JPS6013510A - Method of intimately mixing carbon fiber reinforced mortar - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for mixing carbon fiber-reinforced mortar by uniformly mixing and dispersing carbon fibers.

In view of the fact that mortar reinforcement using glass fibers, which has been widely used in the past, has the drawback of alkali deterioration which causes glass to be eroded by cement components, we developed mortar reinforcement that is chemically inert and has a tensile strength compared to steel fibers. Carbon fiber, which has physical properties about 8 times that of conventional carbon fibers, has attracted attention and is being put into practical use as carbon fiber reinforced concrete (CFRC) or carbon fiber reinforced mortar (CCFRM). Carbon fibers are broadly classified into polyacrylonitrile type (PAN type) and pitch type, and pitch type is used as a reinforcement material for construction due to cost and mass production. Carbon fibers can be either bundled or non-bound, and bundled fibers are
Although they are relatively easily dispersed in the wax, unbound fibers have a wider contact area with the cement system, which improves the tensile strength and tensile modulus of reinforcing mortar compared to bundled fibers. Because the fibers tend to gather together and form clumps, it is extremely difficult to disperse in cement or sand.

In the mortar applied with -i'1 with poor dispersion, the water absorption rate is high in the lumpy parts where the carbon fibers are gathered together, and there are also parts where the fibers and cement are not bonded, so the physical properties of the mortar are significantly reduced. As a means of dispersing carbon fiber,
Various dry mixing methods for cement and sand have been attempted, but satisfactory dispersion is still not achieved due to the large difference in specific gravity between fibers and cement or sand, and the tendency for fibers to stick together due to friction. This is the actual situation, and this is one of the reasons preventing the general spread of carbon fiber reinforced mortar.

The present invention does not use the conventional incomplete dispersion method of dry mixing, but instead immerses carbon fibers in water or an aqueous polymer solution and stirs them to loosen the fiber clumps, as well as cement.
The amount of carbon fiber added to the cement system of mortar is 0.2 to 50% by weight, which is a method of dispersing carbon fiber in mortar that strengthens the adsorption effect of fibers on sand and reduces the difference in specific gravity to obtain uniform dispersion. H, preferably 05~aO%
is suitable.

The filtration system in which carbon fibers are dispersed uses an aqueous solution containing a surfactant-like dispersant, an aqueous solution containing a chemical thickening agent such as MC or PVA, and/or a diluent water for polymer dispersion, either alone or in combination. Dispersion order: Any of the above aqueous dispersion media is placed in a stirring vessel, and the carbon fibers are gradually mixed into the dispersion medium while stirring. When the carbon fibers are sufficiently dispersed in the liquid, add the carbon fiber dispersion to the cement and sand that have been dry-mixed in advance in a mortar mixer and knead. Since the fibers are in a wet state, they easily adhere to cement and aggregate, and there is no phenomenon in which they are released from the matrix material during mixing.

By the dispersion method of the present invention, cement, sand, and carbon fiber-containing aqueous systems are mixed into mortar at the same time, and the carbon fibers are evenly dispersed on the troweled finished surface, eliminating uneven water absorption and physical property variations. This makes it extremely easy to use carbon fiber in general mortar, which has been difficult in the past, and rapid spread is expected.

Example 1 Methyl cellulose (Matsumoto Yushi Co., Ltd., trade name: Marboros) 80F was dissolved in 20 tons of water, and while stirring with a disperse mixer, pitch-based carbon fiber (Sumitomo Metal Industries, Ltd., trade name: Chop, fiber length) was dissolved in 20 tons of water. 10II+++1) 400
The mixed solution prepared by adding and dispersing 2 to 100 g of sand (Tajimi weight No. 5 silica sand) and 40 kg of cement (Onoda Portland ordinary cement) was mixed with stirring into a dry mortar mixer. After kneading for about (9) seconds, the kneaded carbon fiber-containing mortar was troweled to a thickness of 20 wn onto the wet concrete wall surface. Compared to the method using dry mixing, the carbon fibers obtained by the dispersion method of the present invention were uniformly dispersed in the mortar, and the phenomenon of fibers becoming entangled and forming lumps and particles, which often occurs in dry mixing, was not observed at all in Example 11.
2. Dissolve 80f of methyl cellulose (manufactured by A Hon Yushi, trade name: Marboros) in 9 tons of water, and while stirring with a mixer with a disper length, add 800f of pitch-based carbon fiber (manufactured by Sumitomo Metal Industries, Ltd., trade name: Chop, fiber length 6 mm). Styrene butadiene latex (SBR:
Manufactured by Takeda Pharmaceutical Company, trade name Crossren CMX-02F
) in the same way as in Example 1, using 100K sand.
g and 40Kf of cement were mixed into a mortar mixer that had been mixed in advance with stirring. After about 30 seconds,
The kneaded latex carbon fiber-containing mortar was troweled onto a wet concrete wall to a thickness of 5 mm, and it was confirmed that carbon fibers were evenly dispersed even in latex-containing polymer cement mortar.

Patent applicant Chugai Shoko Co., Ltd.

Claims (1)

[Scope of Claims] 1. A predetermined amount of carbon fiber is mechanically dispersed in water for mortar mixing or an aqueous system to which additives for modifying mortar have been added. A method for mixing carbon fiber-reinforced mortar in which the fibers are uniformly dispersed in the mortar by kneading with a sand mixture. 2. The method for mixing carbon fiber reinforced mortar according to claim 1, wherein the carbon fiber has a cut length of 8 to 50 mm. 8. The method for mixing carbon fiber-reinforced mortar according to claim 1, wherein the amount of carbon fiber added to the mortar is 02 to 0% by weight based on the amount of cement mixed in the mortar. 4. The method for mixing carbon fiber-reinforced mortar according to claim 1, which comprises adding a cement-mixing polymer dispersion specified in JISA6208 to an aqueous system in which carbon fibers are dispersed.