JP6439210B2 - Water retention performance test body for materials having water retention capacity, method for producing the same, and water retention performance test method - Google Patents

Description

  The present invention relates to a water retention performance test body for a material having water retention, a method for producing the same, and a water retention performance test method.

 Conventionally, as a pond-like structure, for example, a reinforced concrete water tank as shown in Patent Document 1 is known. In such a water tank, if a member yields and a through crack occurs during a large-scale earthquake, the water storage function is lost. In such a case, it is considered that the facility has been destroyed, and the water storage function is still maintained for the time being. No measures are taken. However, it has been pointed out that a huge earthquake may occur in the future, and in life infrastructure structures such as existing water tanks, the function will be maintained even if members are destroyed, and there will be a negative impact on life after the earthquake. There was a need for measures to make it as small as possible. For this reason, the applicants have developed a resin spraying method on the inner surface of the water tank that does not break and retains the waterproof function even when a through crack or the like occurs when the member yields.

  As a test method for confirming the waterproof performance of a resin material (cement waterproofing material for building) having such a waterproof function, for example, the resin material as described above is applied to one surface of a block made of a uniform mortar material. There is known a test method in which a coated test body is provided and water pressure is applied to the water permeation target surface of the test body using a water pressure tester. Here, the hydraulic testing machine has a back cover attached to one back side of the test piece via a rubber gasket, and a hydraulic action part is attached to the other front side via a rubber gasket. The change in water pressure is measured when a predetermined water pressure is applied to the surface side coated with the material.

Japanese Patent Laid-Open No. 10-314753

  However, the specimen tested by the conventional hydraulic tester as described above is intended for a uniform mortar material. Therefore, a method capable of easily and accurately confirming the water retention of the resin material coated on the inner surface of the reinforced concrete storage tank as described above, which has been cracked by an earthquake, using the above-described hydraulic pressure tester is required. It was done.

  The present invention has been made in view of the above-described problems, and is capable of easily and accurately confirming water retention of a member having a crack coated with a material having water retention on the surface of a concrete structure. It aims at providing the water-retaining performance test body of the material which has, its manufacturing method, and the water-retaining performance test method.

  In order to achieve the above object, a water retention performance test body of a material having water retention according to the present invention is a water retention performance test body in which a surface of a block body made of a concrete structure is coated with a water retention material. In the state in which the block bodies are abutted, the material having the water retention property is coated on both surfaces of the block bodies by coating, spraying, or pasting, and the pair of block bodies is fixed to each of the block bodies. The reaction force plates and the reaction force plates are connected to each other, are movable in a direction in which the pair of block bodies are moved closer to and away from each other, and are fixed at positions where the pair of block bodies are separated from each other. And a gap generating means.

Moreover, the manufacturing method of the water retention performance test body according to the present invention is the manufacturing method of the water retention performance test body described above, and the step of providing the reaction force plate and the gap generating means to the pair of blocks; And a step of covering the surfaces of both block bodies with the material having the water retention property in a state in which the pair of blocks are abutted with each other.

Further, the water retention performance test method according to the present invention is a water retention performance test method using the above-described water retention performance test body, wherein the gap generating means separates the pair of reaction force plates from each other so that there is no gap between them. And a step of observing water leakage in the gap by applying a water pressure from the water- retaining material side of the pair of block bodies.

In the present invention, the pair of block bodies covered with the water-retaining material are separated from each other by the gap generating means, and fixed in a state where a predetermined gap is left. Since the gap between the block bodies at this time simulates a crack generated in a concrete structure, a crack was generated by performing a water pressure test on the water retention performance test specimen in this state. The water retention performance of the material having water retention applied to the concrete structure can be confirmed. In other words, it is possible to apply water pressure from the material side of the water retention performance test piece provided with a gap and observe water leakage in the gap.
In the present invention, the gap generating means can fix the gap in the approaching / separating direction between the pair of block bodies at a position set to an appropriate size, so that the water retention performance test body in which the gap is set easily and accurately. Can be manufactured.

  Further, in the water retention performance test body of the material having water retention according to the present invention, the reaction plate is fixed to the surface on the separation side in the approaching / separating direction of the block body, and protrudes from both sides sandwiching the block body The gap generating means includes a screw bolt that penetrates the locking portion facing the approaching / separating direction between the pair of reaction force plates, and a nut screwed to the screw bolt. The nut preferably comprises an inner nut and an outer nut located on both sides of the reaction force plate.

  In this case, when the gap is provided between the pair of block bodies, the outer nut is loosened and the inner nut is rotated in a direction to be tightened against the reaction force plate. The block body moves in a direction away from the other block body. Thereby, the space | interval of the reaction force plates fixed to each block body becomes large, and a clearance gap is formed between a pair of block bodies. At this time, the position of the reaction force plate (the position of one block body) is determined corresponding to the tightening amount of the inner nut, and the dimension of the gap can be determined. And a desired water-retaining performance test body can be created by tightening the outer nut until it abuts against the reaction force plate side at a position where the gap dimension is determined.

  Moreover, in the water retention performance test body of a material having water retention according to the present invention, the reaction force plate is preferably fixed to an anchor placed on the block body.

  In this case, the anchor strength firmly fixed to the block body can be increased by using the anchor firmly fixed to the block body. For this reason, when the pair of block bodies are separated from each other by the gap generating means, a return force is generated to return to the close direction by the water-retaining material coated on the block bodies, but the fixing strength against this return force is generated. Can be put on the reaction force plate. Therefore, in a state where the gap is formed, the reaction force plate is not detached from the block body, and the pair of block bodies can be maintained at positions separated by a predetermined gap dimension.

  Further, the water retention performance test body of the material having water retention according to the present invention is characterized in that the material having water retention is a resin material and has a flexible primer layer coated on the surfaces of the pair of block bodies. And a resin water-stopping layer made of a polyurethane resin or a polyurea resin coated on the primer layer.

  ADVANTAGE OF THE INVENTION According to this invention, the water retention performance test body which uses the resin material which has flexibility and high water retention performance can be created, and it becomes possible to confirm water retention performance easily and accurately.

  According to the water retention performance test body of the material having water retention capacity of the present invention, the manufacturing method thereof, and the water retention performance test method, the water retention capacity of a member having a crack coated with a material having water retention capacity on the surface of a concrete structure is simplified. And it can be confirmed with high accuracy.

It is the top view which looked at the water retention performance test body of the resin material by embodiment of this invention from upper direction. It is AA sectional view taken on the line shown in FIG. 1, Comprising: It is a side view of a water retention performance test body. It is a side view of a water retention performance test body, and is a view showing a state in which a gap in the proximity / separation direction is provided between a pair of block bodies. It is the longitudinal cross-sectional view which fractured | ruptured partially the state of the water pressure test using the test body by an Example.

  Hereinafter, a water retention performance test body of a material having water retention according to an embodiment of the present invention, a manufacturing method thereof, and a water retention performance test method will be described with reference to the drawings.

  As shown in FIG.1 and FIG.2, the water retention performance test body 1 by this Embodiment has the resin material 3 which has water retention on the upper surface (surface) 2a of the block body 2 (2A, 2B) which consists of concrete structures. An object that is integrally provided by covering is a test body that is used in a test for confirming the water retention and waterproofness of the water retention performance test body 1. The water retention performance test body 1 is, for example, a water pressure tester 17 (see FIG. 4) described later when confirming the effect in the construction for providing water retention by coating a resin material on the inner surface of a concrete water tank. The water pressure test is carried out.

The pair of block bodies 2A and 2B are concrete structures such as concrete, reinforced concrete, and prestressed concrete, each having the same shape. In the present embodiment, the four side surfaces are rectangular in plan view. All are flat. The pair of block bodies 2A, 2B are arranged with their one side surfaces (the contact surfaces 21A, 21B) facing each other.
Here, the block bodies 2A and 2B are provided so as to be movable along a direction orthogonal to the contact surfaces 21A and 21B. This moving direction is referred to as a proximity / separation direction X. In the approaching / separating direction X, the approaching direction is referred to as the inside, and the separating direction is referred to as the outside.

  In the water retention performance test body 1, the resin material 3 is coated on the surfaces of the block bodies 2 </ b> A and 2 </ b> B by coating or spraying in a state where the pair of block bodies 2 </ b> A and 2 </ b> B are abutted.

  As shown in FIG. 2, the resin material 3 includes a primer layer 31 coated over the upper surfaces 2 a of the pair of block bodies 2 </ b> A and 2 </ b> B, and a resin water stop layer 32 coated on the primer layer 31. Yes.

  Even if a pair of block bodies 2A and 2B are deformed in the approaching / separating direction X, the primer body 31 follows the deformation of the block bodies 2A and 2B so that the block bodies 2A and 2B peel off the resin water stop layer 32. It is provided to relieve the power of That is, the primer layer 31 has good adhesion to the block bodies 2A, 2B and the resin water stop layer 32, and is flexible to such an extent that the block bodies 2A, 2B can relieve the force of peeling the resin water stop layer 32. It has sex.

  As a primer which comprises the said primer layer 31 which has the flexibility, a crack followable | trackability (JHS410) is 15 mm or more. When the crack followability of the primer layer 31 is smaller than the lower limit value, the primer layer 31 is broken with the deformation of the block bodies 2A and 2B or peeled off from the resin water stop layer 32. 2B falls and collapse occurs, which is not preferable.

  Examples of the primer having high crack followability include a polyurethane resin primer and a butadiene resin primer.

  The polyurethane resin is made of the same isocyanate as the polyurea resin that forms the resin water blocking layer 32. The butadiene-based resin is produced by a crosslinking reaction between butadiene and isocyanate. Specifically, the butadiene-based resin primer preferably includes a butadiene-based rubber that can form an elastic primer without being heated to high temperature even when mixed with polyisocyanate at room temperature. . Examples of the butadiene rubber include polybutadiene rubber, copolymers of butadiene with other monomers such as styrene and isobutylene, and other vinyl monomers.

  The adhesiveness of the polyurethane resin primer or butadiene resin primer to the concrete is relatively high, and the deformation followability of the polyurethane resin primer or butadiene resin primer to the concrete is extremely good. Due to the composition of each primer described above, the adhesion of the polyurethane resin primer and the butadiene resin primer to the polyurethane resin and the polyurea resin is very high. Accordingly, the block bodies 2A and 2B are in close contact with both the block bodies 2A and 2B and the resin water stop layer 32, and follow the large deformation of the block bodies 2A and 2B, while the block bodies 2A and 2B have a force to peel off the resin water stop layer 32. From the viewpoint of sufficiently relaxing, the primer layer 31 is preferably composed of a polyurethane resin primer or a butadiene resin primer. In particular, the primer layer 31 is preferably composed of a solvent-based primer or a solvent-free primer mainly composed of a polyurethane resin, or contains a polybutadiene-based rubber from the viewpoint of easy preparation of a liquid agent or the like. . As a solvent-based primer or a solvent-free primer having a polyurethane resin as a main component, for example, there is a commercially available sansilar super (manufactured by AGC Polymer Building Materials Co., Ltd.). As a material of the primer layer 31 containing polybutadiene rubber, for example, commercially available Swaerle B-500M (manufactured by Mitsui Chemicals, Inc.) is available.

  As a construction method for covering the block bodies 2A and 2B with the primer layer 31, the upper surface 2a of the block bodies 2A and 2B is sufficiently cleaned to remove dust and the like, and then the primer layer 31 is applied to the upper surfaces 2a of the block bodies 2A and 2B. There is a method of applying or spraying a primer constituting the above with a predetermined thickness dimension.

  The resin water-stopping layer 32 expands or contracts flexibly with respect to the large deformation of the block bodies 2A and 2B, thereby moving the block bodies 2A and 2B in the proximity / separation direction X to form a gap. It is provided to maintain the state. That is, the resin water-stopping layer 32 has a very high toughness, is made of a synthetic resin having high shear adhesion and bending tensile strength and excellent mechanical properties such as strength and elongation. The tensile strength of the synthetic resin constituting the resin water-stopping layer 32 is about 20 MPa (10 to 25 MPa), and the elongation at break of the synthetic resin may be 200% or more. The thickness dimension of the resin water-stopping layer 32 is preferably 2 mm or more from the viewpoint of obtaining good mechanical properties and the uniformity of the coating thickness.

  The resin water stop layer 32 is made of a polyurethane resin or a polyurea resin excellent in mechanical properties and the like. The polyurea resin is a compound formed by a chemical reaction between an isocyanate and a curing agent composed of at least one of a polyol and an amine. An example of such a polyurea resin is SWAEL AR-100 (registered trademark: manufactured by Mitsui Chemicals, Inc.).

  As a construction method for coating the resin water stop layer 32 on the primer layer 31, after the surface of the primer layer 31 is cleaned, the material of the resin water stop layer 32 is applied to the surface of the primer layer 31 with a predetermined thickness dimension. A method is mentioned.

  As shown in FIG. 1, the reaction force plate 4 (4A, 4B) fixed to each of the block bodies 2A, 2B and the reaction force plates 4A, 4B are connected to the pair of block bodies 2A, 2B. And a pair of block bodies 2A, 2B that are movable in the approaching / separating direction X, and a gap generating means 5 that fixes the pair of block bodies 2A, 2B to positions separated from each other.

  The reaction force plates 4A and 4B are formed in a long plate shape, and the surfaces 22A and 22B on the separation side in the proximity / separation direction X of the block bodies 2A and 2B in a state where the longitudinal direction is directed in a direction orthogonal to the proximity / separation direction X. It is fixed to. The reaction force plates 4A and 4B are provided with locking portions 4a protruding from both sides of the block bodies 2A and 2B.

  The reaction force plates 4A and 4B are fixed to a pair of chemical anchors 41 placed on the block bodies 2A and 2B. Specifically, the reaction force plates 4A and 4B have a first through hole 4b formed in each of the locking portions 4a and 4a located on both sides in the length direction, and a pair of first plates in the middle portion in the length direction. Two through holes (not shown) are formed. A screw bolt 51 is passed through the first through hole 4b. The reaction force plates 4A and 4B are fixed to the block body 2 by passing the second through hole through the tip bolt 41a protruding from the block body 2 of the chemical anchor 41 and tightening the nut 42 to the tip bolt. Yes.

The gap generating means 5 includes a screw bolt 51 that penetrates the locking portions 4a and 4a facing each other in the proximity / separation direction X between the pair of reaction force plates 4A and 4B, and a nut 52 that is screwed to the screw bolt 51. I have.
The nut 52 screwed to the screw bolt 51 includes an inner nut 52A and an outer nut 52B located on both sides of the reaction force plates 4A and 4B.

Next, the action of the water retention performance test body of the resin material described above, the method for producing the water retention performance test body, and the water retention performance test method using the water retention performance test body will be described in detail based on the drawings.
In the present embodiment, as shown in FIG. 3, when the gap S is provided between the pair of block bodies 2A, 2B, one reaction force plate 4 side (here, the reaction force of reference numeral 4A on the right side of the page) The outer nut 52B of the plate is loosened, and the inner nut 52A is rotated in the direction X1 (the direction toward the outer side) so as to be tightened with respect to the reaction force plate 4A. The body 2A moves away from the other block body 2B.

  Thereby, the space | interval of reaction force board 4A, 4B fixed to each block body 2A, 2B becomes large, and the clearance gap S is formed between a pair of block bodies 2A, 2B. At this time, the position of the reaction force plate 4A (the position of one block body 2A) is determined corresponding to the tightening amount of the inner nut 52A, and the dimension of the gap S can be determined. And the desired water retention performance test body 1 can be created by tightening the outer nut 52B until it abuts on the reaction force plate 4A side at the position where the gap dimension is determined.

  Thus, in the present embodiment, the pair of block bodies 2A, 2B coated with the resin material 3 are separated from each other by the gap generating means 5 including the screw bolt 51 and the nut 52, and a predetermined gap S is left. Secure with. Since the gap S at this time simulates a crack generated in the concrete structure 2, a concrete structure in which a crack has occurred by performing a water pressure test on the water retention performance test specimen 1 in this state. The water retention performance of the resin material 3 applied to 2 can be confirmed. That is, water pressure can be applied from the resin material 3 side of the water retention performance test body 1 provided with the gap S, and water leakage in the gap S can be observed.

  In the present embodiment, the gap generating means 5 can fix the gap S in the approaching / separating direction X between the pair of block bodies 2A, 2B at a position set to an appropriate size. It becomes possible to manufacture the water retention performance test body 1 in which S is set.

  Further, by using the chemical anchor 41 that is firmly fixed to the block bodies 2A and 2B, the fixing strength of the holding plates 4A and 4B to the block bodies 2A and 2B can be increased. Therefore, when the pair of block bodies 2A, 2B are separated from each other by the gap generating means 5, a return force is generated to return to the approaching direction due to the elasticity of the resin material 3 coated on the block bodies 2A, 2B. The holding plate 4A, 4B can be given a fixing strength against the return force. Therefore, in a state where the gap S is formed, the holding plates 4A and 4B are not detached from the block bodies 2A and 2B, and the pair of block bodies 2A and 2B can be maintained at positions separated by a predetermined gap size. It becomes.

  As described above, in the water retention performance test body of the material having water retention according to the present embodiment, the manufacturing method thereof, and the water retention performance test method, a member having a crack in which the upper surface 2a of the concrete structure 2 is coated with the resin material 3 is used. Water retention can be confirmed easily and accurately.

  Next, examples carried out in order to support the effects of the water retention performance test body of the material having water retention according to the above-described embodiment, its manufacturing method, and the water retention performance test method will be described below.

(Example)
In this example, as shown in FIG. 4, the water retention performance test body of the above-described embodiment (hereinafter simply referred to as test body 10) is manufactured, and a water pressure test is performed using the water pressure tester 17, and the test body is tested. The effect as 10 was confirmed. The test body 10 is used when confirming the waterproof performance of the water storage tank assuming that a large crack has occurred in the water storage tank in a state where water pressure is applied due to a large-scale earthquake (L2 level earthquake).

The test body 10 is made of two unreinforced concrete plates 11 and 12 each having a length of 70 mm, a width of 70 mm, and a thickness of 35 mm as a concrete structure, and a reaction force plate 14 is fixed to each using a chemical anchor 13. Produced. Then, in the state where these two unreinforced concrete plates 11 and 12 are abutted with each other, a ground treatment is performed with keren using a sander or the like, and the resin material 15 is covered. That is, after applying a primer layer on the unreinforced concrete plates 11 and 12 using a brush or the like, a resin waterproofing material (resin waterproofing layer) is coated by spraying. Thereafter, screw bolts were inserted into the through holes of the reaction force plate and fixed with nuts from both sides of the reaction force plate (see FIGS. 1 and 2). Here, as the primer, a two-component solventless type, modified polyurethane primer was used, and the coating amount was 0.5 kg / m ² . As the resin water-stopping material (spraying material), a two-liquid non-solvent type polyurea resin having a thickness of 2.0 mm or 4.0 mm was used and sprayed by spraying.
Then, in a state where the resin material 15 (primer and resin waterproofing material) is applied, the reaction force plate 14 moves to the left and right by rotating the nut inside the test body 10, thereby generating two spreads. A gap 16 (a width of several mm to several tens mm) corresponding to an arbitrary crack is generated in the unreinforced concrete plates 11 and 12. Specifically, five types of gap widths of 2 mm, 4 mm, 6 mm, 8 mm, and 10 mm were created as the conditions for the gap 16.

  The test body 10 is set in the water permeability tester 17. Specifically, rubber gaskets 17A and 17B each having an opening 17a formed in the center are attached to the upper surface and the lower surface of the test body 10 in which the gap 16 is formed, the lid body 17C is fixed to the lower side, and the upper side is fixed to the upper side. A crested cylindrical hydraulic working body 17D is installed. In a state where the lower end 17b of the hydraulic pressure actuating body 17D is in close contact with the upper gasket 17A, water is poured into the inside so as to act on a predetermined water pressure.

And after the set of the test body 10 is completed, the unstressed concrete board which the five types of cracks (gap 16) mentioned above generate | occur | produced by applying the water pressure of 0.1 N / mm < ² > (10m water head) over 1 hour. The water retention performance of the test body 10 in which the resin material 15 was coated on 11 and 12 was confirmed. In addition, the action time of pressure is set to 1 hour according to the water permeability test of the test method for building cement waterproofing material (JIS-A1404).
In the test body 10 according to this embodiment, the water pressure as described above, although the working time is not limited to this water pressure operating conditions, for example, a hydraulic 0.1N ^/ mm ² ~0.3N ^/ mm 2 degree 1-168 It is possible to work with time.

Table 1 shows the test results according to this example. In each of the five types of gaps 16, water leakage from the crack surface (gap 16), excessive deformation of the resin water stop material, local deformation at the corners ( No cracks) were observed, and good results were obtained.
Furthermore, the waterproofness confirmation experiment was continued until about one week, and the passage of time (elapsed time: 1.0 hour, 24 hours (1 day), 48 hours (2 days), 120 hours (5 days), 168 hours ( The result of observing 7th)) was also confirmed to be satisfactory because water leakage from the gap 16 described above, excessive deformation of the resin water-stopping material, and local deformation at the corners were not observed.

As mentioned above, although the embodiment of the water retention performance test body of the material having water retention according to the present invention, its manufacturing method, and the water retention performance test method has been described, the present invention is not limited to the above embodiment, Changes can be made as appropriate without departing from the spirit of the invention.
For example, in the present embodiment, the gap generating means 5 including the screw bolt 51 and the nut 52 is adopted, but the present invention is not limited to such a structure, and other forms are possible. is there. For example, instead of the inner nut 52A, a spring member that is biased in a direction away from each other is provided between the pair of reaction force plates 4A and 4B, and the outer nut 52B is loosened, thereby biasing the spring member. Therefore, the reaction force plates 4A and 4B may be moved toward the outside in the approaching / separating direction X.

  Further, in the present embodiment, the reaction force plates 4A, 4B are fixed to the surface opposite to the contact surfaces 21A, 21B of the block bodies 2A, 2B by the chemical anchor 41. Also, other fixing means may be used. For example, the anchor may be a mechanical anchor, or a fixing bracket embedded in the block body 2 and projecting on both sides of the block body 2 in a direction perpendicular to the approaching / separating direction X in a top view may be used as the reaction force plate. Is possible. That is, in this case, the chemical anchor 41 can be omitted.

  Moreover, in this Embodiment, although the resin material 3 is coat | covered only to the upper surface 2a of a pair of block bodies 2A and 2B, it is also possible to coat | cover with the resin material 3 over front and back both surfaces or a perimeter. . The material having water retention may be a sheet-like material, and the material may not be a resin.

  In addition, it is possible to appropriately replace the components in the above-described embodiments with known components without departing from the spirit of the present invention.

1, 10 Water retention performance test body 2 Concrete structure 2A, 2B Block body 2a Upper surface (surface)
3 Resin materials (materials with water retention)
4, 4A, 4B Reaction force plate 4a Locking portion 5 Crevice generating means 17 Hydraulic tester 31 Primer layer 32 Resin water stop layer 41 Chemical anchor (anchor)
51 Screw bolt 52 Nut 52A Inner nut 52B Outer nut S Clearance X Proximity / separation direction

Claims (6)

A water retention performance test body in which a surface of a block body made of a concrete structure is coated with a material having water retention,
In a state where a pair of the block bodies are butted together, the material having the water retention property is coated, sprayed, or pasted over the surfaces of both block bodies,
In the pair of block bodies,
A reaction force plate fixed to each of the block bodies;
A gap generating means for connecting the reaction force plates together, being movable in a direction in which the pair of block bodies are brought close to and away from each other, and fixing the pair of block bodies to positions separated from each other;
A water-retaining performance specimen for water-retaining material, characterized in that is provided. The reaction force plate is fixed to the surface on the separation side in the approaching / separating direction of the block body, and is provided with a locking portion protruding from both sides sandwiching the block body,
The gap generating means includes a screw bolt that penetrates the locking portion facing the approaching / separating direction between the pair of reaction force plates, and a nut screwed to the screw bolt,
The water retaining performance test body for water-retaining material according to claim 1, wherein the nut comprises an inner nut and an outer nut located on both sides of the reaction force plate.   The said reaction force board is being fixed to the anchor casted in the said block body, The water retention performance test body of the material which has water retention property of Claim 1 or 2 characterized by the above-mentioned. The material having water retention is a resin material,
A flexible primer layer coated on the surface of the pair of block bodies;
A resin water-stopping layer made of polyurethane resin or polyurea resin coated on the primer layer;
The water retention performance test body of the material which has water retention property of any one of Claims 1 thru | or 3 characterized by the above-mentioned. It is a manufacturing method of the water-retaining performance test body according to any one of claims 1 to 4,
Providing the reaction force plate and the gap generating means for the pair of blocks;
A step of covering the surface of both block bodies with the material having the water retention property in a state in which the pair of blocks are abutted with each other;
A method for producing a water-retaining performance specimen, comprising: A water retention performance test method using the water retention performance test body according to any one of claims 1 to 4,
A step of separating the pair of reaction force plates from each other by the gap generating means to provide a gap therebetween;
Applying water pressure from the water- retaining material side of the pair of block bodies and observing water leakage in the gap;
A water retention performance test method characterized by comprising:

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