JP2645514B2 - Covering material for sprayed asbestos - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a covering material having a novel composition used in a method for containing sprayed asbestos such as an existing building.

Conventional technology and its problems Sprayed asbestos was used in the 1950s and 1950s.
In various buildings such as schools, hospitals, factories, parking lots, and general buildings, it has been widely used for applications such as sound absorption of ceilings, beams, and walls, heat insulation, prevention of dew condensation, and fire-resistant coating of steel frames.

However, the actual situation of various health disorders caused by asbestos dust has gradually become clear, and since 1975,
The revision of the Regulations for Prevention of Specific Chemical Injuries has banned asbestos spraying in principle.

On the other hand, asbestos sprayed before 1975 was left without any restrictions, but in recent years due to the aging of buildings, damage to sprayed asbestos, It has been pointed out that there is a risk that the deterioration proceeds and the scattered dust causes a new health hazard.
Therefore, establishment of safety measures for sprayed asbestos of existing buildings is demanded.

The following three methods have been implemented or proposed as methods for preventing asbestos dust from scattering.

(B) Method for completely removing sprayed asbestos (hereinafter referred to as the removal method): (b) Method for surrounding sprayed asbestos with panels (hereinafter referred to as the enclosed method): (c) Sprayed asbestos with chemicals A method of enclosing by means such as solidification or coating (hereinafter referred to as encapsulation method).

At first, the removal method was the mainstream, but in this method,
Since asbestos dust is scattered during the removal and it is difficult to completely recover the asbestos dust, there are many construction examples in which the asbestos concentration is higher than before the removal, which is a problem. Also,
Asbestos, in a sense, is regarded as a dangerous substance comparable to radioactive waste, and therefore, there are many problems in the disposal place after removal, the disposal method, and the like. Furthermore, in the building after removal, it is necessary to reconstruct with a substitute material that has various properties such as excellent sound absorption, heat insulation, fire resistance, etc. of the sprayed asbestos construction surface, which increases costs. It is a difficult point.

In the case of the enclosure method, in the panel attaching process,
Asbestos dust is easily scattered, and there is also a danger that asbestos dust is scattered from a gap between the panels.
Furthermore, when asbestos is sprayed on a place where it is difficult to mount the panel, it is practically impossible even to perform the spraying.

Therefore, recently, a containment method that is easy to operate and has a low risk of secondary pollution is becoming mainstream. However, as a covering material (or a covering material) used in the containment method, a lightweight, nonflammable and elastic material has not yet been completely developed, and there is a long-awaited demand for a new covering material.

Means for Completing the Problems The present inventor has conducted intensive studies in view of the state of the art as described above, and as a result, a composition obtained by mixing a specific aggregate and a polymer with an inorganic binder has been used in a containment method. It has been found that as a covering material for sprayed asbestos, the problems of known materials can be substantially eliminated or greatly reduced.

That is, the present invention provides the following covering material for sprayed asbestos: 100 parts by weight of hydraulic material, 10 to 200 parts by weight of lightweight aggregate and 1 to 50 parts by weight of high elastic emulsion component (as solid content) )
The covering material for sprayed asbestos according to the above item 1, further comprising a covering material for sprayed asbestos, comprising: and 0.01 to 10 parts by weight of a workability improver.

Hereinafter, each component used in the present invention will be described in detail. Each of the components I to III is essential, but the other components are optional components used as needed.

I. Hydraulic material Portland cement, alumina cement, gypsum plaster, etc. are used as hydraulic materials. Even if these materials are used alone or in combination of two or more, there is no significant difference in effect.

Examples of the Portland cement include ordinary Portland cement, early-strength Portland cement, ultra-high-strength Portland cement, sulfate-resistant Portland cement, white Portland cement, and the like.

The primary role of the hydraulic material is to cure lightweight aggregates and highly elastic emulsions.

II. Lightweight Aggregate Lightweight aggregates have the effects of reducing the weight of materials, improving workability, and stabilizing physical properties for a long time. As such lightweight aggregates, those that have been used as building materials conventionally,
It can be used, and examples include expanded perlite, expanded vermiculite, shirasu balloon, pumice stone, and silica gel foam. Since the sprayed asbestos substrate used by the covering material of the present invention has low strength, the specific gravity of the cured covering material is particularly preferably 1 or less in order to prevent the covering material from peeling off due to its own weight. For this reason,
The lightweight aggregate itself preferably has a particle packing density of 0.5 kg / or less. The particle diameter is not particularly limited, but is preferably about 0.3 to 2 mm as an average particle diameter.

The amount of the lightweight aggregate is 1 to 100 parts by weight of hydraulic material.
It should be in the range of 0 to 200 parts by weight. When the amount of the lightweight aggregate is less than 10 parts by weight, the weight reduction becomes insufficient. On the other hand, when the amount exceeds 200 parts by weight, workability at the time of using the covering material is impaired.

III. High Elasticity Emulsion Component The covering material of the present invention needs to have elasticity that can cope with the fluctuation of the sprayed asbestos substrate after curing. Therefore, a high elasticity emulsion component is used as long as the nonflammability is not impaired. As such a high elasticity emulsion component,
Homopolymers composed of soft component acrylic monomers such as ethyl acrylate, butyl acrylate, and 2-ethylhexyl acrylate, and copolymers containing 80% or more of these monomers are used. In the present invention, these polymers are referred to as "high elasticity emulsion components" because these polymers are used in the form of an emulsion.

The amount of the high elastic emulsion component used as the solid content is
It is in the range of 1 to 50 parts by weight based on 100 parts by weight of the hydraulic material. When the amount is less than 1 part by weight, the curing for imparting elasticity is insufficient. On the other hand, when the amount is more than 50 parts by weight, the incombustibility is reduced, and it is difficult to put to practical use.

IV. Workability improver In the present invention, various additives can be used in combination for workability improvement.

First, at the time of application work, the viscosity suitable for the slurry, thixotropy, pot life, as a workability improver used to impart water retention and the like, casein, casein calcium, gelatin, egg albumin, γ-globulin, Protein-based thickeners such as zein, pepsin, pectin, papain, glue, and petroleum artificial protein: Cellulose derivatives such as methylcellulose, carboxymethylcellulose, hydroxymethylcellulose, hydroxyethylcellulose, hydroxypropylmethylcellulose, xanthate cellulose: polyvinyl Alcohol, polyacrylate, polyacrylamide, polyethylene oxide,
Water-soluble polymers such as polyvinylpyrrolidone and polyvinylpyrrolidone: examples include cement dispersants such as melamine sulfonate, naphthalene sulfonate, and lignin sulfonate.

Examples of the workability improver used to prevent sagging after spraying include short fibers of synthetic fibers such as polyacryl, polyethylene, polypropylene, polyvinyl chloride, and polyamide: straw, paper, and hemp. And various kinds of soups such as inorganic fiber sows.

The use amount of these workability improvers is in the range of 0.01 to 10 parts by weight based on 100 parts by weight of the hydraulic material. If this amount is less than 0.01 part by weight, the effect of improving workability and the like will be insufficient, while if it exceeds 10 parts by weight, coarse bubbles will be entrained in the cured body, and There is a tendency for body strength to decrease.

V. Pigment In the present invention, a pigment can be blended to color the surface as needed.

As the pigment, those which are usually used as plastering colorants can be used as they are, and are not particularly limited, and specifically, red iron oxide, various synthetic iron oxides (red, orange, yellow, black) Chrome oxide (green), cement green (green), ultramarine blue (blue), phthalonine blue (blue), maroon bengala (purple), carbon black, and the like.

The amount of the pigment used is 20 parts by weight or less based on 100 parts by weight of the hydraulic material. When the amount of the pigment is more than 20 parts by weight, the strength of the cured product is reduced, efflorescence is easily generated on the surface of the cured product, cracks are easily generated, and weathering is easily generated.

VI. Admixture In the present invention, an admixture can be added in an amount not exceeding 100 parts by weight for increasing the amount. Examples of admixtures include fly ash, blast furnace slag powder, limestone powder, silica sand, shirasu, slaked lime, light yellow clay, calcium carbonate powder, white clay (activated clay, acid clay), siliceous powder (silica fume, silica flower), plaster, dolomite. Plaster and the like.

The amount of filler used per 100 parts by weight of hydraulic material is 100
If the amount is more than the weight part, the strength of the cured product is reduced, which is not preferable.

When performing spraying asbestos coating using the covering material of the present invention, prior to construction, on site,
A homogeneous solid mixture composed of a hydraulic material and a lightweight aggregate and, if necessary, other solid additive components is mixed with an emulsion containing a highly elastic emulsion component, and if necessary, water is further added. May be applied to a predetermined place by an appropriate method.

Effect of the Invention When the covering material according to the present invention is used, a lightweight coating having excellent adhesion, elasticity and fire resistance to a sprayed asbestos substrate is formed. Further, the covering material of the present invention can be easily formed into a uniform slurry on site, and this slurry has excellent workability.

EXAMPLES Examples and comparative examples are shown below to further clarify the features of the present invention.

Examples 1 to 3 and Comparative Examples 1 to 3 Hydraulic materials, lightweight aggregates, highly elastic emulsion components and water were blended, kneaded, molded and cured in the proportions shown in Table 1.

In addition, as the lightweight aggregate, use expanded perlite,
As the high elasticity emulsion component, 2-
A copolymer consisting of 95% of methylhexyl acrylate and 5% of methyl methacrylate as a hard component was used.

Table 2 shows the specific gravity of the kneaded product and the cured product, and the strength and bending Young's modulus of the cured product.

The specific gravity was measured using a specific gravity cup according to the test method of JIS K5400.

The bending Young's modulus was measured for a hardened body of 4 weeks of age according to the Architectural Institute of Japan “GRC bending test method (draft)”.

From the results shown in Table 2, in the covering material of the present invention, in both the kneaded material and the cured product, the specific gravity is:
Approximately 1/2 of conventional products, and bending Young's modulus is approximately 1/10
It has become about. From this, it is clear that the covering material of the present invention can form a lightweight and elastic coating.

Experimental Example 1 A slurry was prepared in the same manner as in Example 1, and the slurry was used to determine the fire resistance according to JIS A 1321. As a result, a result indicating noncombustibility was obtained.

For comparison, a slurry was prepared in the same manner as in Example 1 except that a vinyl acetate resin-based bond was used as an organic binder instead of Portland cement, and JIS A 1
By examining the fire resistance properties of the test piece No.321, it was found that the fire resistance was acceptable.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁶ Identification code Agency reference number FI Technical display location C04B 14:18 24:38) 111: 72

Claims (2)

(57) [Claims] 1. A covering material for sprayed asbestos comprising 100 parts by weight of hydraulic material, 10 to 200 parts by weight of lightweight aggregate and 1 to 50 parts by weight (as solid content) of a highly elastic emulsion component. 2. The covering material for sprayed asbestos according to claim 1, further comprising 0.01 to 10 parts by weight of a workability improving agent.