WO2005087682A1

WO2005087682A1 - Cement admixture, cement composition, mortar and concrete

Info

Publication number: WO2005087682A1
Application number: PCT/JP2005/004532
Authority: WO
Inventors: Yoshiharu Watanabe
Original assignee: Denki Kagaku Kogyo Kabushiki Kaisha
Priority date: 2004-03-17
Filing date: 2005-03-15
Publication date: 2005-09-22
Also published as: MY153230A; JPWO2005087682A1; JP4813355B2; CN1826298A; KR20060123031A; TWI336318B; TW200602283A

Abstract

A cement admixture, which comprises silica fume and a fly ash classified to 20 μm or less, wherein the ratio of silica fume : the classified fly ash is 95:5 to 10:90 in mass ratio; the cement admixture which further comprises gypsum; and a cement composition, a mortar, concrete and a cement hardened article using the above cement admixture. The above cement admixture improves the flow value of a mortar or concrete after mixing and provides good workability, and further provides a resulting mortar or concrete which exhibits high absolute values of compressive strength and flexural strength and also exhibits a high ratio of the flexural strength to the compressive strength. Still further, the reinforcement by compounding a metal fiber can markedly enhance the flexural strength, which results in allowing an economical and advantageous design in producing a civil engineering construction, an architectural structure and a concrete secondary product.

Description

Specification

Cement admixture, cement composition, mortar and concrete

Technical field

The present invention relates to a cement admixture, a cement composition, a mortar and a concrete using the same. More specifically, it is an admixture containing silica fume and fly ash classified to 20 m or less, and a cement composition obtained by adding this to cement. Further, the present invention relates to a mortar and a concrete having an increased bending strength using the cement composition.

Background art

[0002] Mortar or concrete has a problem that the bending strength is basically lower than the compressive strength, and the bending strength is not so high even if the compressive strength is increased. Therefore, road surfaces, beams, girders and many concrete secondary products designed with bending strength tend to be rich and economical in concrete mix. Prestress is introduced by a steel bar. In addition, for fume pipes and the like, an expanding material is mixed with concrete to introduce a chemical press or a chemical prestress to increase the external pressure strength.

[0003] On the other hand, silica fume has a high pozzolanic activity and is used as a strength enhancer. Furthermore, by combining with a relatively large amount of a high-performance water reducing agent, the mortar flow, the concrete slump or the slump flow can be increased, and the mortar or the concrete having a low water binder ratio can be easily produced, so that a high fluidity can be obtained. It is often used as an admixture for strength mortar or concrete.

[0004] Fly ash is spherical coal ash containing hollow particles with a diameter of 100 m or less, produced as a by-product from a pulverized coal-fired thermal power plant, and although its pozzolanic activity is low, it reacts in the long term. It is often used as fly ash cement because it enhances water tightness. As shown in Patent Document 1, by classifying this into 20 m or less or 10 m or less, large hollow particles are removed, resulting in good spherical solid particles. When combined with a high-performance water reducing agent or high-performance AE water reducing agent due to its ball bearing action, it increases the mortar flow, concrete slump or slump flow, and exhibits strong stickiness. . Further, it is also known that even when the same flow or slump is used, the strength of the reduced water is increased as compared with the mortar or concrete containing no classified fly ash.

[0005] Further, for example, as shown in Patent Document 2, gypsum is widely used as a high-strength admixture regardless of the presence or absence of steam curing, and it is also known that higher strength and durability can be obtained by combining with gypsum. Tepuru.

[0006] Further, as shown in Patent Document 3, as a classical method for increasing bending strength and toughness, there is a method of adding a metal fiber. It is also known that a method of improving toughness by using metal fibers can be achieved by adding silica fume and fine needle-like or plate-like powder to cement to limit the maximum aggregate diameter to a small value. RU

Patent Document 1: JP-A-63-8248

Patent Document 2: JP-A-3-40947

Patent Document 3: JP-A-11-246255

[0007] With the general-purpose technology in which only silica fume is blended while pressing, the compressive strength of concrete increases, but the ratio of flexural strength to compressive strength becomes lower due to brittleness, which is lower than in the case where silica fume is not mixed. was there. In addition, as shown in Patent Document 1, fly ash classified to 20 / zm or less or 10 m or less originally has low pozzolanic activity, so the strength of the reduced water increases, but the classification using the same water binder ratio is performed. Compared to the case without fly ash, even in the case of steam curing, the short-term strength increase hardly increased.

[0008] Further, as shown in Patent Document 2, high strength is easily developed by using gypsum alone or in combination with silica fume, and bending strength is also increased by increasing the compressive strength. There was a problem that the ratio was not in the same area as ordinary concrete. As shown in Patent Document 3, in the method of reinforcing with metal fibers, while the fine aggregate for mortar or concrete used in ready-mixed concrete plants and concrete product factories is 5 mm or less, the maximum aggregate diameter is reduced. There is a problem that it cannot be widely spread because it is an essential requirement that the thickness be 2 mm or less or 1 mm or less.

Disclosure of the invention

Problems to be solved by the invention

[0009] The present invention has been made to solve the above-mentioned problems in the prior art, It is an object of the present invention to provide a mortar or concrete in which the absolute values of strength and bending strength are increased and the ratio of bending strength to compressive strength is increased.

Another object of the present invention is to provide a cement admixture for realizing the mortar or concrete, and a cement composition using the cement admixture.

Still another object of the present invention is to provide a hardened cement body obtained from the above mortar or concrete.

Means for solving the problem

As a cement admixture, the ratio of the bending strength to the bending strength and the compressive strength can be independently determined by using a combination of fly ash and gypsum, which are conventionally known as silica fumes with a diameter of 20 m or less, in combination. It has been found that it can be synergistically increased as compared with the case of using. Furthermore, since the bending strength of the base mortar or concrete itself can be increased, the bending strength can be increased by using metal fibers in combination even when using fine aggregate for mortar or concrete that is commonly used. The inventors have found a fact that can be dramatically increased, and have completed the present invention.

That is, the present invention relates to the following cement admixture, cement composition, mortar, concrete, and hardened cement.

(1) A cement admixture comprising silica fume and fly ash classified to 20 μm or less, wherein the mixing ratio of silica fume: classified fly ash is 95: 5—10: 90 by mass. Admixture.

(2) The cement admixture according to the above (1), further containing gypsum.

(3) A cement composition comprising 100 parts of the cement and 1 to 35 parts of the cement admixture described in (1) above.

(4) The cement composition according to the above (3), further comprising 0.5 to 12 parts of gypsum in terms of anhydride based on 100 parts of the cement.

(5) A mortar obtained by mixing the cement composition according to (3) or (4) above, fine aggregate, a water reducing agent, and mixing water.

(6) above (5) to the mortar lm ³ of outer percentage at 1.0 to 6.0% by volume of metal fibers formed by添Ka卩mortar. (7) Concrete obtained by mixing the cement composition according to (3) or (4) above, fine aggregate, coarse aggregate, a water reducing agent, and mixing water.

(8) Concrete obtained by adding 1.0 to 4.0% by volume of metal fibers to the concrete lm ³ described in (7) above.

(9) A hardened cement obtained by hardening the mortar according to (5) or (6).

(10) A cement hardened body obtained by hardening the concrete according to (7) or (8). The invention's effect

According to the present invention, the flow value of kneaded mortar or concrete is improved, and good workability is obtained. As for the mortar and concrete, the obtained mortar and concrete have high absolute values of compressive strength and flexural strength, and also have a high ratio of flexural strength to compressive strength. Furthermore, if metal fibers are mixed and reinforced, the bending strength can be dramatically increased, and an economical and advantageous design for manufacturing civil engineering structures and concrete secondary products becomes possible.

BEST MODE FOR CARRYING OUT THE INVENTION

Hereinafter, the present invention will be described in detail. The parts and percentages used in the present invention to indicate the blending ratio and the amount added are mass units. However, when the metal fibers are outer percentage volume% relative to mortar or concrete lm ³ per.

[0013] Silica fume used in the present invention is a fine particle having a spherical diameter of not more than Lm, which is a by-product produced when silicon alloys such as metallic silicon and Fe-mouth silicon and zirconia are produced in an electric furnace. Is amorphous highly reactive SiO. Compressive strength is silica fume

2

The force gradually increases in accordance with the amount of added silica. The ratio of the bending strength to the compressive strength is lower than in the case where silica fume is not mixed.

[0014] As described above, silica fume significantly enhances fluidity when used in combination with a relatively large amount of a high-performance water reducing agent that can be used not only as a strength enhancer and about 10% of silica fume with respect to cement. However, the flow characteristics vary depending on the type of high-performance water reducing agent. Is small, and shows relatively high viscosity and fluidity. A so-called high-performance AE water reducing agent based on polycarboxylate that entrains air On the other hand, the fluidity becomes large in the state of sticky plastic rather than simply viscous, and the feeling of switching back with a scoop becomes lighter in the former and heavier in the latter. Therefore, a combination system of high performance AE water reducer and silica fume may be used simply because it makes pumping easier.

[0015] Fly ash is a spherical granular residue collected from a boiler's flue together with combustion gas with coal ash produced as a by-product from a pulverized coal-fired thermal power plant as described above, and collected by a dust collector. Usually, it is directly blended with cement and used as fly ash cement. In the present invention, it is an essential condition that a material classified to 20 m or less is used, and fly ash cannot achieve the effects of the present invention without classification. There are two types of commercially available classified fly ash: those classified to 20 μm or less and those classified to 10 μm or less.

[0016] The cement admixture of the present invention has a mass ratio of silica fume: fly ash classified to 20 µm or less to 95: 5-10: 90, preferably 90: 10-10-15: 85, more preferably 80:50. 20-70: 30 ratio. If the classified fly ash is less than 5%, the effect of increasing the bending strength is small. Even if the classified fly ash exceeds 90%, the effect of increasing the bending strength is small. The compressive strength gradually decreases as the proportion of classified fly ash is increased. The effect of increasing the bending strength has a peak at around 60:40.

[0017] On the other hand, as the proportion of the classified fly ash is increased, the mortar flow, the slump or the slump flow (hereinafter, simply referred to as flow) also increases, and a peak appears at a silica fume: classified fly ash ratio of about 50:50. Yes, the moderate stickiness of the classified fly ash suppresses the separation of aggregates and makes it easier to flow even if metal fibers are added.

[0018] The admixture of the present invention is preferably added in an amount of 1 to 35 parts, more preferably 2 to 30 parts, and most preferably 3 to 25 parts, based on 100 parts of cement. Even if it is added in excess of 35 parts, the increase in bending strength reaches a plateau and is not economically favorable.

The gypsum used in the present invention includes various forms of gypsum such as dihydrate gypsum, hemihydrate gypsum, soluble anhydrous gypsum (type III), and insoluble anhydrous gypsum (type II). Water gypsum is preferred. For gypsum, when the cement admixture of “silica fume and fly ash classified to 20 μm or less” is added to the cement, the compressive strength decreases as the proportion of fly ash classified to 20 m or less increases. Further increase the compressive strength and song This has the effect of increasing both absolute values of the bending strength. Gypsum is converted to anhydrous, cement

Preferably, 0.5 to 12 parts, more preferably 0.8 to 10 parts, most preferably 118 parts are added to 100 parts. Even if it exceeds 12 parts, no further strength effect can be obtained.

[0020] In the present invention, a required amount of a high-performance water reducing agent or a high-performance AE water reducing agent is used in combination. The high-performance water reducing agent is mainly composed of any one of polyalkylarylsulfonate, aromatic aminosulfonate, and melamine formalin resin / sulfonate. Two or more are used. Polyalkylaryl sulfonate-based high-performance water reducing agents include methyl naphthalene sulfonic acid formalin condensate, naphthalene sulfonic acid formalin condensate, and anthracene sulfonic acid formalin condensate.The commercial products are Denki Kagaku Kogyo Co., Ltd. Company name "FT-500" and its series, Kao Corporation product name "Mighty-100" (powder) and "Mighty-150" and its series, Daiichi Kogyo Pharmaceutical Co., Ltd. Representative examples include Nippon Paper Industries Co., Ltd. brand name “Sunflow PS” and its series, such as “Flow 110P” (powder), Takemoto Yushi Co., Ltd. brand name “Pole Fine 510N”. As an aromatic aminosulfonate-based high-performance water reducing agent, Fujisawa Pharmaceutical Co., Ltd. has the brand name "Palic FP200HJ and its series. The product name is "FT-3S".

[0021] The high-performance AE water reducing agent is usually called a polycarboxylate-based water reducing agent, and is a copolymer containing an unsaturated carboxylic acid monomer as one component or a salt thereof. For example, copolymers of polyalkylene glycol monoacrylate, polyalkylene glycol monomethacrylate, maleic anhydride and styrene, copolymers of acrylic acid and methacrylate, and copolymerizable with these monomers Examples include copolymers derived from monomers. The brand name of Leobuild SP8N series, the brand name of Nemby Corporation, the series name of Palic FP100S, 300S, the brand name of Fujisawa Pharmaceutical Co., Ltd. ) The company name "Darlex Super 100, 200, 300, 1000" series and others are commercially available.

[0022] The cement used in the present invention is various portland cements, various mixed cements or eco cements. Further, cement in which these arbitrary amounts are mixed may be used.

[0023] There are no special restrictions on the production of the mortar or concrete of the present invention. Fine aggregate or coarse aggregate used can be used. In addition, the ratio of the bending strength to the compressive strength of the mortar or concrete and the absolute value of the bending strength can be arbitrarily selected because the ratio thereof increases irrespective of the water binder ratio / the fine aggregate ratio.

Further, in the present invention, metal fibers can be used in combination. The metal fiber is not special, and may be used for mortar or concrete that is usually sold. The metal fibers maximum amount and in the case where the concrete mortar from the viewpoint of increasing the effect and the workability of the force bending strength to 1. added 0 to 6.0 volume% in outer percentage relative to mortar or concrete lm ³ The preferred ranges are different. The maximum addition amount and the preferable range also differ depending on the concrete molding method such as vibration molding and centrifugal force molding.

[0025] In the case of vibration molding, when the mortar is less than 2% by volume, the increase in bending strength is small, but when it is added at 2% by volume or more, the bending strength gradually increases as the amount of addition increases, and 5.5% by volume or more. in it levels off, 6. can no longer flow hardly molded with more than 0% by volume, 1. outside split 0-6. 0 volume ^_0/0, preferably from 2. 5-5. 0% by volume. For concrete exhibits 1.5 volume ^_0/0 or force effect, 1. 0-4. 0% by volume in outer percentage since deteriorates workability and more than 4% by volume, preferably 1. 5-3 . it is a 5 volume ^_0/0.

[0026] In the case of the mortar and the concrete, the bending tensile strength of the mortar and the concrete increases from 1.0% by volume of the metal fiber, and the workability of the mortar is 5.0% by volume or less. However, for preferred concrete, the content is preferably 3.0% by volume or less. In order to increase the external pressure strength of the fume tube, it is only necessary to concentrate steel fibers on the inside. Therefore, it is economically preferable to reinforce the thickness of the inside of the tube 2Z3 or less.

[0027] The method of adding the admixture of the present invention is not particularly limited. When mixing mortar or concrete, a mixture of silica fume and fly ash classified to 20 m or less may be added, or gypsum may be further added. Alternatively, each component may be separately prepared and added to a mixer together with another mortar or concrete material. The kneading method is not particularly limited, and the kneading method usually used may be used. There is no particular limitation on the method of adding the metal fiber, but a method in which mortar or concrete is kneaded and mixed, and the mixing is continued while stirring the mixer is preferred because it is difficult to form fiber balls. [0028] Further, the method for curing the mortar and concrete of the present invention is not limited, and standard curing, steam curing and autoclave curing are also possible.

Hereinafter, materials, test items, and methods used in Examples and Comparative Examples of the present invention are shown together.

Cement: Ordinary Portland cement manufactured by Denki Kagaku Kogyo Co., Ltd. Fine density: 3.16 g / cm ³ Fine aggregate: Himekawa river sand from Niigata (5 mm below), density: 2.62 g / cm ³

Coarse aggregate: crushed stone from Himekawa, Niigata (13-5 mm), density 2.64 g / cm ³

Silica fume: Russian, (and SF) those in granular form, density 2. 44 g / cm ³ Fly Ash: Shikoku Electric Power Co., Inc., 20 mu m those classified below as (a FA 20) 1

Classify to 0 μm or less (FA10) and do not classify! Fly ash (FA), density 2.44g / cm °

Gypsum: Insoluble anhydrous gypsum (naturally occurring, density 2.82) and industrial dihydrate gypsum powder, density 2.30 Metal fiber: manufactured by Tokyo Seimitsu Co., Ltd., "Daipack" iron, width 0.9 mm, thickness 0.34 mm, length 30mm, Density 8.00gZcm ³

Water reducing agent: High performance AE water reducing agent WRA (l), Grace Chemicals Co., Ltd. "Super 1000N", High performance water reducing agent WRA (2), Daiichi Kogyo Seiyaku Co., Ltd. "Cell Flow 110P" <Test items And how to do it>

[Mortar flow measurement]

According to JIS R 5201, the flow value at the time of extraction was measured. However, an acrylic glass plate of 50 × 50 × 2 cm was placed on the flow table, and the test was performed thereon.

[Method of measuring mortar strength]

The flexural strength conformed to JIS R 5201, and the compressive strength used was one molded into a formwork of φ5 x 10 cm.

[Measurement of concrete flow]

The lateral spread of the concrete when pulled out according to JIS A 1101 was measured.

[Measurement of flexural strength and compressive strength of concrete] Based on JIS A 1132, JIS A 1106, JIS A 1132 and JIS A 1108.

[Measurement of bending tensile strength of centrifugal molding]

17.5kg of concrete is packed into a cylindrical form of 20cm in outer diameter x 30cm in length, initial speed 1.5G x 2 minutes, low speed 3G x 5 minutes, medium speed I: 8G x 1 minute, medium speed II: 15G x 2 minutes After high-speed 30G x 3 minutes, the mold was subjected to centrifugal force molding. After curing, the external pressure load at which cracks occurred and the tube thickness were measured to calculate the bending tensile strength. When the inner 1Z3 was made of mortar containing metal fiber, 12.5 kg of concrete was packed and subjected to centrifugal molding under the above conditions, and then 5 kg of mortar was packed again and similarly centrifugally molded.

[0030] The kneading of the mortar (or concrete) is performed by kneading the cement, the components of the admixture, and the fine aggregate (and coarse aggregate) for 30 seconds, and then dissolving a water reducing agent in water. And kneaded with an omni mixer for 3 minutes. When adding metal fibers, knead the mortar or concrete for 3 minutes, add the metal fibers little by little without stopping stirring, and knead for another 3 minutes.

Example 1

[0031] (mortar)

The mixing amounts of 100 parts of cement, 100 parts of fine aggregate, silica fume and fly ash were changed as shown in Table 1, and 20 parts of water and 3 parts of a high-performance AE water reducing agent were mixed and mixed with water. Mentor or cement + silica fume and Z or fly ash), and the mortar was kneaded with 20 parts of calorie and the flow value was measured. Place the specimen into which this mortar was molded for 8 hours at pre-heating time, raise the temperature to 80 ° C at a heating rate of 20 ° CZ time, hold it for 5 hours, stop the cara steam valve, and leave it in the steam curing tank until the next day. After cooling slowly, the bending strength and compressive strength of one day of age were measured, and the results are shown in Table 1.

[0032] As is clear from Table 1, the flow value became larger and the workability was improved in No. 1-2 in which only silica fume of the comparative example was added, compared to No. 1-1 in which no mixing was performed, and the workability was improved. Although the strength and bending strength also increased tl, the increase in bending strength relative to the increase in compressive strength was slight, and the ratio of bending strength to compressive strength decreased. No.1-14, in which only classified fly ash was added, showed an improvement in flow value. Compressive strength and bending strength hardly increased. On the other hand, experiments No. 1-3—No. 1-13, No. 1-26— As shown in No.1-30, the flow value becomes larger by mixing silica fume and classified fly ash. It was found that the increase in compressive strength gradually decreased as the proportion of silica fume decreased, but the flexural strength increased markedly and the ratio of flexural strength to compressive strength also increased. The bending strength reached the maximum when the ratio of silica fume Z classified fly ash was 60:40.

[0033] Further, as is clear from Experiment Nos. 1-15 to No. 1-25, as the amount of the admixture increases, the flow value, the bending strength, and the compressive strength increase as the addition amount increases. The force of 1 part starts to increase for 100 parts of cement, and the force becomes remarkable in 3 parts. In 35 parts or more, the flow value, bending strength and compressive strength reach a plateau, and considering economics, 30 parts or less is preferable.

[0034] [Table 1-1]

[0035] [Table 1-2]

■ Compounding amount per 100 parts of experimental cement 7 ports-value Bending strength Compressive strength Bending / pressure

: No. SF (part) FA (part) (mm) (N / Dim ^J ) Shrinkage ratio

1-9 6.4 (40) FA20 9.6 (60) 3 6 4 2 8.8 1 2 1 / 5.1

1-10 4.8 (30) FA20 11.2 (70) 3 5 5 2 7.1 1 1 1 / 5,2

1-11 3.2 (20) FA20 12.8 (80) 3 4 2 ■ 2 5.5 1 0 1 / 5.5

1-12 2. (15) FA20 13.6 (85) 3 3 6 2 2.7 1 3 8 1 / B.1

1-13 1.6 (10) FA20 14. (90) 3 1 1 1 7. 1 1 3 6 1 / 8.0

1-14 0 FA20: 16.0h 00) 2 9 0 1 5.3] 3 4 1 / 8.8

1-15 0.5 (.50) FA20 0.5 (50) 2 0 2 1 6.7 1 3 7 1 / 8.2

1-16 1.5 (50) FA20 1.5 (50.) 2 7 S 19.1 1 4 3 1 / 7.5

1-17 2.5 (50) FA20 2.5 (50) 2 9 6 2 1.2 1 4 0 1 / 6.6

1-18 3.5 (50) FA20 3.5 (50;) 3 2 5 2 4.7 1 4 8 1 / 6.0

1-19 5.0 (50) FA20 5.0 (50) 3 4 8 2 8.0 1 0 1 / 5.0

1-20 7.0 (50) FA20 7.0 (50) .3 5 7 2 9.6 1 5 3 1 / 5.2

■】 -21: 10..hi (50) FA20 10.0 (50) 3: 7 4 3 1.5 1 5 8 1 / 5.0

1-22 12.5 (50)? K20- 12.5) 3 8 0 3 2. 0 1 6 0 1 / 5.0

1-23 15.0 '(5.0) FA20 15,0 (50) 3: 8 5 33.0 Ί 6 2 1 / 4.9

1-24 17.5 (50) FA2 17.5 (50) 3 8 7 3 3.4 1 6 3 1 / 4.9

1-25 20.0 (50) FA20 20.0 (50) 3 8 9 3 1.8 1 5 8 1 / 5.0

] -26 15.2 (.95) FA10 0,8 (5) 3.0 5 1 9.7 1 6 0 1 / 8.1

1-27 4 (90) FA10 1.6 (10) 3 23 26.0 0 5 6] /6.0

1-28 9.6 (60) FA1.0 6.4 (4.0) 3 7 1 3 0.4 1 5 2 1 / 5.0

1-29 2.4 (15) FA10 13.6 (85) 3 4 6 24.1】 4 0 1 / 5.8

1-30 1.6 (10) FA10 14,4 (90) 3 2 3 1 7.5 5 3 8 1 / 7.8

1-31 9.6 (60) FA 6.4 (40) 2 5 9 1 6.6] 4 8 1 / 8.9 Note: Figures in parentheses indicate the mass ratio of SF to FA.

Example 2

(Mortar)

Experiment No. 1-1, No. 1-2, No. 7 and No. 14 of Example 1 gypsum of the type and addition amount (based on 100 parts of cement) shown in Table 2 was further added. The same test as in Example 1 was performed. Table 2 shows the results.

[0037] As shown in Table 2, gypsum promotes both compressive strength and bending strength to increase strength. In this example, the effect is apparent when 0.5 part or more is added to 100 parts of cement, becomes more remarkable at 0.8 part or more or 1.0 part or more, and exceeds 12 parts. However, no further strength effect can be obtained. As a result, it was found that adding 10 parts or less, preferably 118 parts of gypsum to 100 parts of cement increases the absolute values of both compressive strength and bending strength.

[Table 2]

Example 3

[0039] (Mortar mixed with metal fiber)

The amount of metal fiber added to the mortar lm ³ (air content 4%) of experiment No. l-8 of Example 1 The test specimens were molded by casting, and steam-cured in the same manner as in Example 1 to carry out a 1-day bending strength test. Table 3 shows the results.

[0040] According to Table 3, the metal fiber dramatically increases the bending strength of the mortar, but the effect is completely lost at 1.5% by volume. The bending strength increased. When it exceeded 5.0% by volume, it reached a plateau. At 6.5% by volume, workability was poor and moldability was poor. It has been found that the range is most preferably 2.5-5% by volume for the mortar of vibration molding.

[Table 3]

Example 4

(Concrete)

Concrete lm ³ of coarse aggregate per 900KgZm ³ added, also except for adjusting the air amount 2.5% and is the experimental No.1-1- experiment No.1-14 Example 2 Example 1 We tested the whole blended in the same manner and mortar experiment No. 2-5-experiment No.2-13 by kneading the concrete was lm ³ The body was molded and the compressive strength and flexural strength of 91 days of standard curing were measured. The results are shown in Table 4.

[0043] As is clear from Table 4, the concrete of Experiment No. 4-2 in which only cement and silica fume were added as binders and the concrete of Experiment No. 4-14 in which only cement and classified fly ash were added. Has a small rate of increase in bending strength. On the other hand, as in Experiment No. 4-3—Experiment No. 4-13, it was found that the flexural strength was significantly increased in the case of the concrete containing both silica fume and classified fly ash. It is particularly remarkable when the ratio of silica fume: classified fly ash is 95: 5-10: 90, preferably 90: 10-20: 80.

[0044] It is also shown that the use of gypsum increases both the compressive strength and the flexural strength of Experiment No. 4-15—Experiment No. 4-23. As in the case of mortar, in the case of concrete, even in the case of concrete, even if it is added in excess of 12 parts to 100 parts of cement, no further strength effect can be obtained.10 parts or less, preferably 118 parts It is.

[Table 4]

Experiment Type of binder Bending strength Compression strength Bending strength / 莶 (: gypsum) (N / mm ² ) (N / mm ² ) Compression strength ratio

4 1 1 o. 1 — 1 1 1. 2 1 2 3 1/1 1.0

4-2 No. 1-2 1 2.1 1 5 6 1/1 2.9

4 1 3 No. 1-3 15, 3 1 5 5 1/1 0.1

4-4 N ρ. 1-4 1 5 9 1 5 4 1 / 9.7

4 1 5 No. 1-5 1 8.8 1 .5 2 1 / 8.1

4 1 6 No. 1 — 6.2 0. 8 1 5 0 1/7. 2

4-7 No. 1-7 2 1.2 1 5 1 1 / 7.1

4 1 8 No. 1-'8 2 0. 5 1 5 0 1 / 7.3

4-9 N o; 1 — 9 2 0. 0 1 4 S 1 / 7.5

4-10 0 No. 1-10 1 8.0 0 1 5 0 1 / 8.3

4-1 1 No. 1 — 1 i 1 7.; 2 1 5 2 1 / 8.8

4-1.2 No. 1-1 2 1 5, 5 15.0 1 / 9.7

4-1 3 No-1-1 3 1 3, 7 1 4 4 1/1 0.5

4-J 4 No-1-1 4 1 1.9 1 2 1 1 1.9

4-15 No. 2-5 2 1.S 16 21 1 / 7.9

4-16 No. 2-6 2 3. 1 1 6 5 1/1. 1

4-17 No.: 2 1 7 2 4.9.1 7 0 1 / 6.8

4 10 8 No. 2-8 2 5.3 1 7 4 1 / 6.9

4-19 No. 2-9 2 5.8 1 7 8 1 / 6.9

4-20 No. 2-1 0 2 6.4 1 7 7 1 &. 7

■ 4 1 2 1 No; 2-1 1 2 6.0 0 1 7 5 1 / 6.7

4-2 2 No. 2-1 2 2 5.9 1 7 6 1 / 6.8

4-2 3 No. 2-1 3 25.0 ϊ 7 3 1 / 6.9 Example 5

(Metal fiber mixed concrete)

Concrete lm ³ experiments Νο.4-8 of Example 4, and kneaded the metal fibers in an amount shown in Table 5 (outer percentage added to the concrete), place the mold on the table vibrator, Pour concrete while applying slight vibration so that the metal fibers do not separate, It was molded, steam-cured in the same manner as in Example 1, and subjected to a 1-day-old flexural strength test. Table 5 shows the results.

[0047] As can be seen from Table 5, metal fibers increase the flexural strength of concrete, but have little effect at 1.0% by volume. The bending strength gradually increases, but reaches a plateau. At 5% by volume, workability is poor and molding is difficult. And it was found that the most preferable range including the workability was 2.0-4.0% by volume in the case of the concrete of vibration molding.

[Table 5]

Example 6

[0049] Using the composition shown in Table 6, the mortar or concrete was kneaded while changing the amount of metal fiber added, and a centrifugal force molded specimen was prepared. Age 1 The external pressure load at the time of cracking was measured, and the bending tensile strength was calculated. Incidentally, the middle column the formulation of concrete, welan is formulated for comparative concrete, expressed in terms of concrete mixing power of the middle column the formulation of mortar under column also remove the coarse aggregate in _lm ^3. The symbols in Table 6 indicate the following.

Gmax: Maximum aggregate size

air ：空直

sL: Slump

sZa: Fine aggregate ratio WZB: Water binder ratio

W: Water

C: cement

s: Fine aggregate

G: Coarse aggregate

[0050] The specimens for centrifugal force molding were prepared by molding the whole with one layer of mortar or concrete with the added amount of metal fiber, and molding the outer 3cm with mortar or concrete without metal fiber, Two-layer molded mortar or concrete with 2 cm inside was prepared using mortar or concrete with added fiber. Table 7 shows the results.

[Table 6]

Gmax air s and s / a W / B Unit amount (kg / m ³⁾

(Mm) C¾) (cm) (¾) (¾) WC S G W AC2) SF FA20 I I-CS

¾Π 3 1.5 65 48.7 28 168 _; 600 799 850 12 0.

13 1.5 65 48.1 28 168 500 782 850 10 48 29 19

― 1.6 35-20 234 984 953-18 94 56 38

(Note) WRA (2): A high-performance water reducing agent, added in powder form and mixed.

1 1-CS is insoluble anhydrous stone. _P

[0052] As can be seen from Table 7, when 1.0% by volume of metal fiber is added, the bending tensile strength increases, and as the amount of addition increases, the bending tensile strength also increases. In the case of concrete and添Ka卩metal fibers with high fluidity concrete, 3.5 volume ^_0/0 At extended is rather poor fiber balls of the concrete is preferably up to 0% by volume 3. To float on the inner surface.

[0053] In the case of mortar, if it exceeds 5.0% by volume, it becomes impossible to mold, and it has been found that ^5.0 / ₀ or less is preferable. In addition, when assuming a fume tube, it is more economical to mix and mold metal fibers only inside the tube thickness than to mold and mix metal fibers to the entire tube, because the bending tensile strength becomes higher. Turned out to be.

[Table 7] Experiment Addition amount of metal fiber (outer volume%) Bending tensile strength Molding method

No. During concrete During molar (N / mm ² )

6-1 0 Mold entire tube 1 layer 1 3.1

6-2 1.0 Mold entire tube 1 layer 1 6.1

6-3 1.5 Molding the entire tube 1-layer 19.0

6-4 2.0 Molding the whole pipe--layer 2 2.5

6-5 2.5 Mold entire tube-layer 2 7 ,. 6

6-6 3.0 Molding the whole pipe ― ―Layer 2 7.5

6-7 3.5 Molding the Entire Tube-Single Layer Fiber Ball

6-8 ― 0 Molding of entire tube —Layer 1 7.0

6-9 One 1.0 Tube. Molding —Layer 2 1.0

6-10-1.5 Mold entire tube Layer 2 4.6

6-11 One 2.0 Molding the entire pipe Layer 2 8.3

6-12-3-0 黉 Molding the whole—Layer 3 3.2

6-13: ― 3.5 Molding the whole pipe —Layer 3 7.2

6-J4 I 4.0 Mold the entire tube —Layer 4 0.0

6-15 5.0 Mold entire tube Layer 4 1.7

6-16 6.0 Mold entire tube

6-17 1.0 Mold inside 2 layers 19.8

6-18 2.0 Molded inside 2 layers 2 5.8

6-19 3.0 Molded inside 2 layers 3 0.1

6-21 1.0 Mold inside 2 layers 2 4.1

6-22 2.0 Molded inside '' Double layer 3 2.5

6-23 3.0 Molded inside 2 layers 3 6.2

6-24 4.0 Molded inside Double layer 4 4.5

6-25 0 Molding of entire tube —Layers 8, 2

(Note) *: This is a comparative example using a concrete formulation marked with * in Table 6. The present invention has been described in detail and with reference to specific embodiments, but without departing from the spirit and scope of the present invention. It will be apparent to those skilled in the art that various changes and modifications can be made. This application is based on Japanese Patent Application (No. 2004-075718) filed on March 17, 2004, the contents of which are incorporated herein by reference.

Industrial applicability

According to the present invention, the flow value of the kneaded mortar or concrete is improved, and good workability is obtained. As for the mortar and concrete, the obtained mortar and concrete have high absolute values of compressive strength and flexural strength, and also have a high ratio of flexural strength to compressive strength. Furthermore, if metal fibers are mixed and reinforced, the bending strength can be dramatically increased, and an economical and advantageous design for manufacturing civil engineering structures and concrete secondary products becomes possible.

Claims

The scope of the claims

[1] A cement admixture comprising silica fume and fly ash classified to 20 μm or less, wherein the mixing ratio of silica fume: classified fly ash is 95: 5—10: 90 by mass. Wood.

[2] The cement admixture according to claim 1, further comprising gypsum.

[3] A cement composition comprising 1 to 35 parts by mass of the cement admixture according to claim 1 with respect to 100 parts by mass of cement.

[4] The cement composition according to claim 3, wherein 0.5 to 12 parts by mass of gypsum in terms of anhydride is further mixed with 100 parts by mass of the cement.

[5] A mortar obtained by mixing the cement composition according to claim 3 or 4, a fine aggregate, a water reducing agent, and mixing water.

[6] The relative mortar lm ^3, outer percentage at 1.0 to 6.0% by volume of metal fibers Ru claim 5 mortar according Na was added.

[7] A concrete obtained by mixing the cement composition according to claim 3 or 4, and fine aggregate, coarse aggregate, a water reducing agent, and mixing water.

[8] the relative concrete lm ^3, outer percentage by 1.0 to become the addition of 4.0% by volume of metal fibers according to claim 7, wherein the concrete.

[9] A cement hardened body obtained by hardening the mortar according to claim 5 or 6.

[10] A hardened cement body obtained by hardening the concrete according to claim 7 or 8.