JPH05329823A - Production of hydraulic inorganic molded object - Google Patents

Abstract

PURPOSE:To produce a hydraulic inorg. molded object having high strength and excellent durability so as to be capable of obtaining a complicated shape in spite of the quantity of water approximate to stoichiometric quantity and achieving the densification of the structure of the molded object. CONSTITUTION:A mixture consisting of Portland cement, a polypropylene fiber, hydroxypropylmethyl cellulose, fly ash and water is subjected to extrusion molding and the molded one is supplied to a vibration press molding machine to be subjected to press molding under vibration.

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 a hydraulic inorganic molded body.

[0002]

2. Description of the Related Art A molded body using water and a hydraulic inorganic substance such as cement, mortar and gypsum is suitably used for structural materials such as construction and civil engineering materials. It has been used for various structural materials since ancient times. The extrusion molding method is excellent in terms of productivity for producing these hydraulic inorganic moldings. However, since fluidity is particularly required in the extrusion molding method, in order to secure fluidity, more than the stoichiometric amount of water in the hydration reaction of cement has been added. A cured product obtained by curing such a hydraulic inorganic molded product is obtained by molding and curing with a water amount in which voids are formed by excess water and strength, freeze-thaw resistance, etc. are close to stoichiometric amounts. There was a problem that it was lower than the cured product.

Therefore, 1) In order to obtain a high-strength hydraulic inorganic molding, silica sand having a Blaine value of 3000 cc / g or more (average particle size: 5-10)
It is less than micron, but there is no exact correspondence because it differs in shape. ) Was mixed with cement to 100 parts by weight of water, and a composition in which water was added in an amount of 20 to 35 parts by weight, which was as close to the stoichiometric amount as possible, was molded by an extrusion molding method, and the voids were fine particles. Method of curing the obtained molded body by filling with (2) Japanese Patent Laid-Open No. 2-160650, 2) using a glass fiber reinforced cement mortar to obtain a molded body having a complicated shape Of press molding while giving vibration so as to repeatedly increase and decrease (Japanese Patent Publication No. 61-111668, Japanese Patent Publication No. 1-604
No. 01) has been proposed.

[0004]

However, in the method 1), since the water-cement ratio is small and the specific surface area of the fine particles is very large, water is adsorbed by the fine particles and the fluidity of the composition is extremely poor. However, there is a problem that only a molded product having a simple shape such as a flat plate described in the above publication can be shaped, and it cannot be applied to a molded product having a complicated shape.

Further, in the method 2), the cement water ratio of the cement mortar to be added is large, and even if a dehydration step is added, there is a limit to the densification of the structure, and the physical properties such as strength and freeze-thaw property become low. Further, if a composition having a low water-cement ratio is molded by the method 2), it is not possible to obtain a uniform integrated molding.

The object of the present invention is to solve the above-mentioned problems and to form a complex shape even if the amount of water is close to the stoichiometric amount.
It is an object of the present invention to provide a method for producing a hydraulic inorganic molded body that has a compacted structure and has high strength and excellent freeze-thaw properties.

[0007]

The hydraulic inorganic substance used in the present invention is not particularly limited as long as it is an inorganic substance that exhibits a hardening property when kneaded with water, and examples thereof include ordinary Portland cement, special Portland cement, and alumina cement. Simple cement such as Roman cement, acid resistant cement, fire resistant cement, special cement such as water glass cement, gypsum,
Examples of the cement include lime and magnesia cement, and portland cement and alumina cement are preferably used in terms of strength and water resistance. These may be used alone or in combination of two or more kinds.

When the amount of water used in the present invention is small, the hydraulic inorganic substance is not sufficiently cured, and
Since the dispersibility of the composition decreases and the strength of the obtained molded product decreases when the amount increases, the amount is preferably 15 to 65 parts by weight, more preferably 2 parts by weight, relative to 100 parts by weight of the hydraulic inorganic substance.
It is 0 to 40 parts by weight.

In the present invention, reinforcing fibers may be further added if necessary. As the reinforcing fiber, any one can be used according to the performance desired to be imparted to the molded product, and examples thereof include synthetic fibers such as vinylon, polyamide, polyester, polypropylene, carbon, aramid, acryl and rayon, glass fibers, potassium titanate, steel and the like. Inorganic fibers can be used. Particularly when synthetic fibers are used, the flexibility is remarkably improved. The thickness of the reinforcing fiber is reaggregated during mixing when it is too thin, fiber balls are easily formed by entanglement, the strength of the obtained molded article is not further improved, and either too thick or too short, tensile strength The reinforcing effect such as improvement is small, and if it is too long, the dispersibility and orientation of the fibers are reduced.
15 mm is preferable. Since the dispersibility of the fibers decreases as the amount of the reinforcing fibers added increases, the hydraulic inorganic substance 100
It is preferably 20 parts by weight or less with respect to parts by weight.

In the present invention, a water-soluble polymer substance may be added if necessary. The water-soluble polymer substance is
It dissolves in water to give viscosity, enhances the fluidity of the composition obtained from the hydraulic inorganic substance and water to improve the shapeability, and absorbs excess water in the cement hardened product There is no particular limitation as long as it is a polymeric substance that can serve as a binder for filling voids between particles, and examples thereof include cellulose ethers such as methyl cellulose, hydroxymethyl cellulose, hydroxyethyl cellulose, carboxymethyl cellulose, hydroxypropyl methyl cellulose, polyvinyl alcohol, polyacrylic acid, and lignin sulfone. Examples include acid salts. If the amount of the above water-soluble polymer substance added is too large, the water resistance of the resulting molded article decreases, so it is preferably 5 parts by weight or less, more preferably 1 to 4 parts by weight, relative to 100 parts by weight of the hydraulic inorganic substance. Is.

In the present invention, an inorganic filler may be added if necessary. The inorganic filler is not particularly limited as long as it does not dissolve in water, does not inhibit the curing reaction of the hydraulic inorganic substance, and does not significantly inhibit the action of any constituent material used in the production method of the present invention, for example, Quartz sand,
Examples include aggregates for cement mortar such as river sand, admixtures for mixed cement such as fly ash, silica flower, silica fume, bentonite and blast furnace slag, natural minerals such as sepiolite, wollastonite and mica, calcium carbonate, diatomaceous earth and the like. For the purpose of further reducing the weight, silica balloon, perlite, fly ash balloon, shirasu balloon, glass balloon, inorganic natural foam such as foamed clay may be used. These may be used alone or in combination of two or more kinds.

When the average particle size of the above-mentioned inorganic filler is small, the strength of the obtained molded article is reduced, and when it is large, the particles of the inorganic filler are difficult to disperse, so that the impact strength is reduced. 500 μm is preferable. The amount of the above-mentioned inorganic filler is preferably 200 parts by weight or less with respect to 100 parts by weight of the hydraulic inorganic substance, since the strength of the obtained molded article decreases as the added amount increases.

The method for producing a hydraulic inorganic molded article of the present invention comprises extrusion molding a mixture of the hydraulic inorganic material, water, and optionally reinforcing fibers, a water-soluble polymeric material and an inorganic filler, The obtained continuous molded body is cut, supplied to a mold for vibration pressure molding, and molded into a desired shape by vibration pressure molding. The mixing method and the extrusion molding method are not particularly limited, and any conventionally known mixer and extruder can be used.

The vibration pressure molding in the present invention is a method of press molding while vibrating a pressing die, and for example, a vibration motor, a vibrator, a vibrator and the like are attached to the pressing die to vibrate. If the frequency given to the mold is too low, the fluidity of the composition in the mold becomes poor, and if it is too high, a lot of energy is required to give the vibration.
A frequency of 00 to 10,000 Hz is preferable. If the amplitude given to the mold is too small, the fluidity of the extruded composition in the mold becomes poor, and if it is too large, the linearity of the obtained molded product is lowered, so the amplitude is preferably 1 to 500 μm.

The direction in which the mold is vibrated is not particularly limited, and it may be vertical, horizontal, or oblique. As an apparatus used for vibration pressure molding, for example, Showa 63
Examples include the vibration press molding machine described in the Aichi Prefecture Tokoname Ceramics Technology Center Research Results Report.

The hydraulic inorganic molded body obtained by the method of the present invention can be heated by heating during molding, for example, at the time of press molding, if a hydraulic inorganic substance having a high curing rate such as gypsum is used. It can be cured at the same time as molding, and the obtained cured product may be naturally cured over time, but when using a hydraulic inorganic substance such as Portland cement, which has a slow curing reaction, By heating the molded body, humidifying, performing autoclave curing, etc., by performing curing by a conventionally known method,
The curing reaction can be promoted and the mechanical properties can be improved.

As the method for curing the inorganic cured body of the present invention, any conventionally known method such as heating and humidifying the molded body obtained by extrusion molding can be used, and the obtained molded body is used over time. Natural curing may be performed.

[0018]

EXAMPLES The present invention will be described in more detail by way of examples.

Examples 1 to 3 In a given amount shown in Table 1, ordinary Portland cement (manufactured by Onoda Cement Co., Ltd.), polypropylene fiber having a fiber diameter of 15 μm and a fiber length of 6 mm, hydroxypropylmethyl cellulose (viscosity of a 2% aqueous solution at 20 ° C.) Is 30,000
cps), fly ash (particle size 100 μm, true specific gravity 2.3, bulk specific gravity 0.6; conforming to JIS A 6201) and water are supplied to a mixer having a capacity of 10 liters,
The mixture obtained by mixing, the screw diameter 200 mm in which a mold having a parallel portion of 100 mm in the extrusion direction is installed
Was extruded by an extruder to obtain a flat plate having a width of 300 mm and a thickness of 7 mm. After cutting this plate into a fiber length of 300 mm, a vibration press molding machine (manufactured by Asahi Engineering Co.,
The product name; SA-50), and the pressure of 20 kg / cm ²
300 mm x 300 mm x 5 mm with a flat plate of 300 mm x 300 mm x 5 mm and a rib 25 mm in height, 5 mm in width, and 300 mm in fiber length and cross-shaped while press-molding while giving a frequency of 1000 Hz and an amplitude of 10 µm.
A flat plate of

Comparative Example 1 A predetermined amount of ordinary Portland cement (manufactured by Onoda Cement Co., Ltd.) shown in Table 1, polypropylene fiber having a fiber diameter of 15 μm and a fiber length of 6 mm, hydroxypropylmethyl cellulose (viscosity of a 2% aqueous solution at 20 ° C. is 30). 1,000
cps), fly ash (particle size 100 μm, true specific gravity 2.3, bulk specific gravity 0.6; conforming to JIS A 6201) and water are supplied to a mixer having a capacity of 10 liters and mixed to obtain a mixture. Supplied to a vibration press molding machine (Asahi Engineering Co., Ltd., trade name; SA-50),
Press molding was carried out at a pressure of 20 kg / cm ² for 5 seconds while applying vibration with a vibration frequency of 1000 Hz and an amplitude of 10 μm, but an integrated molded body was not obtained.

Comparative Examples 2 to 4 In a predetermined amount shown in Table 1, ordinary Portland cement (manufactured by Onoda Cement Co., Ltd.), polypropylene fiber having a fiber diameter of 15 μm and a fiber length of 6 mm, hydroxypropylmethyl cellulose (viscosity of a 2% aqueous solution at 20 ° C.) Is 30,000
cps), fly ash (particle size 100 μm, true specific gravity 2.3, bulk specific gravity 0.6; conforming to JIS A 6201) and water are supplied to a mixer having a capacity of 10 liters,
The mixture obtained by mixing, the screw diameter 200 mm in which a mold having a parallel portion of 100 mm in the extrusion direction is installed
Was extruded by an extruder to obtain a flat plate having a width of 300 mm and a thickness of 5 mm. Cut this plate into 300mm fiber length,
A flat plate of 300 mm × 300 mm × 5 mm was obtained.

Comparative Examples 5 and 6 Predetermined amounts of ordinary Portland cement (manufactured by Onoda Cement Co.), polypropylene fibers having a fiber diameter of 15 μm and a fiber length of 6 mm, and hydroxypropylmethylcellulose (viscosity of a 2% aqueous solution at 20 ° C.) shown in Table 1 Is 30,000
cps), fly ash (particle size 100 μm, true specific gravity 2.3, bulk specific gravity 0.6; conforming to JIS A 6201) and water are supplied to a mixer having a capacity of 10 liters,
The mixture obtained by mixing, the screw diameter 200 mm in which a mold having a parallel portion of 100 mm in the extrusion direction is installed
Was extruded by an extruder to obtain a flat plate having a width of 300 mm and a thickness of 7 mm. After cutting this plate into a fiber length of 300 mm, it is supplied to a press molding machine, press-molded at a pressure of 20 kg / cm ² for 5 seconds, and a flat plate of 300 mm × 300 mm × 5 mm and a height of 25 mm, a width of 5 mm, and a length of 300 mm. A 300 mm × 300 mm × 5 mm flat plate having cross-shaped ribs was obtained.

COMPARATIVE EXAMPLE 7 Predetermined amounts of ordinary Portland cement (manufactured by Onoda Cement Co., Ltd.) shown in Table 1, polypropylene fibers having a fiber diameter of 15 μm and a fiber length of 6 mm, hydroxypropylmethyl cellulose (viscosity of a 2% aqueous solution at 20 ° C. is 30). 1,000
cps), fly ash (particle size 100 μm, true specific gravity 2.3, bulk specific gravity 0.6; conforming to JIS A 6201) and water are supplied to a mixer having a capacity of 10 liters,
The mixture obtained by mixing is supplied to a press molding machine, and 2
Press-molded for 5 seconds at a pressure of 0 kg / cm ² , 300 mm x 30
300 mm x 30 having a 0 mm x 5 mm flat plate and a cross-shaped rib having a height of 25 mm, a width of 5 mm and a length of 300 mm
A flat plate of 0 mm × 5 mm was obtained.

The molded bodies obtained in Examples 1 to 3 and Comparative Examples 2 to 7 were aged at 90% RH for 6 hours to obtain cured bodies.
The obtained cured product was subjected to the following tests.

Shapeability: The rib surface of the obtained flat plate-shaped cured body having cross-shaped ribs was visually judged, and those having no molding defects such as filling defects and sink marks were evaluated as ◯. The thing marked with x.

Bending Strength The obtained flat plate-shaped cured product was cut to obtain a test piece, and the bending strength was measured according to the method of JIS A 1408 to obtain the bending strength of the material.

Pore Volume A small piece of the obtained flat plate-like cured product was subjected to mercury porosimeter (manufactured by Shimadzu Corporation, trade name; Poisizer 9310 type) to measure the pore size distribution, and the total pore volume thereof was noted.

Freezing and thawing property The obtained flat plate-shaped cured product was cut to obtain a test piece, and
Freezing and thawing are performed according to the method of C666A, and a test piece is taken out every 10 cycles, and the bending strength is measured in the same manner as the above bending strength.
The number of cycles in% is shown.

The above results are also shown in Table 2.

[0030]

[Table 1]

[0031]

[Table 2]

[0032]

Industrial Applicability The method for producing a hydraulic inorganic molded article of the present invention is a method in which a hydraulic inorganic substance and water are mixed, kneaded and molded by extrusion molding, and then shaped into a desired shape by vibration pressure molding. Since it is a method, even a material with a low water / cement ratio and poor fluidity can be molded into a complicated shape that could not be obtained by conventional press molding, and the structure of the obtained molded body is dense. Therefore, it is possible to obtain a hydraulic inorganic cured product having high strength and excellent freeze-thaw resistance.

Therefore, according to the method for producing a hydraulic inorganic molded body of the present invention, molded bodies having various shapes having high strength and excellent durability can be manufactured, and are suitably used for building materials and the like. be able to.

Claims (1)

[Claims] 1. A method for producing a hydraulic inorganic molded body, which comprises subjecting a composition comprising a hydraulic inorganic substance and water to extrusion molding and then vibration pressure molding.