JP3279412B2 - Manufacturing method for lightweight refractory concrete - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing lightweight refractory concrete for producing lightweight refractory materials used for refractory structures.

[0002]

2. Description of the Related Art A lightweight refractory material is manufactured using lightweight concrete composed of lightweight aggregate (partially including ordinary aggregate) and cement. Water for kneading the water and cement
It exists in fine voids in the surface layer of the lightweight aggregate. The absorbed moisture remains inside even after a considerable period of time after the production of the lightweight refractory material. For this reason, when the lightweight refractory material is exposed to a high temperature, there is a problem in that the remaining moisture boils and evaporates, and the vapor pressure causes the lightweight refractory material to explode. Therefore, in a fireproof covering structure using such a lightweight fireproof material, it is inevitable to use it together with a spraying material of a heat resistant material such as glass wool.

[0003]

However, as described above, when the spraying material is used in combination with the spraying material, there is a disadvantage that the spraying operation requires extra labor and cost, thereby lowering the construction efficiency and increasing the cost.

[0004] Therefore, in order to suppress the absorption of moisture into the fine voids in the surface layer of the lightweight aggregate, coating with asphalt, coating with a thermosetting resin such as epoxy resin, coating with an elastic resin such as urethane, SBR, etc. It was conceivable to apply a treatment such as coating with a water-soluble polymer and coating with a thickened cement paste (or mortar) to a lightweight aggregate.

However, in producing a lightweight refractory material, it is necessary to sufficiently knead cement, water, lightweight aggregate and the like in a mixer, and the cement must be stable against mechanical exfoliation during kneading. It is required to be chemically stable against strong alkali, not to dissolve during kneading and adversely affect the strength after cement hardening, and to be simple, easy to work, and inexpensive in its coating process. On the other hand, none of the above-mentioned coating agents could satisfy all of these requirements.

The present invention has been made in view of such circumstances, and is excellent not only in fire resistance, but also in physical and chemical stability. It is an object of the present invention to provide a method for inexpensively and easily producing a lightweight refractory material capable of preventing the occurrence of a fire.

[0007]

SUMMARY OF THE INVENTION In order to achieve the above-mentioned object, a method for producing a lightweight refractory concrete according to the present invention is applied to a surface of a lightweight aggregate whose water content is reduced to 10% by weight or less. , A film is formed by coating a low-acid solution having a viscosity that can penetrate into the fine voids in the surface layer and increasing the viscosity to 50 times or more by increasing the pH, forming a film, and cementing the lightweight aggregate having the film formed thereon. And water are added and stirred and mixed to increase the viscosity, and then the remaining cement, water and aggregate are added and mixed with stirring.

[0008] The water content of the lightweight aggregate is 10 wt% or less, preferably for reduced to 1.0% by weight or less. If it exceeds 10% by weight, there is no explosion prevention effect. As a treatment for reducing the water content in this way, a method of limiting the water treatment after baking (including no treatment), a method of drying by applying thermal energy, and a method of dehydrating by a vacuum treatment and so on.

As the low-acidic solution, an aqueous dispersion of a low-acidic anionic acrylic resin composed of a carboxyl group-containing monomer (a) and optionally another monomer (b) is used. As the carboxyl group-containing monomer (a), (meth) acrylic acid [represents acrylic acid and methacrylic acid. Hereinafter, similar expressions are used. ], Unsaturated monocarboxylic acids such as crotonic acid, and unsaturated polycarboxylic acids such as maleic acid and itaconic acid fumaric acid. The other monomer (b) includes (a) an unsaturated carboxylic acid ester, for example, the above unsaturated carboxylic acid [(meth)
Alkyl (e.g., acrylic acid) ester (methyl-, ethyl-, n- or iso-propyl-, n- or iso-butyl-, 2-ethylhexyl ester, etc.), (b) aromatic vinyl Monomers, for example, styrene, (c) vinyl esters, for example, vinyl acetate,
(D) Unsaturated nitriles, for example, (meth) acrylonitrile, (e) halogen-containing monomers, for example, hydrophobic monomers such as vinyl chloride and chloroprene, and (h) amide group-containing monomers, for example, (meth) ) Acrylamide, (g) hydroxyl-containing monomer, for example, vinyl alcohol, (meth)
Hydrophilic monomers such as allyl alcohol, hydroxyethyl (meth) acrylate and the like di- or poly-vinyl compounds, such as divinyl toluene, (li) unsaturated mono- or poly-carboxylic acid and polyol Di- or poly-esters, such as polyethylene glycol diacrylate, di- or poly- (meth) allyl esters of (nu) polycarboxylic acids, such as diallyl maleate, diallyl phthalate, bis (meth) acrylamide, etc. Crosslinkable monomers having at least two polymerizable double bonds described in Japanese Patent No. 4,076,663 are exemplified.

The proportion of the monomer in the polymer substance used in the low-acid solution can be variously changed within a range in which a water-soluble or water-dispersible polymer can be formed, but it is generally based on the weight of all the monomers. The content of the carboxyl group-containing monomer (a) is usually 20% or more, preferably 25 to 75%, more preferably 30 to 70%. If it is less than 20%, the increase in viscosity due to the increase in pH will be insufficient, and the effect of suppressing water absorption will be insufficient. The content of the hydrophobic monomer is usually 80% or less, preferably 25 to 75%, more preferably
30-70%. If it exceeds 80%, there is a disadvantage that the increase in viscosity due to the increase in pH becomes insufficient and the effect of suppressing water absorption becomes insufficient. The content of the crosslinkable monomer is usually 2% or less, preferably 1% or less. If it exceeds 2%, there is a disadvantage that the increase in viscosity due to the increase in pH becomes insufficient and the effect of suppressing water absorption becomes insufficient. The weight ratio of the carboxyl group-containing monomer (a) to the other hydrophilic monomer is usually from 100: 0 to 50:50, preferably from 100: 0 to 75:25.

The polymer substance used for the low-acid solution can be produced by polymerizing the above-mentioned monomer by a usual polymerization method. As a polymerization method, using a polymerization catalyst (persulfate, peroxide, redox catalyst, etc.), ultraviolet rays, radiation, etc. (preferably a polymerization catalyst, particularly a redox catalyst), bulk polymerization, aqueous solution polymerization, emulsification (or suspension) )polymerization,
It can be produced by a known polymerization method such as reverse layer (W / O) emulsion (or suspension) polymerization. A preferred polymerization method is a method by emulsion polymerization using a polymerization catalyst (persulfate, peroxide, redox catalyst, etc.). The acid value of the pure substance of the polymer substance used in the low-acid solution is usually 100 to 50.
0, preferably 200-450. Below 100, pH
There is a disadvantage that the increase in viscosity due to the increase is insufficient, and the effect of suppressing water absorption is insufficient, and even when the viscosity exceeds 500, the increase in viscosity due to the increase in pH becomes insufficient, and the effect of suppressing water absorption becomes insufficient. This is because there is an inconvenience.

[0012] As the polymer substance used in the low acidic solution, a vinyl polymer having an acid value as described in JP-A-60-210555 is preferable, and an anionic acrylic resin is particularly preferable. . This has a (meth) acrylic acid unit represented by the general formula (1) and a (meth) acrylic ester unit represented by the general formula (2).

[0013]

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[0014]

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(Wherein R ₁ is H or CH ₃ , preferably CH ₃ , R ₂ is H or CH ₃ , preferably H or R is an alkyl group, preferably an alkyl group having 1 to 4 carbon atoms.)

The molecular weight of the high molecular substance used in the low acid solution is usually 100,000 or more. If the molecular weight is too low, the effect of suppressing pressurized water absorption becomes insufficient. The concentration of the polymer solids in the low acid solution is usually 1 to 50%, preferably 2 to 30%. If it is less than 1%, there is a disadvantage that a low-acid solution of a polymer substance capable of increasing the viscosity to a sufficient level cannot be obtained, while if it exceeds 50%, there is a disadvantage that the viscosity becomes too large.

The low-acid solution is a low-viscosity liquid in which a polymer substance is emulsified and dispersed in water as fine particles having a diameter of 2 to 3 μm or less in an acidic region having a pH of 5.5 or less. 50 centipoise or less, preferably
Less than 30 centipoise. If it exceeds 50 centipoise, it is difficult to penetrate into fine voids on the surface of the aggregate, and there is a disadvantage that the effect of suppressing water absorption becomes insufficient.

Examples of the cement, usually, OH contact with water ^- as long as it emits ions is not particularly limited, for example, ordinary Portland cement, early-strength Portland cement, colloid cement, such as fly ash cement A mixed cement, and a combination of two or more of these may be used.

Examples of the lightweight aggregate include expanded shale (non-granulated forms such as mesalite, asanolite, and sailite; granulated forms such as bilton and lionite; and crushed forms such as heidite) and granulated expanded clay. Artificial lightweight aggregates such as (keramjet, luca, etc.), crushed expanded slate, granulated fired fly ash (Jawlite, Leidak, Agrite, etc.). Such a lightweight aggregate has fine voids in its surface layer. The gap is usually 0.1-100
It is as fine as about μm.

For reinforcement, a fiber material such as a metal fiber such as a stainless steel fiber or a non-metal fiber such as a glass fiber may be mixed.

The lightweight refractory material of the present invention may optionally include
Aggregates other than water and lightweight aggregates can be used in combination.
Water includes tap water, ion exchange water, distilled water, river water,
Groundwater, and a combination of two or more of these. Of these, tap water, ion-exchanged water, distilled water, and a combination of two or more of these are preferred. Aggregates other than the lightweight aggregate include sand and gravel.

In the lightweight refractory material, a cement water reducing agent such as sodium ligninsulfonate and naphthalenesulfonic acid formalin condensate, a cement fluidizer, various inorganic dispersants, and various surfactants may be used in combination as other components. it can.

The low-acidic solution is prepared by raising the pH (usually at a temperature of 20 ° C.) before the pH rise to a neutral or alkaline range of usually 6 to 13, preferably 7 to 10.
It can be thickened to a viscosity (at a temperature of 20 ° C.) of at least twice, preferably at least 80 times, more preferably at least 300 times.
After thickening, usually 100 centipoise or more, preferably 300 centipoise
It has a high viscosity of not less than centipoise, more preferably not less than 1000 centipoise.

Therefore, after absorbing the low-acid solution into the voids in the surface layer of the lightweight aggregate and then increasing the pH, the viscosity in the voids in the surface layer is extremely high [viscosity (50 times or more the viscosity before thickening). (Generally 100 centipoise or more)].

[0025] Although the control of viscosity of the low acidic solution can be carried out by pH adjustment, the pH rises to neutral to alkaline, it is released by contact with cement and water OH ^-
Preferably, ions are used. When cement comes in contact with water, it reacts with free lime (CaO) in the cement and water, as well as C ₃ S (alite) and C ₂ S (belite).
Hydrates to form Ca (OH) ₂ , which raises the pH of the water while at the same time increasing the K ₂ SO ₄ and Na ₂ S in the cement.
The pH is further increased by the reaction of O ₄ with Ca (OH) ₂ or C ₃ A (for example, a reaction of the following formula (3)). 3K ₂ SO ₄ + 3Ca (OH) ₂ + C ₃ A + 32H ₂ O → C ₃ A · 3CaSO ₄ · 32H ₂ O + 6KOH (3)

Another method for forming a high-viscosity water layer in the fine voids in the lightweight aggregate surface layer is to use a low-viscosity high-molecular material (eg, a partially polymerized product such as a monomer, oligomer or prepolymer). After absorbing the aqueous solution or aqueous dispersion into the voids of the lightweight aggregate surface layer, polymerize them in the voids to form a water layer having a viscosity that is at least 50 times higher than the viscosity before thickening, etc. Is mentioned.

In the method for producing a lightweight refractory concrete according to the present invention, the method for suppressing the pressure and water absorption of the lightweight aggregate includes the steps of adding a low-acid solution (water having a viscosity of 50 centipoise or less, for example, Water containing such anionic anionic polymer) to absorb water by kneading, or by immersing dry lightweight aggregate in a low-acid solution to absorb water. A method of absorbing water by spraying an acidic solution, or a method of absorbing water by inhaling a low-acid solution into a dry and lightweight aggregate in a hermetically-sealed depressurized container. Soak the aggregate,
There is a method of absorbing water by pressurizing with air or the like.

In order to increase the viscosity of the low-acid solution thus absorbed in the pores of the surface layer to 50 times or more (of the viscosity before thickening), the pH of the solution is adjusted by the alkali of the cement.
By increasing the pH with an alkali metal hydroxide and / or carbonate (eg, sodium hydroxide, potassium hydroxide), a polyvalent metal (alkaline earth) Kinds of metals,
A method of increasing the viscosity by increasing the pH with a hydroxide (calcium hydroxide, magnesium hydroxide, aluminum hydroxide) of aluminum or the like, or p by an aluminate (sodium aluminate, potassium aluminate, etc.)
By increasing the pH by increasing H, by increasing the pH with ammonium hydroxide, or by increasing the pH with various compounds that release OH ^- ions in aqueous solution or dispersion. Examples of the method include thickening.

The treatment for suppressing pressure and water absorption of the lightweight aggregate can be carried out simultaneously with mixing of concrete in a ready-mixed concrete plant. As a method performed in this ready-mixed concrete plant, for example, first, a light-weight aggregate (artificial light-weight coarse aggregate) and a low-acid solution [water having a viscosity of 50 centipoise or less, for example, an acidic anionic polymer are mixed in a mixer. (The amount of water is an amount necessary for absorbing the light-weight aggregate surface layer)] and stirring, and during this time, the low-acid solution is absorbed by the surface layer portion of the lightweight aggregate.

Next, the remaining aggregate (sand), water (the remaining amount obtained by subtracting the amount of water in the low-acid solution absorbed into the lightweight aggregate surface layer from the total amount of concrete) and cement are mixed. And mixing the concrete, resulting in an increase in the pH of both the water in the concrete and the low acid solution absorbed into the surface of the lightweight aggregate due to OH ^- ions released from the cement, The viscosity of the low-acid solution in the surface voids of the lightweight aggregate is increased, and a lightweight refractory material subjected to a pressurized water absorption suppression treatment can be manufactured. The lightweight aggregate thus obtained has a surface layer having a water layer of high viscosity (viscosity 50 times or more the viscosity before thickening, generally 100 centipoise or more) in the fine voids.

[0031]

According to the construction of the method for producing lightweight refractory concrete of the present invention, a low acid solution penetrates into fine voids in the surface layer of a lightweight aggregate whose water content has been reduced to 10% by weight or less. Then, the surface layer is coated to form a film, and the lightweight aggregate is stirred and mixed with water and cement, and the pH is increased by OH ^- ions released from the cement to increase the viscosity of the film. It is possible to prevent water from penetrating into the fine voids in the surface layer of the lightweight aggregate when kneading the cement, aggregate and water with the coating, and it is possible to increase the fire resistance and strength with the fiber material. it can.

[0032]

Next, an embodiment of the present invention will be described in detail with reference to the drawings.

Example 1 In a ready-mixed concrete plant mixer, a water content of 0.5
322 kg / m ³ of artificial lightweight coarse aggregate [Asanolite (manufactured by Nippon Cement)] of up to 0.9% by weight is added, and while stirring, anionic acrylic resin emulsion [ethyl acrylate / methacrylic acid (weight ratio 6/4)] 9.27 kg / m2 of a pressurized water absorption inhibitor as an aqueous dispersion of a polymer substance consisting of a polymer, an acid value of 260 (pure content), a resin content of 25%, a pH of 2, and a viscosity of 3 centipoise (temperature of 20 ° C). ³ were charged and uniformly stirred and mixed for about 3 minutes in a mixer. Next, 6.44 kg / m ³ of ordinary Portland cement is charged into the mixer, and further, uniformly stirred and mixed for 1 minute, thereby performing a pressure-absorbing / absorbing treatment having a layer of water thickened in the surface space. Manufactured lightweight aggregates. Subsequently, a river sand 925 kg / m ³ and the stainless steel fibers 108 kg / m ³ ordinary Portland cement 516.56kg / m ³ and water 174.23kg / m ³ as fibrous materials as an aggregate water-reducing agent 6.
28 kg / m ³ were sequentially charged with stirring, sufficiently kneaded for about 2 minutes, taken out, and poured into a mold. Cured by air drying for about 4 weeks to obtain a lightweight refractory material. Water cement ratio is 35%,
The fine aggregate ratio is 56%.

Example 2 330 kg / m ^{3 of the} same artificial lightweight coarse aggregate as in Example 1 was put into a mixer of a ready-mixed concrete plant, and the same pressurized water absorption inhibitor as in Example 1 was mixed with 9.50 kg / m ³ while stirring. m ^{3 was} charged and uniformly stirred and mixed in a mixer for about 3 minutes. Next, 6.60 kg / m ³ of ordinary Portland cement is charged into the mixer,
Furthermore, by performing stirring and mixing uniformly for one minute, a lightweight aggregate having a water layer thickened in the surface layer voids and subjected to a pressurized water absorption suppression treatment was produced. Subsequently, stainless steel fibers as water content from 0.5 to 0.9% by weight of the artificial fine aggregates 598kg / m ³ and a fiber material as an aggregate 108 kg / m ³ ordinary Portland cement 507.40kg / m ³ and water 170.50Kg / m ³ and the water-reducing agent 5.65kg / m ³
Were sequentially added with stirring, kneaded well for about 2 minutes, and taken out. A lightweight refractory material was obtained in the same manner as in Example 1. The water cement ratio is 35% and the fine aggregate ratio is 58%.

Comparative Example 1 925 kg / m ^{3 of} river sand was placed in a mixer of a ready-mixed concrete plant.
322 kg / m ³ of artificial lightweight coarse aggregate with a moisture content of 0.5 to 0.9% by weight
And the stainless steel fibers 108 kg / m ³ ordinary Portland cement 523kg / m ³ and water 184kg / m ³ and a water reducing agent 6.28kg / m ³ sequentially charged with stirring, taken out and sufficiently kneaded for about 2 minutes, EXAMPLE A lightweight refractory material was obtained in the same manner as in Example 1. The water cement ratio is 35% and the fine aggregate ratio is 56%.

Comparative Example 2 A lightweight refractory material was obtained in the same manner as in Comparative Example 1, except that the artificial lightweight coarse aggregate in Comparative Example 1 was used in a water-absorbed state. The water cement ratio is 35% and the fine aggregate ratio is 56%.

Comparative Example 3 In a mixer of a ready-mixed concrete plant, the water content was 0.5
0.5 is to 0.9% by weight of the artificial fine aggregates 598kg / m ³ and the water content
0.9 wt% of artificial lightweight coarse aggregate 330 kg / m ³ and the stainless steel fibers 108 kg / m ³ ordinary Portland cement 514kg / m ³ and water 18
Sequentially charged with stirring and 0 kg / m ³ and a water reducing agent 5.65kg / m ^3, taken out and sufficiently kneaded for about 2 minutes to obtain a lightweight refractory material in the same manner as in Example 1. The water cement ratio is 35% and the fine aggregate ratio is 58%.

Comparative Example 4 A lightweight refractory material was obtained in the same manner as in Comparative Example 3 except that the artificial lightweight coarse aggregate in Comparative Example 3 was used in a water-absorbed state. The water cement ratio is 35% and the fine aggregate ratio is 56%.

Comparative Example 5 River sand 939 kg / m ^{3 was} placed in a mixer of a ready-mixed concrete plant.
And crushed stone 671kg / m ³ and the stainless steel fibers 108 kg / m ³ ordinary Portland cement 543kg / m ³ and water 190 kg / m ³ water reducing agent 6.52kg
/ m ³ were sequentially charged with stirring, kneaded sufficiently for about 2 minutes, and taken out. A lightweight refractory material was obtained in the same manner as in Example 1. The water cement ratio is 35% and the fine aggregate ratio is 60%.

The above Examples 1 and 2, and
For each of Comparative Example 1, Comparative Example 2, Comparative Example 3, Comparative Example 4 and Comparative Example 5, a slump test, a strength test (compression strength, split strength, bending strength) and a water content test were performed. was gotten.

[0041]

[Table 1]

The slump was performed according to the test method of JIS A1101. Compressive strength was measured in accordance with JIS A 1108 test method. The splitting strength was determined in accordance with JIS A 1113 test method. Flexural strength was measured in accordance with the test method of JIS A 1106. The water content is (weight in air-dried state-weight in a state where water content is forcibly dried to be 0%) / (weight in a state where water content is forcibly dried to be 0%) × 10.
It was determined as 0 (unit:%).

Further, for each of Examples 1 and 2, and Comparative Examples 1, 2, 3, and 4, the method of the Ministry of Construction Notification No. 2999 (method of designating a fireproof structure) was used. When the change was observed in a test conforming to the standard, in Comparative Example 1 and Comparative Example 4,
Cracks were generated at locations, in Comparative Example 2, cracks were generated at one peripheral portion, and in Comparative Example 3, the surface was peeled off by explosion. In contrast, neither Example 1 nor Example 2 caused any abnormality.

From the above results, it is clear that in Examples 1 and 2 according to the present invention, the explosion could be prevented by lowering the water content without impairing the fluidity and strength. Was.

[0045]

As described above, according to the method for manufacturing a lightweight refractory concrete of the present invention, the water content is reduced to 10 % by weight.
% Of the surface of the lightweight aggregate, which has been treated to a concentration of less than 10% , the low-acid solution is infiltrated into the fine pores of the surface of the lightweight aggregate, and the surface is coated to form a film. The film can reliably prevent moisture from remaining or infiltrating into the voids, and the film is not affected by the physical or mechanical action during concrete kneading and suppresses pressure absorption even after mixing concrete. Action can be maintained.

Further, in producing a lightweight refractory material, a low-acid solution is sprayed on the lightweight aggregate, the low-acid solution and the lightweight aggregate are mixed, or the lightweight aggregate is immersed in the low-acid solution. In the process of manufacturing lightweight aggregates, no special treatment is required as a pressurized water absorption suppression process, and all necessary work can be performed in a ready-mixed concrete plant. It is possible to produce a lightweight refractory material that is excellent in physical properties and chemical stability as well as harmless to concrete and can prevent explosion, at low cost and easily.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification code FI C04B 14:02 C04B 14:02 20:10 20:10 24:22 24:22 14:48) 14:48) 111: 28 111 : 28 (72) Inventor Takeshi Yoshimura 4-1-1-13 Honcho, Chuo-ku, Osaka City Inside Takenaka Corporation Osaka Main Store (72) Inventor Toshiyuki Tanaka 4-1-1, Honmachi, Chuo-ku, Osaka City Takenaka Corporation Inside the Osaka Main Store Address Daiwa Co., Ltd. (72) Inventor Masayuki Hashimoto 1-6-1, Otemachi, Chiyoda-ku, Tokyo Japan Cement Co., Ltd. (56) References JP-A-63-117938 (JP, A) (58) field (Int.Cl. ^7, B name) C04B 38/00 - 38/10 C04B 14/02 C04B 20/10 C04B 28/02

Claims (1)

(57) [Claims] 1. A surface layer of a lightweight aggregate whose water content has been reduced to 10% by weight or less has a viscosity capable of penetrating into fine pores of the surface layer and a viscosity of 50 times or more due to a rise in pH. After coating with a low-acid solution capable of thickening to form a film, cement and water are added to the light-weight aggregate on which the film is formed, and the mixture is stirred and mixed to increase the viscosity. A method for producing lightweight refractory concrete, characterized by adding a material and stirring and mixing.