JP6349151B2 - Method for reinforcing natural stone used for building exterior materials - Google Patents

Description

  The present invention relates to a method for reinforcing a natural stone material used for a building exterior material.

  Natural stone materials may be used for building exterior materials for the purpose of enhancing luxury and design. In addition, from the viewpoint of texture and the like, it is sometimes desired to use porous limestone among such natural stone materials.

  However, porous limestone is susceptible to erosion of acidic liquids such as acid rain because of its high water absorption and high calcium carbonate content. Therefore, in spite of the above request, JASS9 “Paint Stone Work” (2009) is excluded from application to exterior materials for buildings.

With regard to this point, a silicon-based permeable water absorption preventive material (trade name: AD Super (which is also referred to as acid resistance), which is applied to the surface of natural stone with a brush or the like for the purpose of increasing the resistance to an acidic liquid. Advanced Limited))) is provided.
Moreover, although it is not the technique which concerns on a natural stone material, as patent document 1, as a technique which reinforces concrete, impregnating resin in the fine space | gap of concrete and hardening the resin is disclosed.

Japanese Patent No. 4898034

  However, as a result of intensive studies by the inventors of the present application, it has been found that the former application of the permeable water absorption preventive material can cause frost damage. That is, it was found that if the porous limestone coated with the same material was repeatedly frozen and thawed after water absorption, the surface layer of the limestone would fall off. Incidentally, the reason for this is that the expansion behavior of water during freezing differs between the surface layer impregnated with the permeable water absorption preventing material and the non-impregnated surface layer. This is considered to occur.

  In addition, as a result of intensive studies by the inventors of the present application, if the latter resin impregnation is performed on porous limestone, the acid resistance improvement effect is significantly higher than the improvement effect of cement-based compositions such as concrete. I found it big. That is, it has been found that the resin impregnation is very effective for improving the acid resistance of a porous natural stone containing calcium carbonate such as limestone.

  This invention is made | formed in view of the above conventional problems, The objective is to improve the frost damage resistance and acid resistance of the porous natural stone material containing a calcium carbonate.

A method of reinforcing natural stone used for building exterior materials,
Impregnation treatment for impregnating the porous natural stone containing calcium carbonate with a vinyl-based monomer from the surface of the stone to a central position in the stone;
Have a, a polymerization process for polymerizing the vinyl monomer impregnated in the stone,
The viscosity of the vinyl monomer during the impregnation treatment is 0.1 cps to 10 cps,
The stone has a thickness of 20 mm to 70 mm,
The total volume of the plurality of voids related to the porous material occupies 20% to 50% of the volume of the stone material .

  According to the first aspect of the present invention, a polymer formed by polymerizing a vinyl monomer is filled in a large number of voids of the stone material based on the porous structure. Therefore, the permeation of water into the voids is suppressed based on the polymer, thereby improving the frost damage resistance.

In the above impregnation treatment, the monomer is impregnated from the surface of the stone to the center position in the stone. Therefore, the gap is filled with the polymer over almost the entire area from the surface of the stone to the center position. Therefore, it is possible to effectively prevent a large stress from being generated at the boundary between the surface layer of the stone material and the portion other than the surface layer at the time of freezing, thereby preventing the surface layer of the stone material from peeling off.
Furthermore, the polymer filled in the voids also suppresses the penetration of the acidic liquid into the voids. Therefore, the acid resistance which is the tolerance to an acidic liquid can also be improved.
In addition, the polymer filled in the voids can also have a stiffening effect that supplements the rigidity of the stone. Therefore, the bending strength and tensile strength of the stone can be improved.

The invention shown in claim 2 is a method for reinforcing a natural stone material used for the building exterior material according to claim 1,
The natural stone material is heated as the polymerization treatment.

  According to the second aspect of the present invention, the vinyl monomer impregnated in the stone is heated to be polymerized, but the heat is quickly transmitted from the surface of the stone to the center position in the stone. Therefore, it is possible to reliably polymerize to the center position of the stone material, and thereby it is possible to reliably polymerize the same monomer from the surface to the center position.

Invention shown in claim 3 is the method for reinforcing natural stone materials used for exterior materials of buildings according to claim 1 or 2,
A cutting process for cutting out the natural stone material;
And a degassing process for degassing the cut natural stone material.

According to the third aspect of the present invention, the air in the voids in the stone is removed by the deaeration process, so that the vinyl monomer can easily enter the voids. Thereby, the monomer can be impregnated quickly to the center position in the stone.

Invention of Claim 4 is the reinforcement method of the natural stone material used for the exterior material of the building of Claim 3 , Comprising:
The natural stone is not forcibly dried between the cutting process and the degassing process.

According to the fourth aspect of the present invention, since the stone is not forcibly dried, the time required for reinforcing the stone as a whole can be shortened.

The invention shown in claim 5 is a method for reinforcing a natural stone material used for the building exterior material according to claim 3 ,
Between the cutting process and the degassing process, measure the moisture content of the natural stone material,
When the measured moisture content is larger than a predetermined threshold, the stone is forcibly dried before the deaeration treatment, and when the moisture content is less than the threshold, the stone is not forcibly dried. Features.

According to the fifth aspect of the present invention, it is possible to effectively prevent the impregnation treatment with the vinyl monomer for a long time due to the high moisture content of the stone material, and the moisture content of the stone material is low. In this case, unnecessary forced drying can be prevented, and the time required for reinforcing the stone as a whole can be shortened.

  ADVANTAGE OF THE INVENTION According to this invention, the frost damage resistance and acid resistance of the porous natural stone material containing calcium carbonate can be improved.

FIG. 1A is a schematic plan view of a natural stone material 10 reinforced by the reinforcing method of the present embodiment, and FIG. 1B is a cross-sectional view taken along line BB in FIG. 1A. 2A to 2C are schematic side views showing the procedure of the method for reinforcing the natural stone material 10 according to the present embodiment. It is a measurement result of the water absorption rate of each specimen concerning natural stone material 10. FIG. 4A is an electron micrograph of the center position CS in the untreated test body as the first comparative example, and FIG. 4B is an electron micrograph of the center position CS in the resin-impregnated test body according to the present embodiment. FIG. 5A is an appearance photograph of an untreated specimen as a first comparative example after the artificial acid rain cycle test, and FIG. 5B is an appearance photograph of a specimen of a permeable water absorption preventing material as the second comparative example. FIG. 5C is a photograph of the appearance of a resin-impregnated test body according to this embodiment. It is a graph of the weight reduction rate of the test body of the mortar after immersion in hydrochloric acid aqueous solution, and the weight reduction rate of the test body of the same Savonniere. FIG. 7A and FIG. 7B are external appearance photographs after a test of a permeable water absorption preventing material as a second comparative example and a resin-impregnated test body according to this embodiment, respectively. It is a measurement result of the bending strength of each test body of a 1st comparative example, a 2nd comparative example, and this embodiment.

=== This Embodiment ===
1A is a schematic plan view of a natural stone material reinforced by the reinforcing method of the present embodiment, and FIG. 1B is a cross-sectional view taken along line BB in FIG. 1A.
The natural stone material 10 is used for building exterior materials such as outer wall panels. In this example, as shown in FIGS. 1A and 1B, the shape of the stone material 10 is a rectangular flat plate, the dimension in the longitudinal direction is, for example, 100 mm to 2000 mm, and the dimension in the width direction is, for example, 50 mm to 1000 mm. The dimension in the thickness direction is 20 mm to 70 mm.
However, the shape of the stone 10 is not limited to a rectangular parallelepiped such as the rectangular flat plate. For example, it may be a circular flat plate, a special flat plate, or a shape other than these.

  Incidentally, the cut out to the above dimensions is performed at the quarry, but in some cases, after roughly cutting out at the quarry, the above dimensions may be finished at an appropriate factory.

  This natural stone material 10 is a porous stone material containing calcium carbonate. The average diameter of many voids related to the porous is, for example, 0.05 mm to 0.40 mm, and the total volume of the voids occupies 20% to 50% of the volume of the stone. Further, the content of calcium carbonate in% by weight is greater than 0% and less than 100%, more narrowly 50% or more. That is, narrower is limestone (limestone) whose main component is calcium carbonate, and in this example, is French Savonniere. In addition, since the acid content of the stone material in a blank state (hereinafter, also referred to as a blank material) is low when the calcium carbonate content rate is large, the larger the content rate, the more the reinforcing method of the natural stone material 10 of the present embodiment. The effect can be enjoyed effectively.

  Hereinafter, this reinforcing method will be described. 2A to 2C are schematic side views of the procedure of this reinforcing method.

First, the natural stone material 10 is cut out from the quarry (corresponding to a cut-out process), and the cut-out natural stone material 10 is carried into an appropriate factory. At the same factory, the deaeration process is first performed.
As shown in FIG. 2A, in the deaeration process, the stone material 10 is accommodated in a suitable sealed container 30, and the air in the container 30 is discharged to reduce the pressure to a predetermined degree of vacuum. Since the air in a large number of voids in the stone material 10 is also discharged by this decompression, the impregnation material can be rapidly impregnated into the stone material 10 in the subsequent impregnation process (FIG. 2B). The degree of vacuum can be exemplified by 20 mmHg or less, and the deaeration time can be exemplified by 1 to 2 hours, but is not limited thereto.

  Moreover, in this example, the posture of the stone material 10 accommodated in the sealed container 30 is a horizontal posture in which the thickness direction faces the vertical direction. That is, one of the two largest planes 10sa and 10sb among the six planes 10sa is disposed on the upper surface, and the other 10sb is disposed on the lower surface. In the container 30, a plurality of support members 32, 32, 32 partially contact the lower surface 10 sb of the stone material 10 from below the stone material 10 to support the weight of the stone material 10. Therefore, in the impregnation process (FIG. 2B) described later, the impregnating material 20 quickly wraps around and impregnates not only from the upper surface 10sa but also from the lower surface 10sb.

  However, the posture of the stone 10 is not limited to the horizontal posture described above. For example, a vertically placed posture (not shown) may be used. That is, the flat stone material 10 may be erected so that the two largest planes 10sa and 10sb face the horizontal direction. Also in the case of this vertically placed posture, there can be no obstacle in the vicinity of the two largest planes 10sa and 10sb, so that the thickness can be quickly increased from these two planes 10sa and 10sb. Impregnating material 20 can be impregnated in the direction.

  In the next impregnation treatment, the liquid impregnating material 20 is injected into the container 30 as shown in FIG. It is made into the state immersed in the material 20. FIG. Thus, the impregnating material 20 is impregnated into the stone material 10 in the thickness direction at least from the upper surface 10sa and the lower surface 10sb of the stone material 10, and finally, the center position C10 in the stone material 10, that is, the stone material 10 The impregnating material 20 is impregnated up to the plane center position C10p (FIG. 1A) and the center position C10t (FIG. 1B) in the thickness direction.

  For the impregnating material 20, a vinyl monomer is used, and more specifically, a methyl methacrylate monomer (hereinafter also referred to as MMA monomer) is used. According to such MMA monomer, it is possible to maintain a low viscosity of 0.1 cps to 10 cps, and in some cases less than 1 cps during the impregnation treatment. Can penetrate. Therefore, the MMA monomer can penetrate the stone material 10 in the thickness direction and quickly impregnate it up to the center position C10. In addition, 2-4 hours can be illustrated as time required for the impregnation to the center position C10.

  However, the impregnating material 20 is not limited to the above MMA monomer. That is, any monomer belonging to the vinyl monomer can be used. Incidentally, other examples of vinyl monomers include styrene monomers.

  Further, a polymerization catalyst may be added to the MMA monomer. The polymerization catalyst starts or accelerates the polymerization reaction of the MMA monomer when heated. Examples of the polymerization catalyst include azobisisobutyronitrile (hereinafter also referred to as AIBN), di-tbutyl peroxide, t-butyl hydroperoxide, cumene hydroperoxide, and the like. In this example, AIBN is MMA. It is added in a ratio of 1 to 2% based on the weight of the monomer.

  When the impregnation treatment is finished, the packaging treatment is performed for the purpose of preventing the impregnation material 20 impregnated in the stone material 10 from being dissipated. Specifically, in the packaging process, the impregnating material 20 is discharged from the sealed container 30 and, as shown in FIG. 2C, the packaging liquid 40 such as water or water glass is injected into the container 30 to completely Is immersed in the packaging liquid 40, so that the entire surface of the stone 10 is covered with the packaging liquid 40. Hereinafter, this state is also referred to as a “packed state”.

  Then, the polymerization process is finally performed. The polymerization treatment is performed by heating the stone material 10 in the above packaging state. Here, in this example, the stone 10 is packaged with the packaging liquid 40 as shown in FIG. 2C. Therefore, the stone 10 is heated by heating the packaging liquid 40. An example of a method for heating the packaging liquid 40 includes heating by putting a heat source (not shown) such as steam in the sealed container 30, but is not limited thereto. For example, the entire container 30 may be heated from outside the sealed container 30. Moreover, although the heating temperature and heating time of the packaging liquid 40 may change according to the kind of the impregnating material 20 or the polymerization catalyst, in this example, it is set to 3 to 4 hours at 50 to 80 ° C.

  Incidentally, irradiation can be exemplified as a polymerization method other than heating. However, the heating polymerization described above is preferable in consideration of the fact that heating can easily construct and operate the equipment rather than irradiation. That is, according to the heat polymerization, the stone material 10 is heated by constructing and using a heating facility relatively easily, whereby the amount of heat necessary for the polymerization reaction is increased via the heated packaging liquid 40. 10 is quickly transmitted from the surface of 10 to the center position C10 in the stone 10. Therefore, the polymerization reaction can be surely caused to the center position C10 of the stone material 10.

  And when the MMA monomer in the space | gap of the stone material 10 raise | generates a polymerization reaction and it becomes a polymer, the space | gap will be almost filled with the polymer, and the reinforcement of the stone material 10 is completed by the above.

  Here, when such reinforcement is made, it becomes difficult for the liquid to enter the gap based on the polymer in the gap. Therefore, the frost damage resistance and acid resistance of the stone 10 can be enhanced. In particular, in the present embodiment, a polymer is filled in the gap from the surface of the stone material 10 to the center position C10. That is, the void is filled with the polymer over the entire area of the stone 10. Therefore, it is possible to effectively prevent a large stress from being generated at the boundary between the surface layer of the stone material 10 and a portion other than the surface layer during freezing. As a result, it is possible to reliably prevent the surface layer of the stone material 10 after reinforcement from peeling off. is there.

  Further, the polymer in the gap can also provide a stiffening effect that supplements the rigidity of the stone 10. Therefore, the bending strength and tensile strength of the stone material 10 are also improved.

  In addition, the inventors of this application have also confirmed the improvement effect of the frost damage resistance and acid resistance of the stone 10 after reinforcement by experiment, and also confirmed the improvement effect of bending strength by experiment. Moreover, these improvement effects are mainly derived from the suppression of the water absorption rate of the stone material 10, and the suppression of the water absorption rate is derived from the filling of the polymer into the voids of the stone material 10. For this reason, the water absorption rate and the state of polymer filling into the voids have also been confirmed by experiments. Hereinafter, what has been confirmed in the experiment will be described.

<Test body>
In order to prepare a test body, a savonniere blank was prepared by cutting it into three cuboid shapes of 150 × 70 × 10 mm, 150 × 70 × 25 mm, and 200 × 100 × 100 mm. And after performing vacuum deaeration for 2 hours with respect to each blank material, the MMA monomer is impregnated for 4 hours, and then heat polymerization is performed at 75 ° C. for 3 hours, whereby the resin according to the present embodiment is obtained. An impregnation specimen was prepared. In addition, about the resin impregnation rate after heat polymerization of each shape, 10 mm thickness was 16.7%, 25 mm thickness was 15.8%, and 100 mm thickness was 9.0%.

In addition, as a first comparative example, the above blank material, which is an untreated specimen, is prepared. Further, as a second comparative example, a silicon-based permeable water absorption preventing material (trade name: AD Super (manufactured by Advance Limited Company)) ) Was also prepared by brushing the entire surface with a basis weight of 200 g / m ² .

<Measurement of water absorption rate>
The water absorption was measured in accordance with JIS A 5003: 1995 “Stone” with respect to a 150 × 70 × 25 mm specimen. That is, while the longitudinal surface (surface of 150 × 70 mm) of the same specimen is perpendicular to the water surface, 20 ± 3 with the lower part immersed in water so that the upper part always protrudes upward from the water surface by 10 mm. It was left in a constant temperature room at 0 ° C. and taken out after 48 hours. Then, the water on the surface was wiped off and measured immediately to obtain the water absorption rate. The water absorption rate was calculated by the following formula.
Water absorption rate (%)
= (Mass after water absorption (g) -Mass when dried (g)) / Mass when dried (g) × 100
FIG. 3 shows the measurement results of the water absorption rate. The water absorption rate of the resin-impregnated test body according to this embodiment is about 1/10 of the water absorption rate of the untreated test body as the first comparative example. That is, it has fallen significantly. And it is thought that this contributes effectively to the improvement of acid resistance and the improvement of frost damage resistance described later.

<Polymer filling state in voids>
Both the untreated 150 × 70 × 25 mm test body as the first comparative example and the 150 × 70 × 25 mm test body impregnated with the resin according to the present embodiment were respectively cut, and the center position CS ( The state of the void in the plane center position of the test body and in the thickness direction was observed with an electron microscope (SEM).

  4A and 4B show SEM images of the respective specimens. As shown in FIG. 4A, in the untreated specimen, there are many voids having an average diameter of about 0.3 mm. However, as shown in FIG. 4B, in the resin-impregnated test body, the void is filled with the polymer even at the center position CS in the test body (see the black region in FIG. 4B). And it is thought that the water absorption rate of the test body according to the present embodiment is greatly reduced based on the filling of the polymer into the voids.

<Acid resistance>
In order to evaluate acid resistance, an artificial acid rain cycle test was performed on a 150 × 70 × 10 mm specimen in accordance with JIS H 8502: 1999 “Plating Corrosion Resistance Test Method”. That is, artificial acid rain was sprayed on the test specimen for 2 hours, dried for 4 hours, and wetted for 2 hours, and this was performed for 720 cycles.
The artificial acid rain was generated as follows. First, 10 liters of an aqueous solution (pH 6.5) obtained by adding 50 ± 5 g of sodium chloride to 1 liter of water is produced, and 12 ml of nitric acid and 17.3 ml of sulfuric acid are added to the 10 liter of the aqueous solution. In addition, the resulting solution was designated as artificial acid rain.
Further, spraying of artificial acid rain was carried out while maintaining the temperature in the tank at 35 ± 2 ° C.
Further, in the drying process for 4 hours, the temperature in the tank is maintained at 60 ± 1 ° C. and the relative humidity is maintained at 20 to 30%. In the wet process for 2 hours, the temperature in the tank is 50 ± 1 ° C. and the relative humidity is Was maintained at 95% or more.

  5A to 5C show the appearances of the respective test specimens after the test. As shown in FIG. 5A, the untreated specimen as the first comparative example is greatly eroded, but the permeable water absorption preventing specimen as the second comparative example and the resin-impregnated specimen according to the present embodiment are used. As shown in FIG. 5B and FIG. 5C, there is almost no change from the state before the test, that is, almost no erosion. Therefore, it was also confirmed by experiments that the reinforcing method of the present embodiment impregnated with resin has an effect of improving acid resistance. Incidentally, it is considered that the main cause of this improvement in resistance was that it was possible to suppress the intrusion of artificial acid rain into the voids of the test specimen.

  By the way, it has been experimentally confirmed that this resin impregnation is very effective in improving the acid resistance of a porous natural stone material containing calcium carbonate such as savonier. That is, it has been confirmed through experiments that savoniere has a much greater effect of improving the acid resistance of resin impregnation than cement-based materials, and this will be described below.

  First, a 90 × 70 × 10 mm rectangular parallelepiped mortar blank was prepared as a cement-based material. The blank was produced according to JIS R5201-1997 “Cement physical testing method”. For example, ordinary Portland cement, ISO standard sand, and water were blended at a weight ratio of 450 grams: 1350 grams: 225 grams.

  An epoxy resin was used as the impregnation resin. Specifically, the mortar blank was immersed in a liquid epoxy resin under atmospheric pressure, and then impregnated in a vacuum deaerated state for 2 hours. Then, after impregnation, the resin adhering to the surface was removed, and curing was performed in an air atmosphere at 40 ° C. for 48 hours.

  On the other hand, a 70 × 35 × 25 mm rectangular parallelepiped blank was prepared for the Savoniere specimen. And in this case, the test body was produced | generated by two patterns, the case where MMA is used for the resin for impregnation, and the case where an epoxy resin is used. For impregnation with epoxy resin, immersion, curing, etc. are performed on the Savoniere blank material in the same procedure as described above. For impregnation with MMA, the same procedure as described above is performed on the blank material. The deaeration process, the impregnation process, and the polymerization process were performed.

And these test bodies were immersed in 5% hydrochloric acid aqueous solution for 30 minutes, and the weight reduction rate by immersion was calculated | required based on the weight change of the test body before and behind immersion. That is, when the weight of the test body before immersion is W1 and the weight of the test body after drying for 24 hours at 105 ° C. is W2, the weights W1 and W2 are substituted into the following equation: The weight reduction rate (%) was determined.
Weight reduction rate (%) = (W1-W2) / W1 × 100
FIG. 6 shows the test results. First, comparing an untreated mortar specimen with a resin-impregnated mortar specimen, it can be seen that both have a small weight loss rate, that is, are hardly dissolved. Further, in more detail, the weight reduction rate of the resin-impregnated specimen is only slightly smaller, and the difference is slight. From this, the acid resistance of the mortar by resin impregnation is small. It can be seen that the effect of improving the sex is very small.

  On the other hand, comparing the resin-impregnated Savoniere specimen with the untreated Savoniere specimen, the weight reduction rate of the untreated specimen is 71%, whereas the resin-impregnated specimen Regarding the weight reduction rate, MMA is 10.5% and epoxy resin is 6.7%, both of which are greatly reduced. Therefore, the acid resistance improvement effect of the resin impregnation is very large with respect to Savoniere, and the effect is much larger than the improvement effect with mortar. Therefore, it was found that the resin impregnation is very effective in improving the acid resistance of porous natural stone materials containing calcium carbonate such as Savonière.

<Frost resistance>
In order to evaluate the frost damage resistance, a freeze-thaw test was performed on a 100 × 100 × 200 mm specimen in accordance with JIS A 1435: 2013 “Freeze-thaw test method for building exterior materials”. That is, the test specimen was frozen in air for 2 hours (−20 ° C.) and thawed in water for 1 hour (+ 10 ° C.) as one cycle, and 300 cycles were performed.

  FIG. 7A and FIG. 7B show the appearances after the test of the permeable water absorption preventive material as a second comparative example and the resin-impregnated test sample according to this embodiment, respectively. In the test body of the permeable water absorption preventing material as the second comparative example in FIG. 7A, the surface layer is peeled off. Specifically, peeling occurs at the boundary between the surface layer impregnated with the permeable water absorption preventing material and the portion other than the surface layer not impregnated. Therefore, the reason for this is that the water absorption rate differs between the surface layer impregnated with the permeable water absorption preventing material and the portion other than the surface layer not impregnated, and as a result, the expansion behavior of water during freezing is different. This is probably because a large stress was generated at the boundary.

  On the other hand, in the resin-impregnated test body according to this embodiment in FIG. 7B, damage such as peeling off of the surface layer is not substantially generated, and the appearance is almost the same as that before the test. The reason for this is that the polymer is filled from the surface of the test body to the center position CS in the test body, so that the invasion of water that can expand during freezing is caused from the surface to the center position CS in the test body. This is considered to be due to the suppression. From the above, it was also confirmed by experiments that the reinforcing method according to the present embodiment has high frost damage resistance including prevention of peeling of the surface layer.

<Bending strength>
In order to evaluate the bending strength, a three-point bending test was performed on a 150 × 70 × 10 mm specimen in accordance with JIS A 5411-1994 “Terazo”. That is, a support rod is placed at each position 30 mm from both ends in the longitudinal direction of the test body to support the test specimen at two points from below, and a diameter of 15 mm from above at the central position in the longitudinal direction (position 75 mm from the end). By pressing the steel cylindrical member, a downward load is applied to the center position to break the specimen. Then, the breaking load P, the distance L (= 90 mm) between the two support rods, the width b (= 70 mm) of the specimen, and the average value d (mm) of the thickness of three places on the fracture surface of the specimen. Was substituted into the following equation to obtain the bending strength.
Bending strength (N / mm ² ) = (3 × P × L) / (2 × b × d ² )
FIG. 8 shows the test results. The bending strength of the specimen of the permeable water absorption preventing material as the second comparative example is almost the same as the bending strength of the untreated specimen as the first comparative example, but for the resin-impregnated specimen according to this embodiment, The bending strength more than twice the bending strength of the untreated specimen as the second comparative example is shown. The reason for this is considered that the permeable water absorption preventing material penetrates only into the surface layer of the test specimen, whereas in the resin impregnation, the gap is filled with the MMA polymer up to the center position CS in the test specimen. From the above, it was also confirmed in experiments that the reinforcing method of the present embodiment has a stiffening effect that increases the bending strength.

=== Other Embodiments ===
As mentioned above, although embodiment of this invention was described, said embodiment is for making an understanding of this invention easy, and is not for limiting and interpreting this invention. Further, the present invention can be changed or improved without departing from the gist thereof, and needless to say, the present invention includes equivalents thereof. For example, the following modifications are possible.

  In the above-described embodiment, savonière is mainly exemplified as the porous natural stone material 10 containing calcium carbonate, but the present invention is not limited to this. That is, as long as the porous stone material 10 contains calcium carbonate, stone types other than Savonière may be used.

In the above-described embodiment, the stone 10 is not forcibly dried between the cut-out process and the deaeration process, but may be forcibly dried depending on the case. For example, when the stone material 10 is stored in an outdoor storage place after the stone material 10 is cut out, rainwater or the like may soak into the stone material 10, and the rainwater may remain in the voids in the stone material 10. Then, at the time of the impregnation treatment with the vinyl-based monomer, there is a risk that the penetration of the monomer into the voids may be inhibited. Therefore, you may force-dry the stone material 10 before a deaeration process.
Further, whether or not forced drying is performed may be determined based on the moisture content (%) of the stone 10. That is, the moisture content of the stone material 10 is measured between the cutting process and the deaeration process, and when the moisture content is larger than a predetermined threshold value, the stone material 10 is forcibly dried. May not be forced to dry. Incidentally, as an example of forced drying, it can be illustrated that the hot air of 100 to 150 ° C. generated by a hot air generator such as a dryer is blown against the stone 10. The moisture content (%) is, for example, a percentage notation value obtained by dividing the weight (g) of water contained in the stone 10 by the total weight (g) of the stone, and the threshold value is 0. An arbitrary value greater than% and less than 10% can be exemplified.

10 natural stone, 10sa plane, 10sb plane (surface),
20 Impregnating material (vinyl monomer),
30 airtight container, 32 support member,
40 packaging liquid,
C10 center position, C10p plane center position, C10t thickness center position,

Claims (5)

A method of reinforcing natural stone used for building exterior materials,
Impregnation treatment for impregnating the porous natural stone containing calcium carbonate with a vinyl-based monomer from the surface of the stone to a central position in the stone;
Have a, a polymerization process for polymerizing the vinyl monomer impregnated in the stone,
The viscosity of the vinyl monomer during the impregnation treatment is 0.1 cps to 10 cps,
The stone has a thickness of 20 mm to 70 mm,
The method for reinforcing a natural stone material used for a building exterior material , wherein a total volume of a large number of voids related to the porous material occupies 20% to 50% of a volume of the stone material. A method for reinforcing a natural stone material used for the building exterior material according to claim 1,
The method for reinforcing a natural stone material used for a building exterior material, wherein the natural stone material is heated as the polymerization treatment. A method for reinforcing a natural stone material used for an exterior material of a building according to claim 1 or 2 ,
A cutting process for cutting out the natural stone material;
And a degassing process for degassing the cut out natural stone material. A method for reinforcing a natural stone material used for an exterior material of a building. A method for reinforcing a natural stone material used for the building exterior material according to claim 3 ,
A method for reinforcing a natural stone material used for an exterior material of a building, wherein the natural stone material is not forcibly dried between the cutting process and the deaeration process. A method for reinforcing a natural stone material used for the building exterior material according to claim 3 ,
Between the cutting process and the degassing process, measure the moisture content of the natural stone material,
When the measured moisture content is larger than a predetermined threshold, the stone is forcibly dried before the deaeration treatment, and when the moisture content is less than the threshold, the stone is not forcibly dried. Reinforcement method of natural stone material used for the exterior material of the characteristic building.