcined pumice, the bondability (sinterability) between the calcined pumice stones can be improved, and the strength of the water-permeable block can be further increased.

A frame part having a space inside is molded, and a mixture containing calcined pumice and cement is filled and hardened inside the molded frame part to form a water-permeable part fixed to the frame part. It is said that
According to this feature, the water permeable part can be formed to match the shape of the inside of the previously molded frame part, so the water permeable part can be reliably fixed to the frame part. Furthermore, since it is hardened with cement, a water-permeable part can be formed uniformly within the frame part.

A mixture containing calcined pumice and a sintering aid is packed in a mold and fired together with the mold to form a water-permeable part, and a binder is applied around the water-permeable part removed from the mold. It is characterized in that a frame portion is formed at the bottom, and the water-permeable portion is fixed to the frame portion.
According to this feature, the frame part can be formed to match the shape of the periphery of the water-permeable part that has been previously formed, so that the water-permeable part can be reliably fixed to the frame part. Furthermore, since the water-permeable portion is formed using a sintering aid, the strength is further increased. Furthermore, since the binder is applied around the water permeable part, the water permeable part can be firmly fixed to the frame part.

(a) is a perspective view showing the water-permeable block in Example 1, and (b) is a plan view showing the water-permeable block. (a) is a cross-sectional view showing a water-permeable block in Example 1, and (b) is an enlarged cross-sectional view showing a frame portion and a water-permeable portion fixed to the frame portion. (a), (b), and (c) are a series of perspective views showing the method for manufacturing a water-permeable block in Example 1. (a) is a plan view showing a water permeable block in a modified example, and (b) is a sectional view showing a water permeable block in a modified example. (a) is a perspective view showing a state in which water-permeable blocks are laid in Example 1, and (b) is an explanatory diagram illustrating the water-permeable state of the water-permeable blocks that have been laid. (a) is a plan view showing a water-permeable block in Example 2. (b) is a sectional view showing a water permeable block in Example 2, and (c) is an enlarged sectional view showing a frame part of the water permeable block in Example 2 and a water permeable part fixed to the frame part. (a), (b), and (c) are a series of perspective views showing the method for manufacturing a water-permeable block in Example 2. is a graph showing the relationship between the firing temperature and the density of the fired mullet sample. is a graph showing the relationship between firing temperature and Vickers hardness of fired bora samples. is a graph showing the bending strength of mortar specimens. is a graph showing the relationship between the bending strength and the porous width X of a water-permeable block specimen. is a graph showing the relationship between the permeability coefficient and the porous width X of a permeable block specimen.

EMBODIMENT OF THE INVENTION The form for implementing the water-permeable block based on this invention is demonstrated below based on an Example. The materials, formulations, manufacturing conditions, etc. described in the following examples are examples of the implementation of the present invention, and are not limited thereto.

A water permeable block according to Example 1 will be described with reference to FIGS. 1 to 3. Hereinafter, the left side of the paper in FIG. 1(a) will be described as the front side (front side) of the water permeable block.

As shown in FIGS. 1(a) and 1(b), the water-permeable block 1 is mainly composed of a frame portion 2 that is approximately rectangular in plan view and a water-permeable portion 3 disposed inside the frame portion 2. ing. The frame portion 2 is formed of mortar using fired mullet 3a, which is fired pumice, as a fine aggregate.

As shown in FIGS. 2(a) and 2(b), the water-permeable portion 3 is formed by joining together fired bola 3a made of fired pumice with a cement paste 4. Further, the water-permeable portion 3 is fixed to the frame portion 2 by being joined to the inner circumferential surface 2a of the frame portion 2 with cement paste 4.

As shown in FIGS. 2(a) and 2(b), fired bora 3a is made by firing bora, which is a type of porous pumice, and has many pores 3b on the surface and inside. ing. Gaps 5 are formed between the fired mulch 3a joined with the cement paste 4 and between the fired mulch 3a and the inner circumferential surface 2a, making it easy for water to penetrate. Further, the water-permeable portion 3 is open on both the front surface (upper surface) and the back surface (lower surface). In addition, in FIG. 2, for convenience of explanation, the cement paste 4 is schematically shown as being provided around the firing mullet 3a with a thin and approximately uniform thickness, but in reality, the thickness of the cement paste 4 varies. There are also places where it exists between adjacent firing mullets 3a.

Next, a method of manufacturing the fired mullet 3a will be explained. Bora, which is the raw material for Baked Bora 3a, is pumice that is abundantly produced in the southern Kyushu region, so it can be effectively used as an alternative aggregate for river gravel, etc., which is subject to collection regulations and bans. At the same time, it is possible to mass-produce water-permeable blocks using Bora. In addition, since mullet is porous, it has the property of absorbing moisture and nutrients in an appropriate amount and has good drainage properties. Moreover, the Bora containing 67.2% _{of SiO2} , 20.1% _{of Al2O3} , 5.0% of _Fe2O3 , and 2.98% of _K2O was used. Table 1 shows an example of the chemical composition of mullet.

Mullet from Kagoshima Prefecture and Miyazaki Prefecture was used for producing baked mullet 3a. Further, for the water-permeable block 1, unfired mullet and fired mullet 3a fired at 900 to 1100° C. using an electric furnace were used.

Next, a method for manufacturing the water permeable block 1 will be explained. As shown in FIG. 3(a), first, mortar mixed with cement and water is filled into a square-shaped formwork when viewed from above, and then demolded and cured. The frame portion 2 is molded. By molding the frame portion 2 in advance, the production of the water permeable block 1 becomes easier. The mortar composition at this time was 1120 kg/m ³ of fired mullet 3a, 520 kg/m ³ of cement, and 260 kg/m ³ of water. In addition, in this specification, the particle size is classified by a sieve.

Next, as shown in FIG. 3(b), a mixture consisting of fired mulch 3a with a grain size of 4 to 7 mm and cement paste 4 is filled inside the molded frame part 2 and cured again to make it water permeable. Form part 3. The composition of the water-permeable part 3 at this time is 614 kg/m ³ of fired mullet 3a, 183 kg/m ³ of cement, and 42 kg/m ³ of water. As a result, the water-permeable block 1 in which the water-permeable part 3 is joined to the inner circumferential surface 2a and fixed to the frame part 2 is formed (FIG. 3(c)).

By doing so, the water-permeable part 3 can be formed to match the shape of the inside of the frame part 2 that has been molded previously, so that the water-permeable part 3 can be reliably fixed to the frame part 2. Further, since the water permeable portion 3 is hardened with the cement paste 4, the water permeable portion 3 can be uniformly formed within the frame portion 2. In other words, the voids 5 formed in the water-permeable portion 3 are distributed substantially evenly in the vertical and horizontal directions without significant deviation.

Next, a water permeable block 10 according to a modification will be described with reference to FIG. 4. Note that the same configuration and overlapping configuration as in the previous embodiment will be omitted.

As shown in FIGS. 4A and 4B, a bottom portion 6 coupled to the frame portion 2 is formed at a lower portion of the water permeable block 10 according to the modified example. The water-permeable part 3 (not shown) is bonded and fixed to the inner circumferential surface 2a, bottom surface 6a, and around the drainage hole 7 of the frame part 2 by the cement paste 4, so that it has higher strength than the water-permeable block 1. A water permeable block 10 can be provided.

Moreover, since the drainage hole 7 is formed in the bottom part 6, the water which permeates|transmits the water permeable part 3 of the water permeable block 10 can be discharged underground G.

Next, the usage condition of the water permeable block 1 will be explained. As shown in FIG. 5(a), the water permeable block 1 is laid on the required ground. Possible locations for installation include sidewalks, plazas, parks, and parking lots.

As shown in FIG. 5(b), rainwater W falling on the surface of the laid water permeable block 1 is discharged from the surface of the water permeable part 3 through the void 5 into the underground G. The surface of the sex block 1 is less likely to be submerged in water. Therefore, the permeable block 1 has a drainage capacity that can cope with localized heavy rain that has been increasing in recent years.

Furthermore, as shown in FIG. 5(b), when water-permeable blocks 1 are laid around street trees, etc., rainwater W that permeates through the water-permeable blocks 1 and is discharged into the underground G Since the water reaches the roots R of roadside trees, etc. that are growing in the water, it is possible to prevent roadside trees, etc., from withering due to lack of water.

Next, we investigated how the density and Vickers hardness of fired mullet change by changing the firing temperature of the fired mullet. Firing of the mullet was carried out by raising the firing temperature (maximum 1100°C) at a rate of 100°C per hour, holding it at the firing temperature for 1 hour, and then cooling it in the furnace to room temperature. The baked mullet samples used to measure density were baked mullet samples 4 to 6, and the baked mullet samples used to measure Vickers hardness were baked mullet samples 1 to 6. For comparison, the density and Vickers hardness of unfired mullet were also measured as an unfired mullet sample. Table 2 shows the firing temperature, density, and Vickers hardness of each sample.

As shown in FIG. 8, the density of the baked mullet sample 4 whose firing temperature is 900° C. is lower than the density of the unfired mullet sample. This is thought to be because the moisture contained in the mullet before firing evaporated during firing, and the organic components evaporated, while the sintering process (sintering and shrinkage) had not yet progressed sufficiently. As the firing temperature increases to 1000°C (baked mullet sample 5) and 1100°C (baked mullet sample 6), the density of each fired mullet sample increases. This is because as the firing temperature increases, the firing of the fired mullet sample progresses.

As shown in Figure 9, the Vickers hardness of the fired Bora sample shows almost no change from unfired to 800°C, but a gradual increase from 800°C to 900°C, and a sharp increase from 900°C to 1100°C. A significant increase can be seen. This is because the fired mullet sample starts to become compact due to firing at 800°C.

Looking at the Vickers hardness of materials other than the fired Bora samples, silver has an average of 25 HV, mortar has an average of 45 HV, stainless steel has an average of 187 HV, and tempered glass has an average of 640 HV. From this, it can be seen that fired mullet fired at 900 to 1100°C has sufficient hardness to be used as lightweight aggregate.

Next, we investigated how the bending strength of mortar changes depending on the type of fine aggregate used in mortar and the age of mortar. The bending strength was measured on mortar specimens 1 to 9 formed into blocks of 40 mm x 40 mm x 160 mm. In addition, fired mullet, unfired mulch, and crushed sand were used as fine aggregates in each mortar specimen. Further, the bending strength was measured for each mortar specimen whose age was 3, 7, and 28 days. Table 3 shows the type of fine aggregate used for each mortar specimen, the mortar composition, and the age at the time of measurement.

As shown in Figure 10, when comparing the bending strength at the same age, the bending strength of the mortar specimen using fired mulch as a fine aggregate is higher than that of the mortar specimen using unfired mullet. ing.

Next, we investigated how the specific strength of mortar specimens changes depending on the type of fine aggregate used in mortar. Specific strength is calculated by bending strength of mortar specimen/density of mortar specimen. Table 4 shows the specific strengths of mortar specimens using fired mullet, unfired mulch, and crushed sand as fine aggregates.

As shown in Table 4, the specific strength of the mortar specimen using fired mulch as fine aggregate is 3.89, which is comparable to the specific strength of 3.83 of the specimen using crushed sand as aggregate. have. This shows that fired mullet can be fully used as a lightweight aggregate.

From the density and Vickers hardness of the fired mullet 3a mentioned above, and the bending strength and specific strength of the mortar specimen using the fired mullet 3a as an aggregate, the fired mullet 3a fired in the temperature range of 900 to 1100°C is lightweight and It is fully usable as a high-strength aggregate and is effective as an alternative aggregate resource to river gravel, etc.

Next, by changing the range occupied by the water-permeable portion of the water-permeable block 1 according to Example 1, it was investigated how the bending strength of the water-permeable block 1 changes. The range occupied by the water-permeable portion is adjusted by changing the vertical width of the water-permeable portion (hereinafter referred to as porous width X (see FIG. 1(b))). For measuring bending strength, water permeable block specimens 1 to 4 measuring 98 mm in length x 198 mm in width x 60 mm in height were used. In addition, for comparison, the bending strength was also measured for permeable block specimens 5 to 8 in which unfired mullet was used as the fine aggregate in the frame portion 2, and permeable block specimens 9 to 12 in which crushed sand was used.

Furthermore, by changing the range occupied by the water permeable portion 3 in the water permeable block 1 according to Example 1, it was investigated how the water permeability coefficient of the water permeable block 1 changes. Water permeable block specimens 2, 3, and 4 were used to measure the water permeability coefficient.

Table 5 shows the type of fine aggregate used for the frame portion 2, the mortar composition used for the frame portion 2, and the pore width X of each water permeable block specimen.

As shown in FIG. 11, for water-permeable block specimens using the same fine aggregate for the frame portion 2, as the porous width X increases, the bending strength of the sample decreases. This is because as the porous width X increases, the vertical widths Y1 and Y2 (see FIG. 1(b)) of the frame portions that bear bending stress decrease.

Furthermore, as shown in FIG. 11, when comparing the bending strength of water-permeable block specimens with the same porous width While this value is lower than that of the water-permeable block specimen used, it is higher than that of the water-permeable block specimen whose frame portion was made of unfired bora.

In addition, as shown in FIG. 11, the bending strength of the water permeable block specimens 2 to 4 using fired mulch for the frame portion is 3.0 N/mm ² or more, which is the standard value for the bending strength of water permeable blocks. This value indicates that the block has sufficient strength as a water-permeable block.

As shown in FIG. 12, as the porous width X increases, the permeability coefficient of the permeable block specimen increases. This is because as the porous width X increases, the area occupied by the water-permeable portion in the water-permeable block specimen becomes larger, and the water-permeation effect becomes larger.

Furthermore, as shown in FIG. 12, the permeability coefficients of the permeable block specimens 2, 3, and 4 are 10×10 ⁻² cm/s, 19×10 ⁻² cm/s, and 23.9×10 ^{− 2} cm/s, which is about 10 to 24 times the standard value of the permeability coefficient of a water-permeable block, which is 1.0×10 ⁻² cm/s. A permeable block with a permeability coefficient of 1.0×10 ⁻² cm/s has a rainfall infiltration function of about 36 mm per hour. Therefore, for example, the permeable block specimen 2 with a porous width It has the ability to penetrate about three times as much rain as 120mm. For these reasons, the water-permeable block specimens 2, 3, and 4 have extremely high water permeability that can withstand localized heavy rains that have been increasing in recent years.

Next, a water permeable block 100 according to Example 2 will be described with reference to FIG. 6. Note that the same configuration and overlapping configuration as in the previous embodiment will be omitted.

As shown in FIGS. 6(a), 6(b), and 6(c), the water-permeable portion 30 is formed by joining the fired mulch 3a together using a sintering aid 8. Further, the water-permeable portion 30 is fixed to the frame portion 2 by being joined to the inner circumferential surface 2a of the frame portion 2 using cement paste 4. In addition, in FIG. 6, for convenience of explanation, the sintering aid 8 is schematically shown as being provided around the firing mullet 3a with a thin and approximately uniform thickness, but in reality, the thickness of the sintering aid 8 is In some places, the grains are uneven and exist between adjacent fired grains 3a. Furthermore, the cement paste 4 applied around the water-permeable part 30 is schematically shown as being thin and approximately uniform in thickness around the firing mulch 3a, but in reality, the thickness of the cement paste 4 varies. However, there are some places that do not exist on the fired mullet 3a.

Next, a method for manufacturing the water permeable block 100 according to Example 2 will be described. As shown in FIG. 7(a), fired mulch 3a with a grain size of 4 to 7 mm coated with a sintering aid 8, which is a so-called glaze, is filled into a rectangular mold in plan view, and the mold is fired at 900°C. After that, the water-permeable portion 30 is formed by cooling and demolding.

The density of the fired mullet 3a in the water-permeable portion 30 may be different from the density of the water-permeable portion 3 according to the first embodiment. This is because the bonding strength between the fired mulch 3a is different when the sintering aid 8 is used as the binder and when the cement paste 4 is used as the binder. If higher bonding strength is obtained when using the sintering aid 8 as a binder than when using the cement paste 4, the density of the fired mulch 3a used in the water permeable part 30 may be lowered, and the bonding between the fired mulch 3a may be reduced. Even if the number of locations is reduced, bending strength equivalent to that of the water-permeable portion 3 can be obtained, and water permeability can be increased.

In addition, since the firing mullet 3a and the sintering aid 8 mainly contain SiO ₂ and the sintering aid 8 contains a large amount of CaO, the melting point is lower than that of the sintering mulch, and when the sintering aid 8 is used, the sintering mulch The bondability between 3a becomes high. Further, by appropriately adjusting the amount of CaO in the sintering aid 8, the sintering aid 8 having a melting point suitable for the desired firing temperature of the water permeable portion 30 can be obtained. When forming the water-permeable portion 30 by firing at 900° C., the CaO contained in the sintering aid 8 is preferably 5 wt% or more, more preferably 5 to 30 wt%, and even more preferably 20 wt%. An example of the chemical components of the sintering aid 8 is shown in Table 6.

Next, cement paste 4 is applied around the water permeable portion 30. Thereby, the bondability between the water-permeable portion 30 and the inner circumferential surface 2a of the frame portion 2 can be improved. Further, when filling the periphery of the water-permeable portion 30 with mortar, it is possible to prevent the void 5 from being filled with mortar.

Next, as shown in FIG. 7(b), the water permeable part 30 is placed approximately in the center of the formwork F of the water permeable block 100 which is rectangular in plan view. Then, the periphery of the water-permeable part 30 placed in the formwork F is filled with mortar made by mixing cement and water with the fired mulch 3a having a grain size of 1 to 2 mm. The mortar composition at this time is 1120 kg/m ³ of fired mullet 3a, 520 kg/m ³ of cement, and 260 kg/m ³ of water.

Then, as shown in FIG. 7(c), after the mortar filled in the formwork F has hardened, it is removed from the formwork F and cured, thereby fixing the water-permeable part 30 to the frame part 2. A water permeable block 100 is formed.

Thereby, the frame part 2 can be formed to match the shape of the surroundings of the water-permeable part 30 that has been molded previously, so that the water-permeable part 30 can be reliably fixed to the frame part 2. Moreover, since the cement paste 4 is applied around the water permeable part 30, the water permeable part 30 can be firmly fixed to the frame part 2.

Next, the water permeability coefficient and bending strength of the water permeable block specimen obtained from the water permeable block 100 according to Example 2 were also measured, and the results were similar to those of the water permeable block specimen according to Example 1 above. was gotten.

Although the embodiments of the present invention have been described above with reference to the drawings, the specific configuration is not limited to these embodiments, and any changes or additions that do not depart from the gist of the present invention are included in the present invention. It will be done.

For example, as long as it satisfies the standards for the bending strength of the water-permeable block, the composition of fired mulch and cement in the frame portion may be changed as appropriate.

Moreover, although mortar containing fired mulch is used for the frame portion, the present invention is not limited to this, and known materials such as metal, rock, and hard plastic may be used.

Further, although cement paste and sintering aid are used as the binder, the binder is not limited thereto, and known binders such as epoxy, polyester, acrylic, silicone, and vinyl acetate binders may also be used.

Further, in Example 1, the water-permeable block was formed by pouring the mixture of fired mullet and cement paste into the previously formed frame part, but the present invention is not limited to this, and after first forming the water-permeable part, A frame portion may be formed by placing a water-permeable portion in a formwork and filling the periphery of the water-permeable portion with mortar. Alternatively, the water permeable part and the frame part may be molded separately, cement paste may be applied around the water permeable part, and then the water permeable part may be fitted and fixed inside the frame part.

Moreover, although two drainage holes 7 are formed in the bottom 6 of the water permeable block 100 according to the modified example, the number of drainage holes 7 is not limited to this and may be increased or decreased as appropriate. Further, the shape of the drain hole 7 is not limited to a circle, but may be various shapes such as an ellipse or a rectangle.

In addition, in Example 2, the water-permeable part that has been previously formed and coated with cement paste is placed approximately in the center of the formwork F, the periphery of the water-permeable part is filled with mortar, and the formwork F is fired together. By doing this, a water-permeable part fixed to the frame part was formed. However, the present invention is not limited to this. The previously formed frame part is placed in the formwork F, and calcined pumice and sintering aid are placed inside the frame part. The water-permeable portion fixed to the frame portion may be formed by filling the mixture containing the liquid and firing the mold F together with the mold F.

Further, the material and structure of the formwork used for molding the frame portion and the water-permeable block are not particularly limited. For example, the formwork may be made of metal and a draft slope may be provided on the inside. According to this, since the metal formwork has high rigidity, it is difficult to deform when molding the frame portion and the water-permeable block. Additionally, the draft angle makes it easy to demold the frame portion and water-permeable block, making mass production possible.

Furthermore, the water-permeable blocks according to Examples 1 and 2 and the modified examples have a function of retaining fallen leaves, garbage, etc., and therefore may be used as a simple filter material.

1, 10, 100 Water permeable block 2 Frame portion 2a Inner peripheral surface 3, 30 Water permeable portion 3a Calcined bora (calcined pumice)
3b Pore 4 Cement paste 5 Gap 6 Bottom 6a Bottom surface 7 Drain hole 8 Sintering aid W Rainwater G Underground R Root F Formwork X Porous width Y1, Y2 Frame width

Claims (9)

A water-permeable block comprising a frame portion formed to surround an inner water-permeable portion, the water-permeable portion containing burned pumice and a binder and fixed to the frame portion. The water-permeable block according to claim 1, wherein the calcined pumice is calcined bora having a density of 1.2 to 2.0 g/cm ³ . The permeable block according to claim 1, wherein the frame portion includes the calcined pumice and cement or mixed cement. The water-permeable block according to claim 2, wherein the particle size of the fired pumice included in the frame portion is smaller than the particle size of the fired pumice included in the water-permeable portion. The water-permeable block according to any one of claims 1 to 4, wherein the binder is cement or mixed cement. The water-permeable block according to any one of claims 1 to 4, wherein the binder is a sintering aid. 7. The water-permeable block according to claim 6, wherein the sintering aid mainly contains SiO ₂ and further contains 5 to 30 wt% of CaO. A frame part having a space inside is molded, and a mixture containing calcined pumice and cement is filled and hardened inside the molded frame part to form a water-permeable part fixed to the frame part. A method for manufacturing a water-permeable block. A mixture containing calcined pumice and a sintering aid is packed in a mold and fired together with the mold to form a water-permeable part, and a binder is applied around the water-permeable part removed from the mold. A method for manufacturing a water-permeable block, comprising forming a frame portion on the block and fixing the water-permeable portion to the frame portion.

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