JP5454995B2 - Renovation structure of cement board - Google Patents

Description

  The present invention relates to a repair structure and a repair method for a cement-based plate material, and is particularly suitable for repairing a cement-based plate material such as a slate material.

  Here, a case where an existing asbestos slate (asbestos material) used as a roofing material and deteriorated over time is repaired will be described as an example. The present invention can also be applied to a method for repairing various existing cement-based board materials other than asbestos board materials, such as existing asbestos-cement sizing, when used as an outer wall material other than a roofing material.

  Conventionally, asbestos slate is excellent in heat resistance, fire resistance, sound absorption, and heat insulation, and is light weight and low in price. Therefore, asbestos slate has been used in large quantities as a roofing material and an outer wall material in factories and warehouses.

  In particular, asbestos slate that has been used as a roofing material is most affected by sunlight, rain, snow, and the like, so that aging degradation is promoted as compared to wall materials. For this reason, it is difficult to ensure the required strength, and asbestos particles may be scattered from the outer surface, which requires early replacement. Therefore, a large amount of material waste containing asbestos is generated.

  However, in recent years, from the viewpoint of preventing damage to asbestos (asbestos) dust, it is desirable to reduce the generation of a large amount of asbestos-containing material waste as much as possible.

  As a countermeasure, Patent Document 1 discloses a modified structure of cement material (containment method for asbestos material) having the following configuration that encloses the surface of asbestos material such as asbestos slate to prevent the asbestos from scattering and reinforces asbestos slate R. (See paragraph 1 of paragraph 0010 of the same document and FIG. 1 attached to the present application).

  “A method for repairing asbestos material R includes the following steps.

  (Step A) On the surface of the asbestos material R, a waterproof and liquid lower layer resin 1 that can penetrate the net 2 is applied.

  (Step B) A net 2 is laid on the surface of the roof R to which the lower layer resin 1 is applied.

  (Step C) On the laid net 2, a waterproof upper liquid resin 3 that can penetrate the net 2 is further applied.

  (Step D) A weather-resistant surface layer resin 4 is applied to the surface of the mesh 2 infiltrated with the upper layer resin 3.

  In the above, it is described that washing with water, dry ice blasting, etc. may or may not be performed as appropriate (same paragraph 0011).

  Further, in the same paragraph 0019, “the upper resin 3 in the step C is infiltrated until reaching the surface of the asbestos material R on the lower surface of the net 2. When the upper resin 3 is cured and dried, the net 2 is It is hardened to improve the strength of the modified asbestos material. Further, the upper layer resin 3 bonds the net 2 to the asbestos material R, thereby further improving the strength of the asbestos material R.

However, in the above construction method, it is necessary to use the net 2 for reinforcing asbestos materials. In addition, since the lower layer resin does not have permeability, it is considered necessary to perform base treatment (cleaning) such as washing with water and dry ice blasting in order to ensure adhesive strength. In the figure, reference numeral 5 denotes a base treatment layer (high pressure water washing, blast treatment).
JP-A-2005-194162

  In view of the above, the present invention does not require a reinforcing material such as a net, and can obtain a sufficient reinforcing effect even without a conventional ground treatment (high pressure water washing, electric brush, blasting, etc.). The purpose is to provide a new cement-based plate repair structure and a repair method.

  Therefore, as a result of intensive studies to overcome the above problems, the present inventors have formed a primer layer with a water-permeable epoxy resin, and then formed a mortar layer with a water-curable cement mortar. Based on the knowledge (discovery) that can be obtained, we have come up with a modified structure of cement-based plate material with the following structure.

It is a modified structure of an existing cement-based board used as a roofing material reinforced with inorganic fibers,
In the modified structure in which the cement-based board is asbestos slate,
On the treated surface of the cement-based plate material that is the base material,
A primer layer formed with a two-component water-based epoxy resin primer;
A mortar layer formed of a hydraulic elastic cement mortar in direct contact with the primer layer;
A weather resistant overcoat layer in direct contact with the mortar layer ,
The hydraulic elastic cement mortar contains polyethylene terephthalate fiber coated with polyvinyl alcohol fiber .

  When the two-component aqueous epoxy resin-based primer penetrates into the surface to be treated of the slate, a primer / mortar integrated layer is formed with hydraulic elastic cement mortar that directly contacts the primer layer. This eliminates the need for ground treatment such as sandblasting of the surface to be treated and high-pressure water washing before construction of the repair structure and asbestos may be scattered. Further, since a primer / cement mortar integrated layer having a higher strength than that of a normal resin-based paint is formed, it is possible to expect a strength recovery similar to that of a new product to deteriorated products such as used slate plates.

The hydraulic elastic cement mortar may be a water-soluble polymer- containing type. When it is set as the said structure, the improvement of the toughness (toughness: the magnitude | size of the capability to absorb energy by the time of a material fracture | rupture) of the cement-type board | plate material after repair can be anticipated (refer Examples 1-3). In particular, when applied to a roof slate plate or the like that often receives impact load or bending load from above, an extension of the service life can be expected regardless of whether it is new or used.

  The hydraulic elastic cement mortar may include a polar synthetic fiber. In the case of such a configuration, further improvement in strength and toughness can be expected (see Examples 2 and 4).

As the polar synthetic fiber, polyethylene terephthalate fiber coated with polyvinyl alcohol fiber can be used.

Since the cementitious board material to which the present invention is applied is asbestos slate, as described above, there is an effect based on the fact that the pretreatment of the surface to be treated which is likely to cause asbestos scattering is not necessary.

  The repair method for constructing the repair structure of the present invention has the following configuration.

  A method of repairing a cement-based plate material according to the above-described cement-based plate material repair structure, wherein the slate material is coated and cured with the hydraulic elastic cement mortar after the primer is applied and cured without going through a scouring process. And a step of forming the primer / mortar integrated layer.

According to the present invention, as shown in the examples described later, asbestos can be prevented from scattering, the strength close to that of a new article can be recovered, and further, when the hydraulic elastic cement mortar is an elastic resin-containing type, toughness ( The tenacity) can be improved and the durability of asbestos slate can be increased. Therefore, when it is applied to asbestos slate before deterioration, it contributes to the extension of the service life by improving toughness (in contrast, the conventional epoxy resin for general-purpose slate materials has decreased).

  Hereinafter, desirable modes of the present invention will be described in detail. In the following description, blending units such as content ratio and mixing ratio are mass units unless otherwise specified. The same applies to the claims.

  The modified structure of the cement-based plate material of the present embodiment is formed, for example, as follows (see FIG. 2).

  Here, asbestos slate R1 is taken as an example of the cement-based plate material, but it can also be applied to other cement-based plate materials such as calcium silicate board, color vest, colonial plate and the like.

  “Asbestos slate” is made of cement and asbestos as main raw materials, added with a small amount of admixture and appropriate amount of water (asbestos weight ratio 15-30%), made into a sheet, dried. Yes (from "Rinkan Slate Industry" homepage).

  1) First, an aqueous primer is applied without going through the surface treatment (polishing) step. Here, the surface treatment means removal of adhesion dirt on the surface such as high-pressure water washing, electric brush or blast treatment. Therefore, it does not preclude the removal of large dust and lightly removing dust with water, a tub, or a vacuum cleaner. For this reason, even if the slate contains asbestos, there is almost no possibility that air scattering will be accelerated.

  As the aqueous primer, here, an aqueous two-pack type epoxy resin is used. This is because the water-based two-pack type epoxy resin can easily adjust the viscosity having permeability to the slate with water, and can easily secure an inseparable adhesive strength with the water-curable cement mortar.

  More specifically, what is marketed by Jericho Co., Ltd. under the trade name “Jericho HM360” can be suitably used.

The coating amount of the aqueous two-liquid type epoxy resin (solid content), the deterioration degree of the slate, varies depending on the kind or the like of the epoxy resin, usually 50 g / m ² or more, preferably appropriately selected in the range of 75~250g / m ² To do.

2) After the primer 11 is applied and dried, the hydraulic elastic cement mortar 13 is applied to form the primer / cement mortar integrated layer 15.

  Here, the hydraulic elastic cement mortar is a normal Portland cement containing fine aggregate (fine sand).

  Here, the mixing ratio of cement / aggregate is usually 1/1 to 1/3, preferably 1/1 to 1/2.

  Further, in the present invention, the water cement weight ratio (water mixing amount) is usually appropriately selected in the range of 20 to 100%, desirably 90 to 70%.

  The hydraulic elastic cement mortar of the present invention preferably contains a water-soluble polymer. The water-soluble polymer can impart elasticity to the mortar layer and contributes to improvement of durability.

  Examples of the water-soluble polymer include ethylene vinyl acetate copolymer (EVA), polyvinyl alcohol, polyacrylic acid, and polyacrylamide. The content of the water-soluble polymer in the total solid content is usually 20 to 50%, preferably 30 to 40%.

  Further, it is desirable that the hydraulic elastic cement mortar contains polar synthetic fibers. The reinforcing effect by the mortar layer is further increased. Examples of the polar synthetic fiber include polyester (PET, PBT), polyamide (nylon), polyvinyl alcohol (vinylon), acetate, and composite fibers thereof.

  The content of the polar synthetic fiber is usually 1 to 3%, preferably 1.25 to 2.5%, in the solid content of the water-soluble polymer.

  More specifically, as the hydraulic elastic cement mortar containing polar fiber synthetic fibers, those marketed by Jericho Co., Ltd. under the trade name “Jerico RTX” can be suitably used.

The application amount (solid content) of the hydraulic mortar varies depending on the degree of deterioration of the slate, the required strength, and the like, but is usually selected appropriately in the range of 1 to 6 kg / m ² , preferably ² to 3 kg / m ² .

  3) After the application and drying of the cement mortar layer 13, a general-purpose exterior top coating is appropriately applied to form the top coating film 14.

  As the top coat, those marketed by Jericho Co., Ltd. under the trade name “Jerico CB” can be suitably used.

  4) The modified structure of the cement-based plate material thus formed exhibits sufficient repair strength and contributes to the improvement of toughness as shown in the examples described later.

  Examples carried out together with comparative examples to confirm the effects of the present invention will be described below.

The three-point bending test is performed in accordance with JIS A5430. The untreated specimen is a new asbestos slate (untreated specimen: new article A or new article B) in Test Example A, and the asbestos slate used article (untreated specimen B). 20-year-old untreated test pieces: used goods) were used, and their sizes were 160 × 80 × 5 mmt (cross-sectional area: 400 mm ² ).

  Moreover, each primer and mortar used in the Examples are as follows.

      Primer: "Jericho HM360" (containing epoxy resin 45-50%) diluted with the same amount of water.

      Cement mortar I ... "Jericho RTX" 20kg added with 2.5L of tap water. However, "Jericho RTX" consists of 17 kg of the main agent (Portland cement type) and 3 kg of curing agent (epoxy type).

II ... Cement mortar I and polar fiber ("Tough Binder" manufactured by Toray Industries, Inc.)
Polyester type) with about 3% added.

<Test Example A>
It is the test example performed in order to see the influence which has on the effect (strength and toughness) at the time of applying this invention to a new article.

1) Examples 1 and 2
The primer was applied to asbestos slate (new article A) so that the solid content was 150 g / m ² . After 5 minutes of application, Example 1 and 2 were coated with cement mortar I and Example 2 was coated with cement mortar II so that the solid content was about 2 kg / m ² , respectively. Was prepared.

2) Comparative Examples 1 and 2
Samples of Comparative Examples 1 and 2 were prepared by applying commercially available products A and B (both epoxy) asbestos slate paint (epoxy resin) to asbestos slate (new A) with a solid content of 150 g / m ^2. Was prepared.

  The three-point bending test was performed on each of Examples 1 and 2, Comparative Examples 1 and 2 and Control Examples 1 and 2 (new A and B blanks) prepared above. The following was found from FIG. 3 showing the results.

  In Examples 1 and 2, the amount of displacement at break was about 0.55 to 0.95 mm from around 0.5 mm of Control Example 1 and 2, which is a new article, and elasticity was imparted to the slate material without a decrease in strength. . In particular, in Example 2 using fiber-added mortar, the strength decrease is small and the toughness (displacement at break) is improved. On the other hand, in Comparative Examples 1 and 2 to which a commercially available paint is applied, both strength and toughness are lowered.

<Test Example B>
It is the test example performed in order to see the influence which has on the effect (strength and toughness) at the time of applying this invention to a used article (unprocessed test piece C).

1) Examples 3 and 4
In Examples 1 and 2, test pieces of Examples 3 and 4 were prepared in the same manner except that a new article was replaced with a used article.

2) Comparative Example 3
In Comparative Example 1, a test piece of Comparative Example 3 was prepared in the same manner except that the new article was replaced with a used article.

上記で調製した実施例３・４及び比較例３とともに対照例３（中古品ブランク）について、前記三点曲げ試験を行った。その結果を示す表１から、下記のことが分かった。

The above-mentioned three-point bending test was performed on Control Example 3 (used blank) together with Examples 3 and 4 and Comparative Example 3 prepared above. The following was found from Table 1 showing the results.

  In Examples 3 and 4 to which the present invention is applied, the breaking strength is 3.5 times and 5.5 times that of the second comparative example, and the toughness is double the displacement at break in Example 3. It ’s close. On the other hand, Comparative Example 3 to which a commercially available coating was applied had only 1.5 times the breaking strength, and the toughness (displacement at break) was also reduced as in Test Example A.

The breaking strength in Example 4 is 1.1 kN, and has recovered to about 73% of the breaking strength of the new article A (about 37.5 Nmm ⁻² × 400 mm ² = 15 kN: see FIG. 3).

It is model sectional drawing which shows a conventional example of the repair structure of a cement-type board | plate material. It is a model sectional view showing an example of the present invention similarly. It is a graph which shows the result of the three-point bending test at the time of applying to the new asbestos slate at the time of applying this invention and a commercially available coating material.

Explanation of symbols

11 Primer (layer)
13 Mortar (layer)
15 Primer / mortar integrated layer 17 Top coat

Claims (3)

It is a modified structure of an existing cement-based board used as a roofing material reinforced with inorganic fibers,
In the modified structure in which the cement-based board is asbestos slate,
On the treated surface of the cement-based plate material that is the base material,
A primer layer formed with a two-component water-based epoxy resin primer;
A mortar layer formed of a hydraulic elastic cement mortar in direct contact with the primer layer;
A weather resistant overcoat layer in direct contact with the mortar layer ,
A modified structure of a cement-based board material, wherein the hydraulic elastic cement mortar contains polyethylene terephthalate fiber coated with polyvinyl alcohol fiber . The repair structure for a cement-based board according to claim 1, wherein the hydraulic elastic cement mortar is a water-soluble polymer- containing type. 3. A method for repairing a cement-based plate material according to the modified structure of a cement-based plate material according to claim 1 or 2 , wherein the cement-based plate material is coated and cured without passing through a polishing step, and then the hydraulic cement mortar. A method for repairing a cement-based plate material, comprising a step of forming the primer / mortar integrated layer by applying a coating material.

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