JP2008074659A - Air bubble mixed calcium silicate hardened body - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an air bubble mixed calcium silicate hardened body which is excellent in strength characteristics and water resistance, which is unnecessary for complex controlling and which can lighten in weight at a low cost. <P>SOLUTION: The air bubble mixed calcium silicate hardened body has (A) a specific gravity of 0.2-0.8 g/cm<SP>3</SP>, (B) a pore volume measured by a mercury penetration method in the range of 10-45 μm to that in the range of 10-300 μm of 50 vol% or more and (C) an air permeability measured by JIS R 2115 of 0.5 mL*cm/sec*cm<SP>2</SP>*cm H<SB>2</SB>O or less. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a foamed calcium silicate hardened body excellent in strength characteristics and water resistance.

  Calcium silicate building materials are widely used in the construction field because they are excellent in incombustibility, dimensional stability, and chemical stability. In particular, calcium silicate building materials mixed with air bubbles are widely used as interior and exterior materials, sound absorbing materials, and heat insulating materials for buildings and houses because of demands for building weight reduction and high functionality.

  These foam-mixed calcium silicate building materials contain pores of about 200 to 1000 μm due to a mixed foam, preform, or Al foaming with a surfactant, and exhibit characteristics such as light weight, sound absorption, and heat insulation. However, on the other hand, there is a problem that the bending strength, impact resistance (corner chipping property) and the like of the product are lowered due to the pores.

For this reason, it has been carried out to prevent strength reduction and ensure impact resistance by uniformly dispersing fibers such as organic synthetic fibers and inorganic fibers as a reinforcing agent in the calcium silicate base material (Patent Literature). 1, Patent Document 2).
However, since calcium silicate building materials are subjected to high-temperature and high-pressure curing (autoclave curing) at the time of production, the fibers used are limited to fibers with high moisture and heat resistance, and such fibers are generally expensive. Raw material costs increase.

  For this reason, various studies have been conducted to achieve high strength without using fibers, and the hardened calcium silicate (Patent Document 3) with enhanced crystallinity of tobermorite, the pore shape and pore diameter in the cured body Specificized hardened calcium silicate (Patent Document 4, Patent Document 5) and the like have been proposed.

  Patent Document 3 proposes a technique in which a highly crystalline tobermorite is synthesized and a cured body strength is improved by pulverizing a calcareous raw material such as cement or a siliceous raw material to increase hydrothermal reactivity. However, if a raw material such as cement is used in a fine powder form in order to increase the reactivity, the viscosity of the slurry may increase and the moldability may be significantly reduced. To prevent this, a water reducing agent, a fluidizing agent is used. A large amount of admixture such as is required. Moreover, compared with the raw material currently distribute | circulated, since the raw material atomized requires much energy and time for a grinding | pulverization, raw material cost increases.

  Patent Document 4 proposes a method for producing a lightweight foam cement molded body in which closed cells are formed by mixing organic foam particles and heat-treating at 250 ° C. or lower. According to this method, the foamed particles are melted by the heat treatment, and closed cells are formed in the foamed particle traces to obtain high-strength lightweight cellular concrete. However, the foamed particles are expensive and must be melted. Therefore, the manufacturing cost is high.

In Patent Document 5, the strength of the hardened calcium silicate is increased by substantially eliminating pores of 200 μm or more in the cross section of the hardened body and using microfibrillated pulp fibers. However, in the method of forming pores by foam, it is practically difficult to uniformly produce bubbles of 200 μm or less, and no specific production method is described. In general, the use of an antifoaming agent is known as a method for removing bubbles. However, the defoaming action of the antifoaming agent is very sensitive to the amount of addition, and is generally used in order to completely eliminate bubbles or prevent entrained bubbles from being generated. Therefore, it is extremely difficult to adjust the addition amount.
JP-A-56-37266 Japanese Patent Laid-Open No. 9-263461 JP-A-5-286780 Japanese Patent Laid-Open No. 2-145492 JP 2001-58888 A

  Accordingly, an object of the present invention is to provide a foamed calcium silicate hardened body which is excellent in strength characteristics and water resistance and can be reduced in weight at low cost without requiring complicated control.

  In view of such circumstances, the present inventors have intensively studied, and as a result, found that a foamed calcium silicate cured body having a specific pore volume and air permeability is excellent in strength characteristics and water resistance, and completed the present invention. did.

That is, the present invention provides (A) specific gravity of 0.2 to 0.8 g / cm ³ ,
(B) The volume of the pores in the range of 10 to 45 μm is 50 vol% or more as measured by the mercury intrusion method with respect to the volume of the pores in the range of 10 to 300 μm.
(C) A foamed calcium silicate hardened body having an air permeability measured by JIS R 2115 of 0.5 mL · cm / sec · cm ² · cmH ₂ O or less is provided.

  The foamed calcium silicate cured product of the present invention has excellent strength characteristics and water resistance.

The cured product of the present invention has (A) a specific gravity of 0.2 to 0.8 g / cm ³ , preferably 0.3 to 0.7 g / cm ³ . Specific gravity is calculated | required using the dimension of the vertical, horizontal, and thickness of the hardened | cured body measured with the caliper, and the mass of the hardened | cured body which poured the slurry into the rectangular parallelepiped mold and was hardened.

(B) The volume of the pores in the range of 10 to 45 μm is 50 vol% or more, preferably 60 vol% or more, as measured by the mercury intrusion method with respect to the pore volume in the range of 10 to 300 μm. . When the pore volume ratio is less than 50 vol%, sufficient strength and water resistance cannot be obtained.
In the mercury intrusion method (porosimeter), mercury is intruded into the hardened calcium silicate body, and the pore size distribution is measured in the range of 0.001 to 300 μm from the relationship between the pressure and the amount of penetration.
In the present invention, the target pore size distribution in the range of 10 to 300 μm indicates pores formed by bubbles.

Further, the cured body of the present invention has an air permeability measured in accordance with (C) JIS R 2115 “Test method for air permeability of refractory brick” of 0.5 mL · cm / sec · cm ² · cmH ₂ O or less, preferably 0.25 mL · cm / sec · cm ² · cmH ₂ O or less.
This air permeability is an index indicating the ease of air permeation from the front surface to the back surface of the cured body. The more the pores of the cured body communicate with each other, the more easily air will permeate and the higher the air permeability. On the contrary, when the independent pores are formed, the air permeability shows a low value.
If this air permeability exceeds 0.5 mL · cm / sec · cm ² · cmH ₂ O, the abundance of closed cells decreases, and the strength and water resistance decrease.

Such a cured product can be produced, for example, by curing a slurry containing cement raw material, siliceous raw material, water, bubbles, admixture and polyferric sulfate and / or aluminum polysulfate. .
As the cement raw material used here, cement alone or a mixture of cement, slaked lime and quicklime can be used. As cement components, in addition to the cements specified in JIS R 5201 such as ordinary Portland cement, early-strength Portland cement, ultra-early strong Portland cement, intermediate heat cement, etc., eco-cement specified in JIS R TR 0002 is used. can do. The mixing ratio of cement, slaked lime and quicklime can be selected according to the performance of the target product.

  Examples of the siliceous raw material include silica powder, silica sand, blast furnace slag, fly ash, silica fume and the like, and the type and blending amount can be selected according to the performance of the target product.

The mixing ratio of the cement raw material and the siliceous raw material is 0.5 to 0.9 in terms of the molar ratio of CaO / SiO _2. It is preferable because a high strength can be obtained.

  Common tap water or industrial water can be used as the water. The blending amount is preferably 20 to 70 parts by mass, particularly 30 to 60 parts by mass with respect to a total of 100 parts by mass of the cement raw material and siliceous raw material, taking into account the specific gravity, strength, etc. of the target cured product. It is determined.

In the present invention, in order to mix the bubbles into the slurry, a method of pre-forming from an aqueous solution containing a surfactant and / or a protein-based foaming agent, a mixed foam for foaming by directly adding the foaming agent to the slurry, etc. Can be used.
The surfactant used as the foaming agent is not particularly limited as long as it is usually used. For example, maleated resin, higher alcohol sulfate, alkyl allyl sulfonate, alkyl sulfate ester, polysulfate Examples thereof include oxyethylene alkyl ether sulfates. The protein foaming agent is not particularly limited, and examples thereof include gelatin and casein.

Further, a bubble stabilizer such as polyvinyl alcohol or glycerin can be used in combination. In that case, it is preferable to use the bubble stabilizer diluted 10 to 100 times.
The amount of bubbles mixed is appropriately determined according to the target product specific gravity.

In the present invention, polyferric sulfate and / or aluminum polysulfate is used as a bubble regulator. Polyferric sulfate is represented by [Fe ₂ (OH) _n (SO ₄ ) _{3-n / 2} ] _m , and polyaluminum sulfate is represented by [Al ₂ (OH) _n (SO ₄ ) _{3-n / 2} ] A compound represented by _m , which can be used alone or in combination. In particular, it is preferable to use polyferric sulfate alone from the viewpoint of availability.

  The ferric sulfate and / or aluminum polysulfate is 0.2 to 0.75 parts by mass, particularly 0.2 to 0, in terms of iron ions and / or aluminum ions in terms of 100 parts by mass of the cement raw material. It is preferable to use 0.5 parts by mass because a sufficient bubble adjusting effect can be obtained and the molded state can be improved.

In the present invention, the viscosity of the slurry prepared by mixing the raw materials as described above is preferably 50 dPa · s or more, particularly 50 to 90 dPa · s from the viewpoint of pouring the slurry. The viscosity is measured using a B-type viscometer at 30 ° C. for the slurry that has become uniform by mixing the raw materials.
In order to adjust the slurry to such a viscosity, for example, various admixtures such as a water reducing agent, a setting accelerator, a slurry fluidizing agent, a slurry viscosity adjusting agent, and a dispersing agent can be added.

  The water reducing agent is not particularly limited as long as it is used for the purpose of improving the fluidity of the cement slurry. For example, naphthalene sulfonic acid type, polycarboxylic acid type, lignin sulfonic acid type can be used. . Among these, those having the property of delaying the hydration reaction of cement are preferably adjusted to the above viscosity in combination with a setting accelerator or a slurry viscosity modifier.

  Examples of the setting accelerator include commonly used inorganic compounds such as calcium sulfate (gypsum), sodium sulfate, potassium sulfate, and calcium chloride, Irwin compounds, and calcium aluminate compounds.

  Examples of the slurry viscosity modifier include methyl cellulose, hydroxypropyl methyl cellulose, carboxymethyl cellulose, polyethylene oxide, polyvinyl alcohol, and the like.

  Moreover, the viscosity of a slurry can also be adjusted by controlling the curing temperature of a slurry and controlling the hardening rate of a cement raw material. When controlling by curing temperature, it is preferable that the curing temperature is 20-80 degreeC, especially 40-70 degreeC.

In the present invention, reinforcing fibers can be blended, and powder materials such as hydraulic materials are adsorbed on the surface of the fibers by the aggregating action of polyferric sulfate and / or aluminum sulfate. Can be improved.
Here, the reinforcing fiber is used for the purpose of reinforcing effect, imparting workability, reducing weight, and increasing the weight, and examples thereof include wood fillers such as wood fragments and wood fibers, pulp fibers, inorganic fibers, and organic synthetic fibers. It is done. The types and blending amounts of these fibers can be appropriately selected according to the performance of the target product.

  The cured product of the present invention can be obtained by molding the slurry thus obtained by a mold casting method or a continuous casting method. The casting method is, for example, a molding method in which a slurry is poured into a mold having a desired shape that is being moved by a conveyor, and the slurry is cured while moving.

  The cured product obtained by molding is cured as it is or after being subjected to cutting or cutting as necessary, and then cured by an autoclave. The autoclave curing is preferably performed at 160 to 180 ° C. for 6 hours or more.

  EXAMPLES Next, although an Example demonstrates this invention further, this invention is not limited by these Examples.

First, the raw materials used in the examples are shown below.
(1) Cement: early strong cement (manufactured by Taiheiyo Cement)
(2) Silica powder: Industrial silica (Gunma; Blaine specific surface area 3000cm ² / g)
(3) Water: Tap water (4) Water reducing agent: Polycarboxylic acid water reducing agent
(Core flow manufactured by Taiheiyo Materials Co., Ltd .; solid concentration 50% by mass)
(5) Polyferric sulfate: manufactured by Nippon Steel Mining Co., Ltd. (Fe content: 11% by mass)
(6) Polyaluminum sulfate: Industrial dry aluminum hydroxide and industrial sulfuric acid were used as raw materials and reacted in an autoclave at 140 ° C. and 0.4 MPa for 2 hours. The Al ³⁺ concentration was 14.0% by mass.
(7) Fast-hardening substrate: Irwin-based fast-hardening material. Irwin (3CaO · 3Al ₂ O ₃ · CaSO ₄ ), 2CaO · SiO ₂ and 4CaO · Al ₂ O ₃ · Fe ₂ O ₃ produced by a conventional method using an electric furnace were 60% by mass, 30% by mass and 5%, respectively. Including mass%, adjusted to a Blaine specific surface area of 3800 cm ² / g.

(8) Foaming agent: polyoxyethylene alkyl ether sulfate (Emar D3D, manufactured by Kao Corporation)
(9) Pulp fiber: Crofton (Morri)
(10) Thickener: Hydroxypropyl methylcellulose (High Metroise 90SH-4000, manufactured by Shin-Etsu Chemical Co., Ltd.)
(11) Setting agent: Aluminum chloride (reagent grade 1, manufactured by Kanto Chemical Co., Inc.)
(12) Setting controller: ferrous sulfate (reagent grade 1, manufactured by Kanto Chemical Co., Inc.)
(13) Setting controller: ferric sulfate (reagent grade 1, manufactured by Kanto Chemical Co., Inc.)
(14) Setting controller: Industrial anhydrous gypsum (Asahi Glass Co., Ltd.)

Next, the measurement method used in the examples is shown.
(1) Specific gravity:
A test body having a length of 5 cm, a width of 23 cm, and a thickness of 3 cm was cut out from the obtained bubble-containing calcium silicate cured body. The length, width, and thickness (cm) of the test specimen were measured with a caliper, and the mass (g) was further measured. The specific gravity was calculated from the following formula.
Specific gravity (g / cm ³ ) = (mass) / ((vertical) × (horizontal) × (thickness))

(2) Pore volume ratio:
After curing the autoclave, a 7 mm × 7 mm × 7 mm square piece was cut out as a test piece from a completely dried body, and several pieces were packed in a dedicated column, and the pore volume was measured by a mercury intrusion method. After the measurement, the pore volume (a) in the range of 10 to 45 μm and the pore volume (b) in the range of 10 to 300 μm were determined, and the pore volume ratio was calculated from the following formula.
Pore volume ratio (vol%) = ((a) / (b)) × 100

(3) Air permeability:
After curing the autoclave, a cylinder having a diameter of 50 mm and a thickness of 30 mm was cut out from the cured body that had been completely dried to prepare a test body. Using this test body, the air permeability was measured in accordance with JIS R 2115 “Test method for air permeability of refractory bricks”.

(4) Slurry viscosity:
The bubble-containing slurry was collected in a 150 mL beaker, and the viscosity of the slurry was measured at 30 ° C. using a B-type viscometer (Viscotester VT-04, manufactured by Rion Corporation).

(5) Formability:
The bubble-containing slurry was filled in an acrylic pipe cone having a diameter of 60 mm and a height of 60 mm installed on a flow table specified in JIS R 5201. The flow cone was gently withdrawn 60 seconds after casting the cone, and the spread of the slurry was measured using a caliper to obtain a flow value (mm). When this flow value was 160 mm or more and there was no problem by visually observing the filling condition of the slurry when it was poured into the mold, it was judged as “good”, and when there was a problem in either one, it was judged as “bad”.

(6) Bending strength / specific strength:
A test piece measuring 5 cm in length × 23 cm in width × 3 cm in thickness was cut out from the resulting foam-containing hardened calcium silicate, and loaded using an Instron universal testing machine with a three-point bend. Measured at 5 mm / min. The bending strength and specific strength were calculated from the obtained breaking load based on the following formula.

Bending strength (N / mm ² )
= 3 x (Fracture load) x (Span: 200) / 2 / (Width: 50mm) / (Thickness: 30mm)
Specific strength (N / mm ² ) = (Bending strength) / (Specific gravity) / (Specific gravity)

(7) Water absorption rate:
From the obtained foam-containing hardened calcium silicate body, a specimen having a length of 5 cm, a width of 10 cm, and a thickness of 3 cm was cut out and completely dried (G1), and after 30 minutes of water absorption (G2). ) Was measured. The water absorption was calculated from the following formula.
Water absorption rate (%) = [((G2) − (G1)) / G1] × 100

Examples 1-3 and Comparative Examples 1-3
17 parts by weight of early-strength cement, 26.5 parts by weight of fast-hardening base material, 53 parts by weight of silica powder, 3.5 parts by weight of anhydrous gypsum and 0.2 parts by weight of thickener were premixed to obtain a powder raw material. Examples 1 to 3 were compared with 50 parts by mass of water, 0.5 parts by mass of a water reducing agent, and 2.78 parts by mass of a ferric sulfate aqueous solution (0.65 parts by mass in terms of Fe). In Examples 1 to 3, a polyferric sulfate aqueous solution was not added, and the mixture was mixed with a hand mixer for 1 minute. The bubbles (bubble specific gravity of 0.1) were added so that the specific gravity of the cured body was 0.65, 0.5, and 0.4, and bubble mixed slurry was obtained. This aerated slurry is poured into a 25 cm × 35 cm × 4 cm plastic mold, cured at 30 ° C. for 24 hours, demolded, and then cured at 180 ° C. for 10 hours in an autoclave to form a foamed calcium silicate cured body. Obtained.
About the obtained hardening body, specific gravity, pore volume ratio, air permeability, bending strength, specific strength, and water absorption were measured. The results are shown in Table 1.

From the results of Table 1, in Examples 1 to 3 to which polyferric sulfate was added, the pore volume ratio was 60% or more, and the air permeability was 0.5 mL · cm / sec · cm ² · cmH ₂ O or less, Bending strength was improved as compared with Comparative Examples 1 to 3 having the same specific gravity. Moreover, the water absorption rate was low and the water resistance was improved.

Examples 4-7 and Comparative Examples 4-6
In Examples 4 and 5, 13 parts by weight of early-strength cement, 30 parts by weight of a fast-hardening base material, 53 parts by weight of silica powder, 4 parts by weight of anhydrous gypsum, and 0.2 parts by weight of a thickener are preliminarily mixed. It was. In this powder raw material, 50 parts by mass of water, 0.5 parts by mass of a water reducing agent and Example 4 were 1.75 parts by mass of an aqueous polyferric sulfate solution (0.45 parts by mass in terms of Fe). 2.78 parts by mass of ferric sulfate aqueous solution (0.65 parts by mass in terms of Fe) was added, mixed for 1 minute with a hand mixer, and a foaming agent solution (foaming agent concentration 2 masses) using a rotary foaming machine. %) And air-preformed bubbles (bubble specific gravity of 0.1) were added so that the specific gravity of the cured product was 0.6 to obtain a bubble mixed slurry. This foam-mixed slurry was poured into a mold, and after curing at 60 ° C. for 30 minutes, autoclave curing was performed in the same manner as in Examples 1 to 3 to obtain a foam-mixed calcium silicate cured body.

  In Examples 6 and 7, 31.7 parts by weight of early-strength cement, 13.5 parts by weight of a fast-hardening base material, 53 parts by weight of silica powder, 1.8 parts by weight of anhydrous gypsum, and 0.2 parts by weight of a thickener are reserved. It mixed and it was set as the powder raw material. In this powder raw material, 50 parts by mass of water, 0.5 parts by mass of a water reducing agent, and an aqueous solution of polyaluminum sulfate were used. Example 6 was 0.81 parts by mass (0.25 parts by mass in terms of Al), and Example 7 was 1 .29 parts by mass (0.4 parts by mass in terms of Al) was added, mixed for 1 minute with a hand mixer, and pre-treated with a foaming agent solution (foaming agent concentration 2% by mass) and air using a rotary foaming machine. The foamed bubbles (cell specific gravity 0.1) were added so that the specific gravity of the cured body was 0.55 and 0.7, and a bubble mixed slurry was obtained. This aerated slurry is poured into a mold, and after curing at 60 ° C. for Example 6 and at 80 ° C. for 30 minutes, autoclave curing is performed in the same manner as in Examples 1 to 3, and the aerated calcium silicate cured body is obtained. Obtained.

  The comparative example 4 produced the hardening body like Example 4 except not using polyferric sulfate.

  In Comparative Examples 5 and 6, 31.7 parts by weight of early strength cement, 13.5 parts by weight of fast-hardening base material, 53 parts by weight of silica stone powder, 1.8 parts by weight of anhydrous gypsum, and 0.2 parts by weight of thickening agent are reserved. It mixed and it was set as the powder raw material. In this powder raw material, 50 parts by mass of water, 0.5 parts by mass of a water reducing agent and an aqueous solution of polyferric sulfate were used. Comparative Example 5 was 0.61 parts by mass (0.15 parts by mass in terms of Fe), Comparative Example 6 Add 3.1 parts by mass (0.75 parts by mass in terms of Fe), mix with a hand mixer for 1 minute, and use a rotary foaming machine to create a foaming agent solution (foaming agent concentration of 2% by mass) and air. Bubbles (bubble specific gravity of 0.1) preformed by the above were added so that the specific gravity of the cured product was 0.7 and 0.6 to obtain a bubble mixed slurry. This foam-mixed slurry was poured into a mold, and after curing at 60 ° C. for 30 minutes, autoclave curing was performed in the same manner as in Examples 1 to 3 to obtain a foam-mixed calcium silicate cured body.

  The slurry viscosity and moldability before curing, and the specific weight, pore volume ratio, air permeability, bending strength, specific strength and water absorption of the obtained cured product were measured. The results are shown in Table 2.

  From the results in Table 2, the cured bodies of Examples 4 to 7 all had improved bending strength and water resistance.

Test example 1
About the bubble mixing calcium silicate hardening body obtained in Example 1 and Comparative Example 1, the state of the bubble in a hardening body was observed with the microscope. The results are shown in FIGS.
It was confirmed that fine bubbles were uniformly and independently dispersed in the foam-mixed calcium silicate cured product obtained in Example 1.

1 is a view showing a micrograph of a foam-containing calcium silicate hardened body obtained in Example 1. FIG. It is a figure which shows the microscope picture of the bubble mixing calcium silicate hardening body obtained by the comparative example 1. FIG.

Claims (4)

(A) Specific gravity 0.2-0.8 g / cm ³ ,
(B) The volume of the pores in the range of 10 to 45 μm is 50 vol% or more as measured by the mercury intrusion method with respect to the volume of the pores in the range of 10 to 300 μm.
(C) A foamed calcium silicate hardened body having an air permeability measured by JIS R 2115 of 0.5 mL · cm / sec · cm ² · cmH ₂ O or less.   The foam-mixed calcium silicate hardened body according to claim 1, comprising ferric sulfate and / or aluminum polysulfate.   A slurry obtained by curing a slurry containing cement raw material, siliceous raw material, water, bubbles, admixture and polyferric sulfate and / or aluminum polysulfate, and the viscosity of the slurry is 50 dPa · s or more. Or the foam mixing calcium silicate hardening body of 2 description.   The bubble of Claim 3 which contains 0.2-0.75 mass part of iron ferric ion and / or aluminum ion conversion total with respect to 100 mass parts of cement raw materials with polyferric sulfate and / or aluminum polysulfate. Mixed calcium silicate hardened body.