JPH0421402A - Manufacture of fiber reinforced cement molding - Google Patents

Abstract

PURPOSE:To remove air bubbles at the time of shaking and mixing and to enhance the strength by bringing a shaking and mixing apparatus for performing shaking and mixing to a vacuum state in the first process adding a specific aqueous solution, an inorg. filler and a synthetic fiber and the second process adding cement. CONSTITUTION:In the first process, 200 pts.wt. or less of one kind of an inorg. filler is added to and mixed with an aqueous solution prepared by dissolving 0.1 pts.wt. or more of a water-soluble high-molecular substance in 30 pts.wt. or more of water and 0.3-7 pts.wt. of a synthetic fiber is subsequently added to perform shaking and mixing. In the second process, 100 pts.wt. of cement is added to the mixture obtained in the first process to perform shaking and mixing. In the third process, the mixture obtained in the second process is received in an openable and closable mold and pressed at speed of 0.3mm/sec or more to be molded. A shaking and mixing apparatus performing shaking and mixing is brought to a vacuum state of 0.1-10Torr in the first and second processes to perform the degassing of the mixture to transfer to the third process.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention relates to a method for producing a fiber-reinforced cement molded body with excellent strength.

(Prior Art) Conventionally, as a method for producing a fiber-reinforced cement molded body, for example, 20 parts by weight of one type of inorganic filler is added to an aqueous solution in which 0.1 parts by weight or more of a water-soluble polymer substance is dissolved in 30 parts by weight or more of water.
After adding and mixing 0 parts by weight or less, synthetic fibers 0.3 to 7
A first step in which 100 parts by weight of cement is added to the mixture obtained in the first step and mixed with oscillation, a second step in which 100 parts by weight of cement is added to the mixture obtained in the first step and oscillation is mixed, and A fiber-reinforced cement molded article was produced by a third step of placing the mixture in an openable mold and pressing at a speed of 0.3 mm/sec or more to shape the mixture.

(Problems to be Solved by the Invention) However, in the conventional method described above, air bubbles cannot be sufficiently removed during shaking mixing, and air bubbles remain in the manufactured fiber-reinforced cement molded body. For this reason, in the fiber-reinforced cement molded article, there was a problem in that the portion where the air bubbles are present becomes weak in terms of strength, resulting in variations in strength.

In view of the above-mentioned problems, an object of the present invention is to improve freeze-thaw resistance by removing air bubbles during rocking mixing using a rocking mixer, improving strength, and reducing the amount of pores associated with this. Plan.

(Means for Solving the Problems) The method for producing a fiber-reinforced cement molded article of the present invention includes
200 parts by weight or less of one type of inorganic filler is added to an aqueous solution in which 0.1 parts by weight or more of a water-soluble polymer substance is dissolved in 0.1 parts by weight or more and mixed, and then 0.3 to 7 parts by weight of synthetic fibers are added. A first step in which the mixture obtained in the first step is mixed with oscillation, a second step in which 100 parts by weight of cement is added to the mixture obtained in the first step and mixed in oscillation, and the mixture obtained in the second step is opened and closed. It consists of a third step of placing it in a mold and pressing it at a speed of 0.3 m/sec or more to shape it. 1~1QT
After degassing the mixture by creating a vacuum of orr,
This is to proceed to the third step.

Furthermore, the method for producing a fiber-reinforced cement molded article of the present invention includes:
After adding and mixing 200 parts by weight or less of one type of inorganic filler to an aqueous solution in which 0.1 parts by weight or more of a water-soluble polymer substance is dissolved in 30 parts by weight or more of water, 0.3 to 7 parts by weight of synthetic fibers are added. A first step in which 100 parts by weight of cement is added to the mixture obtained in the first step and mixed by shaking; a second step in which 100 parts by weight of cement is added to the mixture obtained in the first step and mixed by shaking; It consists of a third step of placing it in an openable and closable mold and pressing at a speed of 0.3 m/sec or more to shape it, and in the second step, the inside of the oscillating mixing device that performs the oscillating mixing is ~10T.

After the mixture is brought to a vacuum state of rr and the mixture is degassed, the process proceeds to the third step.

(Function) In the first step and the second step, the inside of the container in which the oscillating mixing is performed is made into a vacuum state of 0.1 to 10 Torr to evacuate the mixture, thereby preventing the generation of air bubbles.

(Example) The present invention will be explained in detail below.

The method for producing a fiber-reinforced cement molded article according to the present invention includes adding 200 parts by weight or less of one type of inorganic filler to an aqueous solution in which 0.1 parts by weight or more of a water-soluble polymer substance is dissolved in 30 parts by weight or more of water. After mixing, a first step of adding 0.3 to 7 parts by weight of synthetic fibers and performing rocking mixing, and a second step of adding 100 parts by weight of cement to the mixture obtained in the first step and performing rocking mixing. 2 steps, and a 3rd step in which the mixture obtained in the 2nd step is placed in an openable and closable mold and pressed at a speed of 0.3 m/sec or more to form the mixture, and the 1st step and the 2nd step are , the inside of the container in which the oscillating mixing is performed is heated to 0.1 to 1 Q Tor.
After the mixture is brought to a vacuum state of r and the mixture is degassed, the process proceeds to the third step.

Examples of water-soluble polymer substances in the first step include:
Examples include methylcellulose, carboxymethylcellulose, polyvinyl alcohol, hydroxyethylcellulose, and polyacrylic acid.

Further, examples of the inorganic filler in the first step include silica sand, river sand, fly ash, silica flour, bentonite, seviolite, volasnite, calcium carbonate, mica, and blast furnace slag. These inorganic fillers may be used in combination of two or more types depending on moldability.

Further, the synthetic fibers used in the first step include, for example, fibers such as vinylon, polyamide, polyester, polypropylene, etc., with a thickness of 2 to 40 deniers and a length of 3 to 1511 m. be done.

The cement used in the second step refers to hydraulic cement such as Portland cement, alumina cement, and blast furnace cement.

In addition, the rocking mixing performed in the first and second steps is
A mixing method using a device in which a flexible rubber container is mounted on a disc-shaped rocking plate without using a stirring blade, the method comprising:
By continuously changing the tilt direction and angle of the rocking plate, the rubber container containing the materials to be mixed deforms and rocks, thereby accelerating the contents and changing the speed and direction. is given, scattering in random directions, and mixing. One cycle of the movement of the rocking plate is usually 1~
3 times/second. As the oscillating mixing device, there is, for example, the Omni-mixer manufactured by Chiyoda Giken Kogyo.

This oscillating mixing device is connected with a vacuum device for evacuating the inside of the oscillating mixing device.

Next, each of the above steps will be explained in detail.

First, in the first step, viscosity is given to water by dissolving 0.1 part by weight or more of a water-soluble polymer substance in 30 parts by weight or more of water, and then the inorganic filler is precipitated, which is added afterwards or at the same time as the dissolution. It is possible to suppress this and improve dispersibility.

Up to 200 parts by weight of an inorganic filler is added to the aqueous solution and mixed. In particular, when using a water-soluble polymeric substance that is easily soluble in water, such as methylcellulose, an inorganic filler is added and mixed at the same time as the water-soluble polymeric substance is dissolved.

By adding synthetic fibers to a viscous aqueous solution in which inorganic fillers are dispersed and mixing them with shaking, the synthetic fibers are uniformly distributed without forming fiber balls, being damaged, or being cut. distributed. In this case, if the average particle size of the inorganic filler is 100 μm or more, it becomes difficult for the inorganic filler particles to enter between the fibers of the synthetic fibers, and the fibers tend to aggregate instead of dispersing. The average particle size is preferably 100 μm or less.

In this example, the amount of synthetic fiber added is 0.3 to 7 parts by weight. If the amount of synthetic fiber added is less than 0.3 parts by weight, the desired strength of the molded product cannot be obtained, and if the amount added is more than 7 parts by weight, the dispersion of the fibers becomes poor and the fluidity during shaping becomes poor. Because it gets worse.

In the second step, 100 parts by weight of cement is added to the mixture obtained in the first step, and the mixture is further mixed by shaking, so that the fine particles of cement are easily interposed between the inorganic filler and the synthetic fibers. A dispersed and homogeneous mixture is obtained. The synthetic fibers are not damaged or cut during this process.

Here, during the oscillating mixing in the first step and the second step, the inside of the oscillating mixing device is heated to 0°1 = I by a vacuum device.
Make OToor vacuum. As a result, the air present in the mixed material being mixed by the oscillating mixer is removed. The reason why the vacuum is set at 0.1 to 10 Toor as described above is because if the vacuum is smaller than 0.1 Toor, the air present in the mixed material cannot be sufficiently removed, resulting in a decrease in strength. This is because if it is larger than 10Toor, the water ratio in the mixed material decreases and the mixture becomes a little dry.

In the third step, the mixture obtained in the second step is placed in a mold that can be opened and closed and pressed to shape it. Since the mixture contains 30 parts by weight or more of water, water is likely to separate from the mixture. For this reason, it is necessary to complete shaping before moisture separation occurs. In this case, the mixture in the mold is 0.
If the mixture is pressed at a speed of 3 wm/sec or more, water will not separate within the mold, and the mixture will quickly fill the entire mold with sufficient fluidity and be completely shaped.

The molded body obtained by the above-mentioned process is dehydrated in a mold to an extent that maintains shape retention, and then demolded, and cured by a conventionally known method to obtain a fiber-reinforced cement molded body.

Next, specific examples of fiber-reinforced cement molded bodies manufactured by the above-mentioned steps will be described.

〔Concrete example〕

Dissolve 0.2 parts by weight of methylcellulose in 45 parts by weight of water at a temperature of 20°C, remove 5 parts by weight of this aqueous solution without using it, and add 30 parts by weight of silica powder to the remaining 40 parts by weight of the aqueous solution. After mixing, add fiber length 6wm and thickness 1.8
Two parts by weight of denier vinylon fibers were added, and the mixture was mixed by shaking in a shaking mixer under a vacuum of lToor. (
1st step) Next, 100 parts by weight of ordinary Portland cement was added to the above mixture, and as in the 1st step, rocking mixing was performed in the rocking mixer in a vacuum state of IToor.

(Second step) Finally, put the above mixture into a mold that can be opened and closed, and
The molded product was pressed into a wave shape at a speed of 65 kg/sec and a pressure of 65 kg/- and dehydrated. After demolding, it was cured at a temperature of 60° C. and a relative humidity of 90% for 10 hours to produce a molded product. (Third Step) For the oscillating mixing in the first and second steps, an omni mixer (capacity 701) manufactured by Chiyoda Giken Kogyo (■) was used.

The table shows that when the inside of the oscillating mixer is in a vacuum state in the first and second steps as described above, when the inside of the oscillating mixer is in a vacuum state only in the first step, and only in the second step, the oscillating mixer is The strength, pore volume, and freeze-thaw properties are compared when the inside of the device is in a vacuum state and when the inside of the oscillating mixing device is manufactured without a vacuum state.

Table As can be seen from this table, fiber-reinforced cement molding with excellent strength, pore volume, and freeze-thaw properties is achieved when the oscillating mixer is in a vacuum state in the first and second steps. body can be manufactured.

In addition, even if the inside of the oscillating mixer is in a vacuum state only in the second step, the strength and pore volume are different from those in the case where the inside of the oscillating mixer is in a vacuum state in the first and second steps described above. ,
Almost the same effect can be obtained with freeze-thaw properties.

(Effects of the Invention) As described above, according to the method of the present invention, in the first step and the second step, the inside of the oscillating mixing device for oscillating mixing is kept in a vacuum state of 0.1 to 10 Torr. After the mixture is degassed, the process moves to the third step, so air bubbles in the mixture can be removed, and a decrease in strength due to air bubbles is prevented, resulting in high-strength fiber-reinforced cement molding. The body can be manufactured. Furthermore, by removing air bubbles, it is possible to reduce the amount of pores present in the fiber-reinforced cement molded body, and it is possible to improve the freeze-thaw resistance.

Patent applicant Sekisui Chemical Co., Ltd. Representative Hiro 1) Kaoru

Claims (1)

[Claims] 1) 200 parts by weight of one type of inorganic filler is added to an aqueous solution in which 0.1 parts by weight or more of a water-soluble polymer substance is dissolved in 30 parts by weight or more of water.
A first step of adding and mixing 0.3 to 7 parts by weight of synthetic fibers and performing rocking mixing, and adding 100 parts by weight of cement to the mixture obtained in the first step. It consists of a second step of performing rocking mixing, and a third step of putting the mixture obtained in the second step into an openable and closable mold and shaping it by pressing at a speed of 0.3 mm/sec or more, In the first step and the second step, the inside of the oscillating mixing device that performs the oscillating mixing is set at 0.1 to 10 Torr.
A method for producing a fiber-reinforced cement molded article, characterized in that the mixture is brought into a vacuum state and the mixture is degassed, and then the third step is performed. 2) Add 200 parts of one type of inorganic filler to an aqueous solution in which 0.1 parts by weight or more of a water-soluble polymer substance is dissolved in 30 parts by weight or more of water.
A first step of adding and mixing 0.3 to 7 parts by weight of synthetic fibers and performing rocking mixing, and adding 100 parts by weight of cement to the mixture obtained in the first step. It consists of a second step of performing rocking mixing, and a third step of putting the mixture obtained in the second step into an openable and closable mold and shaping it by pressing at a speed of 0.3 mm/sec or more, In the second step, the inside of the oscillating mixing device that performs the oscillating mixing is brought into a vacuum state of 0.1 to 10 Torr to degas the mixture, and then the fiber is moved to the third step. A method for producing a reinforced cement molded body.