JPH04114948A - Production of fiber-reinforced cement plate - Google Patents

Abstract

PURPOSE:To prevent blocking of reinforcing fibers during blending, enable ready uniform blending and give a sufficient flexural strength by forming and curing a mixture composed of cement, a filler, a specified silica and a reinforcing fiber in a prescribed state. CONSTITUTION:In blending of a fiber-reinforced cement composed of 35-45wt.% cement, 30-40wt.% silica, 15-25wt.% filler and 3-7wt.% reinforcing fiber, an amorphous silica such as a silica fume having 8000-10000cm<2>/g Blaine value or a fry ash is used as the silica component and a synthetic resin fiber opened into a pulp state is used as the reinforcing fiber. The above-mentioned raw materials are then uniformly mixed and, after adding water thereto, the resultant mixture is formed into a plate shape by the dry belt forming method. The above-mentioned formed material is subsequently subjected to high-pressure curing and then to heat curing at <= the deterioration temperature of the above- mentioned synthetic resin fiber. The final curing is subsequently carried out by water curing, thus obtaining the objective cement plate.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] This invention relates to an improvement in a method for manufacturing fiber-reinforced cement boards.

[Conventional technology]

Asbestos has traditionally been widely used as a reinforcing fiber for fiber reinforcement for menment boards, as it is considered to be extremely effective.However, as asbestos causes pollution, there is a strong demand for its use to be restricted or completely abolished, and reinforcing fibers that can replace asbestos have been developed. are being explored in various ways.

Pulp fiber is seen as a promising alternative to asbestos because of its excellent chemical resistance and heat resistance during autoclaving.

[Problems with conventional technology]

However, when pulp fibers are mixed with dry powder raw materials in a dry manufacturing method, so-called "clumps" in which pulp fibers become entangled and form clumps tend to occur, and if this occurs, the reinforcing effect commensurate with the addition cannot be obtained. In the end, there was a drawback that only a plate material with insufficient strength was obtained.

In addition, glass fibers are easily broken and become very short fibers when mixed, making it impossible to obtain a reinforcing effect commensurate with their addition, and also having low alkali resistance, which prevents deterioration.

[Problem to be solved by the invention]

In view of the above problems, this invention provides a fiber-reinforced cement board that prevents clumping of reinforcing fibers when mixing dry powder raw materials in a dry manufacturing process, easily achieves uniform mixing, and provides sufficient bending strength. [Technology that led to solving the problem] That is, the method for manufacturing a fiber-reinforced cement board of the present invention has been made for the purpose of providing a manufacturing method using 35 to 45% by weight of cement and 30 to 40% by weight of silica. , silica hume with a Blaine value of 8,000 to 10,000 cnt/g as the silica content in a fiber-reinforced cement formulation consisting of 15 to 25% aggregate and 3 to 7% fiber by weight,
In addition to using amorphous silica such as fly ash,
Synthetic resin fibers defibrated into a pulp form are used as reinforcing fibers, and after uniformly mixing the above raw materials, the above raw materials are formed into a plate shape by dry belt molding over water, and after curing the molded body under high pressure, the synthetic resin fibers are It is characterized by heat curing at a temperature below the deterioration temperature of the material, followed by final curing by underwater curing.

[Effect]

The blending amounts of cement, etc. used in this invention are the same as conventional ones, and there is no particular point to note. However, synthetic resin fibers defibrated into pulp, specifically polyethylene fibers, are used as reinforcing fibers, and the silica content is amorphous silica such as silica hume or fly ash with a Blaine value of 8,000 to 10,000 cm2/g. use.

The reason for using the above-mentioned reinforcing fibers is to prevent the formation of "clumps" where the fibers get entangled with each other during mixing due to the smoothness of the fibers themselves. Also, the fibers are defibrated into pulp because they are spread widely within the cement matrix. This is to improve the shape retention of the uncured molded product by uniformly dispersing it.

In addition, the silica content has a Blaine value of 8000 to 10000.
The purpose of using amorphous silica such as cn+/g silica fume or fly ash is to increase the bonding strength of the cement matrix and to reinforce the plate from this side, which is lower than the Blaine value of 8000 cffl/g. Moreover, if it is higher than 10,000 cf/g, the water permeability becomes poor when forming and adding water on a belt in the dry process, resulting in a so-called reduction in water floating, which causes a problem between the roll and the surface of the formed plate. This is because problems such as adhesion and 2N peeling occur.

The reason for performing high-pressure curing after molding a molded body from the homogeneous mixture of the above-mentioned raw materials is to speed up the hardening of the molded body and facilitate handling during subsequent curing.

The reason why high heat curing is then performed is to further promote the silica reaction of the cement component and increase the hardness of the board, and the reason why the curing is performed in water is to further promote the silica reaction.

〔Example〕

Next, this invention will be explained in detail.

Example 1 The raw materials shown in Table 1 were dry-mixed in a mixer and then fed to a forming belt in layers to form a large number of plate-like bodies each having a thickness of 51 cm, a width of 90 a+, and a height of 45 cm.

Then, the plate-like bodies obtained were divided into three groups, and each group was divided into 8 groups.
5aLmG x IQ waiting time Autoclave curing, temperature conditions 80℃, humidity 1 so that the moisture content of the base material is 2% or less
The molded product was cured in steam for 24 hours and cured in water for 14 days under conditions of 0.00% for final curing and hardening.

(The numbers in the table are % by weight) Next, each of the above test plates was subjected to the JTSA bending test and the S
The reaction rate of iO□ was measured. The bending strength and deflection were as shown in Table 2, and the reaction rate of SiO□ was as shown in Table 3.

As is clear from Table 2, it was confirmed that the strength of the Examples was improved compared to the Comparative Examples under all curing conditions.
It was also confirmed that the reaction rate of 5i02 was also good.

〔effect〕

Claims (1)

[Claims] (1) In a fiber-reinforced cement formulation consisting of 35-45% by weight of cement, 30-40% by weight of silica, 15-25% by weight of aggregate, and 3-7% by weight of reinforcing fibers, the Blaine value as silica content is 8000-10000 cm^2 /g of amorphous silica such as silica fume or fly ash, and synthetic resin fibers defibrated into pulp as reinforcing fibers. After uniformly mixing the above raw materials, adding water, and dry belt forming. After molding into a plate shape and curing the molded body under high pressure,
Heat curing at a temperature below the deterioration temperature of the synthetic resin fiber,
A method for manufacturing a fiber-reinforced cement board, characterized in that the final curing is then carried out by underwater curing.