JPH07108799B2 - Kneading method for materials for fiber reinforced cement products - Google Patents

Description

TECHNICAL FIELD The present invention relates to a method for kneading materials for fiber-reinforced cement products.

<Prior Art> When kneading water, cement, aggregate, and fibers, which are materials for fiber-reinforced cement products, the stirring blades rotate in the kneading tank as in the case of ordinary materials in which fibers are not mixed. When the material is agitated and kneaded using a kneading device, the fibers in the material are not uniformly dispersed, but become a mass called a fiber ball. If the fibers in the material are not evenly distributed, a strong fiber-reinforced cement product cannot be obtained.

First Conventional Example As disclosed in Japanese Patent Application Laid-Open No. 61-68363, when kneading water and cement and polyamide short fibers of a polyamide fiber reinforced cement material, polyamide short fibers in the material are uniformly dispersed. Therefore, silica fume is added to the material as a dispersion accelerator.

Second Conventional Example In order to uniformly disperse the fibers in the material for the fiber reinforced cement product, a lower part of the kneading tank is composed of a deformable rubber bag, and a mechanism for swinging the bottom of the rubber bag is provided. Using a kneading device, water, cement, aggregate and fibers, and further a methylcellulose-based thickener or water reducing agent are put into a kneading tank of the kneading device, and the material is diffused and kneaded.

<Problems to be Solved by the Invention> Problem of First Conventional Example A material for fiber-reinforced cement has added silica fume as a dispersion accelerator, but like the usual material in which fibers are not mixed, Since the mortar mixer is used to stir and knead, the fibers are not sufficiently dispersed in the material.
Therefore, the fiber reinforced cement product does not have sufficient strength.

Problem of Second Conventional Example The diffusion type kneading device is expensive because it has a special structure. Also, when applying external kneading force to the materials in the kneading tank,
The kneading efficiency is low and the kneading time is long because it is not directly carried out but indirectly by the rocking deformation of the rubber bag by the rocking mechanism.

Furthermore, when a methylcellulose-based thickener is added to the material, the amount of water in the material is increased and the water-cement ratio is increased. Moreover, when the methylcellulose-based thickener is not added to the material, the fibers in the material are not uniformly dispersed as much as when it is added. In either case, the fiber reinforced cement product is not strong enough.

After all, with the kneading method of the conventional example, a fiber-reinforced cement product having high strength cannot be efficiently manufactured at low cost.

An object of the present invention is to solve the above conventional problems.

<Discovery that solves the problem> The present inventor has conducted various experiments and found that
Using a shear-type kneading device in which a blade with a shape of scooping up the material, that is, a blade with an inclined upper surface with the upper surface inclined downward is rotatably provided, and a blade in the shape of a knife that shears the material on the upper side is rotatably provided. , Water, cement and aggregate, fibers and silica fume of the material for fiber reinforced cement product are put into the kneading tank of this kneading device, and this material is kneaded by the lower and upper rotating blades, that is, the material is lowered. It was discovered that the fibers in the material were uniformly dispersed by scooping up with a blade having an inclined upper surface on the side to flow upward and convection, and shearing and kneading the material in the convection with a blade having an edged shape on the upper side.

<Means for Solving the Problems> In the present invention, a blade having a shape for scooping up a material, that is, an upper surface inclined shape whose upper surface is inclined forward and downward is rotatably provided on the lower side in a kneading tank, and a blade is provided on the upper side. Using a shear-type kneading device with rotatably shaped blades, add water, cement and aggregate, fibers and silica fume, which are the materials for fiber-reinforced cement products, into the kneading tank of this kneading device. A fiber reinforced cement characterized in that it is made to flow upward by a rotating blade with an inclined upper surface in a kneading tank to cause convection, and the material in the convection is kneaded by being sheared by a rotating blade-shaped blade in the kneading tank. This is a kneading method for product materials.

<Operation> In the present invention, water, cement and aggregate, and a material for fiber-reinforced cement products in which silica fume is added to fibers are scooped up by the blades of the lower inclined surface and flow upward and convection. The material in the inside is sheared and kneaded by the blade in the upper knife shape, and the fibers in the material for the fiber reinforced cement product are forcibly dispersed by the shearing and uniformly dispersed.

In the kneading device, a shearing type kneading device in which a blade with an inclined upper surface whose upper surface is inclined forward and downward is rotatably provided on the lower side in the kneading tank and a blade with a blade shape is rotatably provided on the upper side is provided. used.

<Effects of the Invention> In the present invention, when kneading water, cement and aggregate, and a material for fiber-reinforced cement products in which silica fume is added to fibers, the fibers in the material for fiber-reinforced cement products are forced by shearing. Since the fibers are dispersed, the fibers are uniformly dispersed in the material as compared with the first conventional example in which the materials are agitated and kneaded in the same manner as a normal material containing no fibers.

A rotary blade type kneading device is used, and an expensive kneading device having a special structure as in the second conventional example is not used. The external kneading force is applied directly to the material by the blades, so that the kneading efficiency is high and the kneading time is short as compared with the second conventional example which is indirectly performed. It is not necessary to add thickeners to the material which would increase the water cement ratio.

As a result, a fiber-reinforced cement product having high strength can be efficiently manufactured at low cost.

<Example> In the kneading method for the material for fiber-reinforced cement product of this example, the materials are water, cement, fine aggregate and carbon fiber, silica fume and a water reducing agent.

The carbon fiber has a diameter of 18 μm, a length of 10 mm, a specific gravity of 1.63 and a tensile strength of 7,800 Kg · f / cm ² .

Silica fume is spherical ultrafine particles recovered from silica gas generated when ferrosilicon as a deoxidizer is produced. The ultrafine particles have a maximum particle size of 1 μm or less, an average particle size of about 0.1 μm, a specific gravity of 2.1 to 2.2, and a SiO 2
The content rate of ₂ is 84 to 93%.

The weight of silica fume in the material is 10-15% of the weight of cement in the material.

As shown in FIG. 1 and FIG. 2, the kneading device is configured to penetrate the horizontal bottom plate of the kneading tank 1 at the axial center position in the cylindrical kneading tank with a lid 1, projecting the upper part of the rotary shaft 2 to rotate. The shaft 2 is vertically supported, and two blade-shaped blades 3, 4, 3 are horizontally installed on the upper part of the rotating shaft 2 protruding into the kneading tank 1 in three stages of upper, middle and lower.

As shown in the cross section in FIG. 3, the lower blade 5 has a shape in which the upper surface is inclined forward and downward, that is, an upper surface inclined shape that scoops up the material and causes it to flow upward spirally for convection. The bottom plate and the peripheral wall of the kneading tank 1 are slightly curved along the arcuate corners. Each of the middle and upper blades 4, 3 is formed in a blade-like shape that shears the material in convection.

As shown in FIG. 1, the lower part of the rotary shaft 2 is connected to an electric motor 8 via a belt transmission mechanism 6 and a speed reducer 7, and the rotation of the electric motor 8 drives the three-stage blades 3 in the kneading tank 1. The 4,5 are rotated at a desired rotation speed.

When the above materials are kneaded using the above kneading device, the above materials are put into the kneading tank 1 of the above kneading device,
By rotating the electric motor 8 of the kneading device, the
Rotate the blades 3, 4 of the stage at a desired rotation speed.

Then, the material in the kneading tank 1 is rotated in a spiral shape by the rotating lower blade 5 to move up to the peripheral wall side position in the kneading tank 1 and move to the shaft center position side in the kneading tank 1 to descend. Then, so-called convection and mixing are performed, and during convection, the blades 4 and 3 of the rotating middle stage and upper stage are respectively sheared and mixed to uniformly knead.

During kneading, the silica fume in the material acts as a ball bearing between the carbon fibers in the material, defibrating and facilitating uniform dispersion of the carbon fibers.

The kneaded material is molded into a desired shape and cured. That is, a carbon fiber reinforced cement product is produced.

This carbon fiber reinforced cement product has high strength because carbon fibers are uniformly dispersed and silica fume is contained.

<Comparative Experiments> Experiments 1 and 2 of the Present Invention A carbon fiber reinforced cement product was manufactured by carrying out the kneading method of the material for a fiber reinforced cement product of the above-mentioned examples, molding the kneaded material and curing it.

At this time, the mixing ratio of the materials is as follows.

Experiment 1 2 Water cement ratio (%): 40 45 Fine aggregate cement ratio (%): 50 50 Carbon fiber total material ratio (Vol%): 3 3 Silica fume cement ratio (%): 15 15 Water reducing agent cement ratio ( %): 2.0 1.3 The kneading time is 2-3 minutes, and the blade of the kneading device
The rotation speed of 3,4,5 is 400 to 200 rpm.

Then, the compressive strength and bending strength of the manufactured carbon fiber reinforced cement product were measured. The measured values are as follows.

Experiment 1 2 Compressive strength (Kg · f / cm ² ): 965 1070 Bending strength (Kg · f / cm ² ): 170 178 Experiment 3 of prior art 3,4 Use the diffusion type kneading device of the second conventional example A method for kneading a material for a fiber-reinforced cement product was carried out, and the kneaded material was molded and cured to produce a carbon fiber-reinforced cement product.

At this time, the mixing ratio of the materials is as follows.

 Experiment 3 4 Water cement ratio (%): 30 47 Fine aggregate cement ratio (%): 50 50 Carbon fiber total material ratio (Vol%): 3 3 Water reducing agent cement ratio (%): 0.8 Thickener cement ratio ( %): 0.1 The kneading time is 10 minutes.

The bending strength of the produced carbon fiber reinforced cement product was measured. The measured values are as follows.

Experiment 3 4 Bending strength (Kg · f / cm ² ): 142 64 Comparative results Carbon fiber reinforced cement products produced by carrying out the kneading method of the material for fiber reinforced cement products of the examples of the present invention are the same as those of the prior art. In comparison, the bending strength is very high despite the significantly short kneading time.

<Modification> The reinforcing fiber used in the kneading method for the material for fiber-reinforced cement product of the example was carbon fiber, but instead of this, glass fiber, steel fiber or polyethylene fiber, vinylon fiber, cashimiron fiber. Organic fibers such as or nylon fibers are used.

[Brief description of drawings]

FIG. 1 is a schematic vertical sectional front view of a part of a kneading device used in a method for kneading a material for a fiber-reinforced cement product according to an embodiment of the present invention. FIG. 2 is a partially cross-sectional schematic plan view of a kneading device used in the same kneading method. FIG. 3 is an enlarged sectional view taken along the line AA of FIG. 1: Kneading tank, 3,4,5: Feather

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Claims (1)

[Claims] 1. A shear-type kneading device in which a blade having an inclined upper surface whose upper surface is inclined forward and downward is rotatably provided on the lower side in a kneading tank, and a blade having a blade shape is rotatably provided on the upper side. Water, cement and aggregate, fibers and silica fume, which are the materials for fiber reinforced cement products, are put into the kneading tank of this kneading device, and this material is moved upward by the rotating blades of the inclined upper surface in the kneading tank. A method for kneading a material for a fiber-reinforced cement product, which comprises flowing and convection, and shearing the material in the convection with a blade in the shape of a rotating blade in a kneading tank.