JPH08325050A - Carbon fiber reinforced cement molded body, its production and formed body reinforced with the same - Google Patents

Abstract

PURPOSE: To obtain a high strength profitable carbon fiber reinforced cement molded body having satisfactory adhesiveness to the cement matrix. CONSTITUTION: Carbon fibers 1 electrolytically oxidized with 1-100C electricity per 1m<2> surface area are contained in an unhardened cement molded body 3 contg. powder of water granulated blast furnace slag by 20-80wt.% of the total amt. of all pozzolana components so that the carbon fiber content of the cement molded body after hardening is regulated to 0.1-30vol.%.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The present invention relates to a cement-based material for use in building materials such as soundproof walls, windproof walls, outer walls, inner walls, floors, roofs and parapets, to large-scale concrete structures. The present invention relates to a carbon fiber reinforced cement molded product used as a reinforcing material, a method for producing the same, and a molded product reinforced by the molded product.

[0002]

2. Description of the Related Art The use of cement-based materials as a matrix and the use of high-strength fibers as reinforcing materials in place of reinforcing bars is effective for preventing the strength of cement-based materials from decreasing due to the rust of reinforcing bars. The material is being developed.

For example, carbon fibers are cut into short fibers and dispersed in a cement-based matrix to improve the strength as a matrix-fiber composite, and carbon fiber reinforced plastic rods are arranged in the cement matrix to make reinforced concrete. Those used as are well known. In addition, recently, in order to secure the adhesive strength with the cement matrix by omitting the procedure of arranging the carbon fiber reinforced plastic rods, those which are woven into a mesh shape and those which are used as a three-dimensional woven fabric have been developed. .

However, the method of reinforcing short fibers by dispersing them in a cement matrix has a poor reinforcing efficiency, and carbon fibers having a high cost are not economically attractive. Further, although the reinforcing method of arranging the rods has a high reinforcing efficiency, various deformation treatments are required to increase the adhesive strength, which lowers the tensile strength, slows the production rate, and significantly reduces the economical efficiency. Further, when woven into a mesh or a three-dimensional woven fabric, the fibers are damaged by the weaving, so that the tensile strength is lowered and the cost of weaving is increased.
The economy is poor.

Furthermore, recently, avoiding the use of plastics which have problems in durability and non-combustibility, the Japanese Patent Publication No.
09, Japanese Patent Fair 6-25020, Japanese Patent Fair 6-2502
A unidirectional continuous sheet impregnated with cement paste has also been developed, as disclosed in each of the gazettes of No. 1. But,
One-way continuous sheets are not suitable for use as a substitute for reinforcing bars or dispersed in concrete, and there are restrictions on the use site.

[0006]

As described above, the conventional methods for reinforcing cementitious materials still have problems to be solved. The present invention has been proposed to solve the above-mentioned problems, and does not contain a plastic component for providing reinforcement of a cement-based matrix, has a high reinforcement efficiency, is easy to produce, and has no limitation in usage. The object of the present invention is to obtain a carbon fiber reinforced cement molded product used as an economical reinforcing material, a method for producing the same, and a molded product reinforced by the molded product.

[0007]

[Means and Actions for Solving the Problems] In order to achieve the above object, the carbon fiber reinforced cement molded product according to the present invention contains 20 to 8 granulated blast furnace granulated slag powder in all pozzolan components.
In an unhardened cement molded product containing 0% by weight, the carbon content of 1 to 100 coulomb / m ² of electrolytic oxidation per carbon fiber surface area is 0.1 to 30% as a volume content in the hardened cement molded product. It is characterized by containing. Further, the present invention is characterized in that the cement molded product is in a strand form, and the continuous carbon fiber is twisted at 21 times / m or less per length thereof. In addition, the method for producing a carbon fiber-reinforced strand-shaped cement molded product of the present invention is, for example, a continuous carbon fiber subjected to electrolytic oxidation of 1 to 100 coulomb / m ² per surface area of carbon fiber in a wind (gas such as compressed air) without tension. The granulated blast furnace slag powder is contained in all pozzolan components in an amount of 20 to 80% by weight, and the average particle size is 35.
It is characterized in that it is impregnated with a cement slurry made of pozzolan of 00 branes or more and imparted with tension, and then is allowed to set to undergo natural curing and autoclave curing. In FIG. 1, the multifilamentary carbon fiber 1 is opened so that each filament 1a is separated, and then the cement slurry 2 is added.
The carbon fiber reinforced cement molded product 3 produced by impregnating (immersing) the same is shown. Further, the present invention is the above-mentioned manufacturing method, wherein the opened carbon fiber bundle is impregnated (immersed) into the slurry.
After that, the carbon fiber bundle is twisted at 21 times / m or less, and then the carbon fiber bundle is condensed while applying tension. The present invention also features a carbon fiber reinforced cement molded product in which the carbon fiber reinforced cement molded product described above is embedded as a reinforcing material.

The cement slurry used in the present invention contains granulated blast-furnace slag powder as an essential component, and in addition, ordinary Portland cement, fast-strength Portland cement, ultra-fast-strength Portland cement, blast furnace cement, alumina cement, silica cement, , Clay, volcanic ash, powdered silica stone, fly ash, silica fume, etc. are mixed and water is added to form a slurry-like pozzolan. Further, in order to improve the impregnation property of the slurry, a water reducing agent, a defoaming agent and a thickening agent can be added appropriately.

What is important in the above is the components of pozzolan used and the curing method. That is, 20% by weight or more and 80% by weight or less of the whole pozzolan containing the granulated blast furnace slag,
It is necessary to combine natural curing and autoclave curing. By mixing cement with granulated blast furnace slag in this range, CaO, SiO ₂ , Al ₂ O ₃ , Fe ₂ O
Contains ₃ in a well-balanced manner, and these components produce hydrated minerals such as vamorite, hydrogarnet, and calcite by the combined use of natural curing and autoclave curing, increasing the interfacial strength of carbon fibers and the strength of the entire molded product.

If the amount of granulated blast furnace slag is less than 20% by weight, the balance is lost and the formation of hydrogarnet and calcite, which increase the interfacial strength of carbon fibers, is less likely to occur. Also,
On the other hand, if it exceeds 80% by weight, the alkali content brought in from the cement is insufficient, and the granulated blast furnace slag does not harden. The most desirable range is 40% by weight of granulated blast furnace slag powder to 6%.
Between 0% by weight, the rest is pozzolan, which consists entirely of early-strength Portland cement.

The reason for defining the average particle size of the entire pozzolan is to ensure impregnation. Cement having a grain size coarser than 3,500 branes has poor impregnability and is not suitable for use. This is because the diameter of carbon fiber is very fine, 7 microns for PAN system and 10 microns for pitch system, so if the particle size of cement is too large compared to them, the compatibility is poor and the interface strength between carbon fiber and cement decreases. Is. Further, in order to obtain appropriate rheological properties (fluidity and viscosity) necessary for impregnation, it is a condition that the average particle size is small.

From the above, the finer the average particle size of cement is, the more rapidly it becomes if it is excessively fine, and the economical efficiency of crushing is naturally limited, and it is between 4000 and 8000 branes produced commercially. Is appropriate.

The carbon fiber to be used may be either PAN type or pitch type, but since the pitch type having a large fiber diameter is not much different from the particle size of the cement, it is preferable because it is well compatible when impregnated. In this case, what is important is the surface treatment. That is, the surface treatment of carbon fiber is generally performed by air oxidation, electrolytic oxidation, plasma oxidation treatment method, etc., but the type of functional group generated on the surface of carbon fiber by electrolytic oxidation that oxidizes in an aqueous solution It is suitable and has high interfacial strength, which is preferable.

The strength of electrolytic oxidation exceeds 100 coulomb / m ² per surface area of the carbon fiber, and the strength of the fiber decreases, and less than 1 coulomb / m ² has no effect. The preferred range is an elastic modulus of 60 tf /
The conditions are 10 coulombs / m ² or more and 80 coulombs / m ² or less for carbon fibers of mm ² or less.

Further, since the multifilamentary carbon fiber is blown with air to open the fiber and is impregnated (immersed) in the cement slurry, a sizing agent such as an epoxy resin or polyvinyl alcohol used for converging is applied. It is preferable not to do so, but even if it is applied, it can be dealt with by increasing the air blowing air velocity for opening to about 3 m / sec or more. These sizing agents can be appropriately selected in relation to the interfacial strength.

The volume content of carbon fibers in the finally cured carbon fiber-reinforced cement molding is also important. If the volume ratio is small, the finished molded product will be thick and will not be damaged even when kneaded, but if it is less than 0.1%, the strength of the molded product will be low and not practical. On the other hand, if the volume ratio is large, the molded product has high strength per molded product area, but the volume ratio is 3
When it is more than 0%, the impregnation property of the slurry is poor and the interfacial strength is lowered. The most preferable volume ratio is 0.5% to 10
% Range.

If necessary, by twisting the molded body after impregnation, it is possible to align the directionality of the fibers and to increase the strength and reduce the variation. It should be decided in a combined manner. However, if the twisting number exceeds 21 times per 1 m, the fibers are damaged and the impregnated slurry is squeezed out, and the volume ratio of the fibers is excessively increased, which is not preferable.

In the method for producing a carbon fiber-reinforced cement molded product, first, carbon fibers made of multifilaments are opened into air by blown air into each filament and then immersed in cement slurry to obtain cement pozzolan. Are adhered (that is, impregnated) to the surfaces of the filaments located on the outer side and the filaments located on the inner side such as the center side in a large number of filament groups (bundle). Then, tension is applied to align the fibers. The first important point here is the method of opening, combing,
Wind velocity of 1 m / in a tensionless state without using rolls
It is to blow air for more than sec. Wind speed is 10m
If it exceeds / sec, excessive spreading will result in poor alignability required at the end, which is not preferable. 2 is most preferable
It is between m / sec and 5 m / sec. If an open comb or roll is used, the fibers will be damaged and the strength will be reduced, and tension will be applied when impregnating (immersing) the cement slurry.
It is not preferable because its impregnating property becomes poor.

Secondly, it is necessary to tension and align the array of fibers disturbed during impregnation after impregnation (immersion) in the cement slurry and before setting. If the alignment is poor, the strength of the molded product will decrease. The tension can be applied by using a brake with a friction wheel, electromagnet, permanent magnet, etc. in the case of continuous condensing, and in the case of batch type condensing, it is possible to apply a weight for each required length. It can be given by hanging. Regarding the magnitude of tension, it is preferable to add 5 gf to 500 gf in addition to its own weight per 3 k (3000 filaments) of pitch-based carbon fiber. If the tension is less than 5 gf, it is not effective for aligning, and if it exceeds 500 gf, the carbon fiber tends to break,
It is uneconomical.

The molded product obtained by the above-mentioned method can be used as it is as a tensile material, or may be used for reinforcing other cement molded products. These cement moldings, such as soundproof walls, windproof walls, outer walls, inner walls, floors, roofs,
When used to reinforce cement-based panels for building materials such as parapets, large-scale concrete structures, etc., it can also be used as a continuous reinforcing material instead of reinforcing bars, and can be combined into a flat surface to
A three-dimensional reinforcing material can be processed by combining it with a three-dimensional reinforcing material. In particular, when the combination is used as a reinforcing material, it is convenient because other adhesives are not required by combining it before the pozzolan is set.

Still another important usage is a usage in which the molded product obtained by the above-mentioned method is cut into an arbitrary length and then mixed into concrete and mortar as a short length reinforcing material. The length of the molded product is determined depending on the size of the structure to be reinforced, but it is generally from 1 cm to 100 c.
Within a range of about m, they can be appropriately combined or can be mixed by selecting a single length.

Conventionally, when short carbon fibers were mixed, only the fibers were mixed, not as the impregnated and cured molded article according to the present invention, but a special mixer was used to prevent the formation of fiber balls. It was also necessary to prevent the fiber from being broken and shortened during kneading. Also,
Even when mixed with such caution, the matrix concrete and mortar side generally have a low cement content and a high water content, so the interfacial strength of the fibers is low,
The strength of carbon fiber could not be fully utilized and a large amount of fiber was required.

However, if the carbon fiber reinforced cement molded product according to the present invention is used, a long amount can be used in a large amount without worrying about the fiber ball, and the interface between the carbon fiber reinforced cement molded product and the cement matrix is Since it is the same pozzolanic system, it is strong. Therefore, as compared with the case where only fibers are kneaded, high strength can be obtained with a small amount of fibers.

Furthermore, by simultaneously using the molded product according to the present invention as both a continuous reinforcing material and a short reinforcing material, it is possible to obtain a carbon fiber reinforced cement molded product having significantly improved mechanical behavior.

It should be noted that the amount of fibers bears the tensile force of a member or structure as a continuous reinforcing material. When the fibers are embedded and arranged on the tensile side, the cross-sectional area of the carbon fibers generally corresponds to the required area. It is preferably used in the range of about 0.01% to 1%. When mixed as a short length reinforcing material, it is preferable to use the carbon fiber in a volume ratio of about 0.03% to 4% corresponding to the required strength and toughness. The lower limit value corresponds to the tensile strength of a general cement matrix, and the upper limit value corresponds to the state where the strength is saturated, or the physical alignment and mixing are difficult.

[0026]

EXAMPLES The present invention will be specifically described below with reference to examples. Example 1 Carbon fiber composed of pitch-based multifilament (manufactured by Nippon Steel, NT20, tensile strength: 325: kgf / mm ² , tensile elastic modulus: 20 tf / mm ² , filament number: 3000,
Electrolytic oxidation amount: 20 coulomb / m ² ) length 1500 mm
The mixture was cut into pieces and blown with compressed air having a wind speed of 2.5 m / sec to open the fibers, and thereafter, cement pozzolan having the following composition was impregnated. Total particle size of cement and slag fine powder is 52
It was 00 branes. Early strength Portland cement (4500 branes) 50 parts by weight Granulated blast furnace slag fine powder (6000 branes) 49 parts by weight High performance water reducing agent 1 part by weight Water 25 parts by weight After impregnation, a weight of 50 gf per strand is suspended. The sample was allowed to stand for 5 hours in a constant temperature and humidity room at a temperature of 20 degrees and a humidity of 60% RH to allow it to condense. After that, it was cured in water in a water tank at a temperature of 20 ° C. for 3 days, followed by autoclave curing at a temperature of 150 ° C. The cured carbon fiber reinforced cement molding has a carbon fiber volume content of 1.2% and a diameter of 5.
It was a strand-shaped molded product having a length of 1 mm and a length of 1500 mm. The schematic shape of this formed product is shown in FIG.

The strand was cut into a length of 500 mm, tabs of 50 mm were attached to both ends, and the gauge length was 400 m.
A tensile test was performed at m. The load / displacement curve is shown in FIG. As shown in the same figure, the curve sandwiched the pseudo-plastic behavior due to the crack dispersion in the middle, and the whole showed the trilinear behavior which can be approximated by three straight lines. The last straight part before fracture showed the same rigidity as that of carbon fiber only.

The final breaking load was 55.3 kgf, which was 75.2% of the ideal strength of the fiber (73.5 kgf). Also, 5
The rate of change in strength of the book was 21%.

Example 2 Carbon fiber composed of pitch type multifilament (manufactured by Nippon Steel, NT20, tensile strength: 325 kgf / mm ² , tensile elastic modulus: 20 tf / mm ² , number of filaments: 3000, amount of electrolytic oxidation: 20 coulomb / m ² ) was cut into a length of 500 mm, and compressed air having a wind speed of 2.5 m / sec was blown to open the fiber, and thereafter, cement pozzolan having the following composition was impregnated. Total particle size of cement and slag fine powder is 520
It was 0 brain. Early strength Portland cement (4500 branes) 50 parts by weight Granulated blast furnace slag fine powder (6000 branes) 49 parts by weight High performance water reducing agent 1 part by weight Water 25 parts by weight After impregnation, 3 types of twisting are performed as shown below. The given strand was made.

6 times and 12 times, respectively, per 1 m length
With a twist of 18 times, hang a weight of 50 gf per strand, temperature 20 degrees, humidity 60% R
The mixture was left to stand in a constant temperature and humidity chamber of H for 5 hours to be condensed. After that, it was cured in water in a water tank at a temperature of 20 ° C. for 3 days, followed by autoclave curing at a temperature of 150 ° C. The cured carbon fiber reinforced cement molded product had a diameter shown in Table 1 and was a strand-like material having a length of 500 mm.

A tab of 50 mm was attached to both ends, and a tensile test of 5 pieces was conducted at a gauge length of 400 mm. The load-displacement curve was similar to that of Example 1 shown in FIG.

The final breaking load is shown in Table 1.
The strength increased for both twists 6 and 12. Further, when the number of twists was 18, the strength was slightly lowered, but the variation was greatly reduced.

[Table 1]

Example 3 Carbon fiber consisting of pitch type multifilament (manufactured by Nippon Steel, NT20, tensile strength: 325 kgf / mm ² , tensile elastic modulus: 20 tf / mm ² , filament number: 3000, electrolytic oxidation amount: 20 coulomb / m ² ) was cut into a length of 500 mm, and compressed air having a wind speed of 2.5 m / sec was blown to open the fiber, and thereafter, cement pozzolan having the following composition was impregnated. The overall particle size of cement, slag fines and silica fume was 7,000 branes. Early strength Portland cement (4500 branes) 50 parts by weight Granulated blast furnace slag fine powder (6000 branes) 34 parts by weight Silica fume 15 parts by weight Superplasticizer 1 part by weight Water 25 parts by weight After impregnation, a weight of 50 gf per strand is applied. The suspended state was allowed to stand for 5 hours in a constant temperature and humidity room at a temperature of 20 ° C. and a humidity of 60% RH to cause condensation. After that, it was cured in water in a water tank at a temperature of 20 ° C. for 3 days, followed by autoclave curing at a temperature of 150 ° C. The hardened carbon fiber reinforced cement molding has a carbon fiber volume content of 1.0% and a diameter of 5.2.
The material was a strand-shaped material having a length of 500 mm and a length of 500 mm.

A tab of 50 mm was attached to both ends, and a tensile test of 5 pieces was conducted at a gauge length of 400 mm. The load-displacement curve was similar to that of Example 1 shown in FIG.

The final breaking load was 60.5 kgf, which was 82.3% of the ideal strength of the fiber (73.5 kgf). The rate of change in strength of the five pieces was 16%.

Example 4 A bending test was conducted on a cement molded product using the strand-shaped carbon fiber reinforced cement molded product shown in Example 1 as a continuous reinforcing material. A mortar having the following composition was dry-mixed for 3 minutes by using a Hobart type mixer, and water was added and kneaded for 5 minutes. Ordinary Portland cement (3300 brain) 50 parts by weight Toyoura standard sand 50 parts by weight High-performance water reducing agent 1 part by weight Water 30 parts by weight Width 60 mm, thickness 100 mm, length 1500 mm, length shown in Example 1 After arranging 26 carbon fiber reinforced cement molded products of 1500 mm on the bending tensile side, the above mortar was driven in, the mold was removed one day later, and curing was carried out in water for 28 days.

The carbon fiber volume content of the cement molded product reinforced with the strand-shaped carbon fiber reinforced cement molded product is
It was 0.1% based on the whole final molded body. After curing, the molded body was centrally loaded at a distance of 1400 mm between fulcrums and the relationship between load and deflection was recorded. The result is shown in FIG. Regarding bending strength, the initial crack strength was 59.5 kgf / cm ² , and the final breaking strength was 113.8 kgf / cm ² , which was a safe breaking mode in which energy absorption leading to breaking was large.

Example 5 The strand-shaped carbon fiber reinforced cement molding shown in Example 1 was produced and cut into a length of 50 mm. The mortar having the following composition was dry kneaded for 3 minutes using a Hobart type mixer, and then the cut 50 mm carbon fiber reinforced cement molded body was mixed therein, and water was added and kneaded for 5 minutes. Ordinary Portland Cement (3300 Blaine) 50 parts by weight Toyoura standard sand 50 parts by weight High performance water reducing agent 1 part by weight Water 30 parts by weight Mortar after kneading containing carbon fiber reinforced cement compact is 60 mm wide, 100 mm thick, 100 mm long It was cast into a 1500 mm mold frame, demolded one day later, and cured in water for 28 days. After curing, the molded body was centrally loaded at a distance of 1400 mm between fulcrums and the relationship between load and deflection was recorded. The result is shown in FIG.

The carbon fiber volume content of the cement molded product reinforced with the short strand carbon fiber reinforced cement molded product was 0.25% based on the whole final molded product. The bending strength is 58 kgf / cm ^{2 for the} initial crack strength and 9 for the final breaking strength.
It was 2.2 kgf / cm ² , which was a safe destruction mode with large energy absorption leading to destruction.

Example 6 Hybrid reinforced cementitious compacts combining Example 4 and Example 5 were tested. That is, the carbon fiber reinforced cement molded product shown in Example 1 was arranged on the tensile side of 0.1% with respect to the entire final molded product with the volume content of carbon fiber as a continuous reinforcing material, and further in Example 1. The carbon fiber reinforced cement molded product shown in the figure was cut into a length of 50 mm, and as a short reinforcing material, a mortar mixed with 0.25% of the final molded product in terms of volume content of carbon fiber was used as a test sample. The size of the test body is 60 mm in width, 100 mm in thickness, and 15 in length.
It is 00 mm. Curing and bending tests were carried out in the same manner as in Example 5 to obtain the load-deflection relationship shown in FIG.

As shown in the figure, the cracks were dispersed and had a smooth load-deflection relationship, so the initial crack was not clear. The maximum bending strength was 121.2 kgf / cm ² , and continuous reinforcement and short length reinforcement The hybrid effect of the material appeared, and it was a safe destruction mode in which energy absorption leading to destruction was large.

Comparative Example 1 Carbon fiber composed of pitch type multifilament (manufactured by Nippon Steel, NT20, tensile strength: 325 kgf / mm ² , tensile elastic modulus: 20 tf / mm ² , filament number: 3000, electrolytic oxidation amount: 20 coulomb / m ² ) was cut into a length of 500 mm, and compressed air having a wind speed of 2.5 m / sec was blown to open the fiber, and thereafter, cement pozzolan having the following composition was impregnated. The particle size of the cement was 3300 branes. Ordinary Portland cement (3300 branes) 100 parts by weight High performance water reducing agent 1 part by weight Water 25 parts by weight After impregnation, with a weight of 50 gf per strand hanging, a temperature and humidity of 20 ° C and humidity of 60% RH It was allowed to stand for 5 hours to coagulate. After that, it was cured in water in a water tank at a temperature of 20 ° C. for 3 days, followed by autoclave curing at a temperature of 150 ° C. The cured carbon fiber-reinforced cement molded product was a strand-shaped material having a carbon fiber volume content of 0.91%, a diameter of 5.5 mm, and a length of 500 mm.

A tab of 50 mm was attached to both ends, and a tensile test of 5 pieces was conducted at a gauge length of 400 mm. The load / displacement curve is shown in FIG.

The final breaking load was 35.5 kgf, which was 48.3% of the ideal strength of the fiber (73.5 kgf). The rate of change in strength of the five pieces was 22%.

Comparative Example 2 Carbon fiber composed of pitch type multifilament (manufactured by Nippon Steel, NT20, tensile strength: 325 kgf / mm ² , tensile elastic modulus: 20 tf / mm ² , number of filaments: 3000, electrolytic oxidation amount: 20 coulomb / m ² ) was cut into a length of 500 mm, and compressed air having a wind speed of 2.5 m / sec was blown to open the fiber, and thereafter, cement pozzolan having the following composition was impregnated. Total particle size of cement and slag fine powder is 520
It was 0 brain. Early strength Portland cement (4500 branes) 50 parts by weight Granulated blast furnace slag fine powder (6000 branes) 49 parts by weight High performance water reducing agent 1 part by weight Water 25 parts by weight After impregnation, two types of twisting are performed as shown below. The given strand was made. 22 times, 2 times per 1m length
5 per strand with 6 twists
Hanging a 0gf weight, temperature 20 degrees, humidity 60% RH
It was allowed to stand for 5 hours in the constant temperature and humidity room to allow it to coagulate. afterwards,
Underwater curing in a water bath at a temperature of 20 ° C. for 3 days, followed by autoclave curing at a temperature of 150 ° C. The hardened carbon fiber reinforced cement molding has a diameter shown in Table 2 and a length of 5
It was a 00 mm strand material.

A tab of 50 mm was attached to both ends, and a tensile test of 5 pieces was conducted at a gauge length of 400 mm. The load / displacement curve was the same as that of Example 1 in FIG. As shown in Table 2, the rupture strength was significantly reduced after twisting 22 times and twisting 26 times.

[Table 2]

Comparative Example 3 The carbon fiber composed of the multifilament used in Example 1 was not impregnated with the cement slurry but was bent as a continuous reinforcing material as it was. A mortar having the following composition was dry-mixed for 3 minutes by using a Hobart type mixer, and water was added and kneaded for 5 minutes. Ordinary Portland cement (3300 branes) 50 parts by weight Toyoura standard sand 50 parts by weight High-performance water reducing agent 1 part by weight Water 30 parts by weight Width 60 mm, thickness 100 mm, length 1500 mm, only length 1500 mm bent and tension side After arranging in
The above mortar was cast into the mold, the mold was removed one day later, and the mold was cured in water for 28 days.

The carbon fiber volume content of the strand-shaped carbon fiber reinforced cement molded product is 0 based on the whole final molded product.
It was 1%. The molded body after curing is 1400m between fulcrums
Central loading was performed at m, and the relationship between load and deflection was recorded.
The result is shown in FIG. Bending strength is 61.5 initial crack strength
It failed at the same time as the first crack at kgf / cm ² . The carbon fiber was coming out without breaking.

Comparative Example 4 The carbon fiber composed of the multifilament used in Example 1 was cut into a length of 50 mm without impregnating the cement slurry with the carbon fiber. Mortar having the following composition was dry kneaded for 3 minutes using a Hobart type mixer, and then cut 50
mm of carbon fiber was mixed, water was added, and the mixture was kneaded for 5 minutes.
The volume content of carbon fiber is 0.
It was 6%. Normal Portland cement (3300 branes) 50 parts by weight Toyoura standard sand 50 parts by weight Thickener 1 part by weight Water 30 parts by weight Mortar after kneading containing carbon fiber reinforced cement compacts 60 mm wide, 100 mm thick, 1500 mm long The mold was cast into the mold, and after 1 day, the mold was removed and cured in water for 28 days. After curing, the molded body was centrally loaded at a distance of 1400 mm between fulcrums and the relationship between load and deflection was recorded. The result is shown in FIG. The flexural strength was such that the initial crack strength was 51 kgf / cm ² , and fracture occurred without increasing the load after the initial crack. The presence of fiber balls was confirmed by observing the fracture surface.

[0050]

INDUSTRIAL APPLICABILITY According to the present invention, in an uncured cement molded product containing 20 to 80% by weight of granulated blast furnace slag powder in all pozzolan components, electrolysis of 1 to 100 coulomb / m ² per surface area of carbon fiber is performed. Oxidized carbon fiber contains 0.1 to 30% by volume as a volume content in the cement molded product after curing, so it has good adhesion to other cement-based matrix, high strength and economical carbon fiber reinforcement. A cement molded product can be obtained. In addition, the cement molded product reinforced with this component is excellent in durability and nonflammability because the reinforcing material is an inorganic material, and if a continuous reinforcing material is used, high strength can be obtained with a small amount of fiber and short-term reinforcement. If a material is used, high toughness can be obtained, and if they are combined, a molded product having both advantages is obtained.

[Brief description of drawings]

FIG. 1 is a view showing a carbon fiber-reinforced cement molded product shown in Example 1.

FIG. 2 is a view showing a load / elongation relationship of the carbon fiber-reinforced cement molded products shown in Example 1 and Comparative Example 1.

FIG. 3 shows the loads of Examples 4, 5 and 6 and Comparative Examples 3 and 4.
It is a figure which shows a bending relationship.

[Explanation of symbols]

 1 carbon fiber 2 cement slurry 3 carbon fiber reinforced cement molding

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Office reference number FI technical display location D06M 10/00 A

Claims (5)

[Claims] 1. An unoxidized cement molded product containing 20 to 80% by weight of granulated blast furnace slag powder in all pozzolanic components is used to prepare 1 to 100 coulomb / m ² of electrolytically oxidized carbon fibers per carbon fiber surface area. A carbon fiber reinforced cement molded product, characterized by containing 0.1 to 30% as a volume content in the cement molded product after curing. 2. The cement molded product is strand-shaped,
The carbon fiber-reinforced cement molded product according to claim 1, wherein continuous carbon fibers per length thereof are twisted at 21 times / m or less. 3. A continuous carbon fiber subjected to electrolytic oxidation of 1 to 100 coulomb / m ² per carbon fiber surface area is opened,
20-80% by weight of granulated blast furnace slag powder is contained in all pozzolan components and impregnated with a cement slurry made of pozzolan having an average particle size of 3500 branes or more to give tension, and then coagulate to perform natural curing and autoclave curing. A method for producing a carbon fiber-reinforced strand-shaped cement molded product, comprising: 4. An impregnated carbon fiber bundle is impregnated in a slurry, the carbon fiber bundle is twisted at a rate of 21 times / m or less, and then the carbon fiber bundle is condensed while applying tension. Item 4. A method for producing a carbon fiber-reinforced strand-shaped cement molded product according to Item 3. 5. A carbon fiber reinforced cement molded product in which the carbon fiber reinforced cement molded product according to claim 1 or 2 is embedded as a reinforcing material.